Clinical Focus

  • Nuclear Medicine
  • PET-CT Molecular Imaging

Administrative Appointments

  • Professor, Department of Radiology and Bio-X Program (2003 - Present)
  • Director, Molecular Imaging Program at Stanford (MIPS) (2003 - Present)
  • Professor (By courtesy), Bioengineering (2005 - Present)
  • Director, Canary Center for Cancer Early Detection at Stanford (2009 - Present)
  • Professor (By courtesy), Materials Science & Engineering (2009 - Present)
  • Chair, Department of Radiology - Stanford University School of Medicine (2011 - Present)
  • Director, Precision Health & Integrated Diagnostics (PHIND) (2016 - Present)

Honors & Awards

  • Taplin Award, The Society of Nuclear Medicine (2002)
  • Holst Medal, Philips Corp and TU/e, Netherlands (2003)
  • Distinguished Basic Scientist of the Year Award, The Academy of Molecular Imaging (2004)
  • Distinguished Clinical Scientist Award, Doris Duke Charitable Foundation (2004)
  • SMI Achievement Award, The Society for Molecular Imaging (2004)
  • AMI Top Clinical Abstract Award, Academy of Molecular Imaging (2005)
  • SNM Image of the Year, Society of Nuclear Medicine (2005)
  • AIMBE Member, American Institute for Medical and Biological Engineering (2006)
  • Hounsfield Medal, Imperial College, London (2006)
  • Most Influential Radiology Researcher, Aunt Minnie (2006)
  • Paul C. Aebersold Award, Society of Nuclear Medicine (2006)
  • Best Clinical Article, Society of Nuclear Medicine (2007)
  • Best Essay Award, ACNP/Society of Nuclear Medicine (2007)
  • Co-Host, Nobel Symposium on Molecular Imaging, Nobel Committtee, Stockholm (2007)
  • ASCI member, American Society of Clinical Investigation - honor society for physicans/scientists. (2008)
  • IOM member, Institute of Medicine of the National Academies. (2008)
  • Tesla Medal, UK Royal College of Radiologists (2008)
  • Outstanding Researcher Award, Radiological Society of North America (RSNA) (2009)
  • Parmley Prize, American College of Cardiology Foundations (2009)
  • Stanford University Endowed Professorship, Virginia and D. K. Ludwig Professor for Clinical Investigation in Cancer Research (2009)
  • Georg Charles de Hevesy Nuclear Pioneer Award, Society of Nuclear Medicine (SNM) (2011)
  • Distinguished Scientist Award for Distinguished Contributions to Nuclear Medicine, 37th Annual Western Regional Meeting of the Society of Nuclear Medicine (SNM) (2012)
  • Society of Asian American Scientists in Cancer Research Award, The Society of Asian American Scientists in Cancer Research (2013)
  • AAAS Fellow, American Association for the Advancement of Science (2014)
  • AAISCR Lifetime Achievement Award, American Association of Indian Scientists in Cancer Research (AAISCR, Inc.) (2014)
  • J. Allyn Taylor International Prize in Medicine, The Robarts Research Institute (2015)
  • NAI Fellow, National Academy of Inventors (2016)

Boards, Advisory Committees, Professional Organizations

  • External Advisory Committee, Integrative Graduate Education and Research Traineeship (IGERT), Program Member, UT Austin (2004 - 2006)
  • External Advisory Committee, Network for Translational Research in Optical Imaging (NTRO1) Grant, University of Pennsylvania (2003 - 2003)
  • Consultant, Molecular Imaging/Bioengineering Program Development, UCSF (2007 - 2007)
  • Executive Advisory Committee, Medical Scientist Training Program (MSTP), UCLA (2000 - 2003)
  • Faculty Search Committees, UCLA (1998 - 2003)
  • Molecular & Medical Pharmacology Graduate Training Committee, UCLA (1997 - 2003)
  • Bioinformatics Committee on Faculty Recruitment, UCLA (2000 - 2003)
  • Faculty Tenure Review Committee, UCLA (2001 - 2001)
  • External Advisory Board, Department of Biomedical, UC Davis (2002 - 2006)
  • Stanford Medicine Campaign Advisory Committee, Stanford University (2012 - Present)
  • School of Medicine Dean’s Search Committee Co-, Stanford University (2011 - 2012)
  • MSTP Admissions Committee, Stanford University (2004 - 2006)
  • Faculty Search Committee, Chair Search, Dept. of Pathology, Stanford University (2015 - 2015)
  • Faculty Search Committee, Chair Search, Dept. of Radiation Oncology, Stanford University (2010 - 2010)
  • Faculty Search Committee, Division of Hematology/Oncology, Stanford University (2010 - 2010)
  • Faculty Search Committees, Department of Chemical Engineering, Stanford University (2006 - 2006)
  • Faculty Search Committees, Department of Bioengineering, Stanford University (2006 - 2008)
  • Faculty Search Committees, Department of Radiology, Stanford University (2004 - 2011)
  • Cancer Center Executive Committee, Stanford University (2004 - Present)
  • Canary Center Faculty Search Committee Chair, Stanford University (2009 - 2010)
  • Bio-X Graduate Fellowship Selection Committee, Stanford University (2005 - Present)
  • Bio-X Leadership Council, Stanford University (2004 - Present)
  • Advancements & Promotions Executive Committee, Department of Bioengineering, Stanford University (2006 - Present)
  • Positron Emission Tomography (PET) LLC Board, Stanford Hospital (2004 - Present)
  • Member, Society of Chairs of Academic Radiology Departments (SCARD) (2011 - Present)
  • Early Detection Initiative Committee, Oregon Health & Science University (2014 - Present)
  • External Advisory Board for Spatial Systems Biomedicine, Oregon Health & Science University (2011 - Present)
  • Molecular Imaging Database Committee, National Cancer Institute – MOLI (2002 - 2006)
  • Faculty Review, Memorial Sloan-Kettering Cancer Center (2002 - 2002)
  • External Advisory Board for NCI Grant, Memorial Sloan-Kettering Cancer Center (1998 - 1999)
  • External Advisory Board for R25T Training Grant, MITO Program, Memorial Sloan-Kettering Cancer Center (2001 - Present)
  • External Advisory Board, MoSAIC, Katholieke Universiteit (2008 - Present)
  • Executive Board Member, International Society For Strategic Studies in Radiology (2011 - 2013)
  • Advisory Board for Molecular Imaging for Cardiac Repair of Stem Cells, Instituto Superiore di Sanita Viale Regina Elena (2007 - 2007)
  • External Advisory Board for Molecular Genes and Radiation Therapies for Cancer Grant Research, Henry Ford Health System (2001 - 2005)
  • Advisory Committee, Harvard/Massachusetts General Hospital - Center for New Probe Develelopment (2017 - Present)
  • External Advisory Board, Center for BioMedical Imaging (CIBM) (2017 - Present)
  • Advisory Board, Asan Institute for Life Sciences (2009 - Present)
  • Diagnostic Imaging Committee, American College of Surgeons Oncology Group (2004 - 2006)

Professional Education

  • Fellowship:UCLA Medical Center (1996) CA
  • Residency:UCLA Medical Center (1995) CA
  • Internship:UCLA Medical Center (1994) CA
  • Ph.D., UCLA Medical Scientist Training Program, Biomathematics (1990)
  • M.D., UCLA, Medical Scientist Training Program (1993)
  • B.S., Arizona State University, Physics (1983)

Current Research and Scholarly Interests

My laboratory is developing imaging assays to monitor fundamental cellular/molecular events in living subjects including patients. Technologies such as positron emission tomography (PET), optical (fluorescence, bioluminescence, Raman), ultrasound, and photoacoustic imaging are all under active investigation.

Imaging agents for multiple modalities including small molecules, engineered proteins, and nanoparticles are under development and being clinically translated. Our goals are to detect cancer early and to better manage cancer through the use of both in vitro diagnostics and molecular imaging. Strategies are being tested in small animal models and are also clinically translated.

In the early detection setting we are exploring multiple strategies that are pushing the limits of the fewest numbers of detectable cancer cells. The goal is to intercept cancer early so that patient outcomes can be markedly improved.

For the management of cancer we are focused on using imaging to optimize stratification of cancer patients, predicting response to therapy, and monitoring response to therapy and recurrence. We are particularly interested in cell based therapies and immunotherapies where molecular imaging can help optimize these therapies.

When we are successful the role of cost-effective diagnostics in cancer will be markedly enhanced with better patient outcomes.

2016-17 Courses

Graduate and Fellowship Programs

  • Biomedical Informatics (Phd Program)

All Publications

  • A PET Imaging Strategy to Visualize Activated T Cells in Acute Graft-versus-Host Disease Elicited by Allogenic Hematopoietic Cell Transplant. Cancer research Ronald, J. A., Kim, B., Gowrishankar, G., Namavari, M., Alam, I. S., D'Souza, A., Nishikii, H., Chuang, H., Ilovich, O., Lin, C., Reeves, R., Shuhendler, A., Hoehne, A., Chan, C. T., Baker, J., Yaghoubi, S. S., VanBrocklin, H. F., Hawkins, R., Franc, B. L., Jivan, S., Slater, J. B., Verdin, E. F., Gao, K. T., Benjamin, J., Negrin, R., Gambhir, S. S. 2017; 77 (11): 2893-2902


    A major barrier to successful use of allogeneic hematopoietic cell transplantation is acute graft-versus-host disease (aGVHD), a devastating condition that arises when donor T cells attack host tissues. With current technologies, aGVHD diagnosis is typically made after end-organ injury and often requires invasive tests and tissue biopsies. This affects patient prognosis as treatments are dramatically less effective at late disease stages. Here, we show that a novel PET radiotracer, 2'-deoxy-2'-[18F]fluoro-9-β-D-arabinofuranosylguanine ([18F]F-AraG), targeted toward two salvage kinase pathways preferentially accumulates in activated primary T cells. [18F]F-AraG PET imaging of a murine aGVHD model enabled visualization of secondary lymphoid organs harboring activated donor T cells prior to clinical symptoms. Tracer biodistribution in healthy humans showed favorable kinetics. This new PET strategy has great potential for early aGVHD diagnosis, enabling timely treatments and improved patient outcomes. [18F]F-AraG may be useful for imaging activated T cells in various biomedical applications. Cancer Res; 77(11); 2893-902. ©2017 AACR.

    View details for DOI 10.1158/0008-5472.CAN-16-2953

    View details for PubMedID 28572504

  • F-FTC-146 in humans. Journal of nuclear medicine Hjørnevik, T., Cipriano, P. W., Shen, B., Hyung Park, J., Gulaka, P., Holley, D., Gandhi, H., Yoon, D., Mittra, E. S., Zaharchuk, G., Gambhir, S. S., McCurdy, C. R., Chin, F. T., Biswal, S. 2017


    The purpose of this study is to assess safety, biodistribution and radiation dosimetry in humans for the highly selective sigma-1 receptor (S1R) positron emission tomography (PET) agent (18)F-6-(3-fluoropropyl)-3-(2-(azepan-1-yl)ethyl)benzo[d]thiazol-2(3H)-one ((18)F-FTC-146). Methods: Ten healthy volunteers (HV; five female, five male; age: 34.3 ± 6.5 years) were recruited, and written informed consent was obtained from all participants. Series of whole-body PET/magnetic resonance imaging (PET/MRI) examinations were acquired for up to three hours after injection (357.2 ± 48.8 MBq). Blood samples were collected and standard vital signs (heart rate, pulse oximetry, and body temperature) were monitored at regular intervals. Regions-of-interest were delineated, time-activity curves were calculated, and organ uptake and dosimetry was estimated using PMOD 3.7 and Organ Linear Internal Dose Assessment (OLINDA). Results: All subjects tolerated the PET/MRI examination well, and no adverse reactions to (18)F-FTC-146 were reported. High accumulation of (18)F-FTC-146 was observed in S1R dense organs such as the pancreas and spleen, moderate uptake in the brain and myocardium, and low uptake in bone and muscle. High uptake was also observed in the kidneys and bladder, indicating renal tracer clearance. The effective dose (ED) of (18)F-FTC-146 was 0.0259 ± 0.0034 mSv/MBq (range: 0.0215-0.0301 mSv/MBq). Conclusion: First-in-human studies with clinical-grade (18)F-FTC-146 were successful. Injection of (18)F-FTC-146 is safe, and absorbed doses are acceptable. The potential of (18)F-FTC-146 as an imaging agent for a variety of neuroinflammatory diseases is currently under investigation.

    View details for DOI 10.2967/jnumed.117.192641

    View details for PubMedID 28572487

  • A Model-Based Personalized Cancer Screening Strategy for Detecting Early-Stage Tumors Using Blood-Borne Biomarkers CANCER RESEARCH Hori, S. S., Lutz, A. M., Paulmurugan, R., Gambhir, S. S. 2017; 77 (10): 2570-2584


    An effective cancer blood biomarker screening strategy must distinguish aggressive from non-aggressive tumors at an early, intervenable time. However, for blood-based strategies to be useful, the quality and quantiy of the biomarker shed into the blood and its relationship to tumor growth or progression must be validated. To study how blood biomarker levels correlate with early-stage viable tumor growth in an mouse model of human cancer, we monitored early tumor growth of engineered human ovarian cancer cells (A2780) implanted orthotopically into nude mice. Biomarker shedding was monitored by serial blood sampling, while tumor viability and volume was monitored by bioluminescence imaging and ultrasound imaging. From these metrics we developed a mathematical model of cancer biomarker kinetics in different compartments that accounts for biomarker shedding from tumor and healthy cells, biomarker entry into vasculature, biomarker elimination from plasma and subject-specific tumor growth. We validated the model in a separate set of mice where subject-specific tumor growth rates were accurately predicted. To illustrate clinical translation of this strategy, we allometrically scaled model parameters from mouse to human and used parameters for PSA shedding and prostate cancer. In this manner, we found that blood biomarker sampling data alone was capable of enabling the detection and discrimination of simulated aggressive (2-month tumor doubling time) and non-aggressive (18-month tumor doubling time) tumors as early as 7.2 months and 8.9 years before clinical imaging, respectively. Our model and screening strategy offer broad impact in their applicability to any solid cancer and the biomarkers they shed, thereby allowing a distinction between aggressive vs. non-aggressive tumors using blood biomarker sampling data alone.

    View details for DOI 10.1158/0008-5472.CAN-16-2904

    View details for Web of Science ID 000401252900003

    View details for PubMedID 28283654

  • F-Fluoromaltotriose: A Second Generation PET Tracer Targeting the Maltodextrin Transporter in Bacteria. Journal of nuclear medicine Gowrishankar, G., Hardy, J., Wardak, M., Namavari, M., Reeves, R., Neofytou, E., Srinivasan, A., Wu, J., Contag, C., Gambhir, S. 2017


    Purpose: 6"-(18)F-fluoromaltotriose is a novel positron emission tomography (PET) tracer that can potentially be used to image and localize most bacterial infections, much like 2-deoxy-2-(18)F-fluoro-D-glucose ((18)F-FDG) has been used to image and localize many cancers. However, unlike (18)F-FDG, 6"-(18)F-fluoromaltotriose is not taken up by inflammatory lesions and appears to be specific to bacterial infections by targeting the maltodextrin transporter that is expressed in most Gram-positive and Gram-negative strains of bacteria. Materials and Methods: 6"-(18)F-fluoromaltotriose was synthesized with high radiochemical purity and evaluated in several clinically relevant bacterial strains incultures in vitro and in living mice. Results: 6"-(18)F-fluoromaltotriose was taken up in both Gram-positive and Gram-negative bacterial strains. 6"-[(18)F]-fluoromaltotriose was also able to detect Pseudomonas aeruginosa in a clinically relevant mouse model of wound infection. The utility of 6"-(18)F-fluoromaltotriose to help monitor antibiotic therapies was also evaluated in rats. Conclusion: 6"-(18)F-fluoromaltotriose is a promising new tracer that has significant diagnostic utility, with the potential to change the clinical management of patients suffering from infectious diseases of bacterial origin.

    View details for DOI 10.2967/jnumed.117.191452

    View details for PubMedID 28490473

  • Regulatory Aspects of Optical Methods and Exogenous Targets for Cancer Detection CANCER RESEARCH Tummers, W. S., Warram, J. M., Tipirneni, K. E., Fengler, J., Jacobs, P., Shankar, L., Henderson, L., Ballard, B., Pogue, B. W., Weichert, J. P., Bouvet, M., Sorger, J., Contag, C. H., Frangioni, J. V., Tweedle, M. F., Basilion, J. P., Gambhir, S. S., Rosenthal, E. L. 2017; 77 (9): 2197-2206


    Considerable advances in cancer-specific optical imaging have improved the precision of tumor resection. In comparison to traditional imaging modalities, this technology is unique in its ability to provide real-time feedback to the operating surgeon. Given the significant clinical implications of optical imaging, there is an urgent need to standardize surgical navigation tools and contrast agents to facilitate swift regulatory approval. Because fluorescence-enhanced surgery requires a combination of both device and drug, each may be developed in conjunction, or separately, which are important considerations in the approval process. This report is the result of a one-day meeting held on May 4, 2016 with officials from the National Cancer Institute, the FDA, members of the American Society of Image-Guided Surgery, and members of the World Molecular Imaging Society, which discussed consensus methods for FDA-directed human testing and approval of investigational optical imaging devices as well as contrast agents for surgical applications. The goal of this workshop was to discuss FDA approval requirements and the expectations for approval of these novel drugs and devices, packaged separately or in combination, within the context of optical surgical navigation. In addition, the workshop acted to provide clarity to the research community on data collection and trial design. Reported here are the specific discussion items and recommendations from this critical and timely meeting. Cancer Res; 77(9); 2197-206. ©2017 AACR.

    View details for DOI 10.1158/0008-5472.CAN-16-3217

    View details for Web of Science ID 000400270100004

    View details for PubMedID 28428283

  • Ultrasound Molecular Imaging With BR55 in Patients With Breast and Ovarian Lesions: First-in-Human Results. Journal of clinical oncology Willmann, J. K., Bonomo, L., Carla Testa, A., Rinaldi, P., Rindi, G., Valluru, K. S., Petrone, G., Martini, M., Lutz, A. M., Gambhir, S. S. 2017: JCO2016708594-?


    Purpose We performed a first-in-human clinical trial on ultrasound molecular imaging (USMI) in patients with breast and ovarian lesions using a clinical-grade contrast agent (kinase insert domain receptor [KDR] -targeted contrast microbubble [MBKDR]) that is targeted at the KDR, one of the key regulators of neoangiogenesis in cancer. The aim of this study was to assess whether USMI using MBKDR is safe and allows assessment of KDR expression using immunohistochemistry (IHC) as the gold standard. Methods Twenty-four women (age 48 to 79 years) with focal ovarian lesions and 21 women (age 34 to 66 years) with focal breast lesions were injected intravenously with MBKDR (0.03 to 0.08 mL/kg of body weight), and USMI of the lesions was performed starting 5 minutes after injection up to 29 minutes. Blood pressure, ECG, oxygen levels, heart rate, CBC, and metabolic panel were obtained before and after MBKDR administration. Persistent focal MBKDR binding on USMI was assessed. Patients underwent surgical resection of the target lesions, and tissues were stained for CD31 and KDR by IHC. Results USMI with MBKDR was well tolerated by all patients without safety concerns. Among the 40 patients included in the analysis, KDR expression on IHC matched well with imaging signal on USMI in 93% of breast and 85% of ovarian malignant lesions. Strong KDR-targeted USMI signal was present in 77% of malignant ovarian lesions, with no targeted signal seen in 78% of benign ovarian lesions. Similarly, strong targeted signal was seen in 93% of malignant breast lesions with no targeted signal present in 67% of benign breast lesions. Conclusion USMI with MBKDR is clinically feasible and safe, and KDR-targeted USMI signal matches well with KDR expression on IHC. This study lays the foundation for a new field of clinical USMI in cancer.

    View details for DOI 10.1200/JCO.2016.70.8594

    View details for PubMedID 28291391

  • F]FTC-146. Molecular imaging and biology Shen, B., Park, J. H., Hjørnevik, T., Cipriano, P. W., Yoon, D., Gulaka, P. K., Holly, D., Behera, D., Avery, B. A., Gambhir, S. S., McCurdy, C. R., Biswal, S., Chin, F. T. 2017


    Sigma-1 receptors (S1Rs) play an important role in many neurological disorders. Simultaneous positron emission tomography (PET)/magnetic resonance imaging (MRI) with S1R radioligands may provide valuable information for diagnosing and guiding treatment for these diseases. Our previously reported S1R radioligand, [(18)F]FTC-146, demonstrated high affinity for the S1R (K i = 0.0025 nM) and excellent selectivity for the S1R over the sigma-2 receptor (S2Rs; K i = 364 nM) across several species (from mouse to non-human primate). Herein, we report the clinical-grade radiochemistry filed with exploratory Investigational New Drug (eIND) and first-in-human PET/MRI evaluation of [(18)F]FTC-146.[(18)F]FTC-146 is prepared via a direct [(18)F] fluoride nucleophilic radiolabeling reaction and formulated in 0.9 % NaCl containing no more than 10 % ethanol through sterile filtration. Quality control (QC) was performed based on USP 823 before doses were released for clinical use. The safety and whole body biodistribution of [(18)F]FTC-146 were evaluated using a simultaneous PET/MR scanner in two representative healthy human subjects.[(18)F]FTC-146 was synthesized with a radiochemical yield of 3.3 ± 0.7 % and specific radioactivity of 8.3 ± 3.3 Ci/μmol (n = 10, decay corrected to EOB). Both radiochemical and chemical purities were >95 %; the prepared doses were stable for 4 h at ambient temperature. All QC test results met specified clinical criteria. The in vivo PET/MRI investigations showed that [(18)F]FTC-146 rapidly crossed the blood brain barrier and accumulated in S1R-rich regions of the brain. There were also radioactivity distributed in the peripheral organs, i.e., the lungs, spleen, pancreas, and thyroid. Furthermore, insignificant uptake of [(18)F]FTC-146 was observed in cortical bone and muscle.A reliable and automated radiosynthesis for providing routine clinical-grade [(18)F]FTC-146 for human studies was established in a modified GE TRACERlab FXFN. PET/MRI demonstrated the initial tracer biodistribution in humans, and clinical studies investigating different S1R-related diseases are in progress.

    View details for DOI 10.1007/s11307-017-1064-z

    View details for PubMedID 28280965

  • Development of Novel ImmunoPET Tracers to Image Human PD-1 Checkpoint Expression on Tumor-Infiltrating Lymphocytes in a Humanized Mouse Model. Molecular imaging and biology Natarajan, A., Mayer, A. T., Reeves, R. E., Nagamine, C. M., Gambhir, S. S. 2017


    It is well known that cancers exploit immune checkpoints (programmed death 1 receptor (PD-1) and its ligand (PD-L1)) to evade anti-tumor immune responses. Although immune checkpoint (IC) blockade is a promising approach, not all patients respond. Hence, imaging of tumor-infiltrating lymphocytes (TILs) is of high specific interest, as they are known to express PD-1 during activation and subsequent exhaustion in the tumor microenvironment and are thought to be potentially predictive of therapeutic responses to IC blockade.We developed immune-tracers for positron emission tomography (PET) to image hPD-1 status of human peripheral blood mononuclear cells (hPBMCs) adoptively transferred to NOD-scid IL-2Rγ(null) (NSG) mice (hNSG) bearing A375 human skin melanoma tumors. The anti-PD-1 human antibody (IgG; keytruda) was labeled with either Zr-89 or Cu-64 radiometals to image PD-1-expressing human TILs in vivo.[(89)Zr] Keytruda (groups = 2; NSG-ctl (control) and hNSG-nblk (non-blocking), n = 3-5, 3.2 ± 0.4 MBq/15-16 μg/200 μl) and [(64)Cu] Keytruda (groups = 3; NSG-ctl, NSG-blk (blocking), and hNSG-nblk; n = 4, 7.4 ± 0.4 MBq /20-25 μg/200 μl) were administered in mice. PET-CT scans were performed over 1-144 h ([(89)Zr] Keytruda) and 1-48 h ([(64)Cu] Keytruda) on mice. hNSG mice exhibited a high tracer uptake in the spleen, lymphoid organs and tumors. At 24 h, human TILs homing into melanoma of hNSG-nblk mice exhibited high signal (mean %ID/g ± SD) of 3.8 ± 0.4 ([(89)Zr] Keytruda), and 6.4 ± 0.7 ([(64)Cu] Keytruda), which was 1.5- and 3-fold higher uptake compared to NSG-ctl mice (p = 0.01), respectively. Biodistribution measurements of hNSG-nblk mice performed at 144 h ([(89)Zr] Keytruda) and 48 h ([(64)Cu] Keytruda) p.i. revealed tumor to muscle ratios as high as 45- and 12-fold, respectively.Our immunoPET study clearly demonstrates specific imaging of human PD-1-expressing TILs within the tumor and lymphoid tissues. This suggests these anti-human-PD-1 tracers could be clinically translatable to monitor cancer treatment response to IC blockade therapy.

    View details for DOI 10.1007/s11307-017-1060-3

    View details for PubMedID 28247187

  • F]DASA-23 for Imaging Tumor Glycolysis Through Noninvasive Measurement of Pyruvate Kinase M2. Molecular imaging and biology Beinat, C., Alam, I. S., James, M. L., Srinivasan, A., Gambhir, S. S. 2017


    A hallmark of cancer is metabolic reprogramming, which is exploited by cancer cells to ensure rapid growth and survival. Pyruvate kinase M2 (PKM2) catalyzes the final step in glycolysis, a key step in tumor metabolism and growth. Recently, we reported the radiosynthesis of the first positron emission tomography tracer for visualizing PKM2 in vivo-i.e., [(11)C]DASA-23. Due to the highly promising imaging results obtained with [(11)C]DASA-23 in rodent model glioblastoma, we set out to generate an F-18-labeled version of this tracer, with the end goal of clinical translation in mind. Herein, we report the radiosynthesis of 1-((2-fluoro-6-[(18)F]fluorophenyl)sulfonyl)-4-((4-methoxyphenyl)sulfonyl)piperazine ([(18)F]DASA-23) and our initial investigation of its binding properties in cancer cells.We synthesized [(18)F]DASA-23 via fluorination of 1-((2-fluoro-6-nitrophenyl)sulfonyl)-4-((4-methoxyphenyl)sulfonyl)piperazine (10) with K[(18)F]F/K2.2.2 in N,N-dimethylformamide at 110 °C for 20 min. Subsequently, we evaluated uptake of [(18)F]DASA-23 in HeLa cervical adenocarcinoma cells and in vitro stability in human and mouse serum.We successfully prepared [(18)F]DASA-23 in 2.61 ± 1.54 % radiochemical yield (n = 10, non-decay corrected at end of synthesis) with a specific activity of 2.59 ± 0.44 Ci/μmol. Preliminary cell uptake experiments revealed high uptake in HeLa cells, which was effectively blocked by pretreating cells with the structurally distinct PKM2 activator, TEPP-46. [(18)F]DASA-23 remained intact in human and mouse serum up to 120 min.Herein, we have identified a F-18-labeled PKM2 specific radiotracer which shows potential for in vivo imaging. The promising cell uptake results reported herein warrant the further evaluation of [(18)F]DASA-23 for its ability to detect and monitor cancer noninvasively.

    View details for DOI 10.1007/s11307-017-1068-8

    View details for PubMedID 28236227

  • Nanomaterials for In Vivo Imaging. Chemical reviews Smith, B. R., Gambhir, S. S. 2017; 117 (3): 901-986


    In vivo imaging, which enables us to peer deeply within living subjects, is producing tremendous opportunities both for clinical diagnostics and as a research tool. Contrast material is often required to clearly visualize the functional architecture of physiological structures. Recent advances in nanomaterials are becoming pivotal to generate the high-resolution, high-contrast images needed for accurate, precision diagnostics. Nanomaterials are playing major roles in imaging by delivering large imaging payloads, yielding improved sensitivity, multiplexing capacity, and modularity of design. Indeed, for several imaging modalities, nanomaterials are now not simply ancillary contrast entities, but are instead the original and sole source of image signal that make possible the modality's existence. We address the physicochemical makeup/design of nanomaterials through the lens of the physical properties that produce contrast signal for the cognate imaging modality-we stratify nanomaterials on the basis of their (i) magnetic, (ii) optical, (iii) acoustic, and/or (iv) nuclear properties. We evaluate them for their ability to provide relevant information under preclinical and clinical circumstances, their in vivo safety profiles (which are being incorporated into their chemical design), their modularity in being fused to create multimodal nanomaterials (spanning multiple different physical imaging modalities and therapeutic/theranostic capabilities), their key properties, and critically their likelihood to be clinically translated.

    View details for DOI 10.1021/acs.chemrev.6b00073

    View details for PubMedID 28045253

  • Detection of Stem Cell Transplant Rejection with Ferumoxytol MR Imaging: Correlation of MR Imaging Findings with Those at Intravital Microscopy. Radiology Daldrup-Link, H. E., Chan, C., Lenkov, O., Taghavigarmestani, S., Nazekati, T., Nejadnik, H., Chapelin, F., Khurana, A., Tong, X., Yang, F., Pisani, L., Longaker, M., Gambhir, S. S. 2017: 161139-?


    Purpose To determine whether endogenous labeling of macrophages with clinically applicable nanoparticles enables noninvasive detection of innate immune responses to stem cell transplants with magnetic resonance (MR) imaging. Materials and Methods Work with human stem cells was approved by the institutional review board and the stem cell research oversight committee, and animal experiments were approved by the administrative panel on laboratory animal care. Nine immunocompetent Sprague-Dawley rats received intravenous injection of ferumoxytol, and 18 Jax C57BL/6-Tg (Csf1r-EGFP-NGFR/FKBP1A/TNFRSF6) 2Bck/J mice received rhodamine-conjugated ferumoxytol. Then, 48 hours later, immune-matched or mismatched stem cells were implanted into osteochondral defects of the knee joints of experimental rats and calvarial defects of Jax mice. All animals underwent serial MR imaging and intravital microscopy (IVM) up to 4 weeks after surgery. Macrophages of Jax C57BL/6-Tg (Csf1r-EGFP-NGFR/FKBP1A/TNFRSF6) 2Bck/J mice express enhanced green fluorescent protein (GFP), which enables in vivo correlation of ferumoxytol enhancement at MR imaging with macrophage quantities at IVM. All quantitative data were compared between experimental groups by using a mixed linear model and t tests. Results Immune-mismatched stem cell implants demonstrated stronger ferumoxytol enhancement than did matched stem cell implants. At 4 weeks, T2 values of mismatched implants were significantly lower than those of matched implants in osteochondral defects of female rats (mean, 10.72 msec for human stem cells and 11.55 msec for male rat stem cells vs 15.45 msec for sex-matched rat stem cells; P = .02 and P = .04, respectively) and calvarial defects of recipient mice (mean, 21.7 msec vs 27.1 msec, respectively; P = .0444). This corresponded to increased recruitment of enhanced GFP- and rhodamine-ferumoxytol-positive macrophages into stem cell transplants, as visualized with IVM and histopathologic examination. Conclusion Endogenous labeling of macrophages with ferumoxytol enables noninvasive detection of innate immune responses to stem cell transplants with MR imaging. (©) RSNA, 2017 Online supplemental material is available for this article.

    View details for DOI 10.1148/radiol.2017161139

    View details for PubMedID 28128708

  • Reporter gene imaging of targeted T cell immunotherapy in recurrent glioma. Science translational medicine Keu, K. V., Witney, T. H., Yaghoubi, S., Rosenberg, J., Kurien, A., Magnusson, R., Williams, J., Habte, F., Wagner, J. R., Forman, S., Brown, C., Allen-Auerbach, M., Czernin, J., Tang, W., Jensen, M. C., Badie, B., Gambhir, S. S. 2017; 9 (373)


    High-grade gliomas are aggressive cancers that often become rapidly fatal. Immunotherapy using CD8(+) cytotoxic T lymphocytes (CTLs), engineered to express both herpes simplex virus type 1 thymidine kinase (HSV1-TK) and interleukin-13 (IL-13) zetakine chimeric antigen receptor (CAR), is a treatment strategy with considerable potential. To optimize this and related immunotherapies, it would be helpful to monitor CTL viability and trafficking to glioma cells. We show that noninvasive positron emission tomography (PET) imaging with 9-[4-[(18)F]fluoro-3-(hydroxymethyl)butyl]guanine ([(18)F]FHBG) can track HSV1-tk reporter gene expression present in CAR-engineered CTLs. [(18)F]FHBG imaging was safe and enabled the longitudinal imaging of T cells stably transfected with a PET reporter gene in patients. Further optimization of this imaging approach for monitoring in vivo cell trafficking should greatly benefit various cell-based therapies for cancer.

    View details for DOI 10.1126/scitranslmed.aag2196

    View details for PubMedID 28100832

    View details for PubMedCentralID PMC5260938

  • 18F-FDG silicon photomultiplier PET/CT: A pilot study comparing semi-quantitative measurements with standard PET/CT. PloS one Baratto, L., Park, S. Y., Hatami, N., Davidzon, G., Srinivas, S., Gambhir, S. S., Iagaru, A. 2017; 12 (6)


    To evaluate if the new Discovery Molecular Insights (DMI) PET/CT scanner provides equivalent results compared to the standard of care PET/CT scanners (GE Discovery 600 or GE Discovery 690) used in our clinic and to explore any possible differences in semi-quantitative measurements.The local Institutional Review Board approved the protocol and written informed consent was obtained from each patient. Between September and November 2016, 50 patients underwent a single 18F-FDG injection and two scans: the clinical standard PET/CT followed immediately by the DMI PET/CT scan. We measured SUVmax and SUVmean of different background organs and up to four lesions per patient from data acquired using both scanners.DMI PET/CT identified all the 107 lesions detected by standard PET/CT scanners, as well as additional 37 areas of focal increased 18F-FDG uptake. The SUVmax values for all 107 lesions ranged 1.2 to 14.6 (mean ± SD: 2.8 ± 2.8), higher on DMI PET/CT compared with standard of care PET/CT. The mean lesion:aortic arch SUVmax ratio and mean lesion:liver SUVmax ratio were 0.2-15.2 (mean ± SD: 3.2 ± 2.6) and 0.2-8.5 (mean ± SD: 1.9 ± 1.4) respectively, higher on DMI PET/CT than standard PET/CT. These differences were statistically significant (P value < 0.0001) and not correlated to the delay in acquisition of DMI PET data (P < 0.0001).Our study shows high performance of the new DMI PET/CT scanner. This may have a significant role in diagnosing and staging disease, as well as for assessing and monitoring responses to therapies.

    View details for DOI 10.1371/journal.pone.0178936

    View details for PubMedID 28582472

  • Withaferin A and its potential role in glioblastoma (GBM) JOURNAL OF NEURO-ONCOLOGY Dhami, J., Chang, E., Gambhir, S. S. 2017; 131 (2): 201-211


    Within the Ayurvedic medical tradition of India, Ashwagandha (Withania somnifera) is a well-known herb. A large number of withanolides have been isolated from both its roots and its leaves and many have been assessed for their pharmacological activities. Amongst them, Withaferin A is one of its most bioactive phytoconstituents. Due to the lactonal steroid's potential to modulate multiple oncogenic pathways, Withaferin A has gained much attention as a possible anti-neoplastic agent. This review focuses on the use of Withaferin A alone, or in combination with other treatments, as a newer option for therapy against the most aggressive variant of brain tumors, Glioblastoma. We survey the various studies that delineate Withaferin A's anticancer mechanisms, its toxicity profiles, its pharmacokinetics and pharmacodynamics and its immuno-modulating properties.

    View details for DOI 10.1007/s11060-016-2303-x

    View details for Web of Science ID 000394342500001

    View details for PubMedID 27837436

  • Synergistic inhibition of glioma cell proliferation by Withaferin A and tumor treating fields. Journal of neuro-oncology Chang, E., Pohling, C., Beygui, N., Patel, C. B., Rosenberg, J., Ha, D. H., Gambhir, S. S. 2017


    Glioblastoma (GBM) is the most aggressive and lethal form of brain cancer. Standard therapies are non-specific and often of limited effectiveness; thus, efforts are underway to uncover novel, unorthodox therapies against GBM. In previous studies, we investigated Withaferin A, a steroidal lactone from Ayurvedic medicine that inhibits proliferation in cancers including GBM. Another novel approach, tumor treating fields (TTFields), is thought to disrupt mitotic spindle formation and stymie proliferation of actively dividing cells. We hypothesized that combining TTFields with Withaferin A would synergistically inhibit proliferation in glioblastoma. Human glioblastoma cells (GBM2, GBM39, U87-MG) and human breast adenocarcinoma cells (MDA-MB-231) were isolated from primary tumors. The glioma cell lines were genetically engineered to express firefly luciferase. Proliferative potential was assessed either by bioluminescence imaging or cell counting via hemocytometer. TTFields (4 V/cm) significantly inhibited growth of the four cancer cell lines tested (n = 3 experiments per time point, four measurements per sample, p < 0.02 at least; 2-way ANOVA, control vs. treatment). The combination of Withaferin A (10-100 nM) with TTFields significantly inhibited the growth of the glioma cells to a degree beyond that of Withaferin A or TTFields alone. The interaction of the Withaferin A and TTFields on glioma cells was found to be synergistic in nature (p < 0.01, n = 3 experiments). These findings were validated by both bioluminescence and hemocytometric measurements. The combination of Withaferin A with TTFields represents a novel approach to treat GBM in a manner that is likely better than either treatment alone and that is synergistic.

    View details for DOI 10.1007/s11060-017-2534-5

    View details for PubMedID 28681243

  • A novel theranostic strategy for MMP-14 expressing glioblastomas impacts survival. Molecular cancer therapeutics Mohanty, S., Chen, Z., Li, K., Morais, G. R., Klockow, J., Yerneni, K., Pisani, L., Chin, F. T., Mitra, S., Cheshier, S., Chang, E., Gambhir, S. S., Rao, J., Loadman, P. M., Falconer, R. A., Daldrup-Link, H. E. 2017


    Glioblastoma (GBM) has a dismal prognosis. Evidence from preclinical tumor models and human trials indicates the role of GBM initiating cells (GIC) in GBM drug resistance. Here, we propose a new treatment option with tumor enzyme-activatable, combined therapeutic and diagnostic (theranostic) nanoparticles, which caused specific toxicity against GBM tumor cells and GICs. The theranostic cross-linked iron oxide nanoparticles (CLIO) were conjugated to a highly potent vascular disrupting agent (ICT) and secured with a matrix-metalloproteinase (MMP-14) cleavable peptide. Treatment with CLIO-ICT disrupted tumor vasculature of MMP-14 expressing GBM, induced GIC apoptosis and significantly impaired tumor growth. In addition, the iron core of CLIO-ICT enabled in vivo drug tracking with MR imaging. Treatment with CLIO-ICT plus temozolomide achieved tumor remission and significantly increased survival of human GBM bearing mice by more than 2 fold compared to treatment with temozolomide alone. Thus, we present a novel therapeutic strategy with significant impact on survival and great potential for clinical translation.

    View details for DOI 10.1158/1535-7163.MCT-17-0022

    View details for PubMedID 28659432

  • Imaging B cells in a mouse model of multiple sclerosis using (64)Cu-Rituximab-PET. Journal of nuclear medicine : official publication, Society of Nuclear Medicine James, M. L., Hoehne, A., Mayer, A. T., Lechtenberg, K., Moreno, M., Gowrishankar, G., Ilovich, O., Natarajan, A., Johnson, E. M., Nguyen, J., Quach, L., Han, M., Buckwalter, M., Chandra, S., Gambhir, S. S. 2017


    B lymphocytes are a key pathological feature of multiple sclerosis (MS), and are becoming an important therapeutic target for this condition. Currently, there is no approved technique to non-invasively visualize B cells in the central nervous system (CNS) to monitor MS disease progression and response to therapies. Here we evaluated (64)Cu-Rituximab, a radiolabeled antibody specifically targeting the human B cell marker CD20, for its ability to image B cells in a mouse model of MS using positron emission tomography (PET). Methods: To model CNS infiltration by B cells, experimental autoimmune encephalomyelitis (EAE) was induced in transgenic mice that express human CD20 on B cells. EAE mice were given subcutaneous injections of Myelin Oligodendrocyte Glycoprotein fragment1-125 (MOG1-125) emulsified in complete Freund's adjuvant. Control mice received complete Freund's adjuvant alone. PET imaging of EAE and control mice was performed 1, 4, and 19h following (64)Cu-Rituximab administration. Mice were perfused and sacrificed after final PET scan, and radioactivity in dissected tissues was measured with a gamma-counter. CNS tissues from these mice were immunostained to quantify B cells or further analyzed via digital autoradiography. Results: Lumbar spinal cord PET signal was significantly higher in EAE mice compared to controls at all evaluated time points (e.g., 1h post-injection: 5.44 ± 0.37 vs. 3.33 ± 0.20 %ID/g, p<0.05). (64)Cu-Rituximab-PET signal in brain regions ranged between 1.74 ± 0.11 and 2.93 ± 0.15 %ID/g for EAE mice compared to 1.25±0.08 and 2.24±0.11%ID/g for controls, p<0.05 for all regions except striatum and thalamus at 1h post-injection. Similarly, ex vivo biodistribution results revealed notably higher (64)Cu-Rituximab uptake in brain and spinal cord of huCD20tg EAE, and B220 immunostaining verified that increased (64)Cu-Rituximab uptake in CNS tissues corresponded with elevated B cells. Conclusion: B cells can be detected in the CNS of EAE mice using (64)Cu-Rituximab-PET. Results from these studies warrant further investigation of (64)Cu-Rituximab in EAE models and consideration of use in MS patients to evaluate its potential for detecting and monitoring B cells in the progression and treatment of this disease. These results represent an initial step toward generating a platform to evaluate B cell-targeted therapeutics en route to the clinic.

    View details for DOI 10.2967/jnumed.117.189597

    View details for PubMedID 28687602

  • Engineering Intracellularly Retained Gaussia Luciferase Reporters for Improved Biosensing and Molecular Imaging Applications. ACS chemical biology Gaur, S., Bhargava-Shah, A., Hori, S., Afjei, R., Sekar, T. V., Gambhir, S. S., Massoud, T. F., Paulmurugan, R. 2017


    Gaussia luciferase (GLUC) is a bioluminescent reporter protein of increasing importance. As a secretory protein, it has increased sensitivity in vitro and in vivo (∼20 000-fold, and ∼1000-fold, respectively) over its competitor, secreted alkaline phosphatase. Unfortunately, this same advantageous secretory nature of GLUC limits its usefulness for many other possible intracellular applications, e.g., imaging signaling pathways in intact cells, in vivo imaging, and in developing molecular imaging biosensors to study protein-protein interactions and protein folding. Hence, to widen the research applications of GLUC, we developed engineered variants that increase its intracellular retention both by modifying the N-terminal secretory signal peptide and by tagging additional sequences to its C-terminal region. We found that when GLUC was expressed in mammalian cells, its N-terminal secretory signal peptide comprising amino acids 1-16 was essential for GLUC folding and functional activity in addition to its inherent secretory property. Modification of the C-terminus of GLUC by tagging a four amino acid (KDEL) endoplasmic reticulum targeting peptide in multiple repeats significantly improved its intracellular retention, with little impact on its folding and enzymatic activity. We used stable cells expressing this engineered GLUC with KDEL repeats to monitor chemically induced endoplasmic reticulum stress on cells. Additionally, we engineered an apoptotic sensor using modified variants of GLUC containing a four amino acid caspase substrate peptide (DEVD) between the GLUC protein and the KDEL repeats. Its use in cell culture resulted in increased GLUC secretion in the growth medium when cells were treated with the chemotherapeutic drugs doxorubicin, paclitaxel, and carboplatin. We thus successfully engineered a new variant GLUC protein that is retained inside cells rather than secreted extracellularly. We validated this novel reporter by incorporating it in biosensors for detection of cellular endoplasmic reticulum stress and caspase activation. This new molecularly engineered enzymatic reporter has the potential for widespread applications in biological research.

    View details for DOI 10.1021/acschembio.7b00454

    View details for PubMedID 28767220

  • Multigene profiling of single circulating tumor cells. Molecular & cellular oncology Park, S., Wong, D. J., Ooi, C. C., Nesvet, J. C., Nair, V. S., Wang, S. X., Gambhir, S. S. 2017; 4 (2)


    Numerous techniques for isolating circulating tumor cells (CTCs) have been developed. Concurrently, single-cell techniques that can reveal molecular components of CTCs have become widely available. We discuss how the combination of isolation and multigene profiling of single CTCs in our platform can facilitate eventual translation to the clinic.

    View details for DOI 10.1080/23723556.2017.1289295

    View details for PubMedID 28401190

    View details for PubMedCentralID PMC5383366

  • Cancer Diagnostics: On-target Probes for Early Detection Nature Biomedical Engineering Hori, S. S., Willemieke, S., Tummers, S., Gambhir, S. S. 2017; 1 (0062): 1-3
  • [F-18]GE-180 PET Detects Reduced Microglia Activation After LM11A-31 Therapy in a Mouse Model of Alzheimer's Disease THERANOSTICS James, M. L., Belichenko, N. P., Shuhendler, A. J., Hoehne, A., Andrews, L. E., Condon, C., Nguyen, T. V., Reiser, V., Jones, P., Trigg, W., Rao, J., Gambhir, S. S., Longo, F. M. 2017; 7 (6): 1422-1436


    Microglial activation is a key pathological feature of Alzheimer's disease (AD). PET imaging of translocator protein 18 kDa (TSPO) is a strategy to detect microglial activation in vivo. Here we assessed flutriciclamide ([(18)F]GE-180), a new second-generation TSPO-PET radiotracer, for its ability to monitor response to LM11A-31, a novel AD therapeutic in clinical trials. AD mice displaying pathology were treated orally with LM11A-31 for 3 months. Subsequent [(18)F]GE-180-PET imaging revealed significantly lower signal in cortex and hippocampus of LM11A-31-treated AD mice compared to those treated with vehicle, corresponding with decreased levels of TSPO immunostaining and microglial Iba1 immunostaining. In addition to detecting decreased microglial activation following LM11A-31 treatment, [(18)F]GE-180 identified activated microglia in AD mice with greater sensitivity than another second-generation TSPO radiotracer, [(18)F]PBR06. Together, these data demonstrate the promise of [(18)F]GE-180 as a potentially sensitive tool for tracking neuroinflammation in AD mice and for monitoring therapeutic modulation of microglial activation.

    View details for DOI 10.7150/thno.17666

    View details for Web of Science ID 000398783200002

    View details for PubMedID 28529627

    View details for PubMedCentralID PMC5436503

  • Molecular profiling of single circulating tumor cells from lung cancer patients PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Park, S., Wong, D. J., Ooi, C. C., Kurtz, D. M., Vermesh, O., Aalipour, A., Suh, S., Pian, K. L., Chabon, J. J., Lee, S. H., Jamali, M., Say, C., Carter, J. N., Lee, L. P., Kuschner, W. G., Schwartz, E. J., Shrager, J. B., Neal, J. W., Wakelee, H. A., Diehn, M., Nair, V. S., Wang, S. X., Gambhir, S. S. 2016; 113 (52): E8379-E8386


    Circulating tumor cells (CTCs) are established cancer biomarkers for the "liquid biopsy" of tumors. Molecular analysis of single CTCs, which recapitulate primary and metastatic tumor biology, remains challenging because current platforms have limited throughput, are expensive, and are not easily translatable to the clinic. Here, we report a massively parallel, multigene-profiling nanoplatform to compartmentalize and analyze hundreds of single CTCs. After high-efficiency magnetic collection of CTC from blood, a single-cell nanowell array performs CTC mutation profiling using modular gene panels. Using this approach, we demonstrated multigene expression profiling of individual CTCs from non-small-cell lung cancer (NSCLC) patients with remarkable sensitivity. Thus, we report a high-throughput, multiplexed strategy for single-cell mutation profiling of individual lung cancer CTCs toward minimally invasive cancer therapy prediction and disease monitoring.

    View details for DOI 10.1073/pnas.1608461113

    View details for Web of Science ID 000391090800003

    View details for PubMedID 27956614

    View details for PubMedCentralID PMC5206556

  • Practical ImmunoPET radiotracer design considerations for human immune checkpoint imaging. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Mayer, A. T., Natarajan, A., Gordon, S., Maute, R., McCracken, M., Ring, A., Weissman, I., Gambhir, S. S. 2016


    Immune checkpoint blockade has emerged as a promising cancer treatment paradigm. Unfortunately, there are still a large number of patients and malignancies that do not respond to therapy. A major barrier to validating biomarkers for the prediction and monitoring of responders to clinical checkpoint blockade has been the lack of imaging tools to accurately assess dynamic immune checkpoint expression. Here, we sought to optimize noninvasive immuno-PET imaging of human programmed death-ligand 1 (PD-L1) expression, in a preclinical model, using a small high-affinity engineered protein scaffold (HAC-PD1). Six HAC-PD1 radiotracer variants were developed and used in preclinical imaging and biodistribution studies to assess their ability to detect human PD-L1 expression in vivo. Radiotracer design modifications included chelate, glycosylation, and radiometal. HACA-PD1 was adopted as the naming convention for aglycosylated tracer variants. NOD scid γ-(NSG) mice were inoculated with subcutaneous tumors engineered to either be constitutively positive (CT26 hPD-L1) or be negative (ΔmPD-L1 CT26) for human PD-L1 expression. When the tumors had grown to an average size of 1 cm in diameter, mice were injected with 0.75-2.25 MBq (∼10 μg) of an engineered radiotracer variant and imaged. At 1 h after injection, organs were harvested for biodistribution. Of the practical immuno-PET tracer modifications considered, glycosylation was the most prominent design factor affecting tracer uptake, specificity, and clearance. In imaging studies, aglycosylated (64)Cu-NOTA-HACA-PD1 most accurately visualized human PD-L1 expression in vivo. We reasoned that because of the scaffold's small size (14 kDa), its pharmacokinetics may be suitable for labeling with the short-lived and widely clinically available radiometal (68)Ga. At 1 h after injection, (68)Ga-NOTA-HACA-PD1 and (68)Ga-DOTA-HACA-PD1 exhibited promising target-to-background ratios in ex vivo biodistribution studies (12.3 and 15.2 tumor-to-muscle ratios, respectively). Notably, all HAC-PD1 radiotracer variants enabled much earlier detection of human PD-L1 expression (1 h after injection) than previously reported radiolabeled antibodies (>24 h after injection). This work provides a template for assessing immuno-PET tracer design parameters and supports the translation of small engineered protein radiotracers for imaging human immune checkpoints.

    View details for PubMedID 27980047

    View details for PubMedCentralID PMC5373501

  • A Clinical Wide-Field Fluorescence Endoscopic Device for Molecular Imaging Demonstrating Cathepsin Protease Activity in Colon Cancer. Molecular imaging and biology Sensarn, S., Zavaleta, C. L., Segal, E., Rogalla, S., Lee, W., Gambhir, S. S., Bogyo, M., Contag, C. H. 2016; 18 (6): 820-829


    Early and effective detection of cancers of the gastrointestinal tract will require novel molecular probes and advances in instrumentation that can reveal functional changes in dysplastic and malignant tissues. Here, we describe adaptation of a wide-field clinical fiberscope to perform wide-field fluorescence imaging while preserving its white-light capability for the purpose of providing wide-field fluorescence imaging capability to point-of-care microscopes.We developed and used a fluorescent fiberscope to detect signals from a quenched probe, BMV109, that becomes fluorescent when cleaved by, and covalently bound to, active cathepsin proteases. Cathepsins are expressed in inflammation- and tumor-associated macrophages as well as directly from tumor cells and are a promising target for cancer imaging. The fiberscope has a 1-mm outer diameter enabling validation via endoscopic exams in mice, and therefore we evaluated topically applied BMV109 for the ability to detect colon polyps in an azoxymethane-induced colon tumor model in mice.This wide-field endoscopic imaging device revealed consistent and clear fluorescence signals from BMV109 that specifically localized to the polypoid regions as opposed to the normal adjacent colon tissue (p < 0.004) in the murine colon carcinoma model.The sensitivity of detection of BMV109 with the fluorescence fiberscope suggested utility of these tools for early detection at hard-to-reach sites. The fiberscope was designed to be used in conjunction with miniature, endoscope-compatible fluorescence microscopes for dual wide-field and microscopic cancer detection.

    View details for PubMedID 27154508

  • Can multispectral optoacoustic tomography replace sentinel lymph biopsy in melanoma? Annals of translational medicine Leong, S. P., Kothapalli, S., Gambhir, S. S. 2016; 4 (24): 517-?

    View details for DOI 10.21037/atm.2016.12.31

    View details for PubMedID 28149879

    View details for PubMedCentralID PMC5233521

  • Clinically Approved Nanoparticle Imaging Agents. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Thakor, A. S., Jokerst, J. V., Ghanouni, P., Campbell, J., Mittra, E., Gambhir, S. S. 2016


    Nanoparticles are a new class of imaging agent used for both anatomic and molecular imaging. Nanoparticle-based imaging exploits the signal intensity, stability, and biodistribution behavior of submicron-diameter molecular imaging agents. This review focuses on nanoparticles used in human medical imaging, with an emphasis on radionuclide imaging and MRI. Newer nanoparticle platforms are also discussed in relation to theranostic and multimodal uses.

    View details for PubMedID 27738007

  • A transgenic mouse model expressing an ER alpha folding biosensor reveals the effects of Bisphenol A on estrogen receptor signaling SCIENTIFIC REPORTS Sekar, T. V., Foygel, K., Massoud, T. F., Gambhir, S. S., Paulmurugan, R. 2016; 6


    Estrogen receptor-α (ERα) plays an important role in normal and abnormal physiology of the human reproductive system by interacting with the endogenous ligand estradiol (E2). However, other ligands, either analogous or dissimilar to E2, also bind to ERα. This may create unintentional activation of ER signaling in reproductive tissues that can lead to cancer development. We developed a transgenic mouse model that constitutively expresses a firefly luciferase (FLuc) split reporter complementation biosensor (NFLuc-ER-LBDG521T-CFLuc) to simultaneously evaluate the dynamics and potency of ligands that bind to ERα. We first validated this model using various ER ligands, including Raloxifene, Diethylstilbestrol, E2, and 4-hydroxytamoxifen, by employing FLuc-based optical bioluminescence imaging of living mice. We then used the model to investigate the carcinogenic property of Bisphenol A (BPA), an environmental estrogen, by long-term exposure at full and half environmental doses. We showed significant carcinogenic effects on female animals while revealing activated downstream ER signaling as measured by bioluminescence imaging. BPA induced tumor-like outgrowths in female transgenic mice, histopathologically confirmed to be neoplastic and epithelial in origin. This transgenic mouse model expressing an ERα folding-biosensor is useful in evaluation of estrogenic ligands and their downstream effects, and in studying environmental estrogen induced carcinogenesis in vivo.

    View details for DOI 10.1038/srep34788

    View details for Web of Science ID 000385140500001

    View details for PubMedID 27721470

  • A Cystine Knot Peptide Targeting Integrin alpha(v)beta(6) for Photoacoustic and Fluorescence Imaging of Tumors in Living Subjects JOURNAL OF NUCLEAR MEDICINE Zhang, C., Kimura, R., Abou-Elkacem, L., Levi, J., Xu, L., Gambhir, S. S. 2016; 57 (10): 1629-1634


    Photoacoustic imaging is a nonionizing biomedical imaging modality with higher resolution and imaging depth than fluorescence imaging, which has greater sensitivity. The combination of the 2 imaging modalities could improve the detection of cancer. Integrin αvβ6 is a cell surface marker overexpressed in many different cancers. Here, we report the development and evaluation of a dye-labeled cystine knot peptide, which selectively recognizes integrin αvβ6 with high affinity, for photoacoustic and fluorescence imaging. The new dual-modality probe may find clinical application in cancer diagnosis and intraoperative imaging of integrin αvβ6-positive tumors.An engineered cystine knot peptide, R01, that recognizes integrin αvβ6 was labeled with Atto 740 (A740) and evaluated for its specific cell uptake and its sensitivity threshold. A740-R01 was injected via the tail vein into nude mice xenografted with A431 (integrin αvβ6-positive) or 293T (integrin αvβ6-negative) tumors. Photoacoustic and fluorescence scans of tumors were acquired before and at 0.5, 1, 2, and 4 h after injection of A740-R01. Dynamic photoacoustic scans of various normal organs were also acquired. Ex vivo fluorescence imaging of tissues was performed 1 h after injection.The A740-R01 demonstrated integrin αvβ6-dependent binding to A431 cells in culture. Sensitivity studies indicated that the probe may potentially detect lesions as small as 1 or 6 mm(3) by fluorescence or photoacoustic imaging, respectively. The photoacoustic and fluorescence signals of A431 xenografts at 1 h after injection were 1.87 ± 0.25 arbitrary units (AU) and 8.27 ± 0.87 AU, respectively. Target specificity was confirmed by low tumor uptake in 293T tumors at 1 h after injection (1.07 ± 0.15 AU and 1.10 ± 0.14 AU for photoacoustic and fluorescence signals, respectively). A740-R01 exhibited hepatobiliary clearance marked by high uptake in the liver, spleen, and intestine but low uptake in the kidneys.A740-R01 specifically targeted integrin αvβ6 with low nanomolar affinity. A740-R01 was able to detect integrin αvβ6 both in vitro and in vivo by photoacoustic and fluorescence imaging. A740-R01 is able to detect αvβ6-positive tumors in living subjects and may have clinical application in cancer diagnosis and real-time image-guided surgery.

    View details for DOI 10.2967/jnumed.115.169383

    View details for Web of Science ID 000384961900031

    View details for PubMedID 27230926

  • Quantitative photoacoustic image reconstruction improves accuracy in deep tissue structures BIOMEDICAL OPTICS EXPRESS Mastanduno, M. A., Gambhir, S. S. 2016; 7 (10): 3811-3825
  • Imaging approaches to optimize molecular therapies SCIENCE TRANSLATIONAL MEDICINE Weissleder, R., Schwaiger, M. C., Gambhir, S. S., Hricak, H. 2016; 8 (355)


    Imaging, including its use for innovative tissue sampling, is slowly being recognized as playing a pivotal role in drug development, clinical trial design, and more effective delivery and monitoring of molecular therapies. The challenge is that, while a considerable number of new imaging technologies and new targeted tracers have been developed for cancer imaging in recent years, the technologies are neither evenly distributed nor evenly implemented. Furthermore, many imaging innovations are not validated and are not ready for widespread use in drug development or in clinical trial designs. Inconsistent and often erroneous use of terminology related to quantitative imaging biomarkers has also played a role in slowing their development and implementation. We examine opportunities for, and challenges of, the use of imaging biomarkers to facilitate development of molecular therapies and to accelerate progress in clinical trial design. In the future, in vivo molecular imaging, image-guided tissue sampling for mutational analyses ("high-content biopsies"), and noninvasive in vitro tests ("liquid biopsies") will likely be used in various combinations to provide the best possible monitoring and individualized treatment plans for cancer patients.

    View details for DOI 10.1126/scitranslmed.aaf3936

    View details for Web of Science ID 000384015200001

    View details for PubMedID 27605550

  • Multimodality Molecular Imaging of Cardiac Cell Transplantation: Part II. In Vivo Imaging of Bone Marrow Stromal Cells in Swine with PET/CT and MR Imaging. Radiology Parashurama, N., Ahn, B., Ziv, K., Ito, K., Paulmurugan, R., Willmann, J. K., Chung, J., Ikeno, F., Swanson, J. C., Merk, D. R., Lyons, J. K., Yerushalmi, D., Teramoto, T., Kosuge, H., Dao, C. N., Ray, P., Patel, M., Chang, Y., Mahmoudi, M., Cohen, J. E., Goldstone, A. B., Habte, F., Bhaumik, S., Yaghoubi, S., Robbins, R. C., Dash, R., Yang, P. C., Brinton, T. J., Yock, P. G., McConnell, M. V., Gambhir, S. S. 2016; 280 (3): 826-836


    Purpose To quantitatively determine the limit of detection of marrow stromal cells (MSC) after cardiac cell therapy (CCT) in swine by using clinical positron emission tomography (PET) reporter gene imaging and magnetic resonance (MR) imaging with cell prelabeling. Materials and Methods Animal studies were approved by the institutional administrative panel on laboratory animal care. Seven swine received 23 intracardiac cell injections that contained control MSC and cell mixtures of MSC expressing a multimodality triple fusion (TF) reporter gene (MSC-TF) and bearing superparamagnetic iron oxide nanoparticles (NP) (MSC-TF-NP) or NP alone. Clinical MR imaging and PET reporter gene molecular imaging were performed after intravenous injection of the radiotracer fluorine 18-radiolabeled 9-[4-fluoro-3-(hydroxyl methyl) butyl] guanine ((18)F-FHBG). Linear regression analysis of both MR imaging and PET data and nonlinear regression analysis of PET data were performed, accounting for multiple injections per animal. Results MR imaging showed a positive correlation between MSC-TF-NP cell number and dephasing (dark) signal (R(2) = 0.72, P = .0001) and a lower detection limit of at least approximately 1.5 × 10(7) cells. PET reporter gene imaging demonstrated a significant positive correlation between MSC-TF and target-to-background ratio with the linear model (R(2) = 0.88, P = .0001, root mean square error = 0.523) and the nonlinear model (R(2) = 0.99, P = .0001, root mean square error = 0.273) and a lower detection limit of 2.5 × 10(8) cells. Conclusion The authors quantitatively determined the limit of detection of MSC after CCT in swine by using clinical PET reporter gene imaging and clinical MR imaging with cell prelabeling. (©) RSNA, 2016 Online supplemental material is available for this article.

    View details for DOI 10.1148/radiol.2016151150

    View details for PubMedID 27332865

    View details for PubMedCentralID PMC5006717

  • Multimodality Molecular Imaging of Cardiac Cell Transplantation: Part I. Reporter Gene Design, Characterization, and Optical in Vivo Imaging of Bone Marrow Stromal Cells after Myocardial Infarction. Radiology Parashurama, N., Ahn, B., Ziv, K., Ito, K., Paulmurugan, R., Willmann, J. K., Chung, J., Ikeno, F., Swanson, J. C., Merk, D. R., Lyons, J. K., Yerushalmi, D., Teramoto, T., Kosuge, H., Dao, C. N., Ray, P., Patel, M., Chang, Y., Mahmoudi, M., Cohen, J. E., Goldstone, A. B., Habte, F., Bhaumik, S., Yaghoubi, S., Robbins, R. C., Dash, R., Yang, P. C., Brinton, T. J., Yock, P. G., McConnell, M. V., Gambhir, S. S. 2016; 280 (3): 815-825


    Purpose To use multimodality reporter-gene imaging to assess the serial survival of marrow stromal cells (MSC) after therapy for myocardial infarction (MI) and to determine if the requisite preclinical imaging end point was met prior to a follow-up large-animal MSC imaging study. Materials and Methods Animal studies were approved by the Institutional Administrative Panel on Laboratory Animal Care. Mice (n = 19) that had experienced MI were injected with bone marrow-derived MSC that expressed a multimodality triple fusion (TF) reporter gene. The TF reporter gene (fluc2-egfp-sr39ttk) consisted of a human promoter, ubiquitin, driving firefly luciferase 2 (fluc2), enhanced green fluorescent protein (egfp), and the sr39tk positron emission tomography reporter gene. Serial bioluminescence imaging of MSC-TF and ex vivo luciferase assays were performed. Correlations were analyzed with the Pearson product-moment correlation, and serial imaging results were analyzed with a mixed-effects regression model. Results Analysis of the MSC-TF after cardiac cell therapy showed significantly lower signal on days 8 and 14 than on day 2 (P = .011 and P = .001, respectively). MSC-TF with MI demonstrated significantly higher signal than MSC-TF without MI at days 4, 8, and 14 (P = .016). Ex vivo luciferase activity assay confirmed the presence of MSC-TF on days 8 and 14 after MI. Conclusion Multimodality reporter-gene imaging was successfully used to assess serial MSC survival after therapy for MI, and it was determined that the requisite preclinical imaging end point, 14 days of MSC survival, was met prior to a follow-up large-animal MSC study. (©) RSNA, 2016 Online supplemental material is available for this article.

    View details for DOI 10.1148/radiol.2016140049

    View details for PubMedID 27308957

    View details for PubMedCentralID PMC5006716

  • Glioblastoma Multiforme Recurrence: An Exploratory Study of (18)F FPPRGD2 PET/CT. Radiology Iagaru, A., Mosci, C., Mittra, E., Zaharchuk, G., Fischbein, N., Harsh, G., Li, G., Nagpal, S., Recht, L., Gambhir, S. S. 2016; 280 (1): 328-?

    View details for DOI 10.1148/radiol.2016164020

    View details for PubMedID 27322985

  • Characterization of Physiologic F-18 FSPG Uptake in Healthy Volunteers RADIOLOGY Mosci, C., Kumar, M., Smolarz, K., Koglin, N., Stephens, A. W., Schwaiger, M., Gambhir, S. S., Mittra, E. S. 2016; 279 (3): 898-905


    Purpose To evaluate the normal biodistribution and kinetics of (S)-4-(3-[18F]fluoropropyl)-l-glutamic acid ((18)F FSPG) in healthy volunteers and to compare (18)F FSPG mean and maximum standardized uptake values (SUVmean and SUVmax, respectively) with those of (18)F fluorodeoxyglucose (FDG) across a variety of organs. Materials and Methods This protocol was reviewed and approved by all appropriate regulatory authorities. An 8-mCi (±10%) dose of (18)F FSPG was given to five subjects (three women, two men), and seven whole-body positron emission tomography (PET) scans were performed 5, 10, 20, 30, 45, 150, and 240 minutes after injection. Regions of interest were analyzed on the resultant (18)F FSPG images to evaluate the kinetics of this radiotracer. The images obtained 45 minutes after injection were used to measure SUVmean and SUVmax in additional regions of the body. These values were compared with similar values obtained with (18)F FDG PET published previously. Descriptive statistics, including average and standard deviation across the five subjects, were used. (18)F FSPG SUVmean and SUVmax were compared. Results On the (18)F FSPG images obtained 45 minutes after injection, there was only low-grade background activity in the majority of analyzed regions. Prominent activity was seen throughout the pancreas. Clearance of the radiotracer through the kidneys and collection in the bladder also were seen. SUV quantification shows notable differences between (18)F FSPG and (18)F FDG in the pancreas ((18)F FSPG SUVmean, 8.2; (18)F FDG SUVmean, 1.3), stomach ((18)F FSPG SUVmax, 3.6; (18)F FDG SUVmax, 1.6), and brain ((18)F FSPG SUVmean, 0.08; (18)F FDG SUVmean, 7.8). The kinetic data showed rapid clearance of the radiotracer from the blood pool and most organs, except the pancreas. Conclusion (18)F FSPG is a PET radiopharmaceutical characterized by rapid clearance from most healthy tissues, except the pancreas and kidneys. A consistent biodistribution pattern was observed with low background uptake. The physiologic uptake of this new radiotracer throughout the body is described in more detail, which is important for improved interpretative accuracy and understanding potential clinical applications. (©) RSNA, 2016.

    View details for DOI 10.1148/radiol.2015142000

    View details for Web of Science ID 000378719700028

    View details for PubMedID 26785040

  • Protein biomarkers on tissue as imaged via MALDI mass spectrometry: A systematic approach to study the limits of detection PROTEOMICS van de Ven, S. M., Bemis, K. D., Lau, K., Adusumilli, R., Kota, U., Stolowitz, M., Vitek, O., Mallick, P., Gambhir, S. S. 2016; 16 (11-12): 1660-1669


    MALDI mass spectrometry imaging (MSI) is emerging as a tool for protein and peptide imaging across tissue sections. Despite extensive study, there does not yet exist a baseline study evaluating the potential capabilities for this technique to detect diverse proteins in tissue sections. In this study, we developed a systematic approach for characterizing MALDI-MSI workflows in terms of limits of detection, coefficients of variation, spatial resolution, and the identification of endogenous tissue proteins. Our goal was to quantify these figures of merit for a number of different proteins and peptides, in order to gain more insight in the feasibility of protein biomarker discovery efforts using this technique. Control proteins and peptides were deposited in serial dilutions on thinly sectioned mouse xenograft tissue. Using our experimental setup, coefficients of variation were <30% on tissue sections and spatial resolution was 200 μm (or greater). Limits of detection for proteins and peptides on tissue were in the micromolar to millimolar range. Protein identification was only possible for proteins present in high abundance in the tissue. These results provide a baseline for the application of MALDI-MSI towards the discovery of new candidate biomarkers and a new benchmarking strategy that can be used for comparing diverse MALDI-MSI workflows.

    View details for DOI 10.1002/pmic.201500515

    View details for Web of Science ID 000379049100008

    View details for PubMedID 26970438

  • Pilot prospective evaluation of F-18-FPPRGD(2) PET/CT in patients with cervical and ovarian cancer EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Minamimoto, R., Karam, A., Jamali, M., Barkhodari, A., Gambhir, S. S., Dorigo, O., Iagaru, A. 2016; 43 (6): 1047-1055


    We report the effect of antiangiogenic therapy on the biodistribution of (18)F-FPPRGD2 (a surrogate biomarker of integrin αvβ3 expression), and the potential of (18)F-FPPRGD2 to predict the prognosis in patients with cervical cancer and ovarian cancer in this clinical scenario.Data from six women, age range 30 - 59 years (mean ± SD 44.0 ± 12.5 years), who had undergone a (18)F-FPPRGD2 PET/CT scan and bevacizumab-containing therapy were prospectively collected and analyzed. We compared baseline (18)F-FPPRGD2 and (18)F-FDG uptake in the lesions and tumor-to-background (T/B) ratios. The maximum and mean (18)F-FPPRGD2 standardized uptake values (SUVmax and SUVmean) were recorded for 13 normal organs, as well as in all the identified malignant lesions on the pretreatment scan and the 1-week post-treatment scan. We also measured changes in (18)F-FPPRGD2 uptake from before to 1 week after treatment, and compared them to the changes in (18)F-FDG uptake from before to 6 weeks after treatment. Treatment outcomes were correlated with these changes.The uptake in lesions and T/B ratio of (18)F-FPPRGD2 were lower than those of (18)F-FDG (SUVmax 3.7 ± 1.3 vs. 6.0 ± 1.8, P < 0.001; SUVmean 2.6 ± 0.7 vs. 4.2 ± 1.3, P < 0.001; T/B ratio based on SUVmax 2.4 ± 1.0 vs. 2.6 ± 1.0, P < 0.04; T/B ratio based on SUVmean 1.9 ± 0.6 vs. 2.4 ± 1.0, P < 0.003). One patient did not return for the follow-up scan and in another patient no lesions were identified on the pretreatment scan. (18)F-FPPRGD2 uptake in lesions in the remaining four patients had significantly changed 1 week after treatment (SUVmean 3.3 ± 1.0 vs. 2.7 ± 1.0, P < 0.001), while uptake in all normal tissues analyzed was not affected by treatment. One patient with clinical disease progression had a decrease in lesional (18)F-FPPRGD2 SUVmean of 1.6 % and in (18)F-FDG SUVmean of 9.4 %. Two patients with a clinical complete response to treatment had decreases in lesional (18)F-FPPRGD2 SUVmean of 25.2 % and 25.0 % and in (18)F-FDG SUVmean of 6.1 % and 71.8 %. One patient with a clinical partial response had a decrease in lesional (18)F-FPPRGD2 SUVmean of 7.9 % and in (18)F-FDG SUVmean of 76.4 %.This pilot study showed that (18)F-FPPRGD2 and (18)F-FDG provide independent information about the biology of ovarian and cervical cancers. Bevacizumab-containing therapy does not affect (18)F-FPPRGD2 uptake in normal organs, but does result in statistically significant changes in lesions. In addition, (18)F-FPPRGD2 may have potential for early prediction of response to such treatments. These preliminary findings have to be confirmed in larger studies.

    View details for DOI 10.1007/s00259-015-3263-7

    View details for Web of Science ID 000374972900008

    View details for PubMedID 26611425

  • Alk5 inhibition increases delivery of macromolecular and protein-bound contrast agents to tumors. JCI insight Daldrup-Link, H. E., Mohanty, S., Ansari, C., Lenkov, O., Shaw, A., Ito, K., Hong, S. H., Hoffmann, M., Pisani, L., Boudreau, N., Gambhir, S. S., Coussens, L. M. 2016; 1 (6)


    Limited transendothelial permeability across tumor microvessels represents a significant bottleneck in the development of tumor-specific diagnostic agents and theranostic drugs. Here, we show an approach to increase transendothelial permeability of macromolecular and nanoparticle-based contrast agents via inhibition of the type I TGF-β receptor, activin-like kinase 5 (Alk5), in tumors. Alk5 inhibition significantly increased tumor contrast agent delivery and enhancement on imaging studies, while healthy organs remained relatively unaffected. Imaging data correlated with significantly decreased tumor interstitial fluid pressure, while tumor vascular density remained unchanged. This immediately clinically translatable concept involving Alk5 inhibitor pretreatment prior to an imaging study could be leveraged for improved tumor delivery of macromolecular and nanoparticle-based imaging probes and, thereby, facilitate development of more sensitive imaging tests for cancer diagnosis, enhanced tumor characterization, and personalized, image-guided therapies.

    View details for PubMedID 27182558

  • Pilot Comparison of Ga-68-RM2 PET and Ga-68-PSMA-11 PET in Patients with Biochemically Recurrent Prostate Cancer JOURNAL OF NUCLEAR MEDICINE Minamimoto, R., Hancock, S., Schneider, B., Chin, F. T., Jamali, M., Loening, A., Vasanawala, S., Gambhir, S. S., Iagaru, A. 2016; 57 (4): 557-562


    Glu-NH-CO-NH-Lys-(Ahx)-[(68)Ga(HBED-CC)] ((68)Ga-PSMA-11) is a PET tracer that can detect prostate cancer relapses and metastases by binding to the extracellular domain of PSMA.(68)Ga-labeled DOTA-4-amino-1-carboxymethyl-piperidine-d-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2 ((68)Ga-RM2) is a synthetic bombesin receptor antagonist that targets gastrin-releasing peptide receptors. We present pilot data on the biodistribution of these PET tracers in a small cohort of patients with biochemically recurrent prostate cancer.Seven men (mean age ± SD, 74.3 ± 5.9 y) with biochemically recurrent prostate cancer underwent both(68)Ga-PSMA-11 PET/CT and(68)Ga-RM2 PET/MRI scans. SUVmaxand SUVmeanwere recorded for normal tissues and areas of uptake outside the expected physiologic biodistribution.All patients had a rising level of prostate-specific antigen (mean ± SD, 13.5 ± 11.5) and noncontributory results on conventional imaging.(68)Ga-PSMA-11 had the highest physiologic uptake in the salivary glands and small bowel, with hepatobiliary and renal clearance noted, whereas(68)Ga-RM2 had the highest physiologic uptake in the pancreas, with renal clearance noted. Uptake outside the expected physiologic biodistribution did not significantly differ between(68)Ga-PSMA-11 and(68)Ga-RM2; however,(68)Ga-PSMA-11 localized in a lymph node and seminal vesicle in a patient with no abnormal(68)Ga-RM2 uptake. Abdominal periaortic lymph nodes were more easily visualized by(68)Ga-RM2 in two patients because of lack of interference by radioactivity in the small intestine.(68)Ga-PSMA-11 and(68)Ga-RM2 had distinct biodistributions in this small cohort of patients with biochemically recurrent prostate cancer. Additional work is needed to understand the expression of PSMA and gastrin-releasing peptide receptors in different types of prostate cancer.

    View details for DOI 10.2967/jnumed.115.168393

    View details for Web of Science ID 000373627800022

    View details for PubMedID 26659347

  • [F-18]FPRGD(2) PET/CT imaging of integrin alpha(v)beta(3) levels in patients with locally advanced rectal carcinoma EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Withofs, N., Martinive, P., Vanderick, J., Bletard, N., Scagnol, I., Mievis, F., Giacomelli, F., Coucke, P., Delvenne, P., Cataldo, D., Gambhir, S. S., Hustinx, R. 2016; 43 (4): 654-662
  • [(18)F]FPRGD2 PET/CT imaging of integrin avß3 levels in patients with locally advanced rectal carcinoma. European journal of nuclear medicine and molecular imaging Withofs, N., Martinive, P., Vanderick, J., Bletard, N., Scagnol, I., Mievis, F., Giacomelli, F., Coucke, P., Delvenne, P., Cataldo, D., Gambhir, S. S., Hustinx, R. 2016; 43 (4): 654-662


    Our primary objective was to determine if [(18)F]FPRGD2 PET/CT performed at baseline and/or after chemoradiotherapy (CRT) could predict tumour regression grade (TRG) in locally advanced rectal cancer (LARC). Secondary objectives were to compare baseline [(18)F]FPRGD2 and [(18)F]FDG uptake, to evaluate the correlation between posttreatment [(18)F]FPRGD2 uptake and tumour microvessel density (MVD) and to determine if [(18)F]FPRGD2 and FDG PET/CT could predict disease-free survival.Baseline [(18)F]FPRGD2 and FDG PET/CT were performed in 32 consecutive patients (23 men, 9 women; mean age 63 ± 8 years) with LARC before starting any therapy. A posttreatment [(18)F]FPRGD2 PET/CT scan was performed in 24 patients after the end of CRT (median interval 7 weeks, range 3 - 15 weeks) and before surgery (median interval 4 days, range 1 - 15 days).All LARC showed uptake of both [(18)F]FPRGD2 (SUVmax 5.4 ± 1.5, range 2.7 - 9) and FDG (SUVmax 16.5 ± 8, range 7.1 - 36.5). There was a moderate positive correlation between [(18)F]FPRGD2 and FDG SUVmax (Pearson's r = 0.49, p = 0.0026). There was a moderate negative correlation between baseline [(18)F]FPRGD2 SUVmax and the TRG (Spearman's r = -0.37, p = 0.037), and a [(18)F]FPRGD2 SUVmax of >5.6 identified all patients with a complete response (TRG 0; AUC 0.84, 95 % CI 0.68 - 1, p = 0.029). In the 24 patients who underwent a posttreatment [(18)F]FPRGD2 PET/CT scan the response index, calculated as [(SUVmax1 - SUVmax2)/SUVmax1] × 100 %, was not associated with TRG. Post-treatment [(18)F]FPRGD2 uptake was not correlated with tumour MVD. Neither [(18)F]FPRGD2 nor FDG uptake predicted disease-free survival.Baseline [(18)F]FPRGD2 uptake was correlated with the pathological response in patients with LARC treated with CRT. However, the specificity was too low to consider its clinical routine use.

    View details for DOI 10.1007/s00259-015-3219-y

    View details for PubMedID 26490751

  • Comparison of Deconvolution Filters for Photoacoustic Tomography PLOS ONE de Sompel, D. V., Sasportas, L. S., Jokerst, J. V., Gambhir, S. S. 2016; 11 (3)
  • Pilot Preclinical and Clinical Evaluation of (4S)-4-(3-[18F]Fluoropropyl)-L-Glutamate (18F-FSPG) for PET/CT Imaging of Intracranial Malignancies. PloS one Mittra, E. S., Koglin, N., Mosci, C., Kumar, M., Hoehne, A., Keu, K. V., Iagaru, A. H., Mueller, A., Berndt, M., Bullich, S., Friebe, M., Schmitt-Willich, H., Gekeler, V., Fels, L. M., Bacher-Stier, C., Moon, D. H., Chin, F. T., Stephens, A. W., Dinkelborg, L. M., Gambhir, S. S. 2016; 11 (2)


    (S)-4-(3-[18F]Fluoropropyl)-L-glutamic acid (18F-FSPG) is a novel radiopharmaceutical for Positron Emission Tomography (PET) imaging. It is a glutamate analogue that can be used to measure xC- transporter activity. This study was performed to assess the feasibility of 18F-FSPG for imaging orthotopic brain tumors in small animals and the translation of this approach in human subjects with intracranial malignancies.For the small animal study, GS9L glioblastoma cells were implanted into brains of Fischer rats and studied with 18F-FSPG, the 18F-labeled glucose derivative 18F-FDG and with the 18F-labeled amino acid derivative 18F-FET. For the human study, five subjects with either primary or metastatic brain cancer were recruited (mean age 50.4 years). After injection of 300 MBq of 18F-FSPG, 3 whole-body PET/Computed Tomography (CT) scans were obtained and safety parameters were measured. The three subjects with brain metastases also had an 18F-FDG PET/CT scan. Quantitative and qualitative comparison of the scans was performed to assess kinetics, biodistribution, and relative efficacy of the tracers.In the small animals, the orthotopic brain tumors were visualized well with 18F-FSPG. The high tumor uptake of 18F-FSPG in the GS9L model and the absence of background signal led to good tumor visualization with high contrast (tumor/brain ratio: 32.7). 18F-FDG and 18F-FET showed T/B ratios of 1.7 and 2.8, respectively. In the human pilot study, 18F-FSPG was well tolerated and there was similar distribution in all patients. All malignant lesions were positive with 18F-FSPG except for one low-grade primary brain tumor. In the 18F-FSPG-PET-positive tumors a similar T/B ratio was observed as in the animal model.18F-FSPG is a novel PET radiopharmaceutical that demonstrates good uptake in both small animal and human studies of intracranial malignancies. Future studies on larger numbers of subjects and a wider array of brain tumors are NCT01186601.

    View details for DOI 10.1371/journal.pone.0148628

    View details for PubMedID 26890637

  • Artificial MicroRNAs as Novel Secreted Reporters for Cell Monitoring in Living Subjects. PloS one Ronald, J. A., D'Souza, A. L., Chuang, H., Gambhir, S. S. 2016; 11 (7)


    Reporter genes are powerful technologies that can be used to directly inform on the fate of transplanted cells in living subjects. Imaging reporter genes are often employed to quantify cell number, location(s), and viability with various imaging modalities. To complement this, reporters that are secreted from cells can provide a low-cost, in vitro diagnostic test to monitor overall cell viability at relatively high frequency without knowing the locations of all cells. Whereas protein-based secretable reporters have been developed, an RNA-based reporter detectable with amplification inherent PCR-based assays has not been previously described. MicroRNAs (miRNAs) are short non-coding RNAs (18-22 nt) that regulate mRNA translation and are being explored as relatively stable blood-based disease biomarkers. We developed an artificial miRNA-based secreted reporter, called Sec-miR, utilizing a coding sequence that is not expressed endogenously and does not have any known vertebrate target. Sec-miR was detectable in both the cells and culture media of transiently transfected cells. Cells stably expressing Sec-miR also reliably secreted it into the culture media. Mice implanted with parental HeLa cells or HeLa cells expressing both Sec-miR and the bioluminescence imaging (BLI) reporter gene Firefly luciferase (FLuc) were monitored over time for tumor volume, FLuc signal via BLI, and blood levels of Sec-miR. Significantly (p<0.05) higher Sec-miR was found in the blood of mice bearing Sec-miR-expressing tumors compared to parental cell tumors at 21 and 28 days after implantation. Importantly, blood Sec-miR reporter levels after day 21 showed a trend towards correlation with tumor volume (R2 = 0.6090; p = 0.0671) and significantly correlated with FLuc signal (R2 = 0.7067; p<0.05). Finally, we could significantly (p<0.01) amplify Sec-miR secretion into the cell media by chaining together multiple Sec-miR copies (4 instead of 1 or 2) within an expression cassette. Overall, we show that a novel complement of BLI together with a unique Sec-miR reporter adds an in vitro RNA-based diagnostic to enhance the monitoring of transplanted cells. While Sec-miR was not as sensitive as BLI for monitoring cell number, it may be more sensitive than clinically-relevant positron emission tomography (PET) reporter assays. Future work will focus on improving cell detectability via improved secretion of Sec-miR reporters from cells and more sensitive detection platforms, as well as, exploring other miRNA sequences to allow multiplexed monitoring of more than one cell population at a time. Continued development may lead to more refined and precise monitoring of cell-based therapies.

    View details for DOI 10.1371/journal.pone.0159369

    View details for PubMedID 27442530

  • Comparison of Deconvolution Filters for Photoacoustic Tomography. PloS one Van de Sompel, D., Sasportas, L. S., Jokerst, J. V., Gambhir, S. S. 2016; 11 (3)


    In this work, we compare the merits of three temporal data deconvolution methods for use in the filtered backprojection algorithm for photoacoustic tomography (PAT). We evaluate the standard Fourier division technique, the Wiener deconvolution filter, and a Tikhonov L-2 norm regularized matrix inversion method. Our experiments were carried out on subjects of various appearances, namely a pencil lead, two man-made phantoms, an in vivo subcutaneous mouse tumor model, and a perfused and excised mouse brain. All subjects were scanned using an imaging system with a rotatable hemispherical bowl, into which 128 ultrasound transducer elements were embedded in a spiral pattern. We characterized the frequency response of each deconvolution method, compared the final image quality achieved by each deconvolution technique, and evaluated each method's robustness to noise. The frequency response was quantified by measuring the accuracy with which each filter recovered the ideal flat frequency spectrum of an experimentally measured impulse response. Image quality under the various scenarios was quantified by computing noise versus resolution curves for a point source phantom, as well as the full width at half maximum (FWHM) and contrast-to-noise ratio (CNR) of selected image features such as dots and linear structures in additional imaging subjects. It was found that the Tikhonov filter yielded the most accurate balance of lower and higher frequency content (as measured by comparing the spectra of deconvolved impulse response signals to the ideal flat frequency spectrum), achieved a competitive image resolution and contrast-to-noise ratio, and yielded the greatest robustness to noise. While the Wiener filter achieved a similar image resolution, it tended to underrepresent the lower frequency content of the deconvolved signals, and hence of the reconstructed images after backprojection. In addition, its robustness to noise was poorer than that of the Tikhonov filter. The performance of the Fourier filter was found to be the poorest of all three methods, based on the reconstructed images' lowest resolution (blurriest appearance), generally lowest contrast-to-noise ratio, and lowest robustness to noise. Overall, the Tikhonov filter was deemed to produce the most desirable image reconstructions.

    View details for DOI 10.1371/journal.pone.0152597

    View details for PubMedID 27031832

  • AshwaMAX and Withaferin A inhibits gliomas in cellular and murine orthotopic models JOURNAL OF NEURO-ONCOLOGY Chang, E., Pohling, C., Natarajan, A., Witney, T. H., Kaur, J., Xu, L., Gowrishankar, G., D'Souza, A. L., Murty, S., Schick, S., Chen, L., Wu, N., Khaw, P., Mischel, P., Abbasi, T., Usmani, S., Mallick, P., Gambhir, S. S. 2016; 126 (2): 253-264


    Glioblastoma multiforme (GBM) is an aggressive, malignant cancer Johnson and O'Neill (J Neurooncol 107: 359-364, 2012). An extract from the winter cherry plant (Withania somnifera ), AshwaMAX, is concentrated (4.3 %) for Withaferin A; a steroidal lactone that inhibits cancer cells Vanden Berghe et al. (Cancer Epidemiol Biomark Prev 23: 1985-1996, 2014). We hypothesized that AshwaMAX could treat GBM and that bioluminescence imaging (BLI) could track oral therapy in orthotopic murine models of glioblastoma. Human parietal-cortical glioblastoma cells (GBM2, GBM39) were isolated from primary tumors while U87-MG was obtained commercially. GBM2 was transduced with lentiviral vectors that express Green Fluorescent Protein (GFP)/firefly luciferase fusion proteins. Mutational, expression and proliferative status of GBMs were studied. Intracranial xenografts of glioblastomas were grown in the right frontal regions of female, nude mice (n = 3-5 per experiment). Tumor growth was followed through BLI. Neurosphere cultures (U87-MG, GBM2 and GBM39) were inhibited by AshwaMAX at IC50 of 1.4, 0.19 and 0.22 µM equivalent respectively and by Withaferin A with IC50 of 0.31, 0.28 and 0.25 µM respectively. Oral gavage, every other day, of AshwaMAX (40 mg/kg per day) significantly reduced bioluminescence signal (n = 3 mice, p < 0.02, four parameter non-linear regression analysis) in preclinical models. After 30 days of treatment, bioluminescent signal increased suggesting onset of resistance. BLI signal for control, vehicle-treated mice increased and then plateaued. Bioluminescent imaging revealed diffuse growth of GBM2 xenografts. With AshwaMAX, GBM neurospheres collapsed at nanomolar concentrations. Oral treatment studies on murine models confirmed that AshwaMAX is effective against orthotopic GBM. AshwaMAX is thus a promising candidate for future clinical translation in patients with GBM.

    View details for DOI 10.1007/s11060-015-1972-1

    View details for Web of Science ID 000368728300005

  • Prospective Comparison of 99mTc-MDP Scintigraphy, Combined 18F-NaF and 18F-FDG PET/CT, and Whole-Body MRI in Patients with Breast and Prostate Cancer. Journal of nuclear medicine Minamimoto, R., Loening, A., Jamali, M., Barkhodari, A., Mosci, C., Jackson, T., Obara, P., Taviani, V., Gambhir, S. S., Vasanawala, S., Iagaru, A. 2015; 56 (12): 1862-1868


    We prospectively evaluated the combined (18)F-NaF/(18)F-FDG PET/CT in patients with breast and prostate cancers, and compared the results to (99m)Tc MDP bone scintigraphy (BS) and whole-body MRI (WBMRI).30 patients (15 women with breast cancer and 15 men with prostate cancer) referred for standard of care BS were prospectively enrolled in this study. (18)F-NaF/(18)F-FDG PET/CT and WBMRI were performed following BS. WBMRI protocol consisted of both non-contrast enhanced and contrast enhanced sequences. Lesions detected with each test were tabulated and the results were compared.For extra skeletal lesions, (18)F-/(18)F-FDG PET/CT and WBMRI had no statistically significant differences in sensitivity (92.9% vs 92.9%, P = 1.00), PPV (81.3% vs 86.7%, P = 0.68) and accuracy (76.5% vs 82.4%, P = 0.56). However, (18)F-/(18)F-FDG PET/CT showed significantly higher sensitivity and accuracy than WBMRI (96.2% vs 81.4%, P<0.001, 89.8% vs 74.7%, P = 0.01) and BS (96.2% vs 64.6%, P<0.001, 89.8% vs 65.9%, P<0.001) for the detection of skeletal lesions. Overall, (18)F-/(18)F-FDG PET/CT showed higher sensitivity and accuracy than WBMRI (95.7% vs 83.3%, P<0.002, 87.6% vs 76.0%, P< 0.02), but not statistically significant when compared to a combination of WBMRI and BS (95.7% vs 91.6%, P = 0.17, 87.6% vs 83.0%, P = 0.53). (18)F-/(18)F-FDG PET/CT showed no significant difference with a combination of (18)F-/(18)F-FDG PET/CT and WBMRI. No statistically significant differences in PPV were noted among the 3 examinations.The (18)F NaF/(18)F FDG PET/CT is superior to WBMRI and (99m)Tc-MDP scintigraphy for evaluation of skeletal disease extent. Further, (18)F NaF/(18)F FDG PET/CT and WBMRI detected extra-skeletal disease that may change the management of these patients. The (18)F NaF/(18)F FDG PET/CT provide similar diagnostic ability with combination of WBMRI and BS in patients with breast and prostate cancers. Larger cohorts are needed in order to confirm these preliminary findings, ideally using the newly introduced simultaneous PET/MRI scanners.

    View details for DOI 10.2967/jnumed.115.162610

    View details for PubMedID 26405167

  • Multiscale Framework for Imaging Radio labeled Therapeutics MOLECULAR PHARMACEUTICS Natarajan, A., Tuerkcan, S., Gambhir, S. S., Pratx, G. 2015; 12 (12): 4554-4560
  • Further validation to support clinical translation of [(18)F]FTC-146 for imaging sigma-1 receptors. EJNMMI research Shen, B., James, M. L., Andrews, L., Lau, C., Chen, S., Palner, M., Miao, Z., Arksey, N. C., Shuhendler, A. J., Scatliffe, S., Kaneshige, K., Parsons, S. M., McCurdy, C. R., Salehi, A., Gambhir, S. S., Chin, F. T. 2015; 5 (1): 49-?

    View details for DOI 10.1186/s13550-015-0122-2

    View details for PubMedID 26384292

  • Photoacoustic Tomography Detects Early Vessel Regression and Normalization During Ovarian Tumor Response to the Antiangiogenic Therapy Trebananib. Journal of nuclear medicine Bohndiek, S. E., Sasportas, L. S., Machtaler, S., Jokerst, J. V., Hori, S., Gambhir, S. S. 2015; 56 (12): 1942-1947


    The primary aim of this study was to assess the potential of in vivo photoacoustic tomography (PAT) for direct functional measurement of ovarian tumor response to anti-angiogenic therapy.In vivo studies were performed with institutional animal care and use committee approval. We used an orthotopic mouse model of ovarian cancer treated with Trebananib (n = 9) or vehicle (n = 9). Tumor-bearing mice were randomized into Trebananib or vehicle groups at day 10 and dosed on days 12, 15 and 18 post implantation. PAT and blood draws were performed at day 10, then 24 hours after each drug dose. Tumors were excised for histopathology following the final studies on day 19. Data analysis to test for statistical significance was performed blinded.Blockade of angiopoietin signaling using Trebananib resulted in reduced total hemoglobin-weighted PA signal (n = 9, P = 0.01) and increased oxyhemoglobin-weighted PA signal (n = 9, P<0.01). The latter observation indicated normalization of the residual tumor vessels, which was also implied by low levels of angiopoietin 1 in serum biomarker profiling (0.76±0.12ng/mL). These non-invasive measures reflected a 30% reduction in microvessel density and increased vessel maturation in ex vivo sections.PAT is able to evaluate both vessel regression and normalization in response to Trebananib. Non-invasive imaging data was supported by modulation of serum markers in vitro and ex vivo histopathology.

    View details for DOI 10.2967/jnumed.115.160002

    View details for PubMedID 26315834

  • (18)F-FPRGD2 PET/CT imaging of musculoskeletal disorders. Annals of nuclear medicine Withofs, N., Charlier, E., Simoni, P., Alvarez-Miezentseva, V., Mievis, F., Giacomelli, F., Mella, C., Gambhir, S. S., Malaise, O., de Seny, D., Malaise, M., Hustinx, R. 2015; 29 (10): 839-847


    This work reports on musculoskeletal uptake of (18)F-FPRGD2, targeting the integrin αvβ3, in patients who had undergone (18)F-FPRGD2 positron emission tomography combined with computed tomography (PET/CT) for oncologic purposes.Whole-body (18)F-FPRGD2 PET/CT images of 62 cancer patients were retrospectively reviewed to detect foci of musculoskeletal (18)F-FPRGD2 uptake. For 37 patients, a FDG PET/CT performed in clinical settings was available. In each joint with an abnormal uptake, the maximum standardized uptake value (SUVmax) was estimated.A total of 260 musculoskeletal foci of (18)F-FPRGD2 uptake were detected. Most common sites of uptake were joints and discs (n = 160; 61.5 %), entheses (osteotendinous and osteoligamentous junctions; n = 55; 21.2 %) and recent fractures (n = 18; 6.9 %). In addition, 27 (10.4 %) miscellaneous foci were detected. Out of the 146 lesions for which a FDG PET was available, 63 % showed both (18)F-FPRGD2 and FDG uptake, 33.6 % did not show FDG avidity and 3.4 % showed only FDG uptake. The uptake intensity of the 92 lesions positive with (18)F-FPRGD2 and FDG was similar with both radiopharmaceuticals, but the target-to-background (blood pool or muscle) ratios were significantly higher with (18)F-FPRGD2 than with FDG (p < 0.0001).The (18)F-FPRGD2 uptake in joints, spine degenerative diseases and tendons was highly prevalent in our population. Up to one-third of (18)F-FPRGD2 foci showed no FDG uptake suggesting that (18)F-FPRGD2 signal may not be related to inflammatory angiogenesis only.

    View details for DOI 10.1007/s12149-015-1011-5

    View details for PubMedID 26254227

  • Imaging patients with breast and prostate cancers using combined 18F NaF/18F FDG and TOF simultaneous PET/ MRI. EJNMMI physics Iagaru, A., Minamimoto, R., Jamali, M., Barkodhodari, A., Gambhir, S. S., Vasanawala, S. 2015; 2: A65-?

    View details for DOI 10.1186/2197-7364-2-S1-A65

    View details for PubMedID 26956325

  • Engineering high-affinity PD-1 variants for optimized immunotherapy and immuno-PET imaging. Proceedings of the National Academy of Sciences of the United States of America Maute, R. L., Gordon, S. R., Mayer, A. T., McCracken, M. N., Natarajan, A., Ring, N. G., Kimura, R., Tsai, J. M., Manglik, A., Kruse, A. C., Gambhir, S. S., Weissman, I. L., Ring, A. M. 2015; 112 (47): E6506-14


    Signaling through the immune checkpoint programmed cell death protein-1 (PD-1) enables tumor progression by dampening antitumor immune responses. Therapeutic blockade of the signaling axis between PD-1 and its ligand programmed cell death ligand-1 (PD-L1) with monoclonal antibodies has shown remarkable clinical success in the treatment of cancer. However, antibodies have inherent limitations that can curtail their efficacy in this setting, including poor tissue/tumor penetrance and detrimental Fc-effector functions that deplete immune cells. To determine if PD-1:PD-L1-directed immunotherapy could be improved with smaller, nonantibody therapeutics, we used directed evolution by yeast-surface display to engineer the PD-1 ectodomain as a high-affinity (110 pM) competitive antagonist of PD-L1. In contrast to anti-PD-L1 monoclonal antibodies, high-affinity PD-1 demonstrated superior tumor penetration without inducing depletion of peripheral effector T cells. Consistent with these advantages, in syngeneic CT26 tumor models, high-affinity PD-1 was effective in treating both small (50 mm(3)) and large tumors (150 mm(3)), whereas the activity of anti-PD-L1 antibodies was completely abrogated against large tumors. Furthermore, we found that high-affinity PD-1 could be radiolabeled and applied as a PET imaging tracer to efficiently distinguish between PD-L1-positive and PD-L1-negative tumors in living mice, providing an alternative to invasive biopsy and histological analysis. These results thus highlight the favorable pharmacology of small, nonantibody therapeutics for enhanced cancer immunotherapy and immune diagnostics.

    View details for DOI 10.1073/pnas.1519623112

    View details for PubMedID 26604307

    View details for PubMedCentralID PMC4664306

  • Glioblastoma Multiforme Recurrence: An Exploratory Study of F-18 FPPRGD(2) PET/CT1 RADIOLOGY Iagaru, A., Mosci, C., Mittra, E., Zaharchuk, G., Fischbein, N., Harsh, G., Li, G., Nagpal, S., Recht, L., Gambhir, S. S. 2015; 277 (2): 497-506


    Purpose To prospectively evaluate fluorine 18 ((18)F) 2-fluoropropionyl-labeled PEGylated dimeric arginine-glycine-aspartic acid (RGD) peptide (PEG3-E[c{RGDyk}]2) (FPPRGD2) positron emission tomography (PET) in patients with glioblastoma multiforme (GBM). Materials and Methods The institutional review board approved this HIPAA-compliant protocol. Written informed consent was obtained from each patient. (18)F FPPRGD2 uptake was measured semiquantitatively in the form of maximum standardized uptake values (SUVmax) and uptake volumes before and after treatment with bevacizumab. Vital signs and laboratory results were collected before, during, and after the examinations. A nonparametric version of multivariate analysis of variance was used to assess safety outcome measures simultaneously across time points. A paired two-sample t test was performed to compare SUVmax. Results A total of 17 participants (eight men, nine women; age range, 25-65 years) were enrolled prospectively. (18)F FPPRGD2 PET/computed tomography (CT), (18)F fluorodeoxyglucose (FDG) PET/CT, and brain magnetic resonance (MR) imaging were performed within 3 weeks, prior to the start of bevacizumab therapy. In eight of the 17 patients (47%), (18)F FPPRGD2 PET/CT was repeated 1 week after the start of bevacizumab therapy; six patients (35%) underwent (18)F FPPRGD2 PET/CT a third time 6 weeks after starting bevacizumab therapy. There were no changes in vital signs, electrocardiographic findings, or laboratory values that qualified as adverse events. One patient (6%) had recurrent GBM identified only on (18)F FPPRGD2 PET images, and subsequent MR images enabled confirmation of recurrence. Of the 17 patients, 14 (82%) had recurrent GBM identified on (18)F FPPRGD2 PET and brain MR images, while (18)F FDG PET enabled identification of recurrence in 13 (76%) patients. Two patients (12%) had no recurrent GBM. Conclusion (18)F FPPRGD2 is a safe PET radiopharmaceutical that has increased uptake in GBM lesions. Larger cohorts are required to confirm these preliminary findings. (©) RSNA, 2015 Online supplemental material is available for this article.

    View details for DOI 10.1148/radiol.2015141550

    View details for Web of Science ID 000368435100026

  • Biodistribution of the (18)F-FPPRGD2 PET radiopharmaceutical in cancer patients: an atlas of SUV measurements. European journal of nuclear medicine and molecular imaging Minamimoto, R., Jamali, M., Barkhodari, A., Mosci, C., Mittra, E., Shen, B., Chin, F., Gambhir, S. S., Iagaru, A. 2015; 42 (12): 1850-1858


    The aim of this study was to investigate the biodistribution of 2-fluoropropionyl-labeled PEGylated dimeric arginine-glycine-aspartic acid (RGD) peptide (PEG3-E[c{RGDyk}]2) ((18)F-FPPRGD2) in cancer patients and to compare its uptake in malignant lesions with (18)F-FDG uptake.A total of 35 patients (11 men, 24 women, mean age 52.1 ± 10.8 years) were enrolled prospectively and had (18)F-FPPRGD2 PET/CT prior to treatment. Maximum standardized uptake values (SUVmax) and mean SUV (SUVmean) were measured in 23 normal tissues in each patient, as well as in known or suspected cancer lesions. Differences between (18)F-FPPRGD2 uptake and (18)F-FDG uptake were also evaluated in 28 of the 35 patients.Areas of high (18)F-FPPRGD2 accumulation (SUVmax range 8.9 - 94.4, SUVmean range 7.1 - 64.4) included the bladder and kidneys. Moderate uptake (SUVmax range 2.1 - 6.3, SUVmean range 1.1 - 4.5) was found in the choroid plexus, salivary glands, thyroid, liver, spleen, pancreas, small bowel and skeleton. Compared with (18)F-FDG, (18)F-FPPRGD2 showed higher tumor-to-background ratio in brain lesions (13.4 ± 8.5 vs. 1.1 ± 0.5, P < 0.001), but no significant difference in body lesions (3.2 ± 1.9 vs. 4.4 ± 4.2, P = 0.10). There was no significant correlation between the uptake values (SUVmax and SUVmean) for (18)F FPPRGD2 and those for (18)F-FDG.The biodistribution of (18)F-FPPRGD2 in cancer patients is similar to that of other RGD dimer peptides and it is suitable for clinical use. The lack of significant correlation between (18)F-FPPRGD2 and (18)F-FDG uptake confirms that the information provided by each PET tracer is different.

    View details for DOI 10.1007/s00259-015-3096-4

    View details for PubMedID 26062933

  • Novel Radiotracer for ImmunoPET Imaging of PD-1 Checkpoint Expression on Tumor Infiltrating Lymphocytes. Bioconjugate chemistry Natarajan, A., Mayer, A. T., Xu, L., Reeves, R. E., Gano, J., Gambhir, S. S. 2015; 26 (10): 2062-2069


    Immune checkpoint signaling through the programmed death 1 (PD-1) axis to its ligand (PD-L1) significantly dampens anti-tumor immune responses. Cancer patients treated with checkpoint inhibitors that block this suppressive signaling have exhibited objective response rates of 20-40% for advanced solid tumors, lymphomas, and malignant melanomas. This represents a tremendous advance in cancer treatment. Unfortunately, all patients do not respond to immune checkpoint blockade. Recent findings suggest that patients with tumor infiltrating lymphocytes (TILs) expressing PD-1 may be most likely to respond to αPD-1/PD-L1 checkpoint inhibitors. There is a compelling need for diagnostic and prognostic imaging tools to assess the PD-1 status of TILs in vivo. Here we have developed a novel immunoPET tracer to image PD-1 expressing TILs in a transgenic mouse model bearing melanoma. A (64)Cu labeled anti-mouse antibody (IgG) PD-1 immuno positron emission tomography (PET) tracer was developed to detect PD-1 expressing murine TILs. Quality control of the tracer showed >95% purity by HPLC and >70% immunoreactivity in an in vitro cell binding assay. ImmunoPET scans were performed over 1-48 h on Foxp3+.LuciDTR4 mice bearing B16-F10 melanoma tumors. Mice receiving anti-PD-1 tracer (200 ± 10 μCi/10-12 μg/200 μL) revealed high tracer uptake in lymphoid organs and tumors. BLI images of FoxP3(+) CD4(+) Tregs known to express PD-1 confirmed lymphocyte infiltration of tumors at the time of PET imaging. Biodistribution measurements performed at 48 h revealed a high (11×) tumor to muscle uptake ratio of the PET tracer (p < 0.05). PD-1 tumors exhibited 7.4 ± 0.7%ID/g tracer uptake and showed a 2× fold signal decrease when binding was blocked by unlabeled antibody. To the best of our knowledge this data is the first report to image PD-1 expression in living subjects with PET. This radiotracer has the potential to assess the prognostic value of PD-1 in preclinical models of immunotherapy and may ultimately aid in predicting response to therapies targeting immune checkpoints.

    View details for DOI 10.1021/acs.bioconjchem.5b00318

    View details for PubMedID 26307602

  • PET imaging of tumor glycolysis downstream of hexokinase through noninvasive measurement of pyruvate kinase M2. Science translational medicine Witney, T. H., James, M. L., Shen, B., Chang, E., Pohling, C., Arksey, N., Hoehne, A., Shuhendler, A., Park, J., Bodapati, D., Weber, J., Gowrishankar, G., Rao, J., Chin, F. T., Gambhir, S. S. 2015; 7 (310): 310ra169-?


    Cancer cells reprogram their metabolism to meet increased biosynthetic demands, commensurate with elevated rates of replication. Pyruvate kinase M2 (PKM2) catalyzes the final and rate-limiting step in tumor glycolysis, controlling the balance between energy production and the synthesis of metabolic precursors. We report here the synthesis and evaluation of a positron emission tomography (PET) radiotracer, [(11)C]DASA-23, that provides a direct noninvasive measure of PKM2 expression in preclinical models of glioblastoma multiforme (GBM). In vivo, orthotopic U87 and GBM39 patient-derived tumors were clearly delineated from the surrounding normal brain tissue by PET imaging, corresponding to exclusive tumor-associated PKM2 expression. In addition, systemic treatment of mice with the PKM2 activator TEPP-46 resulted in complete abrogation of the PET signal in intracranial GBM39 tumors. Together, these data provide the basis for the clinical evaluation of imaging agents that target this important gatekeeper of tumor glycolysis.

    View details for DOI 10.1126/scitranslmed.aac6117

    View details for PubMedID 26491079

  • Diketopyrrolopyrrole-Based Semiconducting Polymer Nanoparticles for In Vivo Photoacoustic Imaging. Advanced materials Pu, K., Mei, J., Jokerst, J. V., Hong, G., Antaris, A. L., Chattopadhyay, N., Shuhendler, A. J., Kurosawa, T., Zhou, Y., Gambhir, S. S., Bao, Z., Rao, J. 2015; 27 (35): 5184-5190


    Diketopyrrolopyrrole-based semiconducting polymer nanoparticles with high photostability and strong photoacoustic brightness are designed and synthesized, which results in 5.3-fold photoacoustic signal enhancement in tumor xenografts after systemic administration.

    View details for DOI 10.1002/adma.201502285

    View details for PubMedID 26247171

    View details for PubMedCentralID PMC4567488

  • A Systematic Comparison of 18F-C-SNAT to Established Radiotracer Imaging Agents for the Detection of Tumor Response to Treatment. Clinical cancer research Witney, T. H., Hoehne, A., Reeves, R. E., Ilovich, O., Namavari, M., Shen, B., Chin, F. T., Rao, J., Gambhir, S. S. 2015; 21 (17): 3896-3905


    An early readout of tumor response to therapy through measurement of drug or radiation-induced cell death may provide important prognostic indications and improved patient management. It has been shown that the uptake of (18)F-C-SNAT can be used to detect early response to therapy in tumors by positron emission tomography (PET) via a mechanism of caspase-3-triggered nanoaggregation.Here, we compared the preclinical utility of (18)F-C-SNAT for the detection of drug-induced cell death to clinically evaluated radiotracers, (18)F-FDG, (99m)Tc-Annexin V, and (18)F-ML-10 in tumor cells in culture, and in tumor-bearing mice in vivo.In drug-treated lymphoma cells, (18)F-FDG, (99m)Tc-Annexin V, and (18)F-C-SNAT cell-associated radioactivity correlated well to levels of cell death (R(2) > 0.8; P < 0.001), with no correlation measured for (18)F-ML-10 (R(2) = 0.05; P > 0.05). A similar pattern of response was observed in two human NSCLC cell lines following carboplatin treatment. EL-4 tumor uptake of (99m)Tc-Annexin V and (18)F-C-SNAT were increased 1.4- and 2.1-fold, respectively, in drug-treated versus naïve control animals (P < 0.05), although (99m)Tc-Annexin V binding did not correlate to ex vivo TUNEL staining of tissue sections. A differential response was not observed with either (18)F-FDG or (18)F-ML-10.We have demonstrated here that (18)F-C-SNAT can sensitively detect drug-induced cell death in murine lymphoma and human NSCLC. Despite favorable image contrast obtained with (18)F-C-SNAT, the development of next-generation derivatives, using the same novel and promising uptake mechanism, but displaying improved biodistribution profiles, are warranted for maximum clinical utility. Clin Cancer Res; 21(17); 3896-905. ©2015 AACR.

    View details for DOI 10.1158/1078-0432.CCR-14-3176

    View details for PubMedID 25972517

  • Androgen Receptor Splice Variants Dimerize to Transactivate Target Genes CANCER RESEARCH Xu, D., Zhan, Y., Qi, Y., Cao, B., Bai, S., Xu, W., Gambhir, S. S., Lee, P., Sartor, O., Flemington, E. K., Zhang, H., Hu, C., Dong, Y. 2015; 75 (17): 3663-3671


    Constitutively active androgen receptor splice variants (AR-V) lacking the ligand-binding domain have been implicated in the pathogenesis of castration-resistant prostate cancer and in mediating resistance to newer drugs that target the androgen axis. AR-V regulates expression of both canonical AR targets and a unique set of cancer-specific targets that are enriched for cell-cycle functions. However, little is known about how AR-V controls gene expression. Here, we report that two major AR-Vs, termed AR-V7 and AR(v567es), not only homodimerize and heterodimerize with each other but also heterodimerize with full-length androgen receptor (AR-FL) in an androgen-independent manner. We found that heterodimerization of AR-V and AR-FL was mediated by N- and C-terminal interactions and by the DNA-binding domain of each molecule, whereas AR-V homodimerization was mediated only by DNA-binding domain interactions. Notably, AR-V dimerization was required to transactivate target genes and to confer castration-resistant cell growth. Our results clarify the mechanism by which AR-Vs mediate gene regulation and provide a pivotal pathway for rational drug design to disrupt AR-V signaling as a rational strategy for the effective treatment of advanced prostate cancer.

    View details for DOI 10.1158/0008-5472.CAN-15-0381

    View details for Web of Science ID 000361917100021

    View details for PubMedID 26060018

  • Combined F-18-NaF and F-18-FDG PET/CT in the Evaluation of Sarcoma Patients CLINICAL NUCLEAR MEDICINE Jackson, T., Mosci, C., von Eyben, R., Mittra, E., Ganjoo, K., Biswal, S., Gambhir, S. S., Iagaru, A. 2015; 40 (9): 720-724


    The combined administration of F-NaF and F-FDG in a single PET/CT scan has the potential to improve patient convenience and cancer detection. Here we report the use of this approach for patients with sarcomas.This is a retrospective review of 21 patients (12 men, 9 women; age, 19-66 years) with biopsy-proven sarcomas who had separate F-NaF PET/CT, F-FDG PET/CT, and combined F-NaF/F-FDG PET/CT scans for evaluation of malignancy. Two board-certified nuclear medicine physicians and 1 board-certified musculoskeletal radiologist were randomly assigned to review the scans. Results were analyzed for sensitivity and specificity, using linear regression and receiver operating characteristics.A total of 13 patients had metastatic disease on F-NaF PET/CT, F-FDG PET/CT, and combined F-NaF/F-FDG PET/CT. Skeletal disease was more extensive on the F-NaF PET/CT scan than on the F-FDG PET/CT in 3 patients, whereas in 1 patient, F-FDG PET/CT showed skeletal disease and the F-NaF PET/CT was negative. Extraskeletal lesions were detected on both F-FDG and combined F-NaF/F-FDG PET/CT in 20 patients, with 1 discordant finding in the lung.The combined F-NaF/F-FDG PET/CT scan allows for accurate evaluation of sarcoma patients. Further evaluation of this proposed imaging modality is warranted to identify the most suitable clinical scenarios, including initial treatment strategy and evaluation of response to therapy.

    View details for DOI 10.1097/RLU.0000000000000845

    View details for Web of Science ID 000359668600005

    View details for PubMedID 26053718

  • Multitarget, quantitative nanoplasmonic electrical field-enhanced resonating device (NE2RD) for diagnostics. Proceedings of the National Academy of Sciences of the United States of America Inci, F., Filippini, C., Baday, M., Ozen, M. O., Calamak, S., Durmus, N. G., Wang, S., Hanhauser, E., Hobbs, K. S., Juillard, F., Kuang, P. P., Vetter, M. L., Carocci, M., Yamamoto, H. S., Takagi, Y., Yildiz, U. H., Akin, D., Wesemann, D. R., Singhal, A., Yang, P. L., Nibert, M. L., Fichorova, R. N., Lau, D. T., Henrich, T. J., Kaye, K. M., Schachter, S. C., Kuritzkes, D. R., Steinmetz, L. M., Gambhir, S. S., Davis, R. W., Demirci, U. 2015; 112 (32): E4354-63


    Recent advances in biosensing technologies present great potential for medical diagnostics, thus improving clinical decisions. However, creating a label-free general sensing platform capable of detecting multiple biotargets in various clinical specimens over a wide dynamic range, without lengthy sample-processing steps, remains a considerable challenge. In practice, these barriers prevent broad applications in clinics and at patients' homes. Here, we demonstrate the nanoplasmonic electrical field-enhanced resonating device (NE(2)RD), which addresses all these impediments on a single platform. The NE(2)RD employs an immunodetection assay to capture biotargets, and precisely measures spectral color changes by their wavelength and extinction intensity shifts in nanoparticles without prior sample labeling or preprocessing. We present through multiple examples, a label-free, quantitative, portable, multitarget platform by rapidly detecting various protein biomarkers, drugs, protein allergens, bacteria, eukaryotic cells, and distinct viruses. The linear dynamic range of NE(2)RD is five orders of magnitude broader than ELISA, with a sensitivity down to 400 fg/mL This range and sensitivity are achieved by self-assembling gold nanoparticles to generate hot spots on a 3D-oriented substrate for ultrasensitive measurements. We demonstrate that this precise platform handles multiple clinical samples such as whole blood, serum, and saliva without sample preprocessing under diverse conditions of temperature, pH, and ionic strength. The NE(2)RD's broad dynamic range, detection limit, and portability integrated with a disposable fluidic chip have broad applications, potentially enabling the transition toward precision medicine at the point-of-care or primary care settings and at patients' homes.

    View details for DOI 10.1073/pnas.1510824112

    View details for PubMedID 26195743

  • Radiation Dosimetry Study of [(89)Zr]rituximab Tracer for Clinical Translation of B cell NHL Imaging using Positron Emission Tomography. Molecular imaging and biology Natarajan, A., Gambhir, S. S. 2015; 17 (4): 539-547


    We evaluated the dosimetry of [(89)Zr]rituximab, an anti-CD20 immunoPET tracer to image B cell non-Hodgkin's lymphoma (NHL) using a humanized transgenic mouse model that expresses human CD20 transgenic mice (huCD20TM).Rituximab was conjugated to desferrioxamine (Df) for radiolabeling of Zirconium-89. [(89)Zr]rituximab (2.8 ± 0.2 MBq) was tail vein-injected into huCD20T mice. Positron emission tomography (PET)/CT imaging was performed on the two groups of mice (blocking = 2 mg/kg pre-dose of rituximab and non-blocking; n = 5) at eight time points (1, 4, 24, 48, 72, 96, 120, and 168 h) post injection.The novel [(89)Zr]rituximab PET tracer had good immunoreactivity, was stable in human serum, and was able to specifically target human CD20 in mice. The human equivalents of highest dose (mean ± SD) organs with and without pre-dose are liver (345 ± 284 μSv/MBq) and spleen (1165 ± 149 μSv/MBq), respectively.Dosimetry of the human patient whole-body dose was found to be 145 MBq per annum, and the patient dose-limiting organ will be the liver (with rituximab pre-dose blocking) and spleen for non-blocking. The [(89)Zr]rituximab (t½ = 78.4 h) imaging of B cell NHL patients could permit the observation of targeting lesions in NHL patients over an extended period due to longer half-life as compared to the [(64)Cu] rituximab (t½ = 12.7 h).

    View details for DOI 10.1007/s11307-014-0810-8

    View details for PubMedID 25500766

  • Isolation and Characterization of a Monobody with a Fibronectin Domain III Scaffold That Specifically Binds EphA2 PLOS ONE Park, S., Park, S., Kim, D., Pyo, A., Kimura, R. H., Sathirachinda, A., Choy, H. E., Min, J., Gambhir, S. S., Hong, Y. 2015; 10 (7)
  • Development and Validation of an Immuno-PET Tracer as a Companion Diagnostic Agent for Antibody-Drug Conjugate Therapy to Target the CA6 Epitope. Radiology Ilovich, O., Natarajan, A., Hori, S., Sathirachinda, A., Kimura, R., Srinivasan, A., Gebauer, M., Kruip, J., Focken, I., Lange, C., Carrez, C., Sassoon, I., Blanc, V., Sarkar, S. K., Gambhir, S. S. 2015; 276 (1): 191-198


    Purpose To develop and compare three copper 64 ((64)Cu)-labeled antibody fragments derived from a CA6-targeting antibody (huDS6) as immuno-positron emission tomography (immuno-PET)-based companion diagnostic agents for an antibody-drug conjugate by using huDS6. Materials and Methods Three antibody fragments derived from huDS6 were produced, purified, conjugated to 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), and evaluated in the following ways: (a) the affinity of the fragments and the DOTA conjugates was measured via flow cytometry, (b) the stability of the labeled fragments was determined ex vivo in human serum over 24 hours, and (c) comparison of the in vivo imaging potential of the fragments was evaluated in mice bearing subcutaneous CA6-positive and CA6-negative xenografts by using serial PET imaging and biodistribution. Isotype controls with antilysozyme and anti-DM4 B-Fabs and blocking experiments with an excess of either B-Fab or huDS6 were used to determine the extent of the antibody fragment (64)Cu-DOTA-B-Fab binding specificity. Immunoreactivity and tracer kinetics were evaluated by using cellular uptake and 48-hour imaging experiments, respectively. Statistical analyses were performed by using t tests, one-way analysis of variance, and Wilcoxon and Mann-Whitney tests. Results The antibody fragment (64)Cu-DOTA-B-Fab was more than 95% stable after 24 hours in human serum, had an immunoreactivity of more than 70%, and allowed differentiation between CA6-positive and CA6-negative tumors in vivo as early as 6 hours after injection, with a 1.7-fold uptake ratio between tumors. Isotype and blocking studies experiments showed tracer-specific uptake in antigen-positive tumors, despite some nonspecific uptake in both tumor models. Conclusion Three antibody fragments were produced and examined as potential companion diagnostic agents. (64)Cu-DOTA-B-Fab is a stable and effective immuno-PET tracer for CA6 imaging in vivo. (©) RSNA, 2015 Online supplemental material is available for this article.

    View details for DOI 10.1148/radiol.15140058

    View details for PubMedID 25734548

  • Early Detection of Sporadic Pancreatic Cancer Summative Review PANCREAS Chari, S. T., Kelly, K., Hollingsworth, M. A., Thayer, S. P., Ahlquist, D. A., Andersen, D. K., Batra, S. K., Brentnall, T. A., Canto, M., Cleeter, D. F., Firpo, M. A., Gambhir, S. S., Go, V. L., Hines, O. J., Kenner, B. J., Klimstra, D. S., Lerch, M. M., Levy, M. J., Maitra, A., Mulvihill, S. J., Petersen, G. M., Rhim, A. D., Simeone, D. M., Srivastava, S., Tanaka, M., Vinik, A. I., Wong, D. 2015; 44 (5): 693-712


    Pancreatic cancer (PC) is estimated to become the second leading cause of cancer death in the United States by 2020. Early detection is the key to improving survival in PC. Addressing this urgent need, the Kenner Family Research Fund conducted the inaugural Early Detection of Sporadic Pancreatic Cancer Summit Conference in 2014 in conjunction with the 45th Anniversary Meeting of the American Pancreatic Association and Japan Pancreas Society. This seminal convening of international representatives from science, practice, and clinical research was designed to facilitate challenging interdisciplinary conversations to generate innovative ideas leading to the creation of a defined collaborative strategic pathway for the future of the field. An in-depth summary of current efforts in the field, analysis of gaps in specific areas of expertise, and challenges that exist in early detection is presented within distinct areas of inquiry: Case for Early Detection: Definitions, Detection, Survival, and Challenges; Biomarkers for Early Detection; Imaging; and Collaborative Studies. In addition, an overview of efforts in familial PC is presented in an addendum to this article. It is clear from the summit deliberations that only strategically designed collaboration among investigators, institutions, and funders will lead to significant progress in early detection of sporadic PC.

    View details for DOI 10.1097/MPA.0000000000000368

    View details for Web of Science ID 000360629300003

    View details for PubMedCentralID PMC4467589

  • Predictive Modeling of Drug Response in Non-Hodgkin's Lymphoma PLOS ONE Frieboes, H. B., Smith, B. R., Wang, Z., Kotsuma, M., Ito, K., Day, A., Cahill, B., Flinders, C., Mumenthaler, S. M., Mallick, P., Simbawa, E., Al-Fhaid, A. S., Mahmoud, S. R., Gambhir, S. S., Cristini, V. 2015; 10 (6)


    We combine mathematical modeling with experiments in living mice to quantify the relative roles of intrinsic cellular vs. tissue-scale physiological contributors to chemotherapy drug resistance, which are difficult to understand solely through experimentation. Experiments in cell culture and in mice with drug-sensitive (Eµ-myc/Arf-/-) and drug-resistant (Eµ-myc/p53-/-) lymphoma cell lines were conducted to calibrate and validate a mechanistic mathematical model. Inputs to inform the model include tumor drug transport characteristics, such as blood volume fraction, average geometric mean blood vessel radius, drug diffusion penetration distance, and drug response in cell culture. Model results show that the drug response in mice, represented by the fraction of dead tumor volume, can be reliably predicted from these inputs. Hence, a proof-of-principle for predictive quantification of lymphoma drug therapy was established based on both cellular and tissue-scale physiological contributions. We further demonstrate that, if the in vitro cytotoxic response of a specific cancer cell line under chemotherapy is known, the model is then able to predict the treatment efficacy in vivo. Lastly, tissue blood volume fraction was determined to be the most sensitive model parameter and a primary contributor to drug resistance.

    View details for DOI 10.1371/journal.pone.0129433

    View details for Web of Science ID 000355979500143

    View details for PubMedID 26061425

  • Cu-64-Labeled Divalent Cystine Knot Peptide for Imaging Carotid Atherosclerotic Plaques JOURNAL OF NUCLEAR MEDICINE Jiang, L., Tu, Y., Kimura, R. H., Habte, F., Chen, H., Cheng, K., Shi, H., Gambhir, S. S., Cheng, Z. 2015; 56 (6): 939-944


    The rupture of vulnerable atherosclerotic plaques that lead to stroke and myocardial infarction may be induced by macrophage infiltration and augmented by the expression of integrin αvβ3. Indeed, atherosclerotic angiogenesis may be a promising marker of inflammation. In this study, an engineered integrin αvβ3-targeting PET probe, (64)Cu-NOTA-3-4A, derived from a divalent knottin miniprotein was evaluated in a mouse model for carotid atherosclerotic plaques.Atherosclerotic plaques in BALB/C mice, maintained on a high-fat diet, were induced with streptozotocin injection and carotid artery ligation and verified by MR imaging. Knottin 3-4A was synthesized by solid-phase peptide synthesis chemistry and coupled to 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) before radiolabeling with (64)Cu. PET probe stability in mouse serum was evaluated. Mice with carotid atherosclerotic plaques were injected via the tail vein with (64)Cu-NOTA-3-4A or (18)F-FDG, followed by small-animal PET/CT imaging at different time points. Receptor targeting specificity of the probe was verified by coinjection of c(RGDyK) administered in molar excess. Subsequently, carotid artery dissection and immunofluorescence staining were performed to evaluate target expression.(64)Cu-NOTA-3-4A was synthesized in high radiochemical purity and yield and demonstrated molecular stability in both phosphate-buffered saline and mouse serum at 4 h. Small-animal PET/CT showed that (64)Cu-NOTA-3-4A accumulated at significantly higher levels in the neovasculature of carotid atherosclerotic plaques (7.41 ± 1.44 vs. 0.67 ± 0.23 percentage injected dose/gram, P < 0.05) than healthy or normal vessels at 1 h after injection. (18)F-FDG also accumulated in atherosclerotic lesions at 0.5 and 1 h after injection but at lower plaque-to-normal tissue ratios than (64)Cu-NOTA-3-4A. For example, plaque-to-normal carotid artery ratios for (18)F-FDG and (64)Cu-NOTA-3-4A at 1 h after injection were 3.75 and 14.71 (P < 0.05), respectively. Furthermore, uptake of (64)Cu-NOTA-3-4A in atherosclerotic plaques was effectively blocked (∼90% at 1 h after injection) by coinjection of c(RGDyK). Immunostaining confirmed integrin αvβ3 expression in both the infiltrating macrophages and the neovasculature of atherosclerotic plaques.(64)Cu-NOTA-3-4A demonstrates specific accumulation in carotid atherosclerotic plaques in which macrophage infiltration and angiogenesis are responsible for elevated integrin αvβ3 levels. Therefore, (64)Cu-NOTA-3-4A may demonstrate clinical utility as a PET probe for atherosclerosis imaging or for the evaluation of therapies used to treat atherosclerosis.

    View details for DOI 10.2967/jnumed.115.155176

    View details for Web of Science ID 000355570300026

    View details for PubMedID 25908832

  • Development of a High-Throughput Molecular Imaging-Based Orthotopic Hepatocellular Carcinoma Model. Cureus Hwang, G. L., van den Bosch, M. A., Kim, Y. I., Katzenberg, R., Willmann, J. K., Paulmurugan, R., Gambhir, S. S., Hofmann, L. 2015; 7 (6)


    We have developed a novel orthotopic rat hepatocellular (HCC) model and have assessed the ability to use bioluminescence imaging (BLI), positron emission tomography (PET), and ultrasound for early tumor detection and monitoring of disease progression.  Briefly, rat HCC cells were stably transfected with click beetle red as a reporter gene for BLI. Tumor cells were injected under direct visualization into the left or middle lobe of the liver in 37 rats. In six animals, serial PET, BLI, and ultrasound imaging were performed at 10-time points in 28 days. The remainder of the animals underwent PET imaging at 14 days. Tumor implantation was successful in 34 of 37 animals (91.9%). In the six animals that underwent serial imaging, tumor formation was first detected with BLI on Day 4 with continued increase through Day 21, and hypermetabolic activity on PET was first noted on Days 14-15 with continued increase through Day 28. PET activity was seen on Day 14 in the 28 other animals that demonstrated tumor development. Anatomic tumor formation was detected with ultrasound at Days 10-12 with continued growth through Day 28. The first metastases were detected by PET after Day 24.        We have successfully developed and validated a novel orthotopic HCC small animal model that permits longitudinal assessment of change in tumor size using molecular imaging techniques. BLI is the most sensitive imaging method for detection of early tumor formation and growth. This model permits high-throughput in vivo evaluation of image-guided therapies.

    View details for DOI 10.7759/cureus.281

    View details for PubMedID 26180705

  • Semiquantitative Analysis of the Biodistribution of the Combined F-18-NaF and F-18-FDG Administration for PET/CT Imaging JOURNAL OF NUCLEAR MEDICINE Minamimoto, R., Mosci, C., Jamali, M., Barkhodari, A., Habte, F., Jackson, T., Mittra, E., Gambhir, S. S., Iagaru, A. 2015; 56 (5): 688-694


    In this study we evaluated the biodistribution of the (18)F-/(18)F-FDG administration compared to separate (18)F-NaF and (18)F-FDG. We also estimated the interaction of (18)F-NaF and (18)F-FDG in the (18)F-/(18)F-FDG administration by semiquantitative analysis.We retrospectively analyzed data of 49 patients (male 39, female 10; mean ± SD age: 59.3 ± 15.2 years) who had separate (18)F-FDG PET/CT and (18)F-NaF PET/CT, as well as the (18)F-/(18)F-FDG PET/CT sequentially. The most common primary diagnosis was prostate cancer (n = 28), followed by sarcoma (n = 9) and breast cancer (n = 6). The mean standardized uptake values (SUVmean) were recorded for 18 organs in all patients, while maximum SUV (SUVmax) and SUVmean were recorded for all the identified malignant lesions. We also estimated the (18)F-/(18)F-FDG uptake by sum of (18)F-FDG uptake and adjusted (18)F-NaF uptake based on the ratio of (18)F-NaF injected dose in (18)F-/(18)F-FDG PET/CT. Lastly, we compared the results in order to explore the interaction of (18)F-FDG and (18)F-NaF uptake in the (18)F-/(18)F-FDG scan.The (18)F-/(18)F-FDG uptake in the cerebral cortex, cerebellum, parotid grand, myocardium and bowel mostly reflect the (18)F-FDG uptake, while the uptake in the other analyzed structures is influenced by both the (18)F-FDG and the (18)F-NaF uptake. The (18)F-/(18)F-FDG uptake in extra skeletal lesions shows no significant difference when compared to the uptake from the separate (18)F-FDG scan. The (18)F-/(18)F-FDG uptake in skeletal lesions reflected mostly the (18)F-NaF uptake. Tumor to background (T/B) ratio of (18)F-/(18)F-FDG in extra skeletal lesions showed no significant difference when compared with that from (18)F-FDG alone (P = 0.73). For skeletal lesions, T/B ratio of (18)F-/(18)F-FDG was lower than that from (18)F-NaF alone (P <0.001); however, this difference did not result in missed skeletal lesions on the (18)F-/(18)F-FDG scan.The understanding of the biodistribution of radiopharmaceuticals and the lesions uptake of the (18)F-/(18)F-FDG scan, as well as the variations compared to the uptake on the separate (18)F-FDG PET/CT and (18)F-NaF PET/CT are valuable for more in depth evaluation of the combined scanning technique.

    View details for DOI 10.2967/jnumed.115.153767

    View details for Web of Science ID 000353831000013

    View details for PubMedID 25840978

  • Optical coherence contrast imaging using gold nanorods in living mice eyes CLINICAL AND EXPERIMENTAL OPHTHALMOLOGY de la Zerda, A., Prabhulkar, S., Perez, V. L., Ruggeri, M., Paranjape, A. S., Habte, F., Gambhir, S. S., Awdeh, R. M. 2015; 43 (4): 358-366


    Optical coherence tomography (OCT) is a powerful imaging modality to visualize tissue structures, with axial image pixel resolution as high as 1.6 μm in tissue. However, OCT is intrinsically limited to providing structural information as the OCT contrast is produced by optically scattering tissues.Gold nanorods (GNRs) were injected into the anterior chamber (AC) and cornea of mice eyes which could create a significant OCT signal and hence could be used as a contrast agent for in vivo OCT imaging.A dose of 30 nM of GNRs (13 nm in diameter and 45 nm in length) were injected to the AC of mice eyes and produced an OCT contrast nearly 50-fold higher than control mice injected with saline. Furthermore, the lowest detectable concentration of GNRs in living mice AC was experimentally estimated to be as low as 120 pM.The high sensitivity and low toxicity of GNRs brings great promise for OCT to uniquely become a high-resolution molecular imaging modality.

    View details for DOI 10.1111/ceo.12299

    View details for Web of Science ID 000356810200009

    View details for PubMedID 24533647

  • A Real-Time Clinical Endoscopic System for Intraluminal, Multiplexed Imaging of Surface-Enhanced Raman Scattering Nanoparticles PLOS ONE Garai, E., Sensarn, S., Zavaleta, C. L., Loewke, N. O., Rogalla, S., Mandella, M. J., Felt, S. A., Friedland, S., Liu, J. T., Gambhir, S. S., Contag, C. H. 2015; 10 (4)

    View details for DOI 10.1371/journal.pone.0123185

    View details for Web of Science ID 000353711600032

    View details for PubMedID 25923788

  • Synthesis of [(18)F]-labelled Maltose Derivatives as PET Tracers for Imaging Bacterial Infection. Molecular imaging and biology Namavari, M., Gowrishankar, G., Hoehne, A., Jouannot, E., Gambhir, S. S. 2015; 17 (2): 168-176


    To develop novel positron emission tomography (PET) agents for visualization and therapy monitoring of bacterial infections.It is known that maltose and maltodextrins are energy sources for bacteria. Hence, (18)F-labelled maltose derivatives could be a valuable tool for imaging bacterial infections. We have developed methods to synthesize 4-O-(α-D-glucopyranosyl)-6-deoxy-6-[(18)F]fluoro-D-glucopyranoside (6-[(18)F]fluoromaltose) and 4-O-(α-D-glucopyranosyl)-1-deoxy-1-[(18)F]fluoro-D-glucopyranoside (1-[(18)F]fluoromaltose) as bacterial infection PET imaging agents. 6-[(18)F]fluoromaltose was prepared from precursor 1,2,3-tri-O-acetyl-4-O-(2',3',-di-O-acetyl-4',6'-benzylidene-α-D-glucopyranosyl)-6-deoxy-6-nosyl-D-glucopranoside (5). The synthesis involved the radio-fluorination of 5 followed by acidic and basic hydrolysis to give 6-[(18)F]fluoromaltose. In an analogous procedure, 1-[(18)F]fluoromaltose was synthesized from 2,3, 6-tri-O-acetyl-4-O-(2',3',4',6-tetra-O-acetyl-α-D-glucopyranosyl)-1-deoxy-1-O-triflyl-D-glucopranoside (9). Stability of 6-[(18)F]fluoromaltose in phosphate-buffered saline (PBS) and human and mouse serum at 37 °C was determined. Escherichia coli uptake of 6-[(18)F]fluoromaltose was examined.A reliable synthesis of 1- and 6-[(18)F]fluoromaltose has been accomplished with 4-6 and 5-8 % radiochemical yields, respectively (decay-corrected with 95 % radiochemical purity). 6-[(18)F]fluoromaltose was sufficiently stable over the time span needed for PET studies (∼96 % intact compound after 1-h and ∼65 % after 2-h incubation in serum). Bacterial uptake experiments indicated that E. coli transports 6-[(18)F]fluoromaltose. Competition assays showed that the uptake of 6-[(18)F]fluoromaltose was completely blocked by co-incubation with 1 mM of the natural substrate maltose.We have successfully synthesized 1- and 6-[(18)F]fluoromaltose via direct fluorination of appropriate protected maltose precursors. Bacterial uptake experiments in E. coli and stability studies suggest a possible application of 6-[(18)F]fluoromaltose as a new PET imaging agent for visualization and monitoring of bacterial infections.

    View details for DOI 10.1007/s11307-014-0793-5

    View details for PubMedID 25277604

  • Detecting cancers through tumor-activatable minicircles that lead to a detectable blood biomarker. Proceedings of the National Academy of Sciences of the United States of America Ronald, J. A., Chuang, H., Dragulescu-Andrasi, A., Hori, S. S., Gambhir, S. S. 2015; 112 (10): 3068-3073


    Earlier detection of cancers can dramatically improve the efficacy of available treatment strategies. However, despite decades of effort on blood-based biomarker cancer detection, many promising endogenous biomarkers have failed clinically because of intractable problems such as highly variable background expression from nonmalignant tissues and tumor heterogeneity. In this work we present a tumor-detection strategy based on systemic administration of tumor-activatable minicircles that use the pan-tumor-specific Survivin promoter to drive expression of a secretable reporter that is detectable in the blood nearly exclusively in tumor-bearing subjects. After systemic administration we demonstrate a robust ability to differentiate mice bearing human melanoma metastases from tumor-free subjects for up to 2 wk simply by measuring blood reporter levels. Cumulative change in reporter levels also identified tumor-bearing subjects, and a receiver operator-characteristic curve analysis highlighted this test's performance with an area of 0.918 ± 0.084. Lung tumor burden additionally correlated (r(2) = 0.714; P < 0.05) with cumulative reporter levels, indicating that determination of disease extent was possible. Continued development of our system could improve tumor detectability dramatically because of the temporally controlled, high reporter expression in tumors and nearly zero background from healthy tissues. Our strategy's highly modular nature also allows it to be iteratively optimized over time to improve the test's sensitivity and specificity. We envision this system could be used first in patients at high risk for tumor recurrence, followed by screening high-risk populations before tumor diagnosis, and, if proven safe and effective, eventually may have potential as a powerful cancer-screening tool for the general population.

    View details for DOI 10.1073/pnas.1414156112

    View details for PubMedID 25713388

  • Detection of Osseous Metastasis by 18F-NaF/18F-FDG PET/CT Versus CT Alone. Clinical nuclear medicine Sampath, S. C., Sampath, S. C., Mosci, C., Lutz, A. M., Willmann, J. K., Mittra, E. S., Gambhir, S. S., Iagaru, A. 2015; 40 (3): e173-7

    View details for DOI 10.1097/RLU.0000000000000560

    View details for PubMedID 25140557

  • 18F-FPRGD2 PET/CT imaging of integrin avß3 in renal carcinomas: correlation with histopathology. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Withofs, N., Signolle, N., Somja, J., Lovinfosse, P., Nzaramba, E. M., Mievis, F., Giacomelli, F., Waltregny, D., Cataldo, D., Gambhir, S. S., Hustinx, R. 2015; 56 (3): 361-364


    This study aimed to correlate (18)F-FB-mini-PEG-E[c(RGDyK)](2) ((18)F-FPRGD2) uptake to integrin αvβ3 expression and angiogenesis in renal tumors.(18)F-FPRGD2 PET/CT was performed on 27 patients before surgical resection (median 4 d) of a renal mass. The (18)F-FPRGD2 uptake was compared with integrin αvβ3, CD31, CD105, and Ki-67 using immunohistochemistry; with placental growth factor and vascular endothelial growth factor receptors 1 and 2 using reverse transcription polymerase chain reaction; and with vascular endothelial growth factor A isoforms using enzyme-linked immunosorbent assay.Overall, (18)F-FPRGD2 uptake significantly correlated (P < 0.0001) with integrin αvβ3 expression in renal masses. However, it correlated only with integrin αvβ3-positive vessels in the group of papillary carcinomas whereas it correlated with integrin αvβ3 expression by tumor cells in the clear cell carcinoma group.(18)F-FPRGD2 uptake reflects the expression of integrin αvβ3 in renal tumors but represents angiogenesis only when tumor cells do not express the integrin.

    View details for DOI 10.2967/jnumed.114.149021

    View details for PubMedID 25655629

  • PET Imaging of Translocator Protein (18 kDa) in a Mouse Model of Alzheimer's Disease Using N-(2,5-Dimethoxybenzyl)-2-18F-Fluoro-N-(2-Phenoxyphenyl)Acetamide. Journal of nuclear medicine : official publication, Society of Nuclear Medicine James, M. L., Belichenko, N. P., Nguyen, T. V., Andrews, L. E., Ding, Z., Liu, H., Bodapati, D., Arksey, N., Shen, B., Cheng, Z., Wyss-Coray, T., Gambhir, S. S., Longo, F. M., Chin, F. T. 2015; 56 (2): 311-316


    Herein we aimed to evaluate the utility of N-(2,5-dimethoxybenzyl)-2-(18)F-fluoro-N-(2-phenoxyphenyl)acetamide ((18)F-PBR06) for detecting alterations in translocator protein (TSPO) (18 kDa), a biomarker of microglial activation, in a mouse model of Alzheimer's disease (AD).Wild-type (wt) and AD mice (i.e., APP(L/S)) underwent (18)F-PBR06 PET imaging at predetermined time points between the ages of 5-6 and 15-16 mo. MR images were fused with PET/CT data to quantify (18)F-PBR06 uptake in the hippocampus and cortex. Ex vivo autoradiography and TSPO/CD68 immunostaining were also performed using brain tissue from these mice.PET images showed significantly higher accumulation of (18)F-PBR06 in the cortex and hippocampus of 15- to 16-mo-old APP(L/S) mice than age-matched wts (cortex/muscle: 2.43 ± 0.19 vs. 1.55 ± 0.15, P < 0.005; hippocampus/muscle: 2.41 ± 0.13 vs. 1.55 ± 0.12, P < 0.005). And although no significant difference was found between wt and APP(L/S) mice aged 9-10 mo or less using PET (P = 0.64), we were able to visualize and quantify a significant difference in (18)F-PBR06 uptake in these mice using autoradiography (cortex/striatum: 1.13 ± 0.04 vs. 0.96 ± 0.01, P < 0.05; hippocampus/striatum: 1.266 ± 0.003 vs. 1.096 ± 0.017, P < 0.001). PET results for 15- to 16-mo-old mice correlated well with autoradiography and immunostaining (i.e., increased (18)F-PBR06 uptake in brain regions containing elevated CD68 and TSPO staining in APP(L/S) mice, compared with wts).(18)F-PBR06 shows great potential as a tool for visualizing TSPO/microglia in the progression and treatment of AD.

    View details for DOI 10.2967/jnumed.114.141648

    View details for PubMedID 25613536

  • Sol-Gel Synthesis and Electrospraying of Biodegradable (P2O5)(55)-(CaO)(30)-(Na2O)(15) Glass Nanospheres as a Transient Contrast Agent for Ultrasound Stem Cell Imaging ACS NANO Foroutan, F., Jokerst, J. V., Gambhir, S. S., Vermesh, O., Kim, H., Knowles, J. C. 2015; 9 (2): 1868-1877


    Ultrasound imaging is a powerful tool in medicine because of the millisecond temporal resolution and submillimeter spatial resolution of acoustic imaging. However, the current generation of acoustic contrast agents is primarily limited to vascular targets due to their large size. Nanosize particles have the potential to be used as a contrast agent for ultrasound molecular imaging. Silica-based nanoparticles have shown promise here; however, their slow degradation rate may limit their applications as a contrast agent. Phosphate-based glasses are an attractive alternative with controllable degradation rate and easily metabolized degradation components in the body. In this study, biodegradable P2O5-CaO-Na2O phosphate-based glass nanospheres (PGNs) were synthesized and characterized as contrast agents for ultrasound imaging. The structure of the PGNs was characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), (31)P magic angle spinning nuclear magnetic resonance ((31)P MAS NMR), and Fourier transform infrared (FTIR) spectroscopy. The SEM images indicated a spherical shape with a diameter size range of 200-500 nm. The XRD, (31)P NMR, and FTIR results revealed the amorphous and glassy nature of PGNs that consisted of mainly Q(1) and Q(2) phosphate units. We used this contrast to label mesenchymal stem cells and determined in vitro and in vivo detection limits of 5 and 9 μg/mL, respectively. Cell counts down to 4000 could be measured with ultrasound imaging with no cytoxicity at doses needed for imaging. Importantly, ion-release studies confirmed these PGNs biodegrade into aqueous media with degradation products that can be easily metabolized in the body.

    View details for DOI 10.1021/nn506789y

    View details for Web of Science ID 000349940500083

    View details for PubMedID 25625373

  • 18F-FAZA PET Imaging Response Tracks the Reoxygenation of Tumors in Mice upon Treatment with the Mitochondrial Complex I Inhibitor BAY 87-2243. Clinical cancer research Chang, E., Liu, H., Unterschemmann, K., Ellinghaus, P., Liu, S., Gekeler, V., Cheng, Z., Berndorff, D., Gambhir, S. S. 2015; 21 (2): 335-346


    We describe a noninvasive PET imaging method that monitors early therapeutic efficacy of BAY 87-2243, a novel small-molecule inhibitor of mitochondrial complex I as a function of hypoxia-inducible factor-1α (HIF1α) activity.Four PET tracers [(18)F-FDG, (18)F-Fpp(RGD)2, (18)F-FLT, and (18)F-FAZA] were assessed for uptake into tumor xenografts of drug-responsive (H460, PC3) or drug-resistant (786-0) carcinoma cells. Mice were treated with BAY 87-2243 or vehicle. At each point, RNA from treated and vehicle H460 tumor xenografts (n = 3 each) was isolated and analyzed for target genes.Significant changes in uptake of (18)F-FAZA, (18)F-FLT, and (18)F-Fpp(RGD)2 (P < 0.01) occurred with BAY 87-2243 treatment with (18)F-FAZA being the most prominent. (18)F-FDG uptake was unaffected. (18)F-FAZA tumor uptake declined by 55% to 70% (1.21% ± 0.10%ID/g to 0.35 ± 0.1%ID/g; n = 6, vehicle vs. treatment) in both H460 (P < 0.001) and PC3 (P < 0.05) xenografts 1 to 3 days after drug administration. (18)F-FAZA uptake in 786-0 xenografts was unaffected. Decline occurred before significant differences in tumor volume, thus suggesting (18)F-FAZA decrease reflected early changes in tumor metabolism. BAY 87-2243 reduced expression of hypoxia-regulated genes CA IX, ANGPTL4, and EGLN-3 by 99%, 93%, and 83%, respectively (P < 0.001 for all), which corresponds with reduced (18)F-FAZA uptake upon drug treatment. Heterogeneous expression of genes associated with glucose metabolism, vessel density, and proliferation was observed.Our studies suggest suitability of (18)F-FAZA-PET as an early pharmacodynamic monitor on the efficacy of anticancer agents that target the mitochondrial complex I and intratumor oxygen levels (e.g., BAY 87-2243). Clin Cancer Res; 21(2); 335-46. ©2014 AACR.

    View details for DOI 10.1158/1078-0432.CCR-14-0217

    View details for PubMedID 25381339

  • Simultaneous Whole-Body Time-of-Flight F-18-FDG PET/MRI A Pilot Study Comparing SUVmax With PET/CT and Assessment of MR Image Quality CLINICAL NUCLEAR MEDICINE Iagaru, A., Mittra, E., Minamimoto, R., Jamali, M., Levin, C., Quon, A., Gold, G., Herfkens, R., Vasanawala, S., Gambhir, S. S., Zaharchuk, G. 2015; 14 (1): 1-8
  • A Magnetic Bead-Based Sensor for the Quantification of Multiple Prostate Cancer Biomarkers. PloS one Jokerst, J. V., Chen, Z., Xu, L., Nolley, R., Chang, E., Mitchell, B., Brooks, J. D., Gambhir, S. S. 2015; 10 (9)

    View details for DOI 10.1371/journal.pone.0139484

    View details for PubMedID 26421725

  • Parts per billion detection of uranium with a porphyrinoid-containing nanoparticle and in vivo photoacoustic imaging ANALYST Ho, I., Sessler, J. L., Gambhir, S. S., Jokerst, J. V. 2015; 140 (11): 3731-3737


    Chemical tools that can report radioactive isotopes would be of interest to the defense community. Here we report ∼250 nm polymeric nanoparticles containing porphyrinoid macrocycles with and without pre-complexed depleted uranium and demonstrate that the latter species may be detected easily and with high sensitivity via photoacoustic imaging. The porphyrinoid macrocycles used in the present study are non-aromatic in the absence of the uranyl cation, but aromatic after cation complexation. We solubilized both the freebase and metalated forms of the macrocycles in poly(lactic-co-glycolic acid) and found a peak in the photoacoustic spectrum at 910 nm excitation in the case of the uranyl complex. The signal was stable for at least 15 minutes and allowed detection of uranium concentrations down to 6.2 ppb (5.7 nM) in vitro and 0.57 ppm (19 fCi; 0.52 μM) in vivo. To the best of our knowledge, this is the first report of a nanoparticle that detects an actinide cation via photoacoustic imaging.

    View details for DOI 10.1039/c5an00207a

    View details for Web of Science ID 000354650300006

    View details for PubMedID 25854506

  • A multimodal imaging agent for intrinsic surface enhanced Raman scattering of biological tissue Conference on Plasmonics in Biology and Medicine XII Pohling, C. B., Campbell, J. L., Larson, T. A., Gambhir, S. S. SPIE-INT SOC OPTICAL ENGINEERING. 2015

    View details for DOI 10.1117/12.2077890

    View details for Web of Science ID 000353615600006

  • Theranostic mesoporous silica nanoparticles biodegrade after pro-survival drug delivery and ultrasound/magnetic resonance imaging of stem cells. Theranostics Kempen, P. J., Greasley, S., Parker, K. A., Campbell, J. L., Chang, H., Jones, J. R., Sinclair, R., Gambhir, S. S., Jokerst, J. V. 2015; 5 (6): 631-642


    Increasing cell survival in stem cell therapy is an important challenge for the field of regenerative medicine. Here, we report theranostic mesoporous silica nanoparticles that can increase cell survival through both diagnostic and therapeutic approaches. First, the nanoparticle offers ultrasound and MRI signal to guide implantation into the peri-infarct zone and away from the most necrotic tissue. Second, the nanoparticle serves as a slow release reservoir of insulin-like growth factor (IGF)-a protein shown to increase cell survival. Mesenchymal stem cells labeled with these nanoparticles had detection limits near 9000 cells with no cytotoxicity at the 250 µg/mL concentration required for labeling. We also studied the degradation of the nanoparticles and showed that they clear from cells in approximately 3 weeks. The presence of IGF increased cell survival up to 40% (p<0.05) versus unlabeled cells under in vitro serum-free culture conditions.

    View details for DOI 10.7150/thno.11389

    View details for PubMedID 25825602

  • Validation of 64Cu-DOTA-rituximab injection preparation under good manufacturing practices: a PET tracer for imaging of B-cell non-Hodgkin lymphoma. Molecular imaging Natarajan, A., Arksey, N., Iagaru, A., Chin, F. T., Gambhir, S. S. 2015; 14

    View details for DOI 10.2310/7290.2014.00055

    View details for PubMedID 25762106

  • A Magnetic Bead-Based Sensor for the Quantification of Multiple Prostate Cancer Biomarkers. PloS one Jokerst, J. V., Chen, Z., Xu, L., Nolley, R., Chang, E., Mitchell, B., Brooks, J. D., Gambhir, S. S. 2015; 10 (9)


    Novel biomarker assays and upgraded analytical tools are urgently needed to accurately discriminate benign prostatic hypertrophy (BPH) from prostate cancer (CaP). To address this unmet clinical need, we report a piezeoelectric/magnetic bead-based assay to quantitate prostate specific antigen (PSA; free and total), prostatic acid phosphatase, carbonic anhydrase 1 (CA1), osteonectin, IL-6 soluble receptor (IL-6sr), and spondin-2. We used the sensor to measure these seven proteins in serum samples from 120 benign prostate hypertrophy patients and 100 Gleason score 6 and 7 CaP using serum samples previously collected and banked. The results were analyzed with receiver operator characteristic curve analysis. There were significant differences between BPH and CaP patients in the PSA, CA1, and spondin-2 assays. The highest AUC discrimination was achieved with a spondin-2 OR free/total PSA operation-the area under the curve was 0.84 with a p value below 10-6. Some of these data seem to contradict previous reports and highlight the importance of sample selection and proper assay building in the development of biomarker measurement schemes. This bead-based system offers important advantages in assay building including low cost, high throughput, and rapid identification of an optimal matched antibody pair.

    View details for DOI 10.1371/journal.pone.0139484

    View details for PubMedID 26421725

  • Validation of 64Cu-DOTA-rituximab injection preparation under good manufacturing practices: a PET tracer for imaging of B-cell non-Hodgkin lymphoma. Molecular imaging Natarajan, A., Arksey, N., Iagaru, A., Chin, F. T., Gambhir, S. S. 2015; 14


    AbstractManufacturing of 64Cu-1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA)-rituximab injection under good manufacturing practices (GMP) was validated for imaging of patients with CD20+ B-cell non-Hodgkin lymphoma. Rituximab was purified by size exclusion high performance liquid chromatography (HPLC) and conjugated to DOTA-mono-(N-hydroxysuccinimidyl) ester. 64CuCl2, buffers, reagents, and other raw materials were obtained as high-grade quality. Following a semi-automated synthesis of 64Cu-DOTA-rituximab, a series of quality control tests was performed. The product was further tested in vivo using micro-positron emission tomography/computed tomography (PET/CT) to assess targeting ability towards human CD20 in transgenic mice. Three batches of 64Cu-DOTA-rituximab final product were prepared as per GMP specifications. The radiolabeling yield from these batches was 93.1 ± 5.8%; these provided final product with radiopharmaceutical yield, purity, and specific activity of 59.2 ± 5.1% (0.9 ± 0.1 GBq of 64Cu), > 95% (by HPLC and radio-thin layer chromatography), and 229.4 ± 43.3 GBq/µmol (or 1.5 ± 0.3 MBq/µg), respectively. The doses passed apyrogenicity and human serum stability specifications, were sterile up to 14 days, and retained > 60% immunoreactivity. In vivo micro-PET/CT mouse images at 24 hours postinjection showed that the tracer targeted the intended sites of human CD20 expression. Thus, we have validated the manufacturing of GMP grade 64Cu-DOTA-rituximab for injection in the clinical setting.

    View details for DOI 10.2310/7290.2014.00055

    View details for PubMedID 25762106

  • A correlative optical microscopy and scanning electron microscopy approach to locating nanoparticles in brain tumors. Micron Kempen, P. J., Kircher, M. F., de la Zerda, A., Zavaleta, C. L., Jokerst, J. V., Mellinghoff, I. K., Gambhir, S. S., Sinclair, R. 2015; 68: 70-76


    The growing use of nanoparticles in biomedical applications, including cancer diagnosis and treatment, demands the capability to exactly locate them within complex biological systems. In this work a correlative optical and scanning electron microscopy technique was developed to locate and observe multi-modal gold core nanoparticle accumulation in brain tumor models. Entire brain sections from mice containing orthotopic brain tumors injected intravenously with nanoparticles were imaged using both optical microscopy to identify the brain tumor, and scanning electron microscopy to identify the individual nanoparticles. Gold-based nanoparticles were readily identified in the scanning electron microscope using backscattered electron imaging as bright spots against a darker background. This information was then correlated to determine the exact location of the nanoparticles within the brain tissue. The nanoparticles were located only in areas that contained tumor cells, and not in the surrounding healthy brain tissue. This correlative technique provides a powerful method to relate the macro- and micro-scale features visible in light microscopy with the nanoscale features resolvable in scanning electron microscopy.

    View details for DOI 10.1016/j.micron.2014.09.004

    View details for PubMedID 25464144

  • Syntheses and Discovery of a Novel Class of Cinnamic Hydroxamates as Histone Deacetylase Inhibitors by Multimodality Molecular Imaging in Living Subjects CANCER RESEARCH CHAN, C. T., Qi, J., Smith, W., Paranol, R., Mazitschek, R., West, N., Reeves, R., Chiosis, G., Schreiber, S. L., Bradner, J. E., Paulmurugan, R., Gambhir, S. S. 2014; 74 (24): 7475-7486


    Histone deacetylases (HDAC) that regulate gene expression are being explored as cancer therapeutic targets. In this study, we focused on HDAC6 based on its ability to inhibit cancerous Hsp90 chaperone activities by disrupting Hsp90/p23 interactions. To identify novel HDAC6 inhibitors, we used a dual-luciferase reporter system in cell culture and living mice by bioluminescence imaging (BLI). On the basis of existing knowledge, a library of hydrazone compounds was generated for screening by coupling cinnamic hydroxamates with aldehydes and ketones. Potency and selectivity were determined by in vitro HDAC profiling assays, with further evaluation to inhibit Hsp90(α/β)/p23 interactions by BLI. In this manner, we identified compound 1A12 as a dose-dependent inhibitor of Hsp90(α/β)/p23 interactions, UKE-1 myeloid cell proliferation, p21(waf1) upregulation, and acetylated histone H3 levels. 1A12 was efficacious in tumor xenografts expressing Hsp90(α)/p23 reporters relative to carrier control-treated mice as determined by BLI. Small animal (18)F-FDG PET/CT imaging on the same cohort showed that 1A12 also inhibited glucose metabolism relative to control subjects. Ex vivo analyses of tumor lysates showed that 1A12 administration upregulated acetylated-H3 by approximately 3.5-fold. Taken together, our results describe the discovery and initial preclinical validation of a novel selective HDAC inhibitor.

    View details for DOI 10.1158/0008-5472.CAN-14-0197

    View details for Web of Science ID 000346363900031

    View details for PubMedID 25320008

  • Noninvasive Reporter Gene Imaging of Human Oct4 (Pluripotency) Dynamics During the Differentiation of Embryonic Stem Cells in Living Subjects MOLECULAR IMAGING AND BIOLOGY Ahn, B., Parashurama, N., Patel, M., Ziv, K., Bhaumik, S., Yaghoubi, S. S., Paulmurugan, R., Gambhir, S. S. 2014; 16 (6): 865-876
  • A Radiofluorinated Divalent Cystine Knot Peptide for Tumor PET Imaging MOLECULAR PHARMACEUTICS Jiang, L., Kimura, R. H., Ma, X., Tu, Y., Miao, Z., Shen, B., Chin, F. T., Shi, H., Gambhir, S. S., Cheng, Z. 2014; 11 (11): 3885-3892

    View details for DOI 10.1021/mp500018s

    View details for Web of Science ID 000344307700012

  • Cerenkov luminescence endoscopy: improved molecular sensitivity with ß--emitting radiotracers. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Carpenter, C. M., Ma, X., Liu, H., Sun, C., Pratx, G., Wang, J., Gambhir, S. S., Xing, L., Cheng, Z. 2014; 55 (11): 1905-1909


    Cerenkov luminescence endoscopy (CLE) is an optical technique that captures the Cerenkov photons emitted from highly energetic moving charged particles (β(+) or β(-)) and can be used to monitor the distribution of many clinically available radioactive probes. A main limitation of CLE is its limited sensitivity to small concentrations of radiotracer, especially when used with a light guide. We investigated the improvement in the sensitivity of CLE brought about by using a β(-) radiotracer that improved Cerenkov signal due to both higher β-particle energy and lower γ noise in the imaging optics because of the lack of positron annihilation.The signal-to-noise ratio (SNR) of (90)Y was compared with that of (18)F in both phantoms and small-animal tumor models. Sensitivity and noise characteristics were demonstrated using vials of activity both at the surface and beneath 1 cm of tissue. Rodent U87MG glioma xenograft models were imaged with radiotracers bound to arginine-glycine-aspartate (RGD) peptides to determine the SNR.γ noise from (18)F was demonstrated by both an observed blurring across the field of view and a more pronounced fall-off with distance. A decreased γ background and increased energy of the β particles resulted in a 207-fold improvement in the sensitivity of (90)Y compared with (18)F in phantoms. (90)Y-bound RGD peptide produced a higher tumor-to-background SNR than (18)F in a mouse model.The use of (90)Y for Cerenkov endoscopic imaging enabled superior results compared with an (18)F radiotracer.

    View details for DOI 10.2967/jnumed.114.139105

    View details for PubMedID 25300598

  • Endometrial VEGF induces placental sFLT1 and leads to pregnancy complications JOURNAL OF CLINICAL INVESTIGATION Fan, X., Rai, A., Kambham, N., Sung, J. F., Singh, N., Petitt, M., Dhal, S., Agrawal, R., Sutton, R. E., Druzin, M. L., Gambhir, S. S., Ambati, B. K., Cross, J. C., Nayak, N. R. 2014; 124 (11): 4941-4952

    View details for DOI 10.1172/JCI76864

    View details for Web of Science ID 000344203300029

  • F-18-FPPRGD2 PET/CT: Pilot Phase Evaluation of Breast Cancer Patients RADIOLOGY Lagaru, A., Mosci, C., Shen, B., Chin, F. T., Mittra, E., Telli, M. L., Gambhir, S. S. 2014; 273 (2): 549-559
  • Endoscopic molecular imaging of human bladder cancer using a CD47 antibody SCIENCE TRANSLATIONAL MEDICINE Pan, Y., Volkmer, J., Mach, K. E., Rouse, R. V., Liu, J., Sahoo, D., Chang, T. C., Metzner, T. J., Kang, L., van de Rijn, M., Skinner, E. C., Gambhir, S. S., Weissman, I. L., Liao, J. C. 2014; 6 (260)
  • Transferring biomarker into molecular probe: melanin nanoparticle as a naturally active platform for multimodality imaging. Journal of the American Chemical Society Fan, Q., Cheng, K., Hu, X., Ma, X., Zhang, R., Yang, M., Lu, X., Xing, L., Huang, W., Gambhir, S. S., Cheng, Z. 2014; 136 (43): 15185-15194


    Developing multifunctional and easily prepared nanoplatforms with integrated different modalities is highly challenging for molecular imaging. Here, we report the successful transferring an important molecular target, melanin, into a novel mul-timodality imaging nanoplatform. Melanin is abundantly expressed in melanotic melanomas and thus has been actively studied as a target for melanoma imaging. In our work, the multifunctional biopolymer nanoplatform based on ultrasmall (< 10 nm) water-soluble melanin nanoparticle (MNP) was developed and showed unique photoacoustic property and natural binding ability with metal ions (for example, 64Cu2+, Fe3+). Therefore MNP can serve not only as a photoacoustic contrast agent, but also as a nanoplatform for positron emission tomography (PET) and magnetic resonance imaging (MRI). Traditional passive nanoplatforms require complicated and time-consuming processes for pre-building reporting moieties or chemical modifications using active groups to integrate different contrast properties into one entity. In comparison, utilizing functional biomarker melanin can greatly simplify the building process. We further conjugated αvβ3 integrins targeting peptide, cyclic c(RGDfC) peptide, to MNPs and this allowed targeting of these nanoparticles to allow for greater U87MG tumor accumulation than that simply possible due to the enhanced permeability and retention (EPR) effect. The multimodal properties of MNPs demonstrate the high potential of endogenous materials with multifunctions as nanoplatforms for molecular theranostics and clinical translation.

    View details for DOI 10.1021/ja505412p

    View details for PubMedID 25292385

  • Investigation of 6-[F-18]-Fluoromaltose as a Novel PET Tracer for Imaging Bacterial Infection PLOS ONE Gowrishankar, G., Namavari, M., Jouannot, E. B., Hoehne, A., Reeves, R., Hardy, J., Gambhir, S. S. 2014; 9 (9)
  • Cellulose Nanoparticles are a Biodegradable Photoacoustic Contrast Agent for Use in Living Mice. Photoacoustics Jokerst, J. V., Van de Sompel, D., Bohndiek, S. E., Gambhir, S. S. 2014; 2 (3): 119-127


    Molecular imaging with photoacoustic ultrasound is an emerging field that combines the spatial and temporal resolution of ultrasound with the contrast of optical imaging. However, there are few imaging agents that offer both high signal intensity and biodegradation into small molecules. Here we describe a cellulose-based nanoparticle with peak photoacoustic signal at 700 nm and an in vitro limit of detection of 6 pM (0.02 mg/mL). Doses down to 0.35 nM (1.2 mg/mL) were used to image mouse models of ovarian cancer. Most importantly, the nanoparticles were shown to biodegrade in the presence of cellulase both through a glucose assay and electron microscopy.

    View details for PubMedID 25225633

  • Circulating Tumor Microemboli Diagnostics for Patients with Non-Small-Cell Lung Cancer JOURNAL OF THORACIC ONCOLOGY Carlsson, A., Nair, V. S., Luttgen, M. S., Keu, K. V., Horng, G., Vasanawala, M., Kolatkar, A., Jamali, M., Iagaru, A. H., Kuschner, W., Loo, B. W., Shrager, J. B., Bethel, K., Hoh, C. K., Bazhenova, L., Nieva, J., Kuhn, P., Gambhir, S. S. 2014; 9 (8): 1111-1119


    Circulating tumor microemboli (CTM) are potentially important cancer biomarkers, but using them for cancer detection in early-stage disease has been assay limited. We examined CTM test performance using a sensitive detection platform to identify stage I non-small-cell lung cancer (NSCLC) patients undergoing imaging evaluation.First, we prospectively enrolled patients during 18F-FDG PET-CT imaging evaluation for lung cancer that underwent routine phlebotomy where CTM and circulating tumor cells (CTCs) were identified in blood using nuclear (DAPI), cytokeratin (CK), and CD45 immune-fluorescent antibodies followed by morphologic identification. Second, CTM and CTC data were integrated with patient (age, gender, smoking, and cancer history) and imaging (tumor diameter, location in lung, and maximum standard uptake value [SUVmax]) data to develop and test multiple logistic regression models using a case-control design in a training and test cohort followed by cross-validation in the entire group.We examined 104 patients with NSCLC, and the subgroup of 80 with stage I disease, and compared them to 25 patients with benign disease. Clinical and imaging data alone were moderately discriminating for all comers (Area under the Curve [AUC] = 0.77) and by stage I disease only (AUC = 0.77). However, the presence of CTM combined with clinical and imaging data was significantly discriminating for diagnostic accuracy in all NSCLC patients (AUC = 0.88, p value = 0.001) and for stage I patients alone (AUC = 0.87, p value = 0.002).CTM may add utility for lung cancer diagnosis during imaging evaluation using a sensitive detection platform.

    View details for Web of Science ID 000340138700012

    View details for PubMedID 25157764

  • Imaging of hepatocellular carcinoma patient-derived xenografts using Zr-89-labeled anti-glypican-3 monoclonal antibody BIOMATERIALS Yang, X., Liu, H., Sun, C. K., Natarajan, A., Hu, X., Wang, X., Allegretta, M., Guttmann, R. D., Gambhir, S. S., Chua, M., Cheng, Z., So, S. K. 2014; 35 (25): 6964-6971


    Imaging probes for early detection of hepatocellular carcinoma (HCC) are highly desired to overcome current diagnostic limitations which lead to poor prognosis. The membrane protein glypican-3 (GPC3) is a potential molecular target for early HCC detection as it is over-expressed in >50% of HCCs, and is associated with early hepatocarcinogenesis. We synthesized the positron emission tomography (PET) probe (89)Zr-DFO-1G12 by bioconjugating and radiolabeling the anti-GPC3 monoclonal antibody (clone 1G12) with (89)Zr, and evaluated its tumor-targeting capacity. In vitro, (89)Zr-DFO-1G12 was specifically taken up into GPC3-positive HCC cells only, but not in the GPC3-negative prostate cancer cell line (PC3). In vivo, (89)Zr-DFO-1G12 specifically accumulated in subcutaneous GPC3-positive HCC xenografts only, but not in PC3 xenografts. Importantly, (89)Zr-DFO-1G12 delineated orthotopic HCC xenografts from surrounding normal liver, with tumor/liver (T/L) ratios of 6.65 ± 1.33 for HepG2, and 4.29 ± 0.52 for Hep3B xenografts. It also delineated orthotopic xenografts derived from three GPC3-positive HCC patient specimens, with T/L ratios of 4.21 ± 0.64, 2.78 ± 0.26, and 2.31 ± 0.38 at 168 h p.i. Thus, (89)Zr-DFO-1G12 is a highly translatable probe for the specific and high contrast imaging of GPC3-positive HCCs, which may aid early detection of HCC to allow timely intervention.

    View details for DOI 10.1016/j.biomaterials.2014.04.089

    View details for Web of Science ID 000338386800028

  • A High-Affinity, High-Stability Photoacoustic Agent for Imaging Gastrin-Releasing Peptide Receptor in Prostate Cancer CLINICAL CANCER RESEARCH Levi, J., Sathirachinda, A., Gambhir, S. S. 2014; 20 (14): 3721-3729


    To evaluate the utility of targeted photoacoustic imaging (PAI) in providing molecular information to complement intrinsic functional and anatomical details of the vasculature within prostate lesion.We developed a PAI agent, AA3G-740, that targets gastrin-releasing peptide receptor (GRPR), found to be highly overexpressed in prostate cancer. The binding specificity of the agent was evaluated in human prostate cancer cell lines, PC3 and LNCaP, and antagonist properties determined by cell internalization and intracellular calcium mobilization studies. The imaging sensitivity was assessed for the agent itself and for the PC3 cells labeled with agent. The in vivo stability of the agent was determined in human plasma and in the blood of living mice. The in vivo binding of the agent was evaluated in PC3 prostate tumor models in mice, and was validated ex vivo by optical imaging.AA3G-740 demonstrated strong and specific binding to GRPR. The sensitivity of detection in vitro indicated suitability of the agent to image very small lesions. In mice, the agent was able to bind to GRPR even in poorly vascularized tumors leading to nearly 2-fold difference in photoacoustic signal relative to the control agent.The ability to image both vasculature and molecular profile outside the blood vessels gives molecular PAI a unique advantage over currently used imaging techniques. The imaging method presented here can find application both in diagnosis and in image-guided biopsy.

    View details for DOI 10.1158/1078-0432.CCR-13-3405

    View details for Web of Science ID 000339611500013

    View details for PubMedID 24850845

  • Selective uptake of single-walled carbon nanotubes by circulating monocytes for enhanced tumour delivery. Nature nanotechnology Smith, B. R., Ghosn, E. E., Rallapalli, H., Prescher, J. A., Larson, T., Herzenberg, L. A., Gambhir, S. S. 2014; 9 (6): 481-487


    In cancer imaging, nanoparticle biodistribution is typically visualized in living subjects using 'bulk' imaging modalities such as magnetic resonance imaging, computerized tomography and whole-body fluorescence. Accordingly, nanoparticle influx is observed only macroscopically, and the mechanisms by which they target cancer remain elusive. Nanoparticles are assumed to accumulate via several targeting mechanisms, particularly extravasation (leakage into tumour). Here, we show that, in addition to conventional nanoparticle-uptake mechanisms, single-walled carbon nanotubes are almost exclusively taken up by a single immune cell subset, Ly-6C(hi) monocytes (almost 100% uptake in Ly-6C(hi) monocytes, below 3% in all other circulating cells), and delivered to the tumour in mice. We also demonstrate that a targeting ligand (RGD) conjugated to nanotubes significantly enhances the number of single-walled carbon nanotube-loaded monocytes reaching the tumour (P < 0.001, day 7 post-injection). The remarkable selectivity of this tumour-targeting mechanism demonstrates an advanced immune-based delivery strategy for enhancing specific tumour delivery with substantial penetration.

    View details for DOI 10.1038/nnano.2014.62

    View details for PubMedID 24727688

  • 99mTc-labeled cystine knot peptide targeting integrin avß6 for tumor SPECT imaging. Molecular pharmaceutics Zhu, X., Li, J., Hong, Y., Kimura, R. H., Ma, X., Liu, H., Qin, C., Hu, X., Hayes, T. R., Benny, P., Gambhir, S. S., Cheng, Z. 2014; 11 (4): 1208-1217


    Integrin αvβ6 is overexpressed in a variety of cancers, and its expression is often associated with poor prognosis. Therefore, there is a need to develop affinity reagents for noninvasive imaging of integrin αvβ6 expression since it may provide early cancer diagnosis, more accurate prognosis, and better treatment planning. We recently engineered and validated highly stable cystine knot peptides that selectively bind integrin αvβ6 with no cross-reactivity to integrins αvβ5, α5β1, or αvβ3, also known to be overexpressed in many cancers. Here, we developed a single photon emission computed tomography (SPECT) probe for imaging integrin αvβ6 positive tumors. Cystine knot peptide, S02, was first conjugated with a single amino acid chelate (SAAC) and labeled with [(99m)Tc(H2O)3(CO)3](+). The resulting probe, (99m)Tc-SAAC-S02, was then evaluated by in vitro cell uptake studies using two αvβ6 positive cell lines (human lung adenocarcinoma cell line HCC4006 and pancreatic cancer cell line BxPC-3) and two αvβ6 negative cell lines (human lung adenocarcinoma cell line H838 and human embryonic kidney cell line 293T). Next, SPECT/CT and biodistribution studies were performed in nude mice bearing HCC4006 and H838 tumor xenografts to evaluate the in vivo performance of (99m)Tc-SAAC-S02. Significant differences in the uptake of (99m)Tc-SAAC-S02 were observed in αvβ6 positive vs negative cells (P < 0.05). Biodistribution and small animal SPECT/CT studies revealed that (99m)Tc-SAAC-S02 accumulated to moderate levels in antigen positive tumors (∼2% ID/g at 1 and 6 h postinjection, n = 3 or 4/group). Moreover, the probe demonstrated tumor-to-background tissue ratios of 6.81 ± 2.32 (tumor-to-muscle) and 1.63 ± 0.18 (tumor-to-blood) at 6 h postinjection in αvβ6 positive tumor xenografts. Co-incubation of the probe with excess amount of unlabeled S02 as a blocking agent demonstrated significantly reduced tumor uptake, which is consistent with specific binding to the target. Renal filtration was the main route of clearance. In conclusion, knottin peptides are excellent scaffolds for which to develop highly stable imaging probes for a variety of oncological targets. (99m)Tc-SAAC-S02 demonstrates promise for use as a SPECT agent to image integrin αvβ6 expression in living systems.

    View details for DOI 10.1021/mp400683q

    View details for PubMedID 24524409

  • A tunable silk-alginate hydrogel scaffold for stem cell culture and transplantation. Biomaterials Ziv, K., Nuhn, H., Ben-Haim, Y., Sasportas, L. S., Kempen, P. J., Niedringhaus, T. P., Hrynyk, M., Sinclair, R., Barron, A. E., Gambhir, S. S. 2014; 35 (12): 3736-3743


    One of the major challenges in regenerative medicine is the ability to recreate the stem cell niche, which is defined by its signaling molecules, the creation of cytokine gradients, and the modulation of matrix stiffness. A wide range of scaffolds has been developed in order to recapitulate the stem cell niche, among them hydrogels. This paper reports the development of a new silk-alginate based hydrogel with a focus on stem cell culture. This biocomposite allows to fine tune its elasticity during cell culture, addressing the importance of mechanotransduction during stem cell differentiation. The silk-alginate scaffold promotes adherence of mouse embryonic stem cells and cell survival upon transplantation. In addition, it has tunable stiffness as function of the silk-alginate ratio and the concentration of crosslinker - a characteristic that is very hard to accomplish in current hydrogels. The hydrogel and the presented results represents key steps on the way of creating artificial stem cell niche, opening up new paths in regenerative medicine.

    View details for DOI 10.1016/j.biomaterials.2014.01.029

    View details for PubMedID 24484675

  • A titratable two-step transcriptional amplification strategy for targeted gene therapy based on ligand-induced intramolecular folding of a mutant human estrogen receptor. Molecular imaging and biology Chen, I. Y., Paulmurugan, R., Nielsen, C. H., Wang, D. S., Chow, V., Robbins, R. C., Gambhir, S. S. 2014; 16 (2): 224-234


    The efficacy and safety of cardiac gene therapy depend critically on the level and the distribution of therapeutic gene expression following vector administration. We aimed to develop a titratable two-step transcriptional amplification (tTSTA) vector strategy, which allows modulation of transcriptionally targeted gene expression in the myocardium.We constructed a tTSTA plasmid vector (pcTnT-tTSTA-fluc), which uses the cardiac troponin T (cTnT) promoter to drive the expression of the recombinant transcriptional activator GAL4-mER(LBD)-VP2, whose ability to transactivate the downstream firefly luciferase reporter gene (fluc) depends on the binding of its mutant estrogen receptor (ER(G521T)) ligand binding domain (LBD) to an ER ligand such as raloxifene. Mice underwent either intramyocardial or hydrodynamic tail vein (HTV) injection of pcTnT-tTSTA-fluc, followed by differential modulation of fluc expression with varying doses of intraperitoneal raloxifene prior to bioluminescence imaging to assess the kinetics of myocardial or hepatic fluc expression.Intramyocardial injection of pcTnT-tTSTA-fluc followed by titration with intraperitoneal raloxifene led to up to tenfold induction of myocardial fluc expression. HTV injection of pcTnT-tTSTA-fluc led to negligible long-term hepatic fluc expression, regardless of the raloxifene dose given.The tTSTA vector strategy can effectively modulate transgene expression in a tissue-specific manner. Further refinement of this strategy should help maximize the benefit-to-risk ratio of cardiac gene therapy.

    View details for DOI 10.1007/s11307-013-0673-4

    View details for PubMedID 23955099

    View details for PubMedCentralID PMC4154804

  • Construction and validation of nano gold tripods for molecular imaging of living subjects. Journal of the American Chemical Society Cheng, K., Kothapalli, S., Liu, H., Koh, A. L., Jokerst, J. V., Jiang, H., Yang, M., Li, J., Levi, J., Wu, J. C., Gambhir, S. S., Cheng, Z. 2014; 136 (9): 3560-3571


    Anisotropic colloidal hybrid nanoparticles exhibit superior optical and physical properties compared to their counterparts with regular architectures. We herein developed a controlled, stepwise strategy to build novel, anisotropic, branched, gold nanoarchitectures (Au-tripods) with predetermined composition and morphology for bioimaging. The resultant Au-tripods with size less than 20 nm showed great promise as contrast agents for in vivo photoacoustic imaging (PAI). We further identified Au-tripods with two possible configurations as high-absorbance nanomaterials from various gold multipods using a numerical simulation analysis. The PAI signals were linearly correlated with their concentrations after subcutaneous injection. The in vivo biodistribution of Au-tripods favorable for molecular imaging was confirmed using small animal positron emission tomography (PET). Intravenous administration of cyclic Arg-Gly-Asp-d-Phe-Cys (RGDfC) peptide conjugated Au-tripods (RGD-Au-tripods) to U87MG tumor-bearing mice showed PAI contrasts in tumors almost 3-fold higher than for the blocking group. PAI results correlated well with the corresponding PET images. Quantitative biodistribution data revealed that 7.9% ID/g of RGD-Au-tripods had accumulated in the U87MG tumor after 24 h post-injection. A pilot mouse toxicology study confirmed that no evidence of significant acute or systemic toxicity was observed in histopathological examination. Our study suggests that Au-tripods can be reliably synthesized through stringently controlled chemical synthesis and could serve as a new generation of platform with high selectivity and sensitivity for multimodality molecular imaging.

    View details for DOI 10.1021/ja412001e

    View details for PubMedID 24495038

  • Semiconducting polymer nanoparticles as photoacoustic molecular imaging probes in living mice. Nature nanotechnology Pu, K., Shuhendler, A. J., Jokerst, J. V., Mei, J., Gambhir, S. S., Bao, Z., Rao, J. 2014; 9 (3): 233-239


    Photoacoustic imaging holds great promise for the visualization of physiology and pathology at the molecular level with deep tissue penetration and fine spatial resolution. To fully utilize this potential, photoacoustic molecular imaging probes have to be developed. Here, we introduce near-infrared light absorbing semiconducting polymer nanoparticles as a new class of contrast agents for photoacoustic molecular imaging. These nanoparticles can produce a stronger signal than the commonly used single-walled carbon nanotubes and gold nanorods on a per mass basis, permitting whole-body lymph-node photoacoustic mapping in living mice at a low systemic injection mass. Furthermore, the semiconducting polymer nanoparticles possess high structural flexibility, narrow photoacoustic spectral profiles and strong resistance to photodegradation and oxidation, enabling the development of the first near-infrared ratiometric photoacoustic probe for in vivo real-time imaging of reactive oxygen species-vital chemical mediators of many diseases. These results demonstrate semiconducting polymer nanoparticles to be an ideal nanoplatform for developing photoacoustic molecular probes.

    View details for DOI 10.1038/nnano.2013.302

    View details for PubMedID 24463363

  • Ultrasound Molecular Imaging in a Human CD276 Expression-Modulated Murine Ovarian Cancer Model. Clinical cancer research Lutz, A. M., Bachawal, S. V., Drescher, C. W., Pysz, M. A., Willmann, J. K., Gambhir, S. S. 2014; 20 (5): 1313-1322


    To develop a mouse ovarian cancer model that allows modulating the expression levels of human vascular targets in mouse xenograft tumors and to test whether expression of CD276 during tumor angiogenesis can be visualized by molecularly targeted ultrasound in vivo.CD276-expressing MILE SVEN 1 (MS1) mouse endothelial cells were engineered and used for coinjection with 2008 human ovarian cancer cells for subcutaneous xenograft tumor induction in 15 nude mice. Fourteen control mice were injected with 2008 cells only. After confirming their binding specificity in flow chamber cell attachment studies, anti-CD276 antibody-functionalized contrast microbubbles were used for in vivo CD276-targeted contrast-enhanced ultrasound imaging.CD276-targeted ultrasound imaging signal was significantly higher (P = 0.006) in mixed MS1/2008 tumors than in control tumors. Compared with control microbubbles, the ultrasound signal using CD276-targeted microbubbles was significantly higher (P = 0.002), and blocking with purified anti-CD276 antibody significantly decreased (P = 0.0096) the signal in mixed MS1/2008 tumors. Immunofluorescence analysis of the tumor tissue confirmed higher quantitative immunofluorescence signal in mixed MS1/2008 tumors than in control 2008 only tumors, but showed not significantly different (P = 0.54) microvessel density.Our novel small animal model allows for modulating the expression of human tumor-associated vascular endothelial imaging targets in a mouse host and these expression differences can be visualized noninvasively by ultrasound molecular imaging. The animal model can be applied to other human vascular targets and may facilitate the preclinical development of new imaging probes such as microbubbles targeted at human vascular markers not expressed in mice. Clin Cancer Res; 20(5); 1313-22. ©2014 AACR.

    View details for DOI 10.1158/1078-0432.CCR-13-1642

    View details for PubMedID 24389327

  • Light in and sound out: emerging translational strategies for photoacoustic imaging. Cancer research Zackrisson, S., van de Ven, S. M., Gambhir, S. S. 2014; 74 (4): 979-1004


    Photoacoustic imaging (PAI) has the potential for real-time molecular imaging at high resolution and deep inside the tissue, using nonionizing radiation and not necessarily depending on exogenous imaging agents, making this technique very promising for a range of clinical applications. The fact that PAI systems can be made portable and compatible with existing imaging technologies favors clinical translation even more. The breadth of clinical applications in which photoacoustics could play a valuable role include: noninvasive imaging of the breast, sentinel lymph nodes, skin, thyroid, eye, prostate (transrectal), and ovaries (transvaginal); minimally invasive endoscopic imaging of gastrointestinal tract, bladder, and circulating tumor cells (in vivo flow cytometry); and intraoperative imaging for assessment of tumor margins and (lymph node) metastases. In this review, we describe the basics of PAI and its recent advances in biomedical research, followed by a discussion of strategies for clinical translation of the technique. Cancer Res; 74(4); 979-1004. ©2014 AACR.

    View details for DOI 10.1158/0008-5472.CAN-13-2387

    View details for PubMedID 24514041

  • Antiviral drug ganciclovir is a potent inhibitor of microglial proliferation and neuroinflammation. journal of experimental medicine Ding, Z., Mathur, V., Ho, P. P., James, M. L., Lucin, K. M., Hoehne, A., Alabsi, H., Gambhir, S. S., Steinman, L., Luo, J., Wyss-Coray, T. 2014; 211 (2): 189-198


    Aberrant microglial responses contribute to neuroinflammation in many neurodegenerative diseases, but no current therapies target pathogenic microglia. We discovered unexpectedly that the antiviral drug ganciclovir (GCV) inhibits the proliferation of microglia in experimental autoimmune encephalomyelitis (EAE), a mouse model for multiple sclerosis (MS), as well as in kainic acid-induced excitotoxicity. In EAE, GCV largely prevented infiltration of T lymphocytes into the central nervous system (CNS) and drastically reduced disease incidence and severity when delivered before the onset of disease. In contrast, GCV treatment had minimal effects on peripheral leukocyte distribution in EAE and did not inhibit generation of antibodies after immunization with ovalbumin. Additionally, a radiolabeled analogue of penciclovir, [(18)F]FHBG, which is similar in structure to GCV, was retained in areas of CNS inflammation in EAE, but not in naive control mice, consistent with the observed therapeutic effects. Our experiments suggest GCV may have beneficial effects in the CNS beyond its antiviral properties.

    View details for DOI 10.1084/jem.20120696

    View details for PubMedID 24493798

  • Imaging circulating tumor cells in freely moving awake small animals using a miniaturized intravital microscope. PloS one Sasportas, L. S., Gambhir, S. S. 2014; 9 (1)


    Metastasis, the cause for 90% of cancer mortality, is a complex and poorly understood process involving the invasion of circulating tumor cells (CTCs) into blood vessels. These cells have potential prognostic value as biomarkers for early metastatic risk. But their rarity and the lack of specificity and sensitivity in measuring them render their interrogation by current techniques very challenging. How and when these cells are circulating in the blood, on their way to potentially give rise to metastasis, is a question that remains largely unanswered. In order to provide an insight into this "black box" using non-invasive imaging, we developed a novel miniature intravital microscopy (mIVM) strategy capable of real-time long-term monitoring of CTCs in awake small animals. We established an experimental 4T1-GL mouse model of metastatic breast cancer, in which tumor cells express both fluorescent and bioluminescent reporter genes to enable both single cell and whole body tumor imaging. Using mIVM, we monitored blood vessels of different diameters in awake mice in an experimental model of metastasis. Using an in-house software algorithm we developed, we demonstrated in vivo CTC enumeration and computation of CTC trajectory and speed. These data represent the first reported use we know of for a miniature mountable intravital microscopy setup for in vivo imaging of CTCs in awake animals.

    View details for DOI 10.1371/journal.pone.0086759

    View details for PubMedID 24497977

  • Detection and quantitation of circulating tumor cell dynamics by bioluminescence imaging in an orthotopic mammary carcinoma model. PloS one Sasportas, L. S., Hori, S. S., Pratx, G., Gambhir, S. S. 2014; 9 (9)

    View details for DOI 10.1371/journal.pone.0105079

    View details for PubMedID 25188396

  • Cellulose nanoparticles: Photoacoustic contrast agents that biodegrade to simple sugars Conference on Photons Plus Ultrasound: Imaging and Sensing Jokerst, J. V., Bohndiek, S. E., Gambhir, S. S. SPIE-INT SOC OPTICAL ENGINEERING. 2014

    View details for DOI 10.1117/12.2036256

    View details for Web of Science ID 000338768500011

  • Evaluation of s-1 receptor radioligand 18F-FTC-146 in rats and squirrel monkeys using PET. Journal of nuclear medicine : official publication, Society of Nuclear Medicine James, M. L., Shen, B., Nielsen, C. H., Behera, D., Buckmaster, C. L., Mesangeau, C., Zavaleta, C., Vuppala, P. K., Jamalapuram, S., Avery, B. A., Lyons, D. M., McCurdy, C. R., Biswal, S., Gambhir, S. S., Chin, F. T. 2014; 55 (1): 147-153


    The noninvasive imaging of σ-1 receptors (S1Rs) could provide insight into their role in different diseases and lead to novel diagnostic/treatment strategies. The main objective of this study was to assess the S1R radiotracer (18)F-FTC-146 in rats. Preliminary squirrel monkey imaging and human serum/liver microsome studies were performed to gain information about the potential of (18)F-FTC-146 for eventual clinical translation.The distribution and stability of (18)F-FTC-146 in rats were assessed via PET/CT, autoradiography, γ counting, and high-performance liquid chromatography (HPLC). Preliminary PET/MRI of squirrel monkey brain was conducted along with HPLC assessment of (18)F-FTC-146 stability in monkey plasma and human serum.Biodistribution studies showed that (18)F-FTC-146 accumulated in S1R-rich rat organs, including the lungs, pancreas, spleen, and brain. Pretreatment with known S1R compounds, haloperidol, or BD1047, before radioligand administration, significantly attenuated (18)F-FTC-146 accumulation in all rat brain regions by approximately 85% (P < 0.001), suggesting radiotracer specificity for S1Rs. Similarly, PET/CT and autoradiography results demonstrated accumulation of (18)F-FTC-146 in rat brain regions known to contain S1Rs and that this uptake could be blocked by BD1047 pretreatment. Ex vivo analysis of (18)F-FTC-146 in the brain showed that only intact radiotracer was present at 15, 30, and 60 min, whereas rapid metabolism of residual (18)F-FTC-146 was observed in rat plasma. Preliminary monkey PET/MRI studies demonstrated specific accumulation of (18)F-FTC-146 in the brain (mainly in cortical structures, cerebellum, and vermis) that could be attenuated by pretreatment with haloperidol. HPLC of monkey plasma suggested radioligand metabolism, whereas (18)F-FTC-146 appeared to be stable in human serum. Finally, liver microsome studies revealed that (18)F-FTC-146 has a longer half-life in human microsomes, compared with rodents.Together, these results indicate that (18)F-FTC-146 is a promising tool for visualizing S1Rs in preclinical studies and that it has potential for mapping these sites in the human brain.

    View details for DOI 10.2967/jnumed.113.120261

    View details for PubMedID 24337599

  • Photoacoustic Imaging of Mesenchymal Stem Cells in Living Mice via Silica-Coated Gold Nanorods Conference on Photons Plus Ultrasound: Imaging and Sensing Jokerst, J. V., Thangaraj, M., Gambhir, S. S. SPIE-INT SOC OPTICAL ENGINEERING. 2014

    View details for DOI 10.1117/12.2036786

    View details for Web of Science ID 000338768500035

  • Tracking Cellular and Immune Therapies in Cancer EMERGING APPLICATIONS OF MOLECULAR IMAGING TO ONCOLOGY Kurtz, D. M., Gambhir, S. S. 2014; 124: 257-296
  • A simple model for deep tissue attenuation correction and large organ analysis of Cerenkov luminescence imaging Medical Imaging - Physics of Medical Imaging Habte, F., Natarajan, A., Paik, D. S., Gambhir, S. S. SPIE-INT SOC OPTICAL ENGINEERING. 2014

    View details for DOI 10.1117/12.2043879

    View details for Web of Science ID 000338775800154

  • Gold nanorods combine photoacoustic and Raman imaging for detection and treatment of ovarian cancer Conference on Photons Plus Ultrasound: Imaging and Sensing Jokerst, J. V., Cole, A. J., Bohndiek, S. E., Gambhir, S. S. SPIE-INT SOC OPTICAL ENGINEERING. 2014

    View details for DOI 10.1117/12.2036776

    View details for Web of Science ID 000338768500134

  • Detection and quantitation of circulating tumor cell dynamics by bioluminescence imaging in an orthotopic mammary carcinoma model. PloS one Sasportas, L. S., Hori, S. S., Pratx, G., Gambhir, S. S. 2014; 9 (9)


    Circulating tumor cells (CTCs) have been detected in the bloodstream of both early-stage and advanced cancer patients. However, very little is know about the dynamics of CTCs during cancer progression and the clinical relevance of longitudinal CTC enumeration. To address this, we developed a simple bioluminescence imaging assay to detect CTCs in mouse models of metastasis. In a 4T1 orthotopic metastatic mammary carcinoma mouse model, we demonstrated that this quantitative method offers sensitivity down to 2 CTCs in 0.1-1mL blood samples and high specificity for CTCs originating from the primary tumor, independently of their epithelial status. In this model, we simultaneously monitored blood CTC dynamics, primary tumor growth, and lung metastasis progression over the course of 24 days. Early in tumor development, we observed low numbers of CTCs in blood samples (10-15 cells/100 µL) and demonstrated that CTC dynamics correlate with viable primary tumor growth. To our knowledge, these data represent the first reported use of bioluminescence imaging to detect CTCs and quantify their dynamics in any cancer mouse model. This new assay is opening the door to the study of CTC dynamics in a variety of animal models. These studies may inform clinical decision on the appropriate timing of blood sampling and value of longitudinal CTC enumeration in cancer patients.

    View details for DOI 10.1371/journal.pone.0105079

    View details for PubMedID 25188396

  • A Novel Engineered Anti-CD20 Tracer Enables Early Time PET Imaging in a Humanized Transgenic Mouse Model of B-cell Non-Hodgkins Lymphoma CLINICAL CANCER RESEARCH Natarajan, A., Hackel, B. J., Gambhir, S. S. 2013; 19 (24): 6820-6829


    The aim of this article was to evaluate the use of a novel engineered anti-CD20 protein based on the 10 kDa human fibronectin type 3 domain (FN3) and subsequently compare with (64)Cu-rituximab for positron emission tomography (PET) imaging of CD20.The engineered FN3(CD20) and FN3(WT) were produced in Escherichia coli cells at 2 to 5 mg/L, conjugated to DOTA, labeled with (64)Cu, and used for PET imaging of huCD20 expression in B cells. Humanized transgenic mice and subcutaneously xenografted mice each received intravenous (64)Cu-FN3(CD20) or FN3(WT) (3.7 MBq/4 μg Do-FN3 in 200 μL PBS). Control group received a blocking dose (50-fold excess) of unconjugated FN3(CD20) two hours before radiotracer injection. PET imaging was carried out at 1 to 24 hours postinjections.In vitro assay demonstrated FN3 binds CD20 with 20 nmol/L affinity on CD20-expressing cells. (64)Cu-FN3(CD20) showed clear, high-contrast visualization of huCD20-expressing B cells in the spleen of transgenic mice as early as 1 hour postinjection [38 ± 3% injected dose (ID)/g] and exhibited a spleen-to-blood ratio of 13 by 4 hours. This is higher uptake (P = 0.04) and 10-fold greater signal-to-background (P = 0.04) than the (64)Cu-rituximab antibody radiotracer. Tumor uptake (16.8 ± 1.6 vs. 5.6 ± 1.4%ID/g) and tumor:background ratios were superior for FN3CD20 relative to rituximab in xenograft studies as well.The (64)Cu-Do-FN3(CD20) radiotracer represents a novel small, high-affinity binder for imaging human CD20, which may be well suited for B-cell non-Hodgkin's lymphoma imaging in patients at early time points.

    View details for DOI 10.1158/1078-0432.CCR-13-0626

    View details for Web of Science ID 000328938700019

    View details for PubMedID 24097872

  • A F-18-Labeled Saxitoxin Derivative for in Vivo PET-MR Imaging of Voltage-Gated Sodium Channel Expression Following Nerve Injury JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Hoehne, A., Behera, D., Parsons, W. H., James, M. L., Shen, B., Borgohain, P., Bodapati, D., Prabhakar, A., Gambhir, S. S., Yeomans, D. C., Biswal, S., Chin, F. T., Du Bois, J. 2013; 135 (48): 18012-18015


    Both chronic and neuropathic pain conditions are associated with increased expression of certain voltage-gated sodium ion channel (NaV) isoforms in peripheral sensory neurons. A method for noninvasive imaging of these channels could represent a powerful tool for investigating aberrant expression of NaV and its role in pain pathogenesis. Herein, we describe the synthesis and evaluation of a positron emission tomography (PET) radiotracer targeting NaVs, the design of which is based on the potent, NaV-selective inhibitor saxitoxin. Both autoradiography analysis of sciatic nerves excised from injured rats as well as whole animal PET-MR imaging demonstrate that a systemically administered [(18)F]-labeled saxitoxin derivative concentrates at the site of nerve injury, consistent with upregulated sodium channel expression following axotomy. This type of PET agent has potential use for serial monitoring of channel expression levels at injured nerves throughout wound healing and/or following drug treatment. Such information may be correlated with pain behavioral analyses to help shed light on the complex molecular processes that underlie pain sensation.

    View details for DOI 10.1021/ja408300e

    View details for Web of Science ID 000328100000002

    View details for PubMedID 24261833

  • Combined 18F-fluoride and 18F-FDG PET/CT: a response based on actual data from prospective studies. European journal of nuclear medicine and molecular imaging Iagaru, A., Mosci, C., Dick, D. W., Sathekge, M., Lapa, P., de Lima, J. M., Gambhir, S. S. 2013; 40 (12): 1922-1924

    View details for DOI 10.1007/s00259-013-2556-y

    View details for PubMedID 24057457

  • Single-cell photonic nanocavity probes. Nano letters Shambat, G., Kothapalli, S., Provine, J., Sarmiento, T., Harris, J., Gambhir, S. S., Vuckovic, J. 2013; 13 (11): 4999-5005


    In this report, we demonstrate for the first time photonic nanocavities operating inside single biological cells. Here we develop a nanobeam photonic crystal (PC) cavity as an advanced cellular nanoprobe, active in nature, and configurable to provide a multitude of actions for both intracellular sensing and control. Our semiconductor nanocavity probes emit photoluminescence (PL) from embedded quantum dots (QD) and sustain high quality resonant photonic modes inside cells. The probes are shown to be minimally cytotoxic to cells from viability studies, and the beams can be loaded in cells and tracked for days at a time, with cells undergoing regular division with the beams. We present in vitro label-free protein sensing with our probes to detect streptavidin as a path towards real-time biomarker and biomolecule detection inside single cells. The results of this work will enable new areas of research merging the strengths of photonic nanocavities with fundamental cell biology.

    View details for DOI 10.1021/nl304602d

    View details for PubMedID 23387382

  • Nanooncology: The Future of Cancer Diagnosis and Therapy CA-A CANCER JOURNAL FOR CLINICIANS Thakor, A. S., Gambhir, S. S. 2013; 63 (6): 395-418


    In recent years, there has been an unprecedented expansion in the field of nanomedicine with the development of new nanoparticles for the diagnosis and treatment of cancer. Nanoparticles have unique biological properties given their small size and large surface area-to-volume ratio, which allows them to bind, absorb, and carry compounds such as small molecule drugs, DNA, RNA, proteins, and probes with high efficiency. Their tunable size, shape, and surface characteristics also enable them to have high stability, high carrier capacity, the ability to incorporate both hydrophilic and hydrophobic substances and compatibility with different administration routes, thereby making them highly attractive in many aspects of oncology. This review article will discuss how nanoparticles are able to function as carriers for chemotherapeutic drugs to increase their therapeutic index; how they can function as therapeutic agents in photodynamic, gene, and thermal therapy; and how nanoparticles can be used as molecular imaging agents to detect and monitor cancer progression.

    View details for DOI 10.3322/caac.21199

    View details for Web of Science ID 000326887000004

    View details for PubMedID 24114523

  • Integrin-Targeted Molecular Imaging of Experimental Abdominal Aortic Aneurysms by 18F-labeled Arg-Gly-Asp Positron-Emission Tomography. Circulation. Cardiovascular imaging Kitagawa, T., Kosuge, H., Chang, E., James, M. L., Yamamoto, T., Shen, B., Chin, F. T., Gambhir, S. S., Dalman, R. L., McConnell, M. V. 2013; 6 (6): 950-956


    Background- Both inflammation and neoangiogenesis contribute to abdominal aortic aneurysm (AAA) disease. Arg-Gly-Asp-based molecular imaging has been shown to detect the integrin αvβ3. We studied a clinical dimeric (18)F-labeled Arg-Gly-Asp positron-emission tomography (PET) agent ((18)F-FPPRGD2) for molecular imaging of experimental AAAs. Methods and Results- Murine AAAs were induced in Apo-E-deficient mice by angiotensin II infusion, with monitoring of aortic diameter on ultrasound. AAA (n=10) and saline-infused control mice (n=7) were injected intravenously with (18)F-FPPRGD2, as well as an intravascular computed tomography contrast agent, then scanned using a small-animal PET/computed tomography scanner. Aortic uptake of (18)F-FPPRGD2 was quantified by percentage-injected dose per gram and target-to-=0.003; median target-to-=0.0008). Ex vivo autoradiography demonstrated high uptake of (18)F-FPPRGD2 into the AAA wall, with immunohistochemistry showing substantial cluster of differentiation (CD)-11b(+) macrophages and CD-31(+) neovessels. Target-to-=-0.29, P=0.41) but did strongly correlate with both mural macrophage density (r=0.79, P=0.007) and neovessel counts (r=0.87, P=0.001) on immunohistochemistry. Conclusions- PET imaging of experimental AAAs using (18)F-FPPRGD2 detects biologically active disease, correlating to the degree of vascular inflammation and neoangiogenesis. This may provide a clinically translatable molecular imaging approach to characterize AAA biology to predict risk beyond size alone.

    View details for DOI 10.1161/CIRCIMAGING.113.000234

    View details for PubMedID 23995363

  • Preclinical Efficacy of the Anti-Hepatocyte Growth Factor Antibody Ficlatuzumab in a Mouse Brain Orthotopic Glioma Model Evaluated by Bioluminescence, PET, and MRI CLINICAL CANCER RESEARCH Mittra, E. S., Fan-Minogue, H., Lin, F. I., Karamchandani, J., Sriram, V., Han, M., Gambhir, S. S. 2013; 19 (20): 5711-5721


    Ficlatuzumab is a novel therapeutic agent targeting the hepatocyte growth factor (HGF)/c-MET pathway. We summarize extensive preclinical work using this agent in a mouse brain orthotopic model of glioblastoma.Sequential experiments were done using eight- to nine-week-old nude mice injected with 3 × 10(5) U87 MG (glioblastoma) cells into the brain. Evaluation of ficlatuzumab dose response for this brain tumor model and comparison of its response to ficlatuzumab and to temozolamide were conducted first. Subsequently, various small-animal imaging modalities, including bioluminescence imaging (BLI), positron emission tomography (PET), and MRI, were used with a U87 MG-Luc 2 stable cell line, with and without the use of ficlatuzumab, to evaluate the ability to noninvasively assess tumor growth and response to therapy. ANOVA was conducted to evaluate for significant differences in the response.There was a survival benefit with ficlatuzumab alone or in combination with temozolamide. BLI was more sensitive than PET in detecting tumor cells. Fluoro-D-thymidine (FLT) PET provided a better signal-to-background ratio than 2[(18)F]fluoro-2-deoxy-d-glucose (FDG) PET. In addition, both BLI and FLT PET showed significant changes over time in the control group as well as with response to therapy. MRI does not disclose any time-dependent change. Also, the MRI results showed a temporal delay in comparison to the BLI and FLT PET findings, showing similar results one drug cycle later.Targeting the HGF/c-MET pathway with the novel agent ficlatuzumab appears promising for the treatment of glioblastoma. Various clinically applicable imaging modalities including FLT, PET, and MRI provide reliable ways of assessing tumor growth and response to therapy. Given the clinical applicability of these findings, future studies on patients with glioblastoma may be appropriate.

    View details for DOI 10.1158/1078-0432.CCR-12-1015

    View details for Web of Science ID 000325797600019

    View details for PubMedID 23983258

  • A scanning transmission electron microscopy approach to analyzing large volumes of tissue to detect nanoparticles. Microscopy and microanalysis Kempen, P. J., Thakor, A. S., Zavaleta, C., Gambhir, S. S., Sinclair, R. 2013; 19 (5): 1290-1297


    The use of nanoparticles for the diagnosis and treatment of cancer requires the complete characterization of their toxicity, including accurately locating them within biological tissues. Owing to their size, traditional light microscopy techniques are unable to resolve them. Transmission electron microscopy provides the necessary spatial resolution to image individual nanoparticles in tissue, but is severely limited by the very small analysis volume, usually on the order of tens of cubic microns. In this work, we developed a scanning transmission electron microscopy (STEM) approach to analyze large volumes of tissue for the presence of polyethylene glycol-coated Raman-active-silica-gold-nanoparticles (PEG-R-Si-Au-NPs). This approach utilizes the simultaneous bright and dark field imaging capabilities of STEM along with careful control of the image contrast settings to readily identify PEG-R-Si-Au-NPs in mouse liver tissue without the need for additional time-consuming analytical characterization. We utilized this technique to analyze 243,000 μm3 of mouse liver tissue for the presence of PEG-R-Si-Au-NPs. Nanoparticles injected into the mice intravenously via the tail vein accumulated in the liver, whereas those injected intrarectally did not, indicating that they remain in the colon and do not pass through the colon wall into the systemic circulation.

    View details for DOI 10.1017/S143192761300192X

    View details for PubMedID 23803218

  • MicroRNA-regulated non-viral vectors with improved tumor specificity in an orthotopic rat model of hepatocellular carcinoma GENE THERAPY Ronald, J. A., Katzenberg, R., Nielsen, C. H., Jae, H. J., Hofmann, L. V., Gambhir, S. S. 2013; 20 (10): 1006-1013


    In hepatocellular carcinoma (HCC), tumor specificity of gene therapy is of utmost importance to preserve liver function. MicroRNAs (miRNAs) are powerful negative regulators of gene expression and many are downregulated in human HCC. We identified seven miRNAs that are also downregulated in tumors in a rat hepatoma model (P<0.05) and attempted to improve tumor specificity by constructing a panel of luciferase-expressing vectors containing binding sites for these miRNAs. Attenuation of luciferase expression by the corresponding miRNAs was confirmed across various cell lines and in mouse liver. We then tested our vectors in tumor-bearing rats and identified two miRNAs, miR-26a and miR-122, that significantly decreased expression in liver compared with the control vector (6.40 and 0.26%, respectively; P<0.05). In tumor, miR-122 had a nonsignificant trend towards decreased (∼50%) expression, whereas miR-26 had no significant effect on tumor expression. To our knowledge, this is the first work using differentially expressed miRNAs to de-target transgene expression in an orthotopic hepatoma model and to identify miR-26a, in addition to miR-122, for de-targeting liver. Considering the heterogeneity of miRNA expression in human HCC, this information will be important in guiding development of more personalized vectors for the treatment of this devastating disease.Gene Therapy advance online publication, 30 May 2013; doi:10.1038/gt.2013.24.

    View details for DOI 10.1038/gt.2013.24

    View details for Web of Science ID 000325633500006

    View details for PubMedID 23719066

  • Noninvasive imaging of hypoxia-inducible factor-1a gene therapy for myocardial ischemia. Human gene therapy methods Chen, I. Y., Gheysens, O., Li, Z., Rasooly, J. A., Wang, Q., Paulmurugan, R., Rosenberg, J., Rodriguez-Porcel, M., Willmann, J. K., Wang, D. S., Contag, C. H., Robbins, R. C., Wu, J. C., Gambhir, S. S. 2013; 24 (5): 279-288

    View details for DOI 10.1089/hgtb.2013.028

    View details for PubMedID 23937265

  • A c-Myc Activation Sensor-Based High-Throughput Drug Screening Identifies an Antineoplastic Effect of Nitazoxanide. Molecular cancer therapeutics Fan-Minogue, H., Bodapati, S., Solow-Cordero, D., Fan, A., Paulmurugan, R., Massoud, T. F., Felsher, D. W., Gambhir, S. S. 2013; 12 (9): 1896-1905


    Deregulation of c-Myc plays a central role in the tumorigenesis of many human cancers. Yet, the development of drugs regulating c-Myc activity has been challenging. To facilitate the identification of c-Myc inhibitors, we developed a molecular imaging sensor based high throughput-screening (HTS) system. This system uses a cell-based assay to detect c-Myc activation in a HTS format, which is established from a pure clone of a stable breast cancer cell line that constitutively expresses a c-Myc activation sensor. Optimization of the assay performance in the HTS format resulted in uniform and robust signals at the baseline. Using this system, we performed a quantitative HTS against approximately 5,000 existing bioactive compounds from five different libraries. Thirty-nine potential hits were identified, including currently known c-Myc inhibitors. There are a few among the top potent hits that are not known for anti-c-Myc activity. One of these hits is nitazoxanide (NTZ), a thiazolide for treating human protozoal infections. Validation of NTZ in different cancer cell lines revealed a high potency for c-Myc inhibition with IC50 ranging between 10 - 500nM. Oral administration of NTZ in breast cancer xenograft mouse models significantly suppressed tumor growth by inhibition of c-Myc and induction of apoptosis. These findings suggest a potential of NTZ to be repurposed as a new anti-tumor agent for inhibition of c-Myc associated neoplasia. Our work also demonstrated the unique advantage of molecular imaging in accelerating discovery of drugs for c-Myc targeted cancer therapy.

    View details for DOI 10.1158/1535-7163.MCT-12-1243

    View details for PubMedID 23825064

  • High-sensitivity, real-time, ratiometric imaging of surface-enhanced Raman scattering nanoparticles with a clinically translatable Raman endoscope device. Journal of biomedical optics Garai, E., Sensarn, S., Zavaleta, C. L., Van de Sompel, D., Loewke, N. O., Mandella, M. J., Gambhir, S. S., Contag, C. H. 2013; 18 (9): 096008-?


    ABSTRACT. Topical application and quantification of targeted, surface-enhanced Raman scattering (SERS) nanoparticles offer a new technique that has the potential for early detection of epithelial cancers of hollow organs. Although less toxic than intravenous delivery, the additional washing required to remove unbound nanoparticles cannot necessarily eliminate nonspecific pooling. Therefore, we developed a real-time, ratiometric imaging technique to determine the relative concentrations of at least two spectrally unique nanoparticle types, where one serves as a nontargeted control. This approach improves the specific detection of bound, targeted nanoparticles by adjusting for working distance and for any nonspecific accumulation following washing. We engineered hardware and software to acquire SERS signals and ratios in real time and display them via a graphical user interface. We report quantitative, ratiometric imaging with nanoparticles at pM and sub-pM concentrations and at varying working distances, up to 50 mm. Additionally, we discuss optimization of a Raman endoscope by evaluating the effects of lens material and fiber coating on background noise, and theoretically modeling and simulating collection efficiency at various working distances. This work will enable the development of a clinically translatable, noncontact Raman endoscope capable of rapidly scanning large, topographically complex tissue surfaces for small and otherwise hard to detect lesions.

    View details for DOI 10.1117/1.JBO.18.9.096008

    View details for PubMedID 24008818

  • Evaluation of Zr-89-rituximab Tracer by Cerenkov Luminescence Imaging and Correlation with PET in a Humanized Transgenic Mouse Model to Image NHL MOLECULAR IMAGING AND BIOLOGY Natarajan, A., Habte, F., Liu, H., Sathirachinda, A., Hu, X., Cheng, Z., Nagamine, C. M., Gambhir, S. S. 2013; 15 (4): 468-475


    PURPOSE: This research aimed to study the use of Cerenkov luminescence imaging (CLI) for non-Hodgkin's lymphoma (NHL) using (89)Zr-rituximab positron emission tomography (PET) tracer with a humanized transgenic mouse model that expresses human CD20 and the correlation of CLI with PET. PROCEDURES: Zr-rituximab (2.6 MBq) was tail vein-injected into transgenic mice that express the human CD20 on their B cells (huCD20TM). One group (n = 3) received 2 mg/kg pre-dose (blocking) of cold rituximab 2 h prior to tracer; a second group (n = 3) had no pre-dose (non-blocking). CLI was performed using a cooled charge-coupled device optical imager. We also performed PET imaging and ex vivo studies in order to confirm the in vivo CLI results. At each time point (4, 24, 48, 72, and 96 h), two groups of mice were imaged in vivo and ex vivo with CLI and PET, and at 96 h, organs were measured by gamma counter. RESULTS: huCD20 transgenic mice injected with (89)Zr-rituximab demonstrated a high-contrast CLI image compared to mice blocked with a cold dose. At various time points of 4-96 h post-radiotracer injection, the in vivo CLI signal intensity showed specific uptake in the spleen where B cells reside and, hence, the huCD20 biomarker is present at very high levels. The time-activity curve of dose decay-corrected CLI intensity and percent injected dose per gram of tissue of PET uptake in the spleen were increased over the time period (4-96 h). At 96 h, the (89)Zr-rituximab uptake ratio (non-blocking vs blocking) counted (mean ± standard deviation) for the spleen was 1.5 ± 0.6 for CLI and 1.9 ± 0.3 for PET. Furthermore, spleen uptake measurements (non-blocking and blocking of all time points) of CLI vs PET showed good correlation (R (2) = 0.85 and slope = 0.576), which also confirmed the corresponding correlations parameter value (R (2) = 0.834 and slope = 0.47) obtained for ex vivo measurements. CONCLUSIONS: CLI and PET of huCD20 transgenic mice injected with (89)Zr-rituximab demonstrated that the tracer was able to target huCD20-expressing B cells. The in vivo and ex vivo tracer uptake corresponding to the CLI radiance intensity from the spleen is in good agreement with PET. In this report, we have validated the use of CLI with PET for NHL imaging in huCD20TM.

    View details for DOI 10.1007/s11307-013-0624-0

    View details for Web of Science ID 000321972500014

    View details for PubMedID 23471750

  • Molecular imaging with surface-enhanced Raman spectroscopy nanoparticle reporters MRS BULLETIN Jokerst, J. V., Pohling, C., Gambhir, S. S. 2013; 38 (8): 625-630
  • Real-time, continuous, fluorescence sensing in a freely-moving subject with an implanted hybrid VCSEL/CMOS biosensor BIOMEDICAL OPTICS EXPRESS O'Sullivan, T. D., Heitz, R. T., Parashurama, N., Barkin, D. B., Wooley, B. A., Gambhir, S. S., Harris, J. S., Levi, O. 2013; 4 (8): 1332-1341
  • Imaging Tumor Angiogenesis: The Road to Clinical Utility AMERICAN JOURNAL OF ROENTGENOLOGY Iagaru, A., Gambhir, S. S. 2013; 201 (2): W183-W191


    OBJECTIVE. Tumor growth and progression require the formation of new blood vessels from preexisting vasculature, a process called angiogenesis. The ability to noninvasively visualize angiogenesis may provide new opportunities to more appropriately select patients for antiangiogenesis treatment and to monitor treatment efficacy. CONCLUSION. The superior molecular sensitivity of PET and the lack of radiation from MRI and contrast-enhanced ultrasound put these techniques at the forefront of clinical translation.

    View details for DOI 10.2214/AJR.12.8568

    View details for Web of Science ID 000322225400003

    View details for PubMedID 23883233

  • Activatable oligomerizable imaging agents for photoacoustic imaging of furin-like activity in living subjects. Journal of the American Chemical Society Dragulescu-Andrasi, A., Kothapalli, S., Tikhomirov, G. A., Rao, J., Gambhir, S. S. 2013; 135 (30): 11015-11022


    Photoacoustic (PA) imaging is continuing to be applied for physiological imaging and more recently for molecular imaging of living subjects. Owing to its high spatial resolution in deep tissues, PA imaging holds great potential for biomedical applications and molecular diagnostics. There is however a lack of probes for targeted PA imaging, especially in the area of enzyme-activatable probes. Here we introduce a molecular probe, which upon proteolytic processing is retained at the site of enzyme activity and provides PA contrast. The probe oligomerizes via a condensation reaction and accumulates in cells and tumors that express the protease. We demonstrate that this probe reports furin and furin-like activity in cells and tumor models by generating a significantly higher PA signal relative to furin-deficient and nontarget controls. This probe could report enzyme activity in living subjects at depths significantly greater than fluorescence imaging probes and has potential for molecular imaging in deep tumors.

    View details for DOI 10.1021/ja4010078

    View details for PubMedID 23859847

  • A small animal Raman instrument for rapid, wide-area, spectroscopic imaging PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Bohndiek, S. E., Wagadarikar, A., Zavaleta, C. L., Van de Sompel, D., Garai, E., Jokerst, J. V., Yazdanfar, S., Gambhir, S. S. 2013; 110 (30): 12408-12413


    Raman spectroscopy, amplified by surface enhanced Raman scattering (SERS) nanoparticles, is a molecular imaging modality with ultra-high sensitivity and the unique ability to multiplex readouts from different molecular targets using a single wavelength of excitation. This approach holds exciting prospects for a range of applications in medicine, including identification and characterization of malignancy during endoscopy and intraoperative image guidance of surgical resection. The development of Raman molecular imaging with SERS nanoparticles is presently limited by long acquisition times, poor spatial resolution, small field of view, and difficulty in animal handling with existing Raman spectroscopy instruments. Our goal is to overcome these limitations by designing a bespoke instrument for Raman molecular imaging in small animals. Here, we present a unique and dedicated small-animal Raman imaging instrument that enables rapid, high-spatial resolution, spectroscopic imaging over a wide field of view (> 6 cm(2)), with simplified animal handling. Imaging of SERS nanoparticles in small animals demonstrated that this small animal Raman imaging system can detect multiplexed SERS signals in both superficial and deep tissue locations at least an order of magnitude faster than existing systems without compromising sensitivity.

    View details for DOI 10.1073/pnas.1301379110

    View details for Web of Science ID 000322112300062

    View details for PubMedID 23821752

  • An Observational Study of Circulating Tumor Cells and F-18-FDG PET Uptake in Patients with Treatment-Naive Non-Small Cell Lung Cancer PLOS ONE Nair, V. S., Keu, K. V., Luttgen, M. S., Kolatkar, A., Vasanawala, M., Kuschner, W., Bethel, K., Iagaru, A. H., Hoh, C., Shrager, J. B., Loo, B. W., Bazhenova, L., Nieva, J., Gambhir, S. S., Kuhn, P. 2013; 8 (7)

    View details for DOI 10.1371/journal.pone.0067733

    View details for Web of Science ID 000321425300025

    View details for PubMedID 23861795

  • Noninvasive Monitoring of Oxidative Stress in Transplanted Mesenchymal Stromal Cells JACC-CARDIOVASCULAR IMAGING Psaltis, P. J., Peterson, K. M., Xu, R., Franchi, F., Witt, T., Chen, I. Y., Lerman, A., Simari, R. D., Gambhir, S. S., Rodriguez-Porcel, M. 2013; 6 (7): 795-802


    OBJECTIVES: The goal of this study was to validate a pathway-specific reporter gene that could be used to noninvasively image the oxidative status of progenitor cells. BACKGROUND: In cell therapy studies, reporter gene imaging plays a valuable role in the assessment of cell fate in living subjects. After myocardial injury, noxious stimuli in the host tissue confer oxidative stress to transplanted cells that may influence their survival and reparative function. METHODS: Rat mesenchymal stromal cells (MSCs) were studied for phenotypic evidence of increased oxidative stress under in vitro stress. On the basis of their up-regulation of the pro-oxidant enzyme p67(phox) subunit of nicotinamide adenine dinucleotide phosphate (NAD[P]H oxidase p67(phox)), an oxidative stress sensor was constructed, comprising the firefly luciferase (Fluc) reporter gene driven by the NAD(P)H p67(phox) promoter. MSCs cotransfected with NAD(P)H p67(phox)-Fluc and a cell viability reporter gene (cytomegalovirus-Renilla luciferase) were studied under in vitro and in vivo pro-oxidant conditions. RESULTS: After in vitro validation of the sensor during low-serum culture, transfected MSCs were transplanted into a rat model of myocardial ischemia/reperfusion (IR) and monitored by using bioluminescence imaging. Compared with sham controls (no IR), cardiac Fluc intensity was significantly higher in IR rats (3.5-fold at 6 h, 2.6-fold at 24 h, 5.4-fold at 48 h; p < 0.01), indicating increased cellular oxidative stress. This finding was corroborated by ex vivo luminometry after correcting for Renilla luciferase activity as a measure of viable MSC number (Fluc:Renilla luciferase ratio 0.011 ± 0.003 for sham vs. 0.026 ± 0.004 for IR at 48 h; p < 0.05). Furthermore, in IR animals that received MSCs preconditioned with an antioxidant agent (tempol), Fluc signal was strongly attenuated, substantiating the specificity of the oxidative stress sensor. CONCLUSIONS: Pathway-specific reporter gene imaging allows assessment of changes in the oxidative status of MSCs after delivery to ischemic myocardium, providing a template to monitor key biological interactions between transplanted cells and their host environment in living subjects.

    View details for DOI 10.1016/j.jcmg.2012.11.018

    View details for Web of Science ID 000321677300006

    View details for PubMedID 23643284

  • F-18-Fluorobenzoate-Labeled Cystine Knot Peptides for PET Imaging of Integrin alpha(v)beta(6) JOURNAL OF NUCLEAR MEDICINE Hackel, B. J., Kimura, R. H., Miao, Z., Liu, H., Sathirachinda, A., Cheng, Z., Chin, F. T., Gambhir, S. S. 2013; 54 (7): 1101-1105
  • Pilot prospective evaluation of 99mTc-MDP scintigraphy, 18F NaF PET/CT, 18F FDG PET/CT and whole-body MRI for detection of skeletal metastases. Clinical nuclear medicine Iagaru, A., Young, P., Mittra, E., Dick, D. W., Herfkens, R., Gambhir, S. S. 2013; 38 (7): e290-6

    View details for DOI 10.1097/RLU.0b013e3182815f64

    View details for PubMedID 23455520

  • 18F-fluorobenzoate-labeled cystine knot peptides for PET imaging of integrin avß6. Journal of nuclear medicine : official publication, Society of Nuclear Medicine Hackel, B. J., Kimura, R. H., Miao, Z., Liu, H., Sathirachinda, A., Cheng, Z., Chin, F. T., Gambhir, S. S. 2013; 54 (7): 1101-1105


    Integrin αvβ6 is a cell surface receptor minimally expressed by healthy tissue but elevated in lung, colon, skin, ovarian, cervical, and pancreatic cancers. A molecular PET agent for integrin αvβ6 could provide significant clinical utility by facilitating both cancer staging and treatment monitoring to more rapidly identify an effective therapeutic approach. METHODS: Here, we evaluated 2 cystine knot peptides, R01 and S02, previously engineered with a 3-6 nM affinity for integrin αvβ6, for (18)F radiolabeling and PET imaging of BxPC3 pancreatic adenocarcinoma xenografts in mice. Cystine knot peptides were labeled with N-succinimidyl-4-(18)F-fluorobenzoate and evaluated for binding affinity and serum stability. Peptides conjugated with (18)F-fluorobenzoate (2-3 MBq) were injected via the tail vein into nude mice xenografted with BxPC3 (integrin αvβ6-positive) or 293 (integrin αvβ6-negative) tumors. Small-animal PET scans were acquired at 0.5, 1, and 2 h after injection. Ex vivo γ-counting of dissected tissues was performed at 0.5 and 2 h. RESULTS: (18)F-fluorobenzoate peptides were produced in 93% ((18)F-fluorobenzoate-R01) and 99% ((18)F-fluorobenzoate-S02) purity. (18)F-fluorobenzoate-R01 and (18)F-fluorobenzoate-S02 had affinities of 1.1 ± 0.2 and 0.7 ± 0.4 nM, respectively, and were 87% and 94%, respectively, stable in human serum at 37°C for 2 h. (18)F-fluorobenzoate-R01 and (18)F-fluorobenzoate-S02 exhibited 2.3 ± 0.6 and 1.3 ± 0.4 percentage injected dose per gram (%ID/g), respectively, in BxPC3 xenografted tumors at 0.5 h (n = 4-5). Target specificity was confirmed by low tumor uptake in integrin αvβ6-negative 293 tumors (1.4 ± 0.6 and 0.5 ± 0.2 %ID/g, respectively, for (18)F-fluorobenzoate-R01 and (18)F-fluorobenzoate-S02; both P < 0.05; n = 3-4) and low muscle uptake (3.1 ± 1.0 and 2.7 ± 0.4 tumor to muscle for (18)F-fluorobenzoate-R01 and (18)F-fluorobenzoate-S02, respectively). Small-animal PET data were corroborated by ex vivo γ-counting of dissected tissues, which demonstrated low uptake in nontarget tissues with only modest kidney uptake (9.2 ± 3.3 and 1.9 ± 1.2 %ID/g, respectively, at 2 h for (18)F-fluorobenzoate-R01 and (18)F-fluorobenzoate-S02; n = 8). Uptake in healthy pancreas was low (0.3% ± 0.1% for (18)F-fluorobenzoate-R01 and 0.03% ± 0.01% for (18)F-fluorobenzoate-S02; n = 8). CONCLUSION: These cystine knot peptide tracers, in particular (18)F-fluorobenzoate-R01, show translational promise for molecular imaging of integrin αvβ6 overexpression in pancreatic and other cancers.

    View details for DOI 10.2967/jnumed.112.110759

    View details for PubMedID 23670900

  • A Raman-based endoscopic strategy for multiplexed molecular imaging. Proceedings of the National Academy of Sciences of the United States of America Zavaleta, C. L., Garai, E., Liu, J. T., Sensarn, S., Mandella, M. J., Van de Sompel, D., Friedland, S., Van Dam, J., Contag, C. H., Gambhir, S. S. 2013; 110 (25): E2288-97

    View details for DOI 10.1073/pnas.1211309110

    View details for PubMedID 23703909

  • Molecular Imaging of Inflammation in Inflammatory Bowel Disease with a Clinically Translatable Dual-Selectin-targeted US Contrast Agent: Comparison with FDG PET/CT in a Mouse Model. Radiology Wang, H., Machtaler, S., Bettinger, T., Lutz, A. M., Luong, R., Bussat, P., Gambhir, S. S., Tranquart, F., Tian, L., Willmann, J. K. 2013; 267 (3): 818-829


    Purpose: To develop and test a molecular imaging approach that uses ultrasonography (US) and a clinically translatable dual-targeted (P- and E-selectin) contrast agent (MBSelectin) in the quantification of inflammation at the molecular level and to quantitatively correlate selectin-targeted US with fluorodeoxyglucose (FDG) combined positron emission tomography (PET) and computed tomography (CT) in terms of visualization and quantification of different levels of inflammation in a murine acute colitis model. Materials and Methods: Animal studies were approved by the Institutional Administrative Panel on Laboratory Animal Care at Stanford University. MBSelectin was developed by covalently binding an analog of the naturally occurring binding ligand P-selectin glycoprotein ligand 1 fused to a human fragment crystallizable(or Fc) domain onto the lipid shell of perfluorobutane and nitrogen-containing MBs. Binding specificity of MBSelectin was assessed in vitro with a flow chamber assay and in vivo with a chemically induced acute colitis murine model. US signal was quantitatively correlated with FDG uptake at PET/CT and histologic grade. Statistical analysis was performed with the Student t test, analysis of variance, and Pearson correlation analysis. Results: MBSelectin showed strong attachment to both human and mouse P- and E-selectin compared with MBControl in vitro (P ≤ .002). In vivo, US signal was significantly increased (P < .001) in mice with acute colitis (173.8 arbitrary units [au] ± 134.8 [standard deviation]) compared with control mice (5.0 au ± 4.5). US imaging signal strongly correlated with FDG uptake on PET/CT images (ρ = 0.89, P < .001). Ex vivo analysis enabled confirmation of inflammation in mice with acute colitis and high expression levels of P- and E-selectin in mucosal capillaries (P = .014). Conclusion: US with MBSelectin specifically enables detection and quantification of inflammation in a murine acute colitis model, leveraging the natural pathway of leukocyte recruitment in inflammatory tissue. US imaging with MBSelectin correlates well with FDG uptake at PET/CT imaging. © RSNA, 2013 Supplemental material:

    View details for DOI 10.1148/radiol.13122509

    View details for PubMedID 23371306

  • A comparison of noise models in a hybrid reference spectrum and principal components analysis algorithm for Raman spectroscopy JOURNAL OF RAMAN SPECTROSCOPY Van de Sompel, D., Garai, E., Zavaleta, C., Gambhir, S. S. 2013; 44 (6): 841-856

    View details for DOI 10.1002/jrs.4258

    View details for Web of Science ID 000319935700009

  • Advanced Characterization Techniques for Nanoparticles for Cancer Research: Applications of SEM and NanoSIMS for Locating Au Nanoparticles in Cells. Materials Research Society symposia proceedings. Materials Research Society Kempen, P. J., Hitzman, C., Sasportas, L. S., Gambhir, S. S., Sinclair, R. 2013; 1569: 157-163


    The ability of nano secondary ion mass spectrometry (NanoSIMS) to locate and analyze Raman active gold core nanoparticles (R-AuNPs) in a biological system is compared with the standard analysis using the scanning electron microscope (SEM). The same cell with R-AuNPs on and inside the macrophage was analyzed with both techniques to directly compare them. SEM analysis showed a large number of nanoparticles within the cell. Subsequent NanoSIMS analysis showed fewer R-AuNPs with lower spatial resolution. SEM was determined to be superior to NanoSIMS for the analysis of inorganic nanoparticles in complex biological systems.

    View details for PubMedID 25364091

  • [F-18]CAIP a smart PET tracer for imaging caspase-3 induced Apoptosis Shen Bin, B., Jeon, J., Palner, M., Tong Ling, L., Felsher, D., Gambhir, S. S., Chin, F. T., Rao Jianghong, J. H. WILEY-BLACKWELL. 2013: S6–S6
  • Evaluation of the antitumor effects of rilotumumab by PET imaging in a U-87 MG mouse xenograft model NUCLEAR MEDICINE AND BIOLOGY Rex, K., Lewis, X. Z., Sundaresan, G., Glaus, C., Silva, M. D., Radinsky, R., Burgess, T. L., Gambhir, S. S., Coxon, A. 2013; 40 (4): 458-463
  • Evaluation of the antitumor effects of rilotumumab by PET imaging in a U-87 MG mouse xenograft model. Nuclear medicine and biology Rex, K., Lewis, X. Z., Gobalakrishnan, S., Glaus, C., Silva, M. D., Radinsky, R., Burgess, T. L., Gambhir, S. S., Coxon, A. 2013; 40 (4): 458-463


    Dysregulation of the hepatocyte growth factor (HGF)/MET pathway has been implicated in various cancers. Rilotumumab is an investigational, fully human monoclonal antibody that binds and neutralizes HGF. The purpose of this study was to evaluate the efficacy of rilotumumab in a U-87 MG mouse xenograft tumor model using (18)F-FDG and (18)F-FLT PET.U-87 MG tumor-bearing nude mice received rilotumumab or control IgG2. In the dose response study, increasing doses of rilotumumab (10, 30, 100, 300, or 500 μg) were administered, and mice were evaluated with (18)F-FDG PET at baseline and 7 days post-treatment. In the time course study, 300 μg of rilotumumab twice per week was used for the treatment, and mice were evaluated over 7 days using (18)F-FDG and (18)F-FLT PET.In the dose response study, rilotumumab at doses of 300 and 500 μg was similarly effective against tumor growth. Treatment with 300 and 500 μg rilotumumab inhibited (18)F-FDG accumulation with significant decreases of -37% and -40% in the percent injected dose per gram of tissue (%ID/g), respectively. In the time course study, treatment with 300 μg rilotumumab inhibited (18)F-FDG and (18)F-FLT accumulation with a maximum %ID/g of -41% and -64%, respectively. No apparent differences between the use of either tracer to evaluate rilotumumab efficacy were observed.Rilotumumab inhibited (18)F-FDG and (18)F-FLT accumulation as early as 2 and 4 days after treatment, respectively, in a mouse tumor model. Further studies to evaluate (18)F-FDG PET imaging as an early tumor response marker for rilotumumab are warranted. Rilotumumab is currently being tested in patients with MET-positive, advanced gastric and gastroesophageal cancer.

    View details for DOI 10.1016/j.nucmedbio.2013.01.004

    View details for PubMedID 23454250

  • High-resolution, serial intravital microscopic imaging of nanoparticle delivery and targeting in a small animal tumor model NANO TODAY Smith, B. R., Zavaleta, C., Rosenberg, J., Tong, R., Ramunas, J., Liu, Z., Dai, H., Gambhir, S. S. 2013; 8 (2): 126-137
  • Intracellular Aggregation of Multimodal Silica Nanoparticles for Ultrasound-Guided Stem Cell Implantation SCIENCE TRANSLATIONAL MEDICINE Jokerst, J. V., Khademi, C., Gambhir, S. S. 2013; 5 (177)

    View details for DOI 10.1126/scitranslmed.3005228

    View details for Web of Science ID 000316454100004

    View details for PubMedID 23515077

  • Molecular Photoacoustic Imaging of Follicular Thyroid Carcinoma CLINICAL CANCER RESEARCH Levi, J., Kothapalli, S., Bohndiek, S., Yoon, J., Dragulescu-Andrasi, A., Nielsen, C., Tisma, A., Bodapati, S., Gowrishankar, G., Yan, X., Chan, C., Starcevic, D., Gambhir, S. S. 2013; 19 (6): 1494-1502


    To evaluate the potential of targeted photoacoustic imaging as a noninvasive method for detection of follicular thyroid carcinoma.We determined the presence and activity of two members of matrix metalloproteinase family (MMP), MMP-2 and MMP-9, suggested as biomarkers for malignant thyroid lesions, in FTC133 thyroid tumors subcutaneously implanted in nude mice. The imaging agent used to visualize tumors was MMP-activatable photoacoustic probe, Alexa750-CXeeeeXPLGLAGrrrrrXK-BHQ3. Cleavage of the MMP-activatable agent was imaged after intratumoral and intravenous injections in living mice optically, observing the increase in Alexa750 fluorescence, and photoacoustically, using a dual-wavelength imaging method.Active forms of both MMP-2 and MMP-9 enzymes were found in FTC133 tumor homogenates, with MMP-9 detected in greater amounts. The molecular imaging agent was determined to be activated by both enzymes in vitro, with MMP-9 being more efficient in this regard. Both optical and photoacoustic imaging showed significantly higher signal in tumors of mice injected with the active agent than in tumors injected with the control, nonactivatable, agent.With the combination of high spatial resolution and signal specificity, targeted photoacoustic imaging holds great promise as a noninvasive method for early diagnosis of follicular thyroid carcinomas.

    View details for DOI 10.1158/1078-0432.CCR-12-3061

    View details for Web of Science ID 000316188900021

    View details for PubMedID 23349314

    View details for PubMedCentralID PMC3602312

  • Earlier Detection of Breast Cancer with Ultrasound Molecular Imaging in a Transgenic Mouse Model CANCER RESEARCH Bachawal, S. V., Jensen, K. C., Lutz, A. M., Gambhir, S. S., Tranquart, F., Tian, L., Willmann, J. K. 2013; 73 (6): 1689-1698


    While there is an increasing role of ultrasound for breast cancer screening in patients with dense breast, conventional anatomical ultrasound lacks sensitivity and specificity for early breast cancer detection. In this study, we assessed the potential of ultrasound molecular imaging using clinically translatable vascular endothelial growth factor receptor type 2 (VEGFR2)-targeted microbubbles (MB(VEGFR2)) to improve the diagnostic accuracy of ultrasound in earlier detection of breast cancer and ductal carcinoma in situ (DCIS) in a transgenic mouse model [FVB/N-Tg(MMTV-PyMT)634Mul]. In vivo binding specificity studies (n = 26 tumors) showed that ultrasound imaging signal was significantly higher (P < 0.001) using MB(VEGFR2) than nontargeted microbubbles and imaging signal significantly decreased (P < 0.001) by blocking antibodies. Ultrasound molecular imaging signal significantly increased (P < 0.001) when breast tissue (n = 315 glands) progressed from normal [1.65 ± 0.17 arbitrary units (a.u.)] to hyperplasia (4.21 ± 1.16), DCIS (15.95 ± 1.31), and invasive cancer (78.1 ± 6.31) and highly correlated with ex vivo VEGFR2 expression [R(2) = 0.84; 95% confidence interval (CI), 0.72-0.91; P < 0.001]. At an imaging signal threshold of 4.6 a.u., ultrasound molecular imaging differentiated benign from malignant entities with a sensitivity of 84% (95% CI, 78-88) and specificity of 89% (95% CI, 81-94). In a prospective screening trail (n = 63 glands), diagnostic performance of detecting DCIS and breast cancer was assessed and two independent readers correctly diagnosed malignant disease in more than 95% of cases and highly agreed between each other [intraclass correlation coefficient (ICC) = 0.98; 95% CI, 97-99]. These results suggest that VEGFR2-targeted ultrasound molecular imaging allows highly accurate detection of DCIS and breast cancer in transgenic mice and may be a promising approach for early breast cancer detection in women.

    View details for DOI 10.1158/0008-5472.CAN-12-3391

    View details for Web of Science ID 000316187500006

    View details for PubMedID 23328585

  • An Integrated Computational/Experimental Model of Lymphoma Growth PLOS COMPUTATIONAL BIOLOGY Frieboes, H. B., Smith, B. R., Chuang, Y., Ito, K., Roettgers, A. M., Gambhir, S. S., Cristini, V. 2013; 9 (3)


    Non-Hodgkin's lymphoma is a disseminated, highly malignant cancer, with resistance to drug treatment based on molecular- and tissue-scale characteristics that are intricately linked. A critical element of molecular resistance has been traced to the loss of functionality in proteins such as the tumor suppressor p53. We investigate the tissue-scale physiologic effects of this loss by integrating in vivo and immunohistological data with computational modeling to study the spatiotemporal physical dynamics of lymphoma growth. We compare between drug-sensitive Eμ-myc Arf-/- and drug-resistant Eμ-myc p53-/- lymphoma cell tumors grown in live mice. Initial values for the model parameters are obtained in part by extracting values from the cellular-scale from whole-tumor histological staining of the tumor-infiltrated inguinal lymph node in vivo. We compare model-predicted tumor growth with that observed from intravital microscopy and macroscopic imaging in vivo, finding that the model is able to accurately predict lymphoma growth. A critical physical mechanism underlying drug-resistant phenotypes may be that the Eμ-myc p53-/- cells seem to pack more closely within the tumor than the Eμ-myc Arf-/- cells, thus possibly exacerbating diffusion gradients of oxygen, leading to cell quiescence and hence resistance to cell-cycle specific drugs. Tighter cell packing could also maintain steeper gradients of drug and lead to insufficient toxicity. The transport phenomena within the lymphoma may thus contribute in nontrivial, complex ways to the difference in drug sensitivity between Eμ-myc Arf-/- and Eμ-myc p53-/- tumors, beyond what might be solely expected from loss of functionality at the molecular scale. We conclude that computational modeling tightly integrated with experimental data gives insight into the dynamics of Non-Hodgkin's lymphoma and provides a platform to generate confirmable predictions of tumor growth.

    View details for DOI 10.1371/journal.pcbi.1003008

    View details for Web of Science ID 000316864200070

    View details for PubMedID 23555235

  • BIOENGINEERING AND REGENERATIVE MEDICINE Keeping track NATURE MATERIALS Ziv, K., Gambhir, S. S. 2013; 12 (3): 180-181

    View details for Web of Science ID 000315707200009

    View details for PubMedID 23422714

  • Non-Invasive Imaging of Phosphoinositide-3-Kinase-Catalytic-Subunit-Alpha (PIK3CA) Promoter Modulation in Small Animal Models PLOS ONE Gaikwad, S. M., Gunjal, L., Junutula, A. R., Astanehe, A., Gambhir, S. S., Ray, P. 2013; 8 (2)


    Activation of the PI3K/Akt pathway, a critical step for survival in cancer cells is often associated with decreased sensitivity to several chemotherapeutic drugs. PIK3CA gene amplification is observed in 16-24% of epithelial ovarian cancer (EOC) patients in conjunction with p53 mutations. A 900 bp long PIK3CA promoter is shown to be negatively regulated by p53 in ovarian surface epithelial cells but the consequence of chemotherapeutic drug treatments on this promoter in ovarian cancer cells is largely unknown. We aim to study the modulation of this promoter by cisplatin using an improved fusion reporter in ovarian cancer cells and tumor xenografts by non-invasive imaging approach. A PIK3CA sensor was developed using a bi-fusion reporter from a newly constructed library of bi- and tri-fusion vectors comprising of two mutant far red fluorescent proteins (mcherry/mch and tdTomato/tdt), a mutant firefly luciferase (fluc2), and a PET reporter protein (ttk). In vivo imaging of mice implanted with 293T cells transiently expressing these bi- and tri-fusion reporters along with respective controls revealed comparable activity of each reporter in the fusion background and fluc2-tdt as the most sensitive one. Repression of the PIK3CA sensor by drugs was inversely proportional to cellular p53 level in a germline (PA1) and in an EOC (A2780) cell line but not in a p53 deficient EOC (SKOV3) cell line. Bioluminescence imaging of tumor xenografts stably expressing the PIK3CA sensor in PA1 and A2780 cells exhibited attenuating activity without any change in SKOV3 tumors expressing the PIK3CA sensor after cisplatin treatment. Sequential mutation at p53 binding sites showed gradual increase in promoter activity and decreased effects of the drugs. These newly developed PIK3CA-fluc2-tdt and the mutant reporter sensors thus would be extremely useful for screening new drugs and for functional assessment of PIK3CA expression from intact cells to living subjects.

    View details for DOI 10.1371/journal.pone.0055971

    View details for Web of Science ID 000314692800061

    View details for PubMedID 23393606

  • Combined F-18-Fluoride and F-18-FDG PET/CT Scanning for Evaluation of Malignancy: Results of an International Multicenter Trial JOURNAL OF NUCLEAR MEDICINE Iagaru, A., Mittra, E., Mosci, C., Dick, D. W., Sathekge, M., Prakash, V., Iyer, V., Lapa, P., Isidoro, J., de Lima, J. M., Gambhir, S. S. 2013; 54 (2): 176-183


    (18)F-FDG PET/CT is used in a variety of cancers, but because of variable rates of glucose metabolism, not all cancers are reliably identified. (18)F(-) PET/CT allows for the acquisition of highly sensitive and specific images of the skeleton. We prospectively evaluated combined (18)F(-)/(18)F-FDG as a single PET/CT examination for evaluation of cancer patients and compared it with separate (18)F(-) PET/CT and (18)F-FDG PET/CT scans.One hundred fifteen participants with cancer were prospectively enrolled in an international multicenter trial evaluating (18)F(-) PET/CT, (18)F-FDG PET/CT, and combined (18)F(-)/(18)F-FDG PET/CT. The 3 PET/CT scans were performed sequentially within 4 wk of one another for each patient.(18)F(-)/(18)F-FDG PET/CT allowed for accurate interpretation of radiotracer uptake outside the skeleton, with findings similar to those of (18)F-FDG PET/CT. In 19 participants, skeletal disease was more extensive on (18)F(-) PET/CT and (18)F(-)/(18)F-FDG PET/CT than on (18)F-FDG PET/CT. In another 29 participants, (18)F(-) PET/CT and (18)F(-)/(18)F-FDG PET/CT showed osseous metastases where (18)F-FDG PET/CT was negative. The extent of skeletal lesions was similar in 18 participants on all 3 scans.This trial demonstrated that combined (18)F(-)/(18)F-FDG PET/CT shows promising results when compared with separate (18)F(-) PET/CT and (18)F-FDG PET/CT for evaluation of cancer patients. This result opens the possibility for improved patient care and reduction in health-care costs, as will be further evaluated in future trials.

    View details for DOI 10.2967/jnumed.112.108803

    View details for Web of Science ID 000314691200016

    View details for PubMedID 23243299

  • Dissection of the role of the tumor microenvironment in oncogene addiction by ex vivo and in situ imaging AACR/SNMMI Joint Conference on State-of-the-Art Molecular Imaging in Cancer Biology and Therapy Tong, L., Jeon, J., Shen, B., Jianghong, R., Chin, F., Gambhir, S., Felsher, D. SOC NUCLEAR MEDICINE INC. 2013: 25–25
  • Colony-stimulating factor 1 receptor (CSF1R) signaling in injured neurons facilitates protection and survival JOURNAL OF EXPERIMENTAL MEDICINE Luo, J., Elwood, F., Britschgi, M., Villeda, S., Zhang, H., Ding, Z., Zhu, L., Alabsi, H., Getachew, R., Narasimhan, R., Wabl, R., Fainberg, N., James, M. L., Wong, G., Relton, J., Gambhir, S. S., Pollard, J. W., Wyss-Coray, T. 2013; 210 (1): 157-172


    Colony-stimulating factor 1 (CSF1) and interleukin-34 (IL-34) are functional ligands of the CSF1 receptor (CSF1R) and thus are key regulators of the monocyte/macrophage lineage. We discovered that systemic administration of human recombinant CSF1 ameliorates memory deficits in a transgenic mouse model of Alzheimer's disease. CSF1 and IL-34 strongly reduced excitotoxin-induced neuronal cell loss and gliosis in wild-type mice when administered systemically before or up to 6 h after injury. These effects were accompanied by maintenance of cAMP responsive element-binding protein (CREB) signaling in neurons rather than in microglia. Using lineage-tracing experiments, we discovered that a small number of neurons in the hippocampus and cortex express CSF1R under physiological conditions and that kainic acid-induced excitotoxic injury results in a profound increase in neuronal receptor expression. Selective deletion of CSF1R in forebrain neurons in mice exacerbated excitotoxin-induced death and neurodegeneration. We conclude that CSF1 and IL-34 provide powerful neuroprotective and survival signals in brain injury and neurodegeneration involving CSF1R expression on neurons.

    View details for DOI 10.1084/jem.20120412

    View details for Web of Science ID 000313560900014

    View details for PubMedID 23296467

  • Synthesis of ligand-functionalized water-soluble [F-18]YF3 nanoparticles for PET imaging NANOSCALE Xiong, L., Shen, B., Behera, D., Gambhir, S. S., Chin, F. T., Rao, J. 2013; 5 (8): 3253-3256


    We report a simple, efficient synthesis of novel (18)F-labeled imaging agents based on YF3 nanoparticles. Targeting ligands and antitumor drug molecules can be introduced onto the YF3 nanoparticles in a one-pot synthesis. The (18)F-labeling reaction proceeds in aqueous solutions at room temperature with excellent radiolabeling yields (>80%) in a very short time (5-10 min). (18)F-labeled YF3 nanoparticles displayed high stability in mouse and human serum, and their application for mapping lymph nodes in live rats after local injection has also been demonstrated.

    View details for DOI 10.1039/c3nr00335c

    View details for Web of Science ID 000316959500019

    View details for PubMedID 23508229

  • Evolution of BRET Biosensors from Live Cell to Tissue-Scale In vivo Imaging. Frontiers in endocrinology De, A., Jasani, A., Arora, R., Gambhir, S. S. 2013; 4: 131-?


    Development of bioluminescence resonance energy transfer (BRET) based genetic sensors for sensing biological functions such as protein-protein interactions (PPIs) in vivo has a special value in measuring such dynamic events at their native environment. Since its inception in the late nineties, BRET related research has gained significant momentum in terms of adding versatility to the assay format and wider applicability where it has been suitably used. Beyond the scope of quantitative measurement of PPIs and protein dimerization, molecular imaging applications based on BRET assays have broadened its scope for screening pharmacologically important compounds by in vivo imaging as well. In this mini-review we focus on an in-depth analysis of engineered BRET systems developed and their successful application to cell-based assays as well as in vivo non-invasive imaging in live subjects.

    View details for DOI 10.3389/fendo.2013.00131

    View details for PubMedID 24065957

  • A Brain Tumor Molecular Imaging Strategy using a New Triple-Modality MRI-Photoacoustic-Raman Nanoparticle Conference on Photons Plus Ultrasound - Imaging and Sensing de la Zerda, A., Kircher, M. F., Jokerst, J. V., Zavaleta, C. L., Kempen, P. J., Mittra, E., Pitter, K., Huang, R., Campos, C., Habte, F., Sinclair, R., Brennan, C. W., Mellinghoff, I. K., Holland, E. C., Gambhir, S. S. SPIE-INT SOC OPTICAL ENGINEERING. 2013

    View details for DOI 10.1117/12.2001719

    View details for Web of Science ID 000322832800007

  • Development and application of stable phantoms for the evaluation of photoacoustic imaging instruments. PloS one Bohndiek, S. E., Bodapati, S., Van de Sompel, D., Kothapalli, S., Gambhir, S. S. 2013; 8 (9)


    Photoacoustic imaging combines the high contrast of optical imaging with the spatial resolution and penetration depth of ultrasound. This technique holds tremendous potential for imaging in small animals and importantly, is clinically translatable. At present, there is no accepted standard physical phantom that can be used to provide routine quality control and performance evaluation of photoacoustic imaging instruments. With the growing popularity of the technique and the advent of several commercial small animal imaging systems, it is important to develop a strategy for assessment of such instruments. Here, we developed a protocol for fabrication of physical phantoms for photoacoustic imaging from polyvinyl chloride plastisol (PVCP). Using this material, we designed and constructed a range of phantoms by tuning the optical properties of the background matrix and embedding spherical absorbing targets of the same material at different depths. We created specific designs to enable: routine quality control; the testing of robustness of photoacoustic signals as a function of background; and the evaluation of the maximum imaging depth available. Furthermore, we demonstrated that we could, for the first time, evaluate two small animal photoacoustic imaging systems with distinctly different light delivery, ultrasound imaging geometries and center frequencies, using stable physical phantoms and directly compare the results from both systems.

    View details for DOI 10.1371/journal.pone.0075533

    View details for PubMedID 24086557

  • Stable phantoms for characterization of photoacoustic tomography (PAT) systems Conference on Design and Performance Validation of Phantoms Used in Conjunction with Optical Measurement of Tissue V Bohndiek, S. E., Van de Sompel, D., Bodapati, S., Kothapalli, S. R., Gambhir, S. S. SPIE-INT SOC OPTICAL ENGINEERING. 2013

    View details for DOI 10.1117/12.2005195

    View details for Web of Science ID 000322903900005

  • Comparison of Gaussian and Poisson Noise Models in a Hybrid Reference Spectrum and Principal Component Analysis Algorithm for Raman Spectroscopy Conference on Single Molecule Spectroscopy and Superresolution Imaging VI Van de Sompel, D., Garai, E., Zavaleta, C., Gambhir, S. S. SPIE-INT SOC OPTICAL ENGINEERING. 2013

    View details for DOI 10.1117/12.2005455

    View details for Web of Science ID 000321741600011

  • Development and validation of non-integrative, self-limited, and replicating minicircles for safe reporter gene imaging of cell-based therapies. PloS one Ronald, J. A., Cusso, L., Chuang, H., Yan, X., Dragulescu-Andrasi, A., Gambhir, S. S. 2013; 8 (8)


    Reporter gene (RG) imaging of cell-based therapies provides a direct readout of therapeutic efficacy by assessing the fate of implanted cells. To permit long-term cellular imaging, RGs are traditionally required to be integrated into the cellular genome. This poses a potential safety risk and regulatory bottleneck for clinical translation as integration can lead to cellular transformation. To address this issue, we have developed non-integrative, replicating minicircles (MCs) as an alternative platform for safer monitoring of cells in living subjects. We developed both plasmids and minicircles containing the scaffold/matrix attachment regions (S/MAR) of the human interferon-beta gene, driven by the CMV promoter, and expressing the bioluminescence RG firefly luciferase. Constructs were transfected into breast cancer cells, and expanded S/MAR minicircle clones showed luciferase signal for greater than 3 months in culture and minicircles remained as episomes. Importantly, luciferase activity in clonal populations was slowly lost over time and this corresponded to a loss of episome, providing a way to reversibly label cells. To monitor cell proliferation in vivo, 1.5×10(6) cells carrying the S/MAR minicircle were implanted subcutaneously into mice (n = 5) and as tumors developed significantly more bioluminescence signal was noted at day 35 and 43 compared to day 7 post-implant (p<0.05). To our knowledge, this is the first work examining the use of episomal, self-limited, replicating minicircles to track the proliferation of cells using non-invasive imaging in living subjects. Continued development of S/MAR minicircles will provide a broadly applicable vector platform amenable with any of the numerous RG technologies available to allow therapeutic cell fate to be assessed in individual patients, and to achieve this without the need to manipulate the cell's genome so that safety concerns are minimized. This will lead to safe tools to assess treatment response at earlier time points and improve the precision of cell-based therapies.

    View details for DOI 10.1371/journal.pone.0073138

    View details for PubMedID 24015294

  • A transgenic tri-modality reporter mouse. PloS one Yan, X., Ray, P., Paulmurugan, R., Tong, R., Gong, Y., Sathirachinda, A., Wu, J. C., Gambhir, S. S. 2013; 8 (8)


    Transgenic mouse with a stably integrated reporter gene(s) can be a valuable resource for obtaining uniformly labeled stem cells, tissues, and organs for various applications. We have generated a transgenic mouse model that ubiquitously expresses a tri-fusion reporter gene (fluc2-tdTomato-ttk) driven by a constitutive chicken β-actin promoter. This "Tri-Modality Reporter Mouse" system allows one to isolate most cells from this donor mouse and image them for bioluminescent (fluc2), fluorescent (tdTomato), and positron emission tomography (PET) (ttk) modalities. Transgenic colonies with different levels of tri-fusion reporter gene expression showed a linear correlation between all three-reporter proteins (R(2)=0.89 for TdTomato vs Fluc, R(2)=0.94 for Fluc vs TTK, R(2)=0.89 for TdTomato vs TTK) in vitro from tissue lysates and in vivo by optical and PET imaging. Mesenchymal stem cells (MSCs) isolated from this transgenics showed high level of reporter gene expression, which linearly correlated with the cell numbers (R(2)=0.99 for bioluminescence imaging (BLI)). Both BLI (R(2)=0.93) and micro-PET (R(2)=0.94) imaging of the subcutaneous implants of Tri-Modality Reporter Mouse derived MSCs in nude mice showed linear correlation with the cell numbers and across different imaging modalities (R(2)=0.97). Serial imaging of MSCs transplanted to mice with acute myocardial infarction (MI) by intramyocardial injection exhibited significantly higher signals in MI heart at days 2, 3, 4, and 7 (p<0.01). MSCs transplanted to the ischemic hindlimb of nude mice showed significantly higher BLI and PET signals in the first 2 weeks that dropped by 4(th) week due to poor cell survival. However, laser Doppler perfusion imaging revealed that blood circulation in the ischemic limb was significantly improved in the MSCs transplantation group compared with the control group. In summary, this mouse can be used as a source of donor cells and organs in various research areas such as stem cell research, tissue engineering research, and organ transplantation.

    View details for DOI 10.1371/journal.pone.0073580

    View details for PubMedID 23951359

  • Human flexor tendon tissue engineering: revitalization of biostatic allograft scaffolds. Tissue engineering. Part A Woon, C. Y., Farnebo, S., Schmitt, T., Kraus, A., Megerle, K., Pham, H., Yan, X., Gambhir, S. S., Chang, J. 2012; 18 (23-24): 2406-2417


    Cadaveric tendon allografts form a readily available and underutilized source of graft material. Because of their material properties, allografts are biomechanically and biologically superior to synthetic scaffolds. However, before clinical use, allografts must undergo decellularization to reduce immunogenicity and oxidation to increase porosity, leaving a nonvital biostatic scaffold. Ex vivo seeding, or revitalization, is thought to hasten graft incorporation and stimulate intrinsic tendon healing, permitting early mobilization and return to function. In this study, we examined physical and biochemical augmentation methods, including scaffold surface scoring (physical) and rehydration of lyophilized scaffolds in serum (biochemical). Scaffolds were divided into four groups: (1) scored scaffolds, (2) lyophilized scaffolds rehydrated in fetal calf serum (FCS), (3) scaffolds both scored and rehydrated in FCS, and (4) control scaffolds. Scaffolds were reseeded with adipose-derived stem cells (ADSCs). Reseeding efficacy was quantified by a live cell and total cell assays and qualified histologically with hematoxylin and eosin, live/dead and SYTO green nucleic acid stains, TUNEL apoptosis stains, procollagen stains, and transmission electron microscopy. Scaffold-seeded cell viability at up to 2 weeks in vitro and up to 4 weeks in vivo was demonstrated with bioluminescent imaging of scaffolds seeded with luciferase-positive ADSCs. The effect of seeding on scaffold biomechanical properties was demonstrated with evaluation of ultimate tensile stress (UTS) and an elastic modulus (EM). We found that scaffold surface scoring led to an increase in live and total cell attachment and penetration (MTS assay, p<0.001 and DNA assay, p=0.003, respectively). Histology confirmed greater total cell number in both construct core and surface in scored compared with unscored constructs. Cells reseeded on scored constructs displayed reduced apoptosis, persistent procollagen production, and had a similar ultrastructural relationship to the surrounding matrix as native tenocytes on transmission electron microscopy. Rehydration of lyophilized scaffolds in serum did not improve reseeding. Seeded constructs demonstrated greater UTS and EM than unseeded constructs. Scaffolds seeded with ADSC-luc2-eGFP demonstrated persistent viability for at least 2 weeks in vitro. In conclusion, tendon surface scoring increases surface and core reseeding in vitro and may be incorporated as a final step in allograft processing before clinical implantation.

    View details for DOI 10.1089/ten.TEA.2012.0152

    View details for PubMedID 22712522

  • Human Flexor Tendon Tissue Engineering: Revitalization of Biostatic Allograft Scaffolds TISSUE ENGINEERING PART A Woon, C. Y., Farnebo, S., Schmitt, T., Kraus, A., Megerle, K., Hung Pham, H., Yan, X., Gambhir, S. S., Chang, J. 2012; 18 (23-24): 2406-2417
  • Exogenous MC3T3 Preosteoblasts Migrate Systemically and Mitigate the Adverse Effects of Wear Particles TISSUE ENGINEERING PART A Fritton, K., Ren, P., Gibon, E., Rao, A. J., Ma, T., Biswal, S., Gambhir, S. S., Goodman, S. B. 2012; 18 (23-24): 2559-2567


    Understanding how relevant cell types respond to wear particles will reveal new avenues for treating osteolysis following joint replacements. In this study, we investigate the effects of ultrahigh molecular weight polyethylene (UHMWPE) particles on preosteoblast migration and function. We infused UHMWPE particles or saline into the left femur of mice and injected luciferase-expressing preosteoblasts (MC3T3 cells) into each left ventricle. Bioluminescence imaging (BLI) confirmed systemic administration of MC3T3 cells. BLI throughout the 28-day experiment showed greater MC3T3 migration to the site of particle infusion than to the site of saline infusion, with significant differences on days 0, 4, and 6 (p≤0.055). Immunostaining revealed a greater number of osteoblasts and osteoclasts in the particle-infused femora, indicating greater bone turnover. The bone mineralization of the particle-infused femora increased significantly when compared to saline-infused femora (an increase of 146.4±27.9 vs. 12.8±8.7 mg/mL, p=0.008). These results show that infused preosteoblasts can migrate to the site of wear particles. Additionally, as the migrated cells were associated with increased bone mineralization in spite of the presence of particles, increasing osteoblast recruitment is a potential strategy for combating bone loss due to increased osteoclast/macrophage number and decreased osteoblast function.

    View details for DOI 10.1089/ten.tea.2012.0086

    View details for Web of Science ID 000311600800016

    View details for PubMedID 22741555

  • Unexpected Dissemination Patterns in Lymphoma Progression Revealed by Serial Imaging within a Murine Lymph Node CANCER RESEARCH Ito, K., Smith, B. R., Parashurama, N., Yoon, J., Song, S. Y., Miething, C., Mallick, P., Lowe, S., Gambhir, S. S. 2012; 72 (23): 6111-6118


    Non-Hodgkin lymphoma (NHL) is a heterogeneous and highly disseminated disease, but the mechanisms of its growth and dissemination are not well understood. Using a mouse model of this disease, we used multimodal imaging, including intravital microscopy (IVM) combined with bioluminescence, as a powerful tool to better elucidate NHL progression. We injected enhanced green fluorescent protein and luciferase-expressing Eμ-Myc/Arf(-/-) (Cdkn2a(-/-)) mouse lymphoma cells (EL-Arf(-/-)) into C57BL/6NCrl mice intravenously. Long-term observation inside a peripheral lymph node was enabled by a novel lymph node internal window chamber technique that allows chronic, sequential lymph node imaging under in vivo physiologic conditions. Interestingly, during early stages of tumor progression we found that few if any lymphoma cells homed initially to the inguinal lymph node (ILN), despite clear evidence of lymphoma cells in the bone marrow and spleen. Unexpectedly, we detected a reproducible efflux of lymphoma cells from spleen and bone marrow, concomitant with a massive and synchronous influx of lymphoma cells into the ILN, several days after injection. We confirmed a coordinated efflux/influx of tumor cells by injecting EL-Arf(-/-) lymphoma cells directly into the spleen and observing a burst of lymphoma cells, validating that the burst originated in organs remote from the lymph nodes. Our findings argue that in NHL an efflux of tumor cells from one disease site to another, distant site in which they become established occurs in discrete bursts.

    View details for DOI 10.1158/0008-5472.CAN-12-2579

    View details for Web of Science ID 000311893100005

    View details for PubMedID 23033441

  • Continuous sensing of tumor-targeted molecular probes with a vertical cavity surface emitting laser-based biosensor JOURNAL OF BIOMEDICAL OPTICS Parashurama, N., O'Sullivan, T. D., de la Zerda, A., El Kalassi, P., Cho, S., Liu, H., Teed, R., Levy, H., Rosenberg, J., Cheng, Z., Levi, O., Harris, J. S., Gambhir, S. S. 2012; 17 (11)


    Molecular optical imaging is a widespread technique for interrogating molecular events in living subjects. However, current approaches preclude long-term, continuous measurements in awake, mobile subjects, a strategy crucial in several medical conditions. Consequently, we designed a novel, lightweight miniature biosensor for in vivo continuous optical sensing. The biosensor contains an enclosed vertical-cavity surface-emitting semiconductor laser and an adjacent pair of near-infrared optically filtered detectors. We employed two sensors (dual sensing) to simultaneously interrogate normal and diseased tumor sites. Having established the sensors are precise with phantom and in vivo studies, we performed dual, continuous sensing in tumor (human glioblastoma cells) bearing mice using the targeted molecular probe cRGD-Cy5.5, which targets αVβ3 cell surface integrins in both tumor neovasculature and tumor. The sensors capture the dynamic time-activity curve of the targeted molecular probe. The average tumor to background ratio after signal calibration for cRGD-Cy5.5 injection is approximately 2.43±0.95 at 1 h and 3.64±1.38 at 2 h (N=5 mice), consistent with data obtained with a cooled charge coupled device camera. We conclude that our novel, portable, precise biosensor can be used to evaluate both kinetics and steady state levels of molecular probes in various disease applications.

    View details for DOI 10.1117/1.JBO.17.11.117004

    View details for Web of Science ID 000314502700046

    View details for PubMedID 23123976

  • Gold Nanorods for Ovarian Cancer Detection with Photoacoustic Imaging and Resection Guidance via Raman Imaging in Living Mice ACS NANO Jokerst, J. V., Cole, A. J., Van de Sompel, D., Gambhir, S. S. 2012; 6 (11): 10366-10377


    Improved imaging approaches are needed for ovarian cancer screening, diagnosis, staging, and resection guidance. Here, we propose a combined photoacoustic (PA)/Raman approach using gold nanorods (GNRs) as a passively targeted molecular imaging agent. GNRs with three different aspect ratios were studied. Those with an aspect ratio of 3.5 were selected for their highest ex vivo and in vivo PA signal and used to image subcutaneous xenografts of the 2008, HEY, and SKOV3 ovarian cancer cell lines in living mice. Maximum PA signal was observed within 3 h for all three lines tested and increased signal persisted for at least two days postadministration. There was a linear relationship (R(2) = 0.95) between the PA signal and the concentration of injected molecular imaging agent with a calculated limit of detection of 0.40 nM GNRs in the 2008 cell line. The same molecular imaging agent could be used for clear visualization of the margin between tumor and normal tissue and tumor debulking via surface-enhanced Raman spectroscopy (SERS) imaging. Finally, we validated the imaging findings with biodistribution data and elemental analysis. To the best of our knowledge, this is the first report of in vivo imaging of ovarian cancer tumors with a photoacoustic and Raman imaging agent.

    View details for DOI 10.1021/nn304347g

    View details for Web of Science ID 000311521700112

    View details for PubMedID 23101432

  • New Positron Emission Tomography (PET) Radioligand for Imaging sigma-1 Receptors in Living Subjects JOURNAL OF MEDICINAL CHEMISTRY James, M. L., Shen, B., Zavaleta, C. L., Nielsen, C. H., Mesangeau, C., Vuppala, P. K., Chan, C., Avery, B. A., Fishback, J. A., Matsumoto, R. R., Gambhir, S. S., McCurdy, C. R., Chin, F. T. 2012; 55 (19): 8272-8282


    σ-1 receptor (S1R) radioligands have the potential to detect and monitor various neurological diseases. Herein we report the synthesis, radiofluorination, and evaluation of a new S1R ligand 6-(3-fluoropropyl)-3-(2-(azepan-1-yl)ethyl)benzo[d]thiazol-2(3H)-one ([(18)F]FTC-146, [(18)F]13). [(18)F]13 was synthesized by nucleophilic fluorination, affording a product with >99% radiochemical purity (RCP) and specific activity (SA) of 2.6 ± 1.2 Ci/μmol (n = 13) at end of synthesis (EOS). Positron emission tomography (PET) and ex vivo autoradiography studies of [(18)F]13 in mice showed high uptake of the radioligand in S1R rich regions of the brain. Pretreatment with 1 mg/kg haloperidol (2), nonradioactive 13, or BD1047 (18) reduced the binding of [(18)F]13 in the brain at 60 min by 80%, 82%, and 81%, respectively, suggesting that [(18)F]13 accumulation in mouse brain represents specific binding to S1Rs. These results indicate that [(18)F]13 is a promising candidate radiotracer for further evaluation as a tool for studying S1Rs in living subjects.

    View details for DOI 10.1021/jm300371c

    View details for Web of Science ID 000309643500008

    View details for PubMedID 22853801

  • Improving Image Quality by Accounting for Changes in Water Temperature during a Photoacoustic Tomography Scan PLOS ONE Van de Sompel, D., Sasportas, L. S., Dragulescu-Andrasi, A., Bohndiek, S., Gambhir, S. S. 2012; 7 (10)


    The emerging field of photoacoustic tomography is rapidly evolving with many new system designs and reconstruction algorithms being published. Many systems use water as a coupling medium between the scanned object and the ultrasound transducers. Prior to a scan, the water is heated to body temperature to enable small animal imaging. During the scan, the water heating system of some systems is switched off to minimize the risk of bubble formation, which leads to a gradual decrease in water temperature and hence the speed of sound. In this work, we use a commercially available scanner that follows this procedure, and show that a failure to model intra-scan temperature decreases as small as 1.5°C leads to image artifacts that may be difficult to distinguish from true structures, particularly in complex scenes. We then improve image quality by continuously monitoring the water temperature during the scan and applying variable speed of sound corrections in the image reconstruction algorithm. While upgrading to an air bubble-free heating pump and keeping it running during the scan could also solve the changing temperature problem, we show that a software correction for the temperature changes provides a cost-effective alternative to a hardware upgrade. The efficacy of the software corrections was shown to be consistent across objects of widely varying appearances, namely physical phantoms, ex vivo tissue, and in vivo mouse imaging. To the best of our knowledge, this is the first study to demonstrate the efficacy of modeling temporal variations in the speed of sound during photoacoustic scans, as opposed to spatial variations as focused on by previous studies. Since air bubbles pose a common problem in ultrasonic and photoacoustic imaging systems, our results will be useful to future small animal imaging studies that use scanners with similarly limited heating units.

    View details for DOI 10.1371/journal.pone.0045337

    View details for Web of Science ID 000309807700008

    View details for PubMedID 23071512

  • The Impact of Partial Volume Correction in the Evaluation of Solitary Pulmonary Nodules by FDG PET/CT in a Population at Intermediate Risk of Lung Cancer 4th International Symposium on Targeted Radiotherapy and Dosimetry (ISTARD) in Conjunction with the 25th Annual Congress of the European-Association-of-Nuclear-Medicine (EANM) Keu, K., Nair, V. S., Mittra, E., Gambhir, S. S., Iagaru, A. SPRINGER. 2012: S455–S455
  • Intraoperative Imaging of Tumors Using Cerenkov Luminescence Endoscopy: A Feasibility Experimental Study JOURNAL OF NUCLEAR MEDICINE Liu, H., Carpenter, C. M., Jiang, H., Pratx, G., Sun, C., Buchin, M. P., Gambhir, S. S., Xing, L., Cheng, Z. 2012; 53 (10): 1579-1584


    Cerenkov luminescence imaging (CLI) is an emerging new molecular imaging modality that is relatively inexpensive, easy to use, and has high throughput. CLI can image clinically available PET and SPECT probes using optical instrumentation. Cerenkov luminescence endoscopy (CLE) is one of the most intriguing applications that promise potential clinical translation. We developed a prototype customized fiberscopic Cerenkov imaging system to investigate the potential in guiding minimally invasive surgical resection.All experiments were performed in a dark chamber. Cerenkov luminescence from (18)F-FDG samples containing decaying radioactivity was transmitted through an optical fiber bundle and imaged by an intensified charge-coupled device camera. Phantoms filled with (18)F-FDG were used to assess the imaging spatial resolution. Finally, mice bearing subcutaneous C6 glioma cells were injected intravenously with (18)F-FDG to determine the feasibility of in vivo imaging. The tumor tissues were exposed, and CLI was performed on the mouse before and after surgical removal of the tumor using the fiber-based imaging system and compared with a commercial optical imaging system.The sensitivity of this particular setup was approximately 45 kBq (1.21 μCi)/300 μL. The 3 smallest sets of cylindric holes in a commercial SPECT phantom were identifiable via this system, demonstrating that the system has a resolution better than 1.2 mm. Finally, the in vivo tumor imaging study demonstrated the feasibility of using CLI to guide the resection of tumor tissues.This proof-of-concept study explored the feasibility of using fiber-based CLE for the detection of tumor tissue in vivo for guided surgery. With further improvements of the imaging sensitivity and spatial resolution of the current system, CLE may have a significant application in the clinical setting in the near future.

    View details for DOI 10.2967/jnumed.111.098541

    View details for Web of Science ID 000309432400017

    View details for PubMedID 22904353

  • Exploratory Clinical Trial of (4S)-4-(3-[F-18]fluoropropyl)-L-glutamate for Imaging x(C) Transporter Using Positron Emission Tomography in Patients with Non-Small Cell Lung or Breast Cancer CLINICAL CANCER RESEARCH Baek, S., Choi, C., Ahn, S. H., Lee, J. W., Gong, G., Ryu, J., Oh, S. J., Bacher-Stier, C., Fels, L., Koglin, N., Hultsch, C., Schatz, C. A., Dinkelborg, L. M., Mittra, E. S., Gambhir, S. S., Moon, D. H. 2012; 18 (19): 5427-5437


    (4S)-4-(3-[(18)F]fluoropropyl)-l-glutamate (BAY 94-9392, alias [(18)F]FSPG) is a new tracer to image x(C)(-) transporter activity with positron emission tomography (PET). We aimed to explore the tumor detection rate of [(18)F]FSPG in patients relative to 2-[(18)F]fluoro-2-deoxyglucose ([(18)F]FDG). The correlation of [(18)F]FSPG uptake with immunohistochemical expression of x(C)(-) transporter and CD44, which stabilizes the xCT subunit of system x(C)(-), was also analyzed.Patients with non-small cell lung cancer (NSCLC, n = 10) or breast cancer (n = 5) who had a positive [(18)F]FDG uptake were included in this exploratory study. PET images were acquired following injection of approximately 300 MBq [(18)F]FSPG. Immunohistochemistry was done using xCT- and CD44-specific antibody.[(18)F]FSPG PET showed high uptake in the kidney and pancreas with rapid blood clearance. [(18)F]FSPG identified all 10 NSCLC and three of the five breast cancer lesions that were confirmed by pathology. [(18)F]FSPG detected 59 of 67 (88%) [(18)F]FDG lesions in NSCLC, and 30 of 73 (41%) in breast cancer. Seven lesions were additionally detected only on [(18)F]FSPG in NSCLC. The tumor-to-blood pool standardized uptake value (SUV) ratio was not significantly different from that of [(18)F]FDG in NSCLC; however, in breast cancer, it was significantly lower (P < 0.05). The maximum SUV of [(18)F]FSPG correlated significantly with the intensity of immunohistochemical staining of x(C)(-) transporter and CD44 (P < 0.01).[(18)F]FSPG seems to be a promising tracer with a relatively high cancer detection rate in patients with NSCLC. [(18)F]FSPG PET may assess x(C)(-) transporter activity in patients with cancer.

    View details for DOI 10.1158/1078-0432.CCR-12-0214

    View details for Web of Science ID 000311906600027

    View details for PubMedID 22893629

  • Positron Emission Tomography of Cu-64-DOTA-Rituximab in a Transgenic Mouse Model Expressing Human CD20 for Clinical Translation to Image NHL MOLECULAR IMAGING AND BIOLOGY Natarajan, A., Gowrishankar, G., Nielsen, C. H., Wang, S., Iagaru, A., Goris, M. L., Gambhir, S. S. 2012; 14 (5): 608-616


    This study aims to evaluate (64)Cu-DOTA-rituximab (PETRIT) in a preclinical transgenic mouse model expressing human CD20 for potential clinical translation.(64)Cu was chelated to DOTA-rituximab. Multiple radiolabeling, quality assurance, and imaging experiments were performed. The human CD20 antigen was expressed in B cells of transgenic mice (CD20TM). The mice groups studied were: (a) control (nude mice, n = 3) that received 7.4 MBq/dose, (b) with pre-dose (CD20TM, n = 6) received 2 mg/kg pre-dose of cold rituximab prior to PETRIT of 7.4 MBq/dose, and (c) without pre-dose (CD20TM, n = 6) PETRIT alone received 7.4 MBq/dose. Small animal PET was used to image mice at various time points (0, 1, 2, 4, 24, 48, and 72 h). The OLINDA/EXM software was used to determine the human equivalent dose for individual organs.PETRIT was obtained with a specific activity of 545 ± 38.91 MBq/nmole, radiochemical purity >95%, and immunoreactivity >75%. At 24 h, spleenic uptake of PETRIT%ID/g (mean ± STD) with and without pre-dose was 1.76 ± 0.43% and 16.5 ± 0.45%, respectively (P value = 0.01). Liver uptake with and without pre-dose was 0.41 ± 0.51% and 0.52 ± 0.17% (P value = 0.86), respectively. The human equivalents of highest dose organs with and without pre-dose are osteogenic cells at 30.8 ± 0.4 μSv/MBq and the spleen at 99 ± 4 μSv/MBq, respectively.PET imaging with PETRIT in huCD20 transgenic mice provided human dosimetry data for eventual applications in non-Hodgkins lymphoma patients.

    View details for DOI 10.1007/s11307-011-0537-8

    View details for Web of Science ID 000308819300011

    View details for PubMedID 22231277

  • alpha v beta 3 Integrins as a Biomarker of Disease Recurrence in Glioblastoma Multiforme: Initial Clinical Results Using 18F FPPRGD2 PET/CT 4th International Symposium on Targeted Radiotherapy and Dosimetry (ISTARD) in Conjunction with the 25th Annual Congress of the European-Association-of-Nuclear-Medicine (EANM) Iagaru, A., Mosci, C., Mittra, E. S., Shin, B., Chin, F., Gambhir, S. S. SPRINGER. 2012: S244–S245
  • Remodeling of Endogenous Mammary Epithelium by Breast Cancer Stem Cells STEM CELLS Parashurama, N., Lobo, N. A., Ito, K., Mosley, A. R., Habte, F. G., Zabala, M., Smith, B. R., Lam, J., Weissman, I. L., Clarke, M. F., Gambhir, S. S. 2012; 30 (10): 2114-2127


    Poorly regulated tissue remodeling results in increased breast cancer risk, yet how breast cancer stem cells (CSC) participate in remodeling is unknown. We performed in vivo imaging of changes in fluorescent, endogenous duct architecture as a metric for remodeling. First, we quantitatively imaged physiologic remodeling of primary branches of the developing and regenerating mammary tree. To assess CSC-specific remodeling events, we isolated CSC from MMTV-Wnt1 (mouse mammary tumor virus long-term repeat enhancer driving Wnt1 oncogene) breast tumors, a well studied model in which tissue remodeling affects tumorigenesis. We confirm that CSC drive tumorigenesis, suggesting a link between CSC and remodeling. We find that normal, regenerating, and developing gland maintain a specific branching pattern. In contrast, transplantation of CSC results in changes in the branching patterns of endogenous ducts while non-CSC do not. Specifically, in the presence of CSC, we identified an increased number of branches, branch points, ducts which have greater than 40 branches (5/33 for CSC and 0/39 for non-CSC), and histological evidence of increased branching. Moreover, we demonstrate that only CSC implants invade into surrounding stroma with structures similar to developing mammary ducts (nine for CSC and one for non-CSC). Overall, we demonstrate a novel approach for imaging physiologic and pathological remodeling. Furthermore, we identify unique, CSC-specific, remodeling events. Our data suggest that CSC interact with the microenvironment differently than non-CSC, and that this could eventually be a therapeutic approach for targeting CSC.

    View details for DOI 10.1002/stem.1205

    View details for Web of Science ID 000308928300005

    View details for PubMedID 22899386

  • Designed hydrophilic and charge mutations of the fibronectin domain: towards tailored protein biodistribution PROTEIN ENGINEERING DESIGN & SELECTION Hackel, B. J., Sathirachinda, A., Gambhir, S. S. 2012; 25 (10): 639-647


    Engineered proteins are attractive affinity scaffolds for molecular imaging and drug delivery. Although exquisite binding specificity and affinity can be engineered, many proteins exhibit off-target uptake, particularly in the kidneys and liver, from physiologic effects. We quantified the ability to alter renal and hepatic uptake via hydrophilic and charge mutations. As a model protein, we used the 10th type III domain of human fibronectin, which has been engineered to bind many targets and has been validated for molecular imaging. We screened rational mutants, identified by structural and phylogenetic analyses, to yield eight mutations that collectively substantially increase protein hydrophilicity. Mutation of two parental clones yielded four domains with a range of hydrophilicity. These proteins were labeled with (64)Cu, injected intravenously into nu/nu mice (n = 3-5 each) and evaluated by positron emission tomography. Renal uptake strongly correlated with hydrophilicity (Pearson's correlation coefficient = 0.97), ranging from 29 ± 11 to 100 ± 22% ID/g at 1 h. Hepatic uptake inversely correlated with hydrophilicity (Pearson's correlation coefficient = -0.92), ranging from 30 ± 7 to 3 ± 1% ID/g. Thus, renal and hepatic uptake are directly tunable through hydrophilic mutation, identifiable by structural and phylogenetic analyses. To investigate charge, we mutated acidic and basic residues in both parental clones and evaluated (64)Cu-labeled mutants in nu/nu mice (n = 5-7). Selected charge removal reduced kidney signal: 78 ± 13 to 51 ± 8%ID/g (P < 0.0001) for the hydrophilic clone and 32 ± 10 to 21 ± 3 (P = 0.0005) for the hydrophobic clone. Elucidation of hydrophilicity and charge enabled modulation of background signal thereby enhancing the utility of protein scaffolds as translatable targeting agents for molecular imaging and therapy.

    View details for DOI 10.1093/protein/gzs036

    View details for Web of Science ID 000309468100016

    View details for PubMedID 22691700

  • Microfluidic Single-Cell Analysis Shows That Porcine Induced Pluripotent Stem Cell-Derived Endothelial Cells Improve Myocardial Function by Paracrine Activation CIRCULATION RESEARCH Gu, M., Nguyen, P. K., Lee, A. S., Xu, D., Hu, S., Plews, J. R., Han, L., Huber, B. C., Lee, W. H., Gong, Y., de Almeida, P. E., Lyons, J., Ikeno, F., Pacharinsak, C., Connolly, A. J., Gambhir, S. S., Robbins, R. C., Longaker, M. T., Wu, J. C. 2012; 111 (7): 882-893


    Induced pluripotent stem cells (iPSCs) hold great promise for the development of patient-specific therapies for cardiovascular disease. However, clinical translation will require preclinical optimization and validation of large-animal iPSC models.To successfully derive endothelial cells from porcine iPSCs and demonstrate their potential utility for the treatment of myocardial ischemia.Porcine adipose stromal cells were reprogrammed to generate porcine iPSCs (piPSCs). Immunohistochemistry, quantitative PCR, microarray hybridization, and angiogenic assays confirmed that piPSC-derived endothelial cells (piPSC-ECs) shared similar morphological and functional properties as endothelial cells isolated from the autologous pig aorta. To demonstrate their therapeutic potential, piPSC-ECs were transplanted into mice with myocardial infarction. Compared with control, animals transplanted with piPSC-ECs showed significant functional improvement measured by echocardiography (fractional shortening at week 4: 27.2±1.3% versus 22.3±1.1%; P<0.001) and MRI (ejection fraction at week 4: 45.8±1.3% versus 42.3±0.9%; P<0.05). Quantitative protein assays and microfluidic single-cell PCR profiling showed that piPSC-ECs released proangiogenic and antiapoptotic factors in the ischemic microenvironment, which promoted neovascularization and cardiomyocyte survival, respectively. Release of paracrine factors varied significantly among subpopulations of transplanted cells, suggesting that transplantation of specific cell populations may result in greater functional recovery.In summary, this is the first study to successfully differentiate piPSCs-ECs from piPSCs and demonstrate that transplantation of piPSC-ECs improved cardiac function after myocardial infarction via paracrine activation. Further development of these large animal iPSC models will yield significant insights into their therapeutic potential and accelerate the clinical translation of autologous iPSC-based therapy.

    View details for DOI 10.1161/CIRCRESAHA.112.269001

    View details for Web of Science ID 000308868800015

    View details for PubMedID 22821929

    View details for PubMedCentralID PMC3473073

  • Discovery and validation of small-molecule heat-shock protein 90 inhibitors through multimodality molecular imaging in living subjects PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Chan, C. T., Reeves, R. E., Geller, R., Yaghoubi, S. S., Hoehne, A., Solow-Cordero, D. E., Chiosis, G., Massoud, T. F., Paulmurugan, R., Gambhir, S. S. 2012; 109 (37): E2476-E2485


    Up-regulation of the folding machinery of the heat-shock protein 90 (Hsp90) chaperone protein is crucial for cancer progression. The two Hsp90 isoforms (α and β) play different roles in response to chemotherapy. To identify isoform-selective inhibitors of Hsp90(α/β)/cochaperone p23 interactions, we developed a dual-luciferase (Renilla and Firefly) reporter system for high-throughput screening (HTS) and monitoring the efficacy of Hsp90 inhibitors in cell culture and live mice. HTS of a 30,176 small-molecule chemical library in cell culture identified a compound, N-(5-methylisoxazol-3-yl)-2-[4-(thiophen-2-yl)-6-(trifluoromethyl)pyrimidin-2-ylthio]acetamide (CP9), that binds to Hsp90(α/β) and displays characteristics of Hsp90 inhibitors, i.e., degradation of Hsp90 client proteins and inhibition of cell proliferation, glucose metabolism, and thymidine kinase activity, in multiple cancer cell lines. The efficacy of CP9 in disrupting Hsp90(α/β)/p23 interactions and cell proliferation in tumor xenografts was evaluated by non-invasive, repetitive Renilla luciferase and Firefly luciferase imaging, respectively. At 38 h posttreatment (80 mg/kg × 3, i.p.), CP9 led to selective disruption of Hsp90α/p23 as compared with Hsp90β/p23 interactions. Small-animal PET/CT in the same cohort of mice showed that CP9 treatment (43 h) led to a 40% decrease in (18)F-fluorodeoxyglucose uptake in tumors relative to carrier control-treated mice. However, CP9 did not lead to significant degradation of Hsp90 client proteins in tumors. We performed a structural activity relationship study with 62 analogs of CP9 and identified A17 as the lead compound that outperformed CP9 in inhibiting Hsp90(α/β)/p23 interactions in cell culture. Our efforts demonstrated the power of coupling of HTS with multimodality molecular imaging and led to identification of Hsp90 inhibitors.

    View details for DOI 10.1073/pnas.1205459109

    View details for Web of Science ID 000309208000012

    View details for PubMedID 22895790

    View details for PubMedCentralID PMC3443147

  • Cationic versus Neutral Microbubbles for Ultrasound-mediated Gene Delivery in Cancer RADIOLOGY Wang, D. S., Panje, C., Pysz, M. A., Paulmurugan, R., Rosenberg, J., Gambhir, S. S., Schneider, M., Willmann, J. K. 2012; 264 (3): 721-732


    To test whether plasmid-binding cationic microbubbles (MBs) enhance ultrasound-mediated gene delivery efficiency relative to control neutral MBs in cell culture and in vivo tumors in mice.Animal studies were approved by the institutional animal care committee. Cationic and neutral MBs were characterized in terms of size, charge, circulation time, and DNA binding. Click beetle luciferase (CBLuc) reporter plasmids were mixed with cationic or neutral MBs. The ability of cationic MBs to protect bound plasmids from nuclease degradation was tested by means of a deoxyribonuclease (DNase) protection assay. Relative efficiencies of ultrasound-mediated transfection (ultrasound parameters: 1 MHz, 1 W/cm(2), 20% duty cycle, 1 minute) of CBLuc to endothelial cells by using cationic, neutral, or no MBs were compared in cell culture. Ultrasound-mediated gene delivery to mouse hind limb tumors was performed in vivo (n = 24) with insonation (1 MHz, 2 W/cm(2), 50% duty cycle, 5 minutes) after intravenous administration of CBLuc with cationic, neutral, or no MBs. Tumor luciferase activity was assessed by means of serial in vivo bioluminescence imaging and ex vivo analysis. Results were compared by using analysis of variance.Cationic MBs (+15.8 mV; DNA binding capacity, 0.03 pg per MB) partially protected bound DNA from DNase degradation. Mean CBLuc expression of treated endothelial cells in culture was 20-fold higher with cationic than with neutral MBs (219.0 relative light units [RLUs]/µg protein ± 92.5 [standard deviation] vs 10.9 RLUs/µg protein ± 2.7, P = .001) and was significantly higher (P < .001) than that in the no MB and no ultrasound control groups. Serial in vivo bioluminescence of mouse tumors was significantly higher with cationic than with neutral MBs ([5.9 ± 2.2] to [9.3 ± 5.2] vs [2.4 ± 0.8] to [2.9 ± 1.1] × 10(4) photons/sec/cm(2)/steradian, P < .0001) and versus no MB and no ultrasound controls (P < .0001). Results of ex vivo analysis confirmed these results (ρ = 0.88, P < .0001).Plasmid-binding cationic MBs enhance ultrasound-mediated gene delivery efficiency relative to neutral MBs in both cell culture and mouse hind limb tumors.

    View details for DOI 10.1148/radiol.12112368

    View details for Web of Science ID 000308645500013

    View details for PubMedID 22723497

    View details for PubMedCentralID PMC3426857

  • Circulating tumour cells in early breast cancer LANCET ONCOLOGY Nair, V. S., Keu, K. V., Kuhn, P., Gambhir, S. S. 2012; 13 (9): E370-E371

    View details for Web of Science ID 000308425600024

    View details for PubMedID 22935234

  • Tissue-engineered collateral ligament composite allografts for scapholunate ligament reconstruction: an experimental study. journal of hand surgery Endress, R., Woon, C. Y., Farnebo, S. J., Behn, A., Bronstein, J., Pham, H., Yan, X., Gambhir, S. S., Chang, J. 2012; 37 (8): 1529-1537


    In patients with chronic scapholunate (SL) dissociation or dynamic instability, ligament repair is often not possible, and surgical reconstruction is indicated. The ideal graft ligament would recreate both anatomical and biomechanical properties of the dorsal scapholunate ligament (dorsal SLIL). The finger proximal interphalangeal joint (PIP joint) collateral ligament could possibly be a substitute ligament.We harvested human PIP joint collateral ligaments and SL ligaments from 15 cadaveric limbs. We recorded ligament length, width, and thickness, and measured the biomechanical properties (ultimate load, stiffness, and displacement to failure) of native dorsal SLIL, untreated collateral ligaments, decellularized collateral ligaments, and SL repairs with bone-collateral ligament-bone composite collateral ligament grafts. As proof of concept, we then reseeded decellularized bone-collateral ligament-bone composite grafts with green fluorescent protein-labeled adipo-derived mesenchymal stem cells and evaluated them histologically.There was no difference in ultimate load, stiffness, and displacement to failure among native dorsal SLIL, untreated and decellularized collateral ligaments, and SL repairs with tissue-engineered collateral ligament grafts. With pair-matched untreated and decellularized scaffolds, there was no difference in ultimate load or stiffness. However, decellularized ligaments revealed lower displacement to failure compared with untreated ligaments. There was no difference in displacement between decellularized ligaments and native dorsal SLIL. We successfully decellularized grafts with recently described techniques, and they could be similarly reseeded.Proximal interphalangeal joint collateral ligament-based bone-collateral ligament-bone composite allografts had biomechanical properties similar to those of native dorsal SLIL. Decellularization did not adversely affect material properties.These tissue-engineered grafts may offer surgeons another option for reconstruction of chronic SL instability.

    View details for DOI 10.1016/j.jhsa.2012.05.020

    View details for PubMedID 22835583

  • Tissue-engineered Collateral Ligament Composite Allografts for Scapholunate Ligament Reconstruction: An Experimental Study JOURNAL OF HAND SURGERY-AMERICAN VOLUME Endress, R., Woon, C. Y., Farnebo, S. J., Behn, A., Bronstein, J., Pham, H., Yan, X., Gambhir, S. S., Chang, J. 2012; 37A (8): 1529-1537
  • Impact of Screening Test Performance and Cost on Mortality Reduction and Cost-effectiveness of Multimodal Ovarian Cancer Screening CANCER PREVENTION RESEARCH Drescher, C. W., Hawley, S., Thorpe, J. D., Marticke, S., McIntosh, M., Gambhir, S. S., Urban, N. 2012; 5 (8): 1015-1024


    Ongoing ovarian cancer screening trials are investigating the efficacy of a two-step screening strategy using currently available blood and imaging tests [CA125 and transvaginal sonography (TVS)]. Concurrently, efforts to develop new biomarkers and imaging tests seek to improve screening performance beyond its current limits. This study estimates the mortality reduction, years of life saved, and cost-effectiveness achievable by annual multimodal screening using increasing CA125 to select women for TVS, and predicts improvements achievable by replacing currently available screening tests with hypothetical counterparts with better performance characteristics. An existing stochastic microsimulation model is refined and used to screen a virtual cohort of 1 million women from ages 45 to 85 years. Each woman is assigned a detailed disease course and screening results timeline. The preclinical behavior of CA125 and TVS is simulated using empirical data derived from clinical trials. Simulations in which the disease incidence and performance characteristics of the screening tests are independently varied are conducted to evaluate the impact of these factors on overall screening performance and costs. Our results show that when applied to women at average risk, annual screening using increasing CA125 to select women for TVS achieves modest mortality reduction (~13%) and meets currently accepted cost-effectiveness guidelines. Screening outcomes are relatively insensitive to second-line test performance and costs. Identification of a first-line test that does substantially better than CA125 and has similar costs is required for screening to reduce ovarian mortality by at least 25% and be reasonably cost-effective.

    View details for DOI 10.1158/1940-6207.CAPR-11-0468

    View details for Web of Science ID 000308223500004

    View details for PubMedID 22750949

  • Fluorescent Magnetic Nanoparticles for Magnetically Enhanced Cancer Imaging and Targeting in Living Subjects ACS NANO Fu, A., Wilson, R. J., Smith, B. R., Mullenix, J., Earhart, C., Akin, D., Guccione, S., Wang, S. X., Gambhir, S. S. 2012; 6 (8): 6862-6869


    Early detection and targeted therapy are two major challenges in the battle against cancer. Novel imaging contrast agents and targeting approaches are greatly needed to improve the sensitivity and specificity of cancer theranostic agents. Here, we implemented a novel approach using a magnetic micromesh and biocompatible fluorescent magnetic nanoparticles (FMN) to magnetically enhance cancer targeting in living subjects. This approach enables magnetic targeting of systemically administered individual FMN, containing a single 8 nm superparamagnetic iron oxide core. Using a human glioblastoma mouse model, we show that nanoparticles can be magnetically retained in both the tumor neovasculature and surrounding tumor tissues. Magnetic accumulation of nanoparticles within the neovasculature was observable by fluorescence intravital microscopy in real time. Finally, we demonstrate that such magnetically enhanced cancer targeting augments the biological functions of molecules linked to the nanoparticle surface.

    View details for DOI 10.1021/nn301670a

    View details for Web of Science ID 000307988900039

    View details for PubMedID 22857784

  • Shape Matters: Intravital Microscopy Reveals Surprising Geometrical Dependence for Nanoparticles in Tumor Models of Extravasation NANO LETTERS Smith, B. R., Kempen, P., Bouley, D., Xu, A., Liu, Z., Melosh, N., Dai, H., Sinclair, R., Gambhir, S. S. 2012; 12 (7): 3369-3377


    Delivery is one of the most critical obstacles confronting nanoparticle use in cancer diagnosis and therapy. For most oncological applications, nanoparticles must extravasate in order to reach tumor cells and perform their designated task. However, little understanding exists regarding the effect of nanoparticle shape on extravasation. Herein we use real-time intravital microscopic imaging to meticulously examine how two different nanoparticles behave across three different murine tumor models. The study quantitatively demonstrates that high-aspect ratio single-walled carbon nanotubes (SWNTs) display extravasational behavior surprisingly different from, and counterintuitive to, spherical nanoparticles although the nanoparticles have similar surface coatings, area, and charge. This work quantitatively indicates that nanoscale extravasational competence is highly dependent on nanoparticle geometry and is heterogeneous.

    View details for DOI 10.1021/nl204175t

    View details for Web of Science ID 000306296200004

    View details for PubMedID 22650417

  • In vivo targeting of HER2-positive tumor using 2-helix affibody molecules AMINO ACIDS Ren, G., Webster, J. M., Liu, Z., Zhang, R., Miao, Z., Liu, H., Gambhir, S. S., Syud, F. A., Cheng, Z. 2012; 43 (1): 405-413


    Molecular imaging of human epidermal growth factor receptor type 2 (HER2) expression has drawn significant attention because of the unique role of the HER2 gene in diagnosis, therapy and prognosis of human breast cancer. In our previous research, a novel cyclic 2-helix small protein, MUT-DS, was discovered as an anti-HER2 Affibody analog with high affinity through rational protein design and engineering. MUT-DS was then evaluated for positron emission tomography (PET) of HER2-positive tumor by labeling with two radionuclides, 68Ga and 18F, with relatively short half-life (t1/2<2 h). In order to fully study the in vivo behavior of 2-helix small protein and demonstrate that it could be a robust platform for labeling with a variety of radionuclides for different applications, in this study, MUT-DS was further radiolabeled with 64Cu or 111In and evaluated for in vivo targeting of HER2-positive tumor in mice. Design 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) conjugated MUT-DS (DOTA-MUT-DS) was chemically synthesized using solid phase peptide synthesizer and I2 oxidation. DOTA-MUT-DS was then radiolabeled with 64Cu or 111In to prepare the HER2 imaging probe (64Cu/111In-DOTA-MUT-DS). Both biodistribution and microPET imaging of the probe were evaluated in nude mice bearing subcutaneous HER2-positive SKOV3 tumors. DOTA-MUT-DS could be successfully synthesized and radiolabeled with 64Cu or 111In. Biodistribution study showed that tumor uptake value of 64Cu or 111In-labeled DOTA-MUT-DS was 4.66±0.38 or 2.17±0.15%ID/g, respectively, in nude mice bearing SKOV3 xenografts (n=3) at 1 h post-injection (p.i.). Tumor-to-blood and tumor-to-muscle ratios for 64Cu-DOTA-MUT-DS were attained to be 3.05 and 3.48 at 1 h p.i., respectively, while for 111In-DOTA-MUT-DS, they were 2.04 and 3.19, respectively. Co-injection of the cold Affibody molecule ZHER2:342 with 64Cu-DOTA-MUT-DS specifically reduced the SKOV3 tumor uptake of the probe by 48%. 111In-DOTA-MUT-DS displayed lower liver uptake at all the time points investigated and higher tumor to blood ratios at 4 and 20 h p.i., when compared with 64Cu-DOTA-MUT-DS. This study demonstrates that the 2-helix protein based probes, 64Cu/111In DOTA-MUT-DS, are promising molecular probes for imaging HER2-positive tumor. Two-helix small protein scaffold holds great promise as a novel and robust platform for imaging and therapy applications.

    View details for DOI 10.1007/s00726-011-1096-7

    View details for Web of Science ID 000305210800041

    View details for PubMedID 21984380

  • Photoacoustic Imaging of Mesenchymal Stem Cells in Living Mice via Silica-Coated Gold Nanorods ACS NANO Jokerst, J. V., Thangaraj, M., Kempen, P. J., Sinclair, R., Gambhir, S. S. 2012; 6 (7): 5920-5930


    Improved imaging modalities are critically needed for optimizing stem cell therapy. Techniques with real-time content to guide and quantitate cell implantation are especially important in applications such as musculoskeletal regenerative medicine. Here, we report the use of silica-coated gold nanorods as a contrast agent for photoacoustic imaging and quantitation of mesenchymal stem cells in rodent muscle tissue. The silica coating increased the uptake of gold into the cell more than 5-fold, yet no toxicity or proliferation changes were observed in cells loaded with this contrast agent. Pluripotency of the cells was retained, and secretome analysis indicated that only IL-6 was disregulated more than 2-fold from a pool of 26 cytokines. The low background of the technique allowed imaging of down to 100,000 cells in vivo. The spatial resolution is 340 μm, and the temporal resolution is 0.2 s, which is at least an order of magnitude below existing cell imaging approaches. This approach has significant advantages over traditional cell imaging techniques like positron emission tomography and magnetic resonance imaging including real time monitoring of stem cell therapy.

    View details for DOI 10.1021/nn302042y

    View details for Web of Science ID 000306673800020

    View details for PubMedID 22681633

  • A Hybrid Least Squares and Principal Component Analysis Algorithm for Raman Spectroscopy PLOS ONE Van de Sompel, D., Garai, E., Zavaleta, C., Gambhir, S. S. 2012; 7 (6)


    Raman spectroscopy is a powerful technique for detecting and quantifying analytes in chemical mixtures. A critical part of Raman spectroscopy is the use of a computer algorithm to analyze the measured Raman spectra. The most commonly used algorithm is the classical least squares method, which is popular due to its speed and ease of implementation. However, it is sensitive to inaccuracies or variations in the reference spectra of the analytes (compounds of interest) and the background. Many algorithms, primarily multivariate calibration methods, have been proposed that increase robustness to such variations. In this study, we propose a novel method that improves robustness even further by explicitly modeling variations in both the background and analyte signals. More specifically, it extends the classical least squares model by allowing the declared reference spectra to vary in accordance with the principal components obtained from training sets of spectra measured in prior characterization experiments. The amount of variation allowed is constrained by the eigenvalues of this principal component analysis. We compare the novel algorithm to the least squares method with a low-order polynomial residual model, as well as a state-of-the-art hybrid linear analysis method. The latter is a multivariate calibration method designed specifically to improve robustness to background variability in cases where training spectra of the background, as well as the mean spectrum of the analyte, are available. We demonstrate the novel algorithm's superior performance by comparing quantitative error metrics generated by each method. The experiments consider both simulated data and experimental data acquired from in vitro solutions of Raman-enhanced gold-silica nanoparticles.

    View details for DOI 10.1371/journal.pone.0038850

    View details for Web of Science ID 000305583300060

    View details for PubMedID 22723895

  • Family of Enhanced Photoacoustic Imaging Agents for High-Sensitivity and Multiplexing Studies in Living Mice ACS NANO de la Zerda, A., Bodapati, S., Teed, R., May, S. Y., Tabakman, S. M., Liu, Z., Khuri-Yakub, B. T., Chen, X., Dai, H., Gambhir, S. S. 2012; 6 (6): 4694-4701


    Photoacoustic imaging is a unique modality that overcomes to a great extent the resolution and depth limitations of optical imaging while maintaining relatively high contrast. However, since many diseases will not manifest an endogenous photoacoustic contrast, it is essential to develop exogenous photoacoustic contrast agents that can target diseased tissue(s). Here we present a family of novel photoacoustic contrast agents that are based on the binding of small optical dyes to single-walled carbon nanotubes (SWNT-dye). We synthesized five different SWNT-dye contrast agents using different optical dyes, creating five "flavors" of SWNT-dye nanoparticles. In particular, SWNTs that were coated with either QSY(21) (SWNT-QSY) or indocyanine green (SWNT-ICG) exhibited over 100-times higher photoacoustic contrast in living animals compared to plain SWNTs, leading to subnanomolar sensitivities. We then conjugated the SWNT-dye conjugates with cyclic Arg-Gly-Asp peptides to molecularly target the α(v)β(3) integrin, which is associated with tumor angiogenesis. Intravenous administration of these tumor-targeted imaging agents to tumor-bearing mice showed significantly higher photoacoustic signal in the tumor than in mice injected with the untargeted contrast agent. Finally, we were able to spectrally separate the photoacoustic signals of SWNT-QSY and SWNT-ICG in living animals injected subcutaneously with both particles in the same location, opening the possibility for multiplexing in vivo studies.

    View details for DOI 10.1021/nn204352r

    View details for Web of Science ID 000305661300017

    View details for PubMedID 22607191

  • Transatlantic Consensus Group on active surveillance and focal therapy for prostate cancer BJU INTERNATIONAL Ahmed, H. U., Akin, O., Coleman, J. A., Crane, S., Emberton, M., Goldenberg, L., Hricak, H., Kattan, M. W., Kurhanewicz, J., Moore, C. M., Parker, C., Polascik, T. J., Scardino, P., Van As, N., Villers, A. 2012; 109 (11): 1636-1647


    What's known on the subject? and What does the study add? Active surveillance for prostate cancer is gaining increasing acceptance for low risk prostate cancer. Focal therapy is an emerging tissue preservation strategy that aims for treat only areas of cancer. Early phase trials have shown that side-effects can be significantly reduced using focal therapy. There is significant uncertainty in both active surveillance and focal therapy. This consensus group paper provides a road-map for clinical practice and research for both tissue-preserving strategies in the areas of patient population, tools for risk stratification and cancer localisation, treatment interventions as well as comparators and outcome measures in future comparative trials.To reach consensus on key issues for clinical practice and future research in active surveillance and focal therapy in managing localized prostate cancer.A group of expert urologists, oncologists, radiologists, pathologists and computer scientists from North America and Europe met to discuss issues in patient population, interventions, comparators and outcome measures to use in both tissue-preserving strategies of active surveillance and focal therapy. Break-out sessions were formed to provide agreement or highlight areas of disagreement on individual topics which were then collated by a writing group into statements that formed the basis of this report and agreed upon by the whole Transatlantic Consensus Group.The Transatlantic group propose that emerging diagnostic tools such as precision imaging and transperineal prostate mapping biopsy can improve prostate cancer care. These tools should be integrated into prostate cancer management and research so that better risk stratification and more effective treatment allocation can be applied. The group envisaged a process of care in which active surveillance, focal therapy, and radical treatments lie on a continuum of complementary therapies for men with a range of disease grades and burdens, rather than being applied in the mutually exclusive and competitive way they are now.The changing landscape of prostate cancer epidemiology requires the medical community to re-evaluate the entire prostate cancer diagnostic and treatment pathway in order to minimize harms resulting from over-diagnosis and over-treatment. Precise risk stratification at every point in this pathway is required alongside paradigm shifts in our thinking about what constitutes cancer in the prostate.

    View details for DOI 10.1111/j.1464-410X.2011.10633.x

    View details for Web of Science ID 000303598400015

    View details for PubMedID 22077593

  • Endoscopic imaging of Cerenkov luminescence BIOMEDICAL OPTICS EXPRESS Kothapalli, S., Liu, H., Liao, J. C., Cheng, Z., Gambhir, S. S. 2012; 3 (6): 1215-1225


    We demonstrate feasibility of endoscopic imaging of Cerenkov light originated when charged nuclear particles, emitted from radionuclides, travel through a biological tissue of living subjects at superluminal velocity. The endoscopy imaging system consists of conventional optical fiber bundle/ clinical endoscopes, an optical imaging lens system, and a sensitive low-noise charge coupled device (CCD) camera. Our systematic studies using phantom samples show that Cerenkov light from as low as 1 µCi of radioactivity emitted from (18)F-Fluorodeoxyglucose (FDG) can be coupled and transmitted through conventional optical fibers and endoscopes. In vivo imaging experiments with tumor bearing mice, intravenously administered with (18)F-FDG, further demonstrated that Cerenkov luminescence endoscopy is a promising new tool in the field of endoscopic molecular imaging.

    View details for Web of Science ID 000304965700007

    View details for PubMedID 22741069

  • A photonic crystal cavity-optical fiber tip nanoparticle sensor for biomedical applications APPLIED PHYSICS LETTERS Shambat, G., Kothapalli, S. R., Khurana, A., Provine, J., Sarmiento, T., Cheng, K., Cheng, Z., Harris, J., Daldrup-Link, H., Gambhir, S. S., Vuckovic, J. 2012; 100 (21)

    View details for DOI 10.1063/1.4719520

    View details for Web of Science ID 000304489900085

  • Effect of a CCR1 receptor antagonist on systemic trafficking of MSCs and polyethylene particle-associated bone loss BIOMATERIALS Gibon, E., Yao, Z., Rao, A. J., Zwingenberger, S., Batke, B., Valladares, R., Smith, R. L., Biswal, S., Gambhir, S. S., Goodman, S. B. 2012; 33 (14): 3632-3638


    Particle-associated periprosthetic osteolysis remains a major issue in joint replacement. Ongoing bone loss resulting from wear particle-induced inflammation is accompanied by continued attempts at bone repair. Previously we showed that mesenchymal stem cells (MSCs) are recruited systemically to bone exposed to continuous infusion of ultra high molecular weight polyethylene (UHMWPE) particles. The chemokine-receptor axis that mediates this process is unknown. We tested two hypotheses: (1) the CCR1 receptor mediates the systemic recruitment of MSCs to UHMWPE particles and (2) recruited MSCs are able to differentiate into functional mature osteoblasts and decrease particle-associated bone loss. Nude mice were allocated randomly to four groups. UHMWPE particles were continuously infused into the femoral shaft using a micro-pump. Genetically modified murine wild type reporter MSCs were injected systemically via the left ventricle. Non-invasive imaging was used to assay MSC migration and bone mineral density. Bioluminescence and immunohistochemistry confirmed the chemotaxis of reporter cells and their differentiation into mature osteoblasts in the presence of infused particles. Injection of a CCR1 antagonist decreased reporter cell recruitment to the UHMWPE particle infusion site and increased osteolysis. CCR1 appears to be a critical receptor for chemotaxis of MSCs in the presence of UHMWPE particles. Interference with CCR1 exacerbates particle-induced bone loss.

    View details for DOI 10.1016/j.biomaterials.2012.02.003

    View details for Web of Science ID 000302425400003

    View details for PubMedID 22364730

  • Intratumoral versus Intravenous Gene Therapy Using a Transcriptionally Targeted Viral Vector in an Orthotopic Hepatocellular Carcinoma Rat Model JOURNAL OF VASCULAR AND INTERVENTIONAL RADIOLOGY Kim, Y. I., Ahn, B., Ronald, J. A., Katzenberg, R., Singh, A., Paulmurugan, R., Ray, S., Gambhir, S. S., Hofmann, L. V. 2012; 23 (5): 704-711


    To evaluate the feasibility of intratumoral delivery of adenoviral vector carrying a bidirectional two-step transcriptional amplification (TSTA) system to amplify transcriptional strength of cancer-specific Survivin promoter in a hepatocellular carcinoma model.MCA-RH7777 cells were implanted in rat liver, and tumor formation was confirmed with [(18)F]fluorodeoxyglucose (18F-FDG) positron emission tomography (PET). The adenoviral vector studied had Survivin promoter driving a therapeutic gene (tumor necrosis factor-α-related apoptosis-inducing ligand [TRAIL]) and a reporter gene (firefly luciferase [FL]; Ad-pSurvivin-TSTA-TRAIL-FL). Tumor-bearing rats were administered Ad-pSurvivin-TSTA-TRAIL-FL intravenously (n = 7) or intratumorally (n = 8). For control groups, adenovirus FL under cytomegalovirus (CMV) promoter (Ad-pCMV-FL) was administered intravenously (n = 3) or intratumorally (n = 3). One day after delivery, bioluminescence imaging was performed to evaluate transduction. At 4 and 7 days after delivery, 18F-FDG-PET was performed to evaluate therapeutic efficacy.With intravenous delivery, Ad-pSurvivin-TSTA-TRAIL-FL showed no measurable liver tumor FL signal on day 1 after delivery, but showed better therapeutic efficacy than Ad-pCMV-FL on day 7 (PET tumor/liver ratio, 3.5 ± 0.58 vs 6.0 ± 0.71; P = .02). With intratumoral delivery, Ad-pSurvivin-TSTA-TRAIL-FL showed positive FL signal from all tumors and better therapeutic efficacy than Ad-pCMV-FL on day 7 (2.4 ± 0.50 vs 5.4 ± 0.78; P = .01). In addition, intratumoral delivery of Ad-pSurvivin-TSTA-TRAIL-FL demonstrated significant decrease in tumoral viability compared with intravenous delivery (2.4 ± 0.50 vs 3.5 ± 0.58; P = .03).Intratumoral delivery of a transcriptionally targeted therapeutic vector for amplifying tumor-specific effect demonstrated better transduction efficiency and therapeutic efficacy for liver cancer than systemic delivery, and may lead to improved therapeutic outcome for future clinical practice.

    View details for DOI 10.1016/j.jvir.2012.01.053

    View details for Web of Science ID 000303557000020

    View details for PubMedID 22387029

    View details for PubMedCentralID PMC4132166

  • A brain tumor molecular imaging strategy using a new triple-modality MRI-photoacoustic-Raman nanoparticle NATURE MEDICINE Kircher, M. F., de la Zerda, A., Jokerst, J. V., Zavaleta, C. L., Kempen, P. J., Mittra, E., Pitter, K., Huang, R., Campos, C., Habte, F., Sinclair, R., Brennan, C. W., Mellinghoff, I. K., Holland, E. C., Gambhir, S. S. 2012; 18 (5): 829-U235


    The difficulty in delineating brain tumor margins is a major obstacle in the path toward better outcomes for patients with brain tumors. Current imaging methods are often limited by inadequate sensitivity, specificity and spatial resolution. Here we show that a unique triple-modality magnetic resonance imaging-photoacoustic imaging-Raman imaging nanoparticle (termed here MPR nanoparticle) can accurately help delineate the margins of brain tumors in living mice both preoperatively and intraoperatively. The MPRs were detected by all three modalities with at least a picomolar sensitivity both in vitro and in living mice. Intravenous injection of MPRs into glioblastoma-bearing mice led to MPR accumulation and retention by the tumors, with no MPR accumulation in the surrounding healthy tissue, allowing for a noninvasive tumor delineation using all three modalities through the intact skull. Raman imaging allowed for guidance of intraoperative tumor resection, and a histological correlation validated that Raman imaging was accurately delineating the brain tumor margins. This new triple-modality-nanoparticle approach has promise for enabling more accurate brain tumor imaging and resection.

    View details for DOI 10.1038/nm.2721

    View details for Web of Science ID 000303763500053

    View details for PubMedID 22504484

  • Deep Tissue Photoacoustic Imaging Using a Miniaturized 2-D Capacitive Micromachined Ultrasonic Transducer Array IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING Kothapalli, S., Ma, T., Vaithilingam, S., Oralkan, O., Khuri-Yakub, B. T., Gambhir, S. S. 2012; 59 (5): 1199-1204


    In this paper, we demonstrate 3-D photoacoustic imaging (PAI) of light absorbing objects embedded as deep as 5 cm inside strong optically scattering phantoms using a miniaturized (4 mm × 4 mm × 500 μm), 2-D capacitive micromachined ultrasonic transducer (CMUT) array of 16 × 16 elements with a center frequency of 5.5 MHz. Two-dimensional tomographic images and 3-D volumetric images of the objects placed at different depths are presented. In addition, we studied the sensitivity of CMUT-based PAI to the concentration of indocyanine green dye at 5 cm depth inside the phantom. Under optimized experimental conditions, the objects at 5 cm depth can be imaged with SNR of about 35 dB and a spatial resolution of approximately 500 μm. Results demonstrate that CMUTs with integrated front-end amplifier circuits are an attractive choice for achieving relatively high depth sensitivity for PAI.

    View details for DOI 10.1109/TBME.2012.2183593

    View details for Web of Science ID 000303201000001

    View details for PubMedID 22249594

  • Twist1 Suppresses Senescence Programs and Thereby Accelerates and Maintains Mutant Kras-Induced Lung Tumorigenesis PLOS GENETICS Tran, P. T., Shroff, E. H., Burns, T. F., Thiyagarajan, S., Das, S. T., Zabuawala, T., Chen, J., Cho, Y., Luong, R., Tamayo, P., Salih, T., Aziz, K., Adam, S. J., Vicent, S., Nielsen, C. H., Withofs, N., Sweet-Cordero, A., Gambhir, S. S., Rudin, C. M., Felsher, D. W. 2012; 8 (5)


    KRAS mutant lung cancers are generally refractory to chemotherapy as well targeted agents. To date, the identification of drugs to therapeutically inhibit K-RAS have been unsuccessful, suggesting that other approaches are required. We demonstrate in both a novel transgenic mutant Kras lung cancer mouse model and in human lung tumors that the inhibition of Twist1 restores a senescence program inducing the loss of a neoplastic phenotype. The Twist1 gene encodes for a transcription factor that is essential during embryogenesis. Twist1 has been suggested to play an important role during tumor progression. However, there is no in vivo evidence that Twist1 plays a role in autochthonous tumorigenesis. Through two novel transgenic mouse models, we show that Twist1 cooperates with Kras(G12D) to markedly accelerate lung tumorigenesis by abrogating cellular senescence programs and promoting the progression from benign adenomas to adenocarcinomas. Moreover, the suppression of Twist1 to physiological levels is sufficient to cause Kras mutant lung tumors to undergo senescence and lose their neoplastic features. Finally, we analyzed more than 500 human tumors to demonstrate that TWIST1 is frequently overexpressed in primary human lung tumors. The suppression of TWIST1 in human lung cancer cells also induced cellular senescence. Hence, TWIST1 is a critical regulator of cellular senescence programs, and the suppression of TWIST1 in human tumors may be an effective example of pro-senescence therapy.

    View details for DOI 10.1371/journal.pgen.1002650

    View details for Web of Science ID 000304864000004

    View details for PubMedID 22654667

  • MC3T3-E1 Osteoprogenitor Cells Systemically Migrate to a Bone Defect and Enhance Bone Healing TISSUE ENGINEERING PART A Gibon, E., Batke, B., Jawad, M. U., Fritton, K., Rao, A., Yao, Z., Biswal, S., Gambhir, S. S., Goodman, S. B. 2012; 18 (9-10): 968-973


    Although iliac crest autologous bone graft remains the gold standard for treatment of bone defects, delayed- and nonunions, and arthrodeses, several alternative strategies have been attempted, including the use of mesenchymal stem cells. Whether cells from the osteoblast lineage demonstrate systemic recruitment to an acute bone defect or fracture, and whether these cells directly participate in bone healing is controversial. This study tests two hypotheses: (1) that exogenous murine MC3T3-E1 osteoprogenitor cells with a high propensity for osteoblast differentiation are able to systemically migrate to a bone defect and (2) that the migrated MC3T3-E1 cells enhance bone healing. Two groups of nude mice were used; a bone defect was drilled in the left femoral shaft in both groups. MC3T3-E1 were used as reporter cells and injected in the left ventricle of the heart, to avoid sequestration in the lungs. Injection of saline served as a control. We used bioluminescence and microCT to assay cell recruitment and bone mineral density (BMD). Immunohistochemical staining was used to confirm the migration of reporter cells. MC3T3-E1 cells were found to systemically migrate to the bone defect. Further, BMD at the defect was significantly increased when cells were injected. Systemic cell therapy using osteoprogenitor cells may be a potential strategy to enhance bone healing.

    View details for DOI 10.1089/ten.tea.2011.0545

    View details for Web of Science ID 000303540400008

    View details for PubMedID 22129134

  • Glioblastoma Therapy with Cytotoxic Mesenchymal Stromal Cells Optimized by Bioluminescence Imaging of Tumor and Therapeutic Cell Response PLOS ONE Alieva, M., Bago, J. R., Aguilar, E., Soler-Botija, C., Vila, O. F., Molet, J., Gambhir, S. S., Rubio, N., Blanco, J. 2012; 7 (4)


    Genetically modified adipose tissue derived mesenchymal stromal cells (hAMSCs) with tumor homing capacity have been proposed for localized therapy of chemo- and radiotherapy resistant glioblastomas. We demonstrate an effective procedure to optimize glioblastoma therapy based on the use of genetically modified hAMSCs and in vivo non invasive monitoring of tumor and therapeutic cells. Glioblastoma U87 cells expressing Photinus pyralis luciferase (Pluc) were implanted in combination with hAMSCs expressing a trifunctional Renilla reniformis luciferase-red fluorescent protein-thymidine kinase reporter in the brains of SCID mice that were subsequently treated with ganciclovir (GCV). The resulting optimized therapy was effective and monitoring of tumor cells by bioluminescence imaging (BLI) showed that after 49 days GCV treatment reduced significantly the hAMSC treated tumors; by a factor of 10(4) relative to controls. Using a Pluc reporter regulated by an endothelial specific promoter and in vivo BLI to image hAMSC differentiation we gained insight on the therapeutic mechanism. Implanted hAMSCs homed to tumor vessels, where they differentiated to endothelial cells. We propose that the tumor killing efficiency of genetically modified hAMSCs results from their association with the tumor vascular system and should be useful vehicles to deliver localized therapy to glioblastoma surgical borders following tumor resection.

    View details for DOI 10.1371/journal.pone.0035148

    View details for Web of Science ID 000305347400033

    View details for PubMedID 22529983

    View details for PubMedCentralID PMC3328467



    Molecular imaging is revolutionizing the way we study the inner workings of the human body, diagnose diseases, approach drug design, and assess therapies. The field as a whole is making possible the visualization of complex biochemical processes involved in normal physiology and disease states, in real time, in living cells, tissues, and intact subjects. In this review, we focus specifically on molecular imaging of intact living subjects. We provide a basic primer for those who are new to molecular imaging, and a resource for those involved in the field. We begin by describing classical molecular imaging techniques together with their key strengths and limitations, after which we introduce some of the latest emerging imaging modalities. We provide an overview of the main classes of molecular imaging agents (i.e., small molecules, peptides, aptamers, engineered proteins, and nanoparticles) and cite examples of how molecular imaging is being applied in oncology, neuroscience, cardiology, gene therapy, cell tracking, and theranostics (therapy combined with diagnostics). A step-by-step guide to answering biological and/or clinical questions using the tools of molecular imaging is also provided. We conclude by discussing the grand challenges of the field, its future directions, and enormous potential for further impacting how we approach research and medicine.

    View details for DOI 10.1152/physrev.00049.2010

    View details for Web of Science ID 000306562500009

    View details for PubMedID 22535898

  • Use of Cu-64-labeled Fibronectin Domain with EGFR-Overexpressing Tumor Xenograft: Molecular Imaging RADIOLOGY Hackel, B. J., Kimura, R. H., Gambhir, S. S. 2012; 263 (1): 179-188


    To assess the ability of an engineered epidermal growth factor receptor (EGFR)-binding fibronectin domain to serve as a positron emission tomographic (PET) probe for molecular imaging of EGFR in a xenograft mouse model.An EGFR-binding fibronectin domain (fibronectin abbreviated to Fn when bound) was site-specifically labeled with copper 64 ((64)Cu) (8 MBq/nmol). Copper 64-Fn binding was tested in cell cultures with varying EGFR expression. Stability in human and mouse serum was measured in vitro. Animal experiments were approved by the Stanford University Institutional Animal Care and Use Committee. Copper 64-Fn (approximately 2 MBq) was used for PET in mice (n = 5) bearing EGFR-overexpressing xenografted tumors (approximately 5-10 mm in diameter). Results of tomography were compared with those of ex vivo gamma counting of dissected tissues. Statistical analysis was performed with t tests and adjustment for multiple comparisons.Copper 64-Fn exhibited EGFR-dependent binding to multiple cell lines in culture. The tracer was stable for 24 hours in human and mouse serum at 37°C. The tracer exhibited good tumor localization (3.4% injected dose [ID]/g ± 1.0 [standard deviation] at 1 hour), retention (2.7% ID/g ± 0.6 at 24 hours), and specificity (8.6 ± 3.0 tumor-to-muscle ratio, 8.9 ± 4.7 tumor-to-blood ratio at 1 hour). Specific targeting was verified with low localization to low-expressing MDA-MB-435 tumors (0.7% ID/g ± 0.8 at 1 hour, P = .018); specificity was further demonstrated, as a nonbinding control fibronectin had low localization to EGFR-overexpressing xenografts (0.8% ID/g ± 0.2 at 1 hour, P = .013).The stability, low background, and target-specific tumor uptake and retention of the engineered fibronectin domain make it a promising EGFR molecular imaging agent. More broadly, it validates the fibronectin domain as a potential scaffold for a generation of various molecular imaging agents.

    View details for DOI 10.1148/radiol.12111504

    View details for Web of Science ID 000302642700018

    View details for PubMedID 22344401

  • Prospective Evaluation of Tc-99m MDP Scintigraphy, F-18 NaF PET/CT, and F-18 FDG PET/CT for Detection of Skeletal Metastases MOLECULAR IMAGING AND BIOLOGY Iagaru, A., Mittra, E., Dick, D. W., Gambhir, S. S. 2012; 14 (2): 252-259


    Technetium (Tc) methylene diphosphonate (MDP) has been the standard method for bone scintigraphy for three decades. (18)F sodium fluoride ((18)F NaF) positron emission tomography (PET)/computed tomography (CT) has better resolution and is considered superior. The role of 2-deoxy-2-[(18)F]fluoro-D-glucose ((18)F FDG) PET/CT is proven in a variety of cancers, for which it has changed the practice of oncology. There are few prospective studies comparing these three methods of detection of skeletal metastases. Thus, we were prompted to initiate this prospective pilot trial.This is a prospective study (Sep 2007-Dec 2010) of 52 patients with proven malignancy referred for evaluation of skeletal metastases. There were 37 men and 15 women, 19-84 years old (average, 55.6 ± 15.9). Technetium-99m ((99m)Tc) MDP bone scintigraphy, (18)F NaF PET/CT, and (18)F FDG PET/CT were subsequently performed within 1 month.Skeletal lesions were detected by (99m)Tc MDP bone scintigraphy in 22 of 52 patients, by (18)F NaF PET/CT in 24 of 52 patients, and by (18)F FDG PET/CT in 16 of 52 patients. The image quality and evaluation of extent of disease were superior by (18)F NaF PET/CT over (99m)Tc MDP scintigraphy in all 22 patients with skeletal lesions on both scans and over (18)F FDG PET/CT in 11 of 16 patients with skeletal metastases on (18)F FDG PET/CT. In two patients, (18)F NaF PET/CT showed skeletal metastases not seen on either of the other two scans. Extraskeletal lesions were identified by (18)F FDG PET/CT in 28 of 52 subjects.Our prospective pilot-phase trial demonstrates superior image quality and evaluation of skeletal disease extent with (18)F NaF PET/CT over (99m)Tc MDP scintigraphy and (18)F FDG PET/CT. At the same time, (18)F FDG PET detects extraskeletal disease that can significantly change disease management. As such, a combination of (18)F FDG PET/CT and (18)F NaF PET/CT may be necessary for cancer detection. Additional evaluation with larger cohorts is required to confirm these preliminary findings.

    View details for DOI 10.1007/s11307-011-0486-2

    View details for Web of Science ID 000301584100013

    View details for PubMedID 21479710

  • Immunomodulation of Curcumin on Adoptive Therapy with T Cell Functional Imaging in Mice CANCER PREVENTION RESEARCH Chang, Y., Chuang, H., Hsu, C., Liu, R., Gambhir, S. S., Hwang, J. 2012; 5 (3): 444-452


    Adoptive T-cell therapy involves the ex vivo expansion and subsequent transfusion of tumor-specific T lymphocytes to eliminate tumors. Using immune modulators to block immunosuppressive factors in the tumor microenvironment has emerged as a promising strategy to enhance T-cell-mediated tumor regression. Curcumin, a major component of turmeric, has been shown to possess antitumor and immunomodulatory effects by regulating a diverse range of molecular targets. Thus, we hypothesize that these beneficial effects of curcumin may improve the therapeutic efficacy of adoptive therapy. Here, we have shown that curcumin enhances cytotoxicity of CD8(+) T cells toward tumors via alteration of the tumor microenvironment when combined with adoptive therapy. We found that T-cell accumulation and function were increased in combined treatment due to the blockade of different immunosuppressors, including TGF-β, indoleamine 2,3-dioxygenase, and regulatory T cells. Furthermore, bioluminescent imaging with a granzyme B promoter-conjugated optical reporter also reflected improved cytotoxicity of antigen-specific CD8(+) T cells in tumor-bearing mice during treatment. These findings suggest that combination of multitargeting drugs, such as curcumin, with adoptive therapy may have potential for clinical application. In addition, using a granzyme B-specific imaging reporter to assess T-cell function may also be applied for the development and therapeutic evaluation of new immunotherapy in preclinical studies.

    View details for DOI 10.1158/1940-6207.CAPR-11-0308

    View details for Web of Science ID 000300987800011

    View details for PubMedID 22135043

  • Optical Imaging with Her2-Targeted Affibody Molecules Can Monitor Hsp90 Treatment Response in a Breast Cancer Xenograft Mouse Model CLINICAL CANCER RESEARCH van de Ven, S. M., Elias, S. G., Chan, C. T., Miao, Z., Cheng, Z., De, A., Gambhir, S. S. 2012; 18 (4): 1073-1081


    To determine whether optical imaging can be used for in vivo therapy response monitoring as an alternative to radionuclide techniques. For this, we evaluated the known Her2 response to 17-dimethylaminoethylamino-17-demethoxygeldanamycin hydrochloride (17-DMAG) treatment, an Hsp90 inhibitor.After in vitro 17-DMAG treatment response evaluation of MCF7 parental cells and 2 HER2-transfected clones (clone A medium, B high Her2 expression), we established human breast cancer xenografts in nude mice (only parental and clone B) for in vivo evaluation. Mice received 120 mg/kg of 17-DMAG in 4 doses at 12-hour intervals intraperitonially (n = 14) or PBS as carrier control (n = 9). Optical images were obtained both pretreatment (day 0) and posttreatment (day 3, 6, and 9), always 5 hours postinjection of 500 pmol of anti-Her2 Affibody-AlexaFluor680 via tail vein (with preinjection background subtraction). Days 3 and 9 in vivo optical imaging signal was further correlated with ex vivo Her2 levels by Western blot after sacrifice.Her2 expression decreased with 17-DMAG dose in vitro. In vivo optical imaging signal was reduced by 22.5% in clone B (P = 0.003) and by 9% in MCF7 parental tumors (P = 0.23) 3 days after 17-DMAG treatment; optical imaging signal recovered in both tumor types at days 6 to 9. In the carrier group, no signal reduction was observed. Pearson correlation of in vivo optical imaging signal with ex vivo Her2 levels ranged from 0.73 to 0.89.Optical imaging with an affibody can be used to noninvasively monitor changes in Her2 expression in vivo as a response to treatment with an Hsp90 inhibitor, with results similar to response measurements in positron emission tomography imaging studies.

    View details for DOI 10.1158/1078-0432.CCR-10-3213

    View details for Web of Science ID 000300628100017

    View details for PubMedID 22235098

    View details for PubMedCentralID PMC3288571

  • First Experience with Clinical-Grade [F-18]FPP(RGD)(2): An Automated Multi-step Radiosynthesis for Clinical PET Studies MOLECULAR IMAGING AND BIOLOGY Chin, F. T., Shen, B., Liu, S., Berganos, R. A., Chang, E., Mittra, E., Chen, X., Gambhir, S. S. 2012; 14 (1): 88-95


    A reliable and routine process to introduce a new ¹⁸F-labeled dimeric RGD-peptide tracer ([¹⁸F]FPP(RGD₂) for noninvasive imaging of α(v)β₃ expression in tumors needed to be developed so the tracer could be evaluated for the first time in man. Clinical-grade [¹⁸F]FPP(RGD)₂ was screened in mouse prior to our first pilot study in human.[¹⁸F]FPP(RGD)₂ was synthesized by coupling 4-nitrophenyl-2-[¹⁸F]fluoropropionate ([¹⁸F]NPE) with the dimeric RGD-peptide (PEG₃-c(RGDyK)₂). Imaging studies with [¹⁸F]FPP(RGD)₂ in normal mice and a healthy human volunteer were carried out using small animal and clinical PET scanners, respectively.Through optimization of each radiosynthetic step, [¹⁸F]FPP(RGD)₂ was obtained with RCYs of 16.9 ± 2.7% (n = 8, EOB) and specific radioactivity of 114 ± 72 GBq/μmol (3.08 ± 1.95 Ci/μmol; n = 8, EOB) after 170 min of radiosynthesis. In our mouse studies, high radioactivity uptake was only observed in the kidneys and bladder with the clinical-grade tracer. Favorable [¹⁸F]FPP(RGD)₂ biodistribution in human studies, with low background signal in the head, neck, and thorax, showed the potential applications of this RGD-peptide tracer for detecting and monitoring tumor growth and metastasis.A reliable, routine, and automated radiosynthesis of clinical-grade [¹⁸F]FPP(RGD)₂ was established. PET imaging in a healthy human volunteer illustrates that [¹⁸F]FPP(RGD)₂ possesses desirable pharmacokinetic properties for clinical noninvasive imaging of α(v)β₃ expression. Further imaging studies using [¹⁸F]FPP(RGD)₂ in patient volunteers are now under active investigation.

    View details for DOI 10.1007/s11307-011-0477-3

    View details for Web of Science ID 000301583900012

    View details for PubMedID 21400112

  • Prospective comparison of combined F-18-FDG and F-18-NaF PET/CT vs. F-18-FDG PET/CT imaging for detection of malignancy EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Lin, F. I., Rao, J. E., Mittra, E. S., Nallapareddy, K., Chengapa, A., Dick, D. W., Gambhir, S. S., Iagaru, A. 2012; 39 (2): 262-270


    Typically, (18)F-FDG PET/CT and (18)F-NaF PET/CT scans are done as two separate studies on different days to allow sufficient time for the radiopharmaceutical from the first study to decay. This is inconvenient for the patients and exposes them to two doses of radiation from the CT component of the examinations. In the current study, we compared the clinical usefulness of a combined (18)F-FDG/(18)F-NaF PET/CT scan with that of a separate (18)F-FDG-only PET/CT scan.There were 62 patients enrolled in this prospective trial. All had both an (18)F-FDG-alone PET/CT scan and a combined (18)F-FDG/(18)F-NaF PET/CT scan. Of the 62 patients, 53 (85%) received simultaneous tracer injections, while 9 (15%) received (18)F-NaF subsequent to the initial (18)F-FDG dose (average delay 2.2 h). Images were independently reviewed for PET findings by two Board-Certified nuclear medicine physicians, with discrepancies resolved by a third reader. Interpreters were instructed to only report findings that were concerning for malignancy. Reading the (18)F-FDG-only scan first for half of the patients controlled for order bias.In 15 of the 62 patients (24%) neither the (18)F-FDG-only PET/CT scan nor the combined (18)F-FDG/(18)F-NaF PET/CT scan identified malignancy. In the remaining 47 patients who had PET findings of malignancy, a greater number of lesions were detected in 16 of 47 patients (34%) using the combined (18)F-FDG/(18)F-NaF PET/CT scan compared to the (18)F-FDG-only PET/CT scan. In 2 of these 47 patients (4%), the (18)F-FDG-only scan demonstrated soft tissue lesions that were not prospectively identified on the combined study. In 29 of these 47 patients (62%), the combined scan detected an equal number of lesions compared to the (18)F-FDG-only scan. Overall, 60 of all the 62 patients (97%) showed an equal or greater number of lesions on the combined scan than on the (18)F-FDG-only scan.The current study demonstrated that (18)F-FDG and (18)F-NaF can be combined in a single PET/CT scan by administering the two radiopharmaceuticals simultaneously or in sequence on the same day. In addition to patient convenience and reduced radiation exposure from the CT component, the combined (18)F-FDG/(18)F-NaF PET/CT scan appeared to increase the sensitivity for detection of osseous lesions compared to the (18)F-FDG-only PET/CT scan in the studied population.

    View details for DOI 10.1007/s00259-011-1971-1

    View details for Web of Science ID 000302286600009

    View details for PubMedID 22065013

  • Pharmacokinetically Stabilized Cystine Knot Peptides That Bind Alpha-v-Beta-6 Integrin with Single-Digit Nanomolar Affinities for Detection of Pancreatic Cancer CLINICAL CANCER RESEARCH Kimura, R. H., Teed, R., Hackel, B. J., Pysz, M. A., Chuang, C. Z., Sathirachinda, A., Willmann, J. K., Gambhir, S. S. 2012; 18 (3): 839-849


    Detection of pancreatic cancer remains a high priority and effective diagnostic tools are needed for clinical applications. Many cancer cells overexpress integrin α(v)β(6), a cell surface receptor being evaluated as a novel clinical biomarker.To validate this molecular target, several highly stable cystine knot peptides were engineered by directed evolution to bind specifically and with high affinity (3-6 nmol/L) to integrin α(v)β(6). The binders do not cross-react with related integrin α(v)β(5), integrin α(5)β(1), or tumor-angiogenesis-associated integrin, α(v)β(3).Positron emission tomography showed that these disulfide-stabilized peptides rapidly accumulate at tumors expressing integrin α(v)β(6). Clinically relevant tumor-to-muscle ratios of 7.7 ± 2.4 to 11.3 ± 3.0 were achieved within 1 hour after radiotracer injection. Minimization of off-target dosing was achieved by reformatting α(v)β(6)-binding activities across various natural and pharmacokinetically stabilized cystine knot scaffolds with different amino acid content. We show that the primary sequence of a peptide scaffold directs its pharmacokinetics. Scaffolds with high arginine or glutamic acid content suffered high renal retention of more than 75% injected dose per gram (%ID/g). Substitution of these amino acids with renally cleared amino acids, notably serine, led to significant decreases in renal accumulation of less than 20%ID/g 1 hour postinjection (P < 0.05, n = 3).We have engineered highly stable cystine knot peptides with potent and specific integrin α(v)β(6)-binding activities for cancer detection. Pharmacokinetic engineering of scaffold primary sequence led to significant decreases in off-target radiotracer accumulation. Optimization of binding affinity, specificity, stability, and pharmacokinetics will facilitate translation of cystine knots for cancer molecular imaging.

    View details for DOI 10.1158/1078-0432.CCR-11-1116

    View details for Web of Science ID 000300115000027

    View details for PubMedID 22173551

  • Proof-of-Concept Study of Monitoring Cancer Drug Therapy with Cerenkov Luminescence Imaging JOURNAL OF NUCLEAR MEDICINE Xu, Y., Chang, E., Liu, H., Jiang, H., Gambhir, S. S., Cheng, Z. 2012; 53 (2): 312-317


    Cerenkov luminescence imaging (CLI) has emerged as a less expensive, easier-to-use, and higher-throughput alternative to other nuclear imaging modalities such as PET. It is expected that CLI will find many applications in biomedical research such as cancer detection, probe development, drug screening, and therapy monitoring. In this study, we explored the possibility of using CLI to monitor drug efficacy by comparisons against PET. To assess the performance of both modalities in therapy monitoring, 2 murine tumor models (large cell lung cancer cell line H460 and prostate cancer cell line PC3) were given bevacizumab versus vehicle treatments. Two common radiotracers, 3'-deoxy-3'-(18)F-fluorothymidine ((18)F-FLT) and (18)F-FDG, were used to monitor bevacizumab treatment efficacy.One group of mice (n = 6) was implanted with H460 xenografts bilaterally in the shoulder region, divided into treatment and control groups (n = 3 each), injected with (18)F-FLT, and imaged with PET immediately followed by CLI. The other group of mice (n = 6) was implanted with PC3 xenografts in the same locations, divided into treatment and control groups (n = 3 each), injected with (18)F-FDG, and imaged by the same modalities. Bevacizumab treatment was performed by 2 injections of 20 mg/kg at days 0 and 2.On (18)F-FLT scans, both CLI and PET revealed significantly decreased signals from H460 xenografts in treated mice from pretreatment to day 3. Moderately increased to unchanged signals were observed in untreated mice. On (18)F-FDG scans, both CLI and PET showed relatively unchanged signals from PC3 tumors in both treated and control groups. Quantifications of tumor signals of Cerenkov luminescence and PET images showed that the 2 modalities had excellent correlations (R(2) > 0.88 across all study groups).CLI and PET exhibit excellent correlations across different tumor xenografts and radiotracers. This is the first study, to our knowledge, demonstrating the use of CLI for monitoring cancer treatment. The findings warrant further exploration and optimization of CLI as an alternative to PET in preclinical therapeutic monitoring and drug screening.

    View details for DOI 10.2967/jnumed.111.094623

    View details for Web of Science ID 000300032800024

    View details for PubMedID 22241909

  • Development of a Novel Long-Lived ImmunoPET Tracer for Monitoring Lymphoma Therapy in a Humanized Transgenic Mouse Model. Bioconjugate chemistry 2012


    Positron emission tomography (PET) is an attractive imaging tool to localize and quantify tracer biodistribution. ImmunoPET with an intact mAb typically requires two to four days to achieve optimized tumor-to-normal ratios. Thus, a positron emitter with a half-life of two to four days such as zirconium-89 [(89)Zr] (t(1/2): 78.4 h) is ideal. We have developed an antibody-based, long-lived immunoPET tracer (89)Zr-Desferrioxamine-p-SCN (Df-Bz-NCS)-rituximab (Zr-iPET) to image tumor for longer durations in a humanized CD20-expressing transgenic mouse model. To optimize the radiolabeling efficiency of (89)Zr with Df-Bz-rituximab, multiple radiolabelings were performed. Radiochemical yield, purity, immunoreactivity, and stability assays were carried out to characterize the Zr-iPET for chemical and biological integrity. This tracer was used to image transgenic mice that express the human CD20 on their B cells (huCD20TM). Each huCD20TM mouse received a 7.4 MBq/dose. One group (n = 3) received a 2 mg/kg predose (blocking) of cold rituximab 2 h prior to (89)Zr-iPET; the other group (n = 3) had no predose (nonblocking). Small animal PET/CT was used to image mice at 1, 4, 24, 48, 72, and 120 h. Quality assurance of the (89)Zr-iPET demonstrated NCS-Bz-Df: antibody ratio (c/a: 1.5 ± 0.31), specific activity (0.44-1.64 TBq/mol), radiochemical yield (>70%), and purity (>98%). The Zr-iPET immunoreactivity was >80%. At 120 h, Zr-iPET uptake (% ID/g) as mean ± STD for blocking and nonblocking groups in spleen was 3.2 ± 0.1% and 83.3 ± 2.0% (p value <0.0013.). Liver uptake was 1.32 ± 0.05% and 0.61 ± 0.001% (p value <0.0128) for blocking and nonblocking, respectively. The small animal PET/CT image shows the spleen specific uptake of Zr-iPET in mice at 120 h after tracer injection. Compared to the liver, the spleen specific uptake of Zr-iPET is very high due to the expression of huCD20. We optimized the radiolabeling efficiency of (89)Zr with Df-Bz-rituximab. These radioimmunoconjugate lots were stable up to 5 days in serum in vitro. The present study showed that (89)Zr is well-suited for mAbs to image cancer over an extended period of time (up to 5 days).

    View details for DOI 10.1021/bc300039r

    View details for PubMedID 22621257

  • Photoacoustic Imaging Using a 9F MicroLinear CMUT ICE Catheter IEEE International Ultrasonics Symposium (IUS) Nikoozadeh, A., Choe, J. W., Kothapalli, S., Moini, A., Sanjani, S. S., Kamaya, A., Oralkan, O., Gambhir, S. S., Khuri-Yakub, P. T. IEEE. 2012: 24–27
  • A Novel Clinically Translatable Fluorescent Nanoparticle for Targeted Molecular Imaging of Tumors in Living Subjects NANO LETTERS Gao, J., Chen, K., Luong, R., Bouley, D. M., Mao, H., Qiao, T., Gambhir, S. S., Cheng, Z. 2012; 12 (1): 281-286


    The use of quantum dots (QDs) in biomedical research has grown tremendously, yet successful examples of clinical applications are absent due to many clinical concerns. Here, we report on a new type of stable and biocompatible dendron-coated InP/ZnS core/shell QD as a clinically translatable nanoprobe for molecular imaging applications. The QDs (QD710-Dendron) were demonstrated to hold several significant features: near-infrared (NIR) emission, high stability in biological media, suitable size with possible renal clearance, and ability of extravasation. More importantly, a pilot mouse toxicity study confirmed that QD710-Dendron lacks significant toxicity at the doses tested. The acute tumor uptake of QD710-Dendron resulted in good contrast from the surrounding nontumorous tissues, indicating the possibility of passive targeting of the QDs. The highly specific targeting of QD710-Dendron-RGD(2) to integrin α(v)β(3)-positive tumor cells resulted in high tumor uptake and long retention of the nanoprobe at tumor sites. In summary, QD710-Dendron and RGD-modified nanoparticles demonstrate small size, high stability, biocompatibility, favorable in vivo pharmacokinetics, and successful tumor imaging properties. These features satisfy the requirements for clinical translation and should promote efforts to further investigate the possibility of using QD710-Dendron-based nanoprobes in the clinical setting in the near future.

    View details for DOI 10.1021/nl203526f

    View details for Web of Science ID 000298943100049

    View details for PubMedID 22172022

  • Response to Intra-Arterial Oncolytic Virotherapy with the Herpes Virus NV1020 Evaluated by [F-18]Fluorodeoxyglucose Positron Emission Tomography and Computed Tomography HUMAN GENE THERAPY Sze, D. Y., Iagaru, A. H., Gambhir, S. S., de Haan, H. A., Reid, T. R. 2012; 23 (1): 91-97


    Oncolytic virotherapy poses unique challenges to the evaluation of tumor response. We hypothesized that the addition of [(18)F]fluorodeoxyglucose (FDG) positron emission tomography (PET) to standard computed tomography (CT) evaluation would improve diagnostic and prognostic power of the measurement of tumor response to oncolytic virotherapy. A phase I/II trial was conducted to investigate treatment of hepatic metastases from colorectal carcinoma using intra-arterial administration of the oncolytic herpes virus NV1020. Both contrast-enhanced CT and FDG PET were obtained on each patient at each time point. Quantitative FDG PET and CT responses were correlated with each other and with clinical outcome metrics. A majority of patients showed initial post-viral infusion increases in tumor size (69%) or in standardized uptake value (SUV) (80%) large enough to qualify as progressive disease. Most showed subsequent decreases in tumor size (64%) or SUV (83%) enough to be reclassified as partial response or stable disease. Late PET and CT imaging results correlated well with each other and with clinical outcomes, but results from early in the treatment scheme did not correlate with each other, with later results, or with clinical outcomes. The addition of FDG PET to the evaluation of tumor response to the oncolytic virus NV1020 did not provide useful diagnostic or prognostic data. More sophisticated molecular imaging will need to be developed to monitor the effects of this novel class of antineoplastic agents.

    View details for DOI 10.1089/hum.2011.141

    View details for Web of Science ID 000299604000011

    View details for PubMedID 21895536

  • Raman's "Effect" on Molecular Imaging JOURNAL OF NUCLEAR MEDICINE Zavaleta, C. L., Kircher, M. F., Gambhir, S. S. 2011; 52 (12): 1839-1844


    Raman spectroscopy is an optical technique that offers unsurpassed sensitivity and multiplexing capabilities to the field of molecular imaging. In the past, Raman spectroscopy had predominantly been used as an analytic tool for routine chemical analysis, but more recently, researchers have been able to harness its unique properties for imaging and spectral analysis of molecular interactions in cell populations and preclinical animal models. Additionally, researchers have already begun to translate this optical technique into a novel clinical diagnostic tool using various endoscopic strategies.

    View details for DOI 10.2967/jnumed.111.087775

    View details for Web of Science ID 000298162500016

    View details for PubMedID 21868625

  • Non-invasive Bioluminescence Imaging of Myoblast-Mediated Hypoxia-Inducible Factor-1 Alpha Gene Transfer MOLECULAR IMAGING AND BIOLOGY Gheysens, O., Chen, I. Y., Rodriguez-Porcel, M., Chan, C., Rasooly, J., Vaerenberg, C., Paulmurugan, R., Willmann, J. K., Deroose, C., Wu, J., Gambhir, S. S. 2011; 13 (6): 1124-1132


    We tested a novel imaging strategy, in which both the survival of transplanted myoblasts and their therapeutic transgene expression, a recombinant hypoxia-inducible factor-1α (HIF-1α-VP2), can be monitored using firefly luciferase (fluc) and Renilla luciferase (hrl) bioluminescence reporter genes, respectively.The plasmid pUbi-hrl-pUbi-HIF-1α-VP2, which expresses both hrl and HIF-1α-VP2 using two ubiquitin promoters, was characterized in vitro. C2c12 myoblasts stably expressing fluc and transiently transfected with pUbi-hrl-pUbi-HIF-1α-VP2 were injected into the mouse hindlimb. Both hrl and fluc expression were monitored using bioluminescence imaging (BLI).Strong correlations existed between the expression of hRL and each of HIF-1α-VP2, VEGF, and PlGF (r(2) > 0.83, r(2) > 0.82, and r(2) > 0.97, respectively). In vivo, both transplanted cells and HIF-1α-VP2 transgene expression were successfully imaged using BLI.An objective evaluation of myoblast-mediated gene transfer in living mice can be performed by monitoring both the survival and the transgene expression of transplanted myoblasts using the techniques developed herein.

    View details for DOI 10.1007/s11307-011-0471-9

    View details for Web of Science ID 000296794400009

    View details for PubMedID 21267661

    View details for PubMedCentralID PMC4657136

  • In Vitro and in Vivo Molecular Imaging of Estrogen Receptor alpha and beta Homo- and Heterodimerization: Exploration of New Modes of Receptor Regulation MOLECULAR ENDOCRINOLOGY Paulmurugan, R., Tamrazi, A., Massoud, T. F., Katzenellenbogen, J. A., Gambhir, S. S. 2011; 25 (12): 2029-2040


    Estrogen receptor (ER) biology reflects the actions of estrogens through the two receptors, ERα and ERβ, although little is known regarding the preference for formation of ER homo- vs. heterodimers, and how this is affected by the level of ligand occupancy and preferential ligand affinity for one of the ER subtypes. In this report, we use a split optical reporter-protein complementation system to demonstrate the physical interaction between ERα and ERβ in response to different ER ligands in cells and, for the first time, by in vivo imaging in living animals. The genetically encoded reporter vectors constructed with the ligand-binding domains of ERα and ERβ, fused to split firefly or Renilla luciferase (Fluc or hRluc) fragments, were used for this study. This molecular proteomic technique was used to detect ERα/ERα or ERβ/ERβ homodimerization, or ERα/ERβ heterodimerization induced by ER subtype-selective and nonselective ligands, and selective ER modulators (SERM), as well as in dimers in which one mutant monomer was unable to bind estradiol. The SERM-bound ERα and ERβ form the strongest dimers, and subtype-preferential homodimerization was seen with ERα-selective ligands (methyl piperidino pyrazole/propyl pyrazole triol) and the ERβ-selective ligands (diarylpropionitrile/tetrahydrochrysene/genistein). We also demonstrated that a single ligand-bound monomer can form homo- or heterodimers with an apo-monomer. Xenografts of human embryonic kidney 293T cells imaged in living mice by bioluminescence showed real-time ligand induction of ERα/ERβ heterodimerization and reversal of dimerization upon ligand withdrawal. The results from this study demonstrate the value of the split luciferase-based complementation system for studying ER-subtype interactions in cells and for evaluating them in living animals by noninvasive imaging. They also probe what combinations of ERα and ERβ dimers might be the mediators of the effects of different types of ER ligands given at different doses.

    View details for DOI 10.1210/me.2011-1145

    View details for Web of Science ID 000298055800005

    View details for PubMedID 22052998

  • Non-Invasive Imaging of Cysteine Cathepsin Activity in Solid Tumors Using a Cu-64-Labeled Activity-Based Probe PLOS ONE Ren, G., Blum, G., Verdoes, M., Liu, H., Syed, S., Edgington, L. E., Gheysens, O., Miao, Z., Jiang, H., Gambhir, S. S., Bogyo, M., Cheng, Z. 2011; 6 (11)


    The papain family of cysteine cathepsins are actively involved in multiple stages of tumorigenesis. Because elevated cathepsin activity can be found in many types of human cancers, they are promising biomarkers that can be used to target radiological contrast agents for tumor detection. However, currently there are no radiological imaging agents available for these important molecular targets. We report here the development of positron emission tomography (PET) radionuclide-labeled probes that target the cysteine cathepsins by formation of an enzyme activity-dependent bond with the active site cysteine. These probes contain an acyloxymethyl ketone (AOMK) functional group that irreversibly labels the active site cysteine of papain family proteases attached to a 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) tag for labeling with (64)Cu for PET imaging studies. We performed biodistribution and microPET imaging studies in nude mice bearing subcutaneous tumors expressing various levels of cysteine cathepsin activity and found that the extent of probe uptake by tumors correlated with overall protease activity as measured by biochemical methods. Furthermore, probe signals could be reduced by pre-treatment with a general cathepsin inhibitor. We also found that inclusion of a Cy5 tag on the probe increased tumor uptake relative to probes lacking this fluorogenic dye. Overall, these results demonstrate that small molecule activity-based probes carrying radio-tracers can be used to image protease activity in living subjects.

    View details for DOI 10.1371/journal.pone.0028029

    View details for Web of Science ID 000297789900039

    View details for PubMedID 22132198

    View details for PubMedCentralID PMC3221694

  • Mathematical Model Identifies Blood Biomarker-Based Early Cancer Detection Strategies and Limitations SCIENCE TRANSLATIONAL MEDICINE Hori, S. S., Gambhir, S. S. 2011; 3 (109)


    Most clinical blood biomarkers lack the necessary sensitivity and specificity to reliably detect cancer at an early stage, when it is best treatable. It is not yet clear how early a clinical blood assay can be used to detect cancer or how biomarker-based strategies can be improved to enable earlier detection of smaller tumors. To address these issues, we developed a mathematical model describing dynamic plasma biomarker kinetics in relation to the growth of a tumor, beginning with a single cancer cell. To exemplify a realistic scenario in which biomarker is shed by both cancerous and noncancerous cells, we primed the model on ovarian tumor growth and CA125 shedding data, for which tumor growth parameters and shedding rates are readily available in published literature. We found that a tumor could grow unnoticed for more than 10.1 years and reach a volume of about π/6(25.36 mm)(3), corresponding to a spherical diameter of about 25.36 mm, before becoming detectable by current clinical blood assays. Model parameters were perturbed over log orders of magnitude to quantify ideal shedding rates and identify other blood-based strategies required for early submillimeter tumor detectability. The detection times we estimated are consistent with recently published tumor progression time lines based on clinical genomic sequencing data for several cancers. Here, we rigorously showed that shedding rates of current clinical blood biomarkers are likely 10(4)-fold too low to enable detection of a developing tumor within the first decade of tumor growth. The model presented here can be extended to virtually any solid cancer and associated biomarkers.

    View details for DOI 10.1126/scitranslmed.3003110

    View details for Web of Science ID 000297218300004

    View details for PubMedID 22089452

  • GLUT 5 Is Not Over-Expressed in Breast Cancer Cells and Patient Breast Cancer Tissues PLOS ONE Gowrishankar, G., Zitzmann-Kolbe, S., Junutula, A., Reeves, R., Levi, J., Srinivasan, A., Bruus-Jensen, K., Cyr, J., Dinkelborg, L., Gambhir, S. S. 2011; 6 (11)


    F18 2-Fluoro 2-deoxyglucose (FDG) has been the gold standard in positron emission tomography (PET) oncologic imaging since its introduction into the clinics several years ago. Seeking to complement FDG in the diagnosis of breast cancer using radio labeled fructose based analogs, we investigated the expression of the chief fructose transporter-GLUT 5 in breast cancer cells and human tissues. Our results indicate that GLUT 5 is not over-expressed in breast cancer tissues as assessed by an extensive immunohistochemistry study. RT-PCR studies showed that the GLUT 5 mRNA was present at minimal amounts in breast cancer cell lines. Further knocking down the expression of GLUT 5 in breast cancer cells using RNA interference did not affect the fructose uptake in these cell lines. Taken together these results are consistent with GLUT 5 not being essential for fructose uptake in breast cancer cells and tissues.

    View details for DOI 10.1371/journal.pone.0026902

    View details for Web of Science ID 000297154900052

    View details for PubMedID 22073218

  • A novel F-18-labeled two-helix scaffold protein for PET imaging of HER2-positive tumor EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Miao, Z., Ren, G., Jiang, L., Liu, H., Webster, J. M., Zhang, R., Namavari, M., Gambhir, S. S., Syud, F., Cheng, Z. 2011; 38 (11): 1977-1984


    Two-helix scaffold proteins (~ 5 kDa) against human epidermal growth factor receptor type 2 (HER2) have been discovered in our previous work. In this research we aimed to develop an (18)F-labeled two-helix scaffold protein for positron emission tomography (PET) imaging of HER2-positive tumors.An aminooxy-functionalized two-helix peptide (AO-MUT-DS) with high HER2 binding affinity was synthesized through conventional solid phase peptide synthesis. The purified linear peptide was cyclized by I(2) oxidation to form a disulfide bridge. The cyclic peptide was then conjugated with a radiofluorination synthon, 4-(18)F-fluorobenzyl aldehyde ((18)F-FBA), through the aminooxy functional group at the peptide N terminus (30% yield, non-decay corrected). The binding affinities of the peptides were analyzed by Biacore analysis. Cell uptake assay of the resulting PET probe, (18)F-FBO-MUT-DS, was performed at 37°C. (18)F-FBO-MUT-DS with high specific activity (20-32 MBq/nmol, 88-140 μCi/μg, end of synthesis) was injected into mice xenograft model bearing SKOV3 tumor. MicroPET and biodistribution and metabolic stability studies were then conducted.Cell uptake assays showed high and specific cell uptake (~12% applied activity at 1 h) by incubation of (18)F-FBO-MUT-DS with HER2 high-expressing SKOV3 ovarian cancer cells. The affinities (K(D)) of AO-MUT-DS and FBO-MUT-DS as tested by Biacore analysis were 2 and 1 nM, respectively. In vivo small animal PET demonstrated fast tumor targeting, high tumor accumulation, and good tumor to normal tissue contrast of (18)F-FBO-MUT-DS. Biodistribution studies further revealed that the probe had excellent tumor uptake (6.9%ID/g at 1 h post-injection) and was cleared through both liver and kidneys. Co-injection of the probe with 500 μg of HER2 Affibody protein reduced the tumor uptake (6.9 vs 1.8%ID/g, p < 0.05).F-FBO-MUT-DS displays excellent HER2 targeting ability and tumor PET imaging quality. The two-helix scaffold proteins are suitable for development of (18)F-based PET probes.

    View details for DOI 10.1007/s00259-011-1879-9

    View details for Web of Science ID 000295680200004

    View details for PubMedID 21761266

  • Noninvasive cell-tracking methods NATURE REVIEWS CLINICAL ONCOLOGY Kircher, M. F., Gambhir, S. S., Grimm, J. 2011; 8 (11): 677-688


    Cell-based therapies, such as adoptive immunotherapy and stem-cell therapy, have received considerable attention as novel therapeutics in oncological research and clinical practice. The development of effective therapeutic strategies using tumor-targeted cells requires the ability to determine in vivo the location, distribution, and long-term viability of the therapeutic cell populations as well as their biological fate with respect to cell activation and differentiation. In conjunction with various noninvasive imaging modalities, cell-labeling methods, such as exogenous labeling or transfection with a reporter gene, allow visualization of labeled cells in vivo in real time, as well as monitoring and quantifying cell accumulation and function. Such cell-tracking methods also have an important role in basic cancer research, where they serve to elucidate novel biological mechanisms. In this Review, we describe the basic principles of cell-tracking methods, explain various approaches to cell tracking, and highlight recent examples for the application of such methods in animals and humans.

    View details for DOI 10.1038/nrclinonc.2011.141

    View details for Web of Science ID 000296812500009

    View details for PubMedID 21946842

  • Endothelial Cells Derived From Human iPSCS Increase Capillary Density and Improve Perfusion in a Mouse Model of Peripheral Arterial Disease ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY Rufaihah, A. J., Huang, N. F., Jame, S., Lee, J. C., Nguyen, H. N., Byers, B., De, A., Okogbaa, J., Rollins, M., Reijo-Pera, R., Gambhir, S. S., Cooke, J. P. 2011; 31 (11): E72-U44


    Stem cell therapy for angiogenesis and vascular regeneration has been investigated using adult or embryonic stem cells. In the present study, we investigated the potential of endothelial cells (ECs) derived from human induced pluripotent stem cells (hiPSCs) to promote the perfusion of ischemic tissue in a murine model of peripheral arterial disease.Endothelial differentiation was initiated by culturing hiPSCs for 14 days in differentiation media supplemented with BMP-4 and vascular endothelial growth factor. The hiPSC-ECs exhibited endothelial characteristics by forming capillary-like structures in matrigel and incorporating acetylated-LDL. They stained positively for EC markers such as KDR, CD31, CD144, and eNOS. In vitro exposure of hiPSC-ECs to hypoxia resulted in increased expression of various angiogenic related cytokines and growth factors. hiPSC-ECs were stably transduced with a double fusion construct encoded by the ubiquitin promoter, firefly luciferase for bioluminescence imaging and green fluorescence protein for fluorescent detection. The hiPSC-ECs (5×10(5)) were delivered by intramuscular injection into the ischemic hindlimb of SCID mice at day 0 and again on day 7 after femoral artery ligation (n=8). Bioluminescence imaging showed that hiPSC-ECs survived in the ischemic limb for at least 2 weeks. In addition, laser Doppler imaging showed that the ratio of blood perfusion was increased by hiPSC-EC treatment by comparison to the saline-treated group (0.58±0.12 versus 0.44±0.04; P=0.005). The total number of capillaries in the ischemic limb of mice receiving hiPSC-EC injections was greater than those in the saline-treated group (1284±155 versus 797±206 capillaries/mm(2)) (P<0.002).This study is a first step toward development of a regenerative strategy for peripheral arterial disease based on the use of ECs derived from hiPSCs.

    View details for DOI 10.1161/ATVBAHA.111.230938

    View details for Web of Science ID 000296605400001

    View details for PubMedID 21836062

    View details for PubMedCentralID PMC3210551

  • Theranostic nanomedicine. Accounts of chemical research Chen, X., Gambhir, S. S., Cheon, J. 2011; 44 (10): 841-?

    View details for DOI 10.1021/ar200231d

    View details for PubMedID 22004477

  • Immobilizing Reporters for Molecular Imaging of the Extracellular Microenvironment in Living Animals ACS CHEMICAL BIOLOGY Xia, Z., Xing, Y., Jeon, J., Kim, Y., Gall, J., Dragulescu-Andrasi, A., Gambhir, S. S., Rao, J. 2011; 6 (10): 1117-1126


    We report here an immobilization strategy using a collagen binding protein to deliver and confine synthetic reporters to the extracellular microenvironment in vivo for noninvasively imaging the activity of targets in the microenvironment. We show that the immobilization of reporters on collagens in the local microenvironment is highly efficient and physiologically stable for repetitive, long-term imaging. By using this strategy we successfully developed an immobilized bioluminescent activatable reporter and a dual-modality reporter to map and quantitatively image the activity of extracellular matrix metalloproteinases (MMP) in tumor-bearing mice. The inhibition of MMP activity by chemical inhibitor was also demonstrated in living subjects. We further demonstrated the general applicability of this immobilization strategy by imaging MMP activity at the inflammation site in a mouse model. Our results show that the in vivo immobilization of reporters can be used as a general strategy for probing the local extracellular microenvironment.

    View details for DOI 10.1021/cb200135e

    View details for Web of Science ID 000296208100018

    View details for PubMedID 21830814

    View details for PubMedCentralID PMC3199358

  • Molecular Imaging with Theranostic Nanoparticles ACCOUNTS OF CHEMICAL RESEARCH Jokerst, J. V., Gambhir, S. S. 2011; 44 (10): 1050-1060


    Nanoparticles (NPs) offer diagnostic and therapeutic capabilities not available with small molecules or microscale tools. As the field of molecular imaging has emerged from the blending of molecular biology with medical imaging, NP imaging is increasingly common for both therapeutic and diagnostic applications. The term theranostic describes technology with concurrent and complementary diagnostic and therapeutic capabilities. Although NPs have been FDA-approved for clinical use as transport vehicles for nearly 15 years, full translation of their theranostic potential is incomplete. However, NPs have shown remarkable success in the areas of drug delivery and magnetic resonance imaging. Emerging applications include image-guided resection, optical/photoacoustic imaging in vivo, contrast-enhanced ultrasound, and thermoablative therapy. Diagnosis with NPs in molecular imaging involves the correlation of the signal with a phenotype. The location and intensity of NP signals emanating from a living subject indicate the disease area's size, stage, and biochemical signature. Therapy with NPs uses the image for resection or delivery of a small molecule or RNA therapeutic. Ablation of the affected area is also possible via heat or radioactivity. The ideal theranostic NP includes several features: (1) it selectively and rapidly accumulates in diseased tissue; (2) it reports biochemical and morphological characteristics of the area; (3) it delivers an effective therapeutic; and (4) it is safe and biodegrades with nontoxic byproducts. Such a system contains a central imaging core surrounded by small molecule therapeutics. The system targets via ligands such as IgG and is protected from immune scavengers by a cloak of protective polymer. Although no NP has achieved all of the above criteria, many NPs possess one or more of these features. While the most clinically translatable NPs have been used in the field of magnetic resonance imaging, other types in development are quickly becoming more biocompatible through methods that modify their toxicity and biodistribution profiles. In this Account, we describe diagnostic imaging and therapeutic uses of NPs. We propose and offer examples of five primary types of nanoparticles with concurrent diagnostic and therapeutic uses.

    View details for DOI 10.1021/ar200106e

    View details for Web of Science ID 000296682400022

    View details for PubMedID 21919457

  • Synthesis of 2 '-Deoxy-2 '-[F-18]Fluoro-9-beta-D-Arabinofuranosylguanine: a Novel Agent for Imaging T-Cell Activation with PET MOLECULAR IMAGING AND BIOLOGY Namavari, M., Chang, Y., Kusler, B., Yaghoubi, S., Mitchell, B. S., Gambhir, S. S. 2011; 13 (5): 812-818


    9-(β-D-Arabinofuranosyl)guanine (AraG) is a guanosine analog that has a proven efficacy in the treatment of T-cell lymphoblastic disease. To test the possibility of using a radiofluorinated AraG as an imaging agent, we have synthesized 2'-deoxy-2'-[(18)F]fluoro-9-β-D-arabinofuranosylguanine ([(18)F]F-AraG) and investigated its uptake in T cells.We have synthesized [(18)F]F-AraG via a direct fluorination of 2-N-acetyl-6-O-((4-nitrophenyl)ethyl)-9-(3',5'-di-O-trityl-2'-O-trifyl-β-D-ribofuranosyl)guanine with [(18)F]KF/K.2.2.2 in DMSO at 85°C for 45 min. [(18)F]F-AraG uptake in both a CCRF-CEM leukemia cell line (unactivated) and activated primary thymocytes was evaluated.We have successfully prepared [(18)F]F-AraG in 7-10% radiochemical yield (decay corrected) with a specific activity of 0.8-1.3 Ci/μmol. Preliminary cell uptake experiments showed that both a CCRF-CEM leukemia cell line and activated primary thymocytes take up the [(18)F]F-AraG.For the first time to the best of our knowledge, [(18)F]F-AraG has been successfully synthesized by direct fluorination of an appropriate precursor of a guanosine nucleoside. This approach maybe also useful for the synthesis of other important positron emission tomography (PET) probes such as [(18)F]FEAU, [(18)F]FMAU, and [(18)F]FBAU which are currently synthesized by multiple steps and involve lengthy purification. The cell uptake studies support future studies to investigate the use of [(18)F]F-AraG as a PET imaging agent of T cells.

    View details for DOI 10.1007/s11307-010-0414-x

    View details for Web of Science ID 000295176200002

    View details for PubMedID 20838911

  • Gold Nanoparticles: A Revival in Precious Metal Administration to Patients NANO LETTERS Thakor, A. S., Jokerst, J., Zavaleta, C., Massoud, T. F., Gambhir, S. S. 2011; 11 (10): 4029-4036


    Gold has been used as a therapeutic agent to treat a wide variety of rheumatic diseases including psoriatic arthritis, juvenile arthritis, and discoid lupus erythematosus. Although the use of gold has been largely superseded by newer drugs, gold nanoparticles are being used effectively in laboratory based clinical diagnostic methods while concurrently showing great promise in vivo either as a diagnostic imaging agent or a therapeutic agent. For these reasons, gold nanoparticles are therefore well placed to enter mainstream clinical practice in the near future. Hence, the present review summarizes the chemistry, pharmacokinetics, biodistribution, metabolism, and toxicity of bulk gold in humans based on decades of clinical observation and experiments in which gold was used to treat patients with rheumatoid arthritis. The beneficial attributes of gold nanoparticles, such as their ease of synthesis, functionalization, and shape control are also highlighted demonstrating why gold nanoparticles are an attractive target for further development and optimization. The importance of controlling the size and shape of gold nanoparticles to minimize any potential toxic side effects is also discussed.

    View details for DOI 10.1021/nl202559p

    View details for Web of Science ID 000295667000001

    View details for PubMedID 21846107

  • Preclinical Derivation and Imaging of Autologously Transplanted Canine Induced Pluripotent Stem Cells JOURNAL OF BIOLOGICAL CHEMISTRY Lee, A. S., Xu, D., Plews, J. R., Nguyen, P. K., Nag, D., Lyons, J. K., Han, L., Hu, S., Lan, F., Liu, J., Huang, M., Narsinh, K. H., Long, C. T., de Almeida, P. E., Levi, B., Kooreman, N., Bangs, C., Pacharinsak, C., Ikeno, F., Yeung, A. C., Gambhir, S. S., Robbins, R. C., Longaker, M. T., Wu, J. C. 2011; 286 (37): 32697-32704


    Derivation of patient-specific induced pluripotent stem cells (iPSCs) opens a new avenue for future applications of regenerative medicine. However, before iPSCs can be used in a clinical setting, it is critical to validate their in vivo fate following autologous transplantation. Thus far, preclinical studies have been limited to small animals and have yet to be conducted in large animals that are physiologically more similar to humans. In this study, we report the first autologous transplantation of iPSCs in a large animal model through the generation of canine iPSCs (ciPSCs) from the canine adipose stromal cells and canine fibroblasts of adult mongrel dogs. We confirmed pluripotency of ciPSCs using the following techniques: (i) immunostaining and quantitative PCR for the presence of pluripotent and germ layer-specific markers in differentiated ciPSCs; (ii) microarray analysis that demonstrates similar gene expression profiles between ciPSCs and canine embryonic stem cells; (iii) teratoma formation assays; and (iv) karyotyping for genomic stability. Fate of ciPSCs autologously transplanted to the canine heart was tracked in vivo using clinical positron emission tomography, computed tomography, and magnetic resonance imaging. To demonstrate clinical potential of ciPSCs to treat models of injury, we generated endothelial cells (ciPSC-ECs) and used these cells to treat immunodeficient murine models of myocardial infarction and hindlimb ischemia.

    View details for DOI 10.1074/jbc.M111.235739

    View details for Web of Science ID 000294726800078

    View details for PubMedID 21719696

    View details for PubMedCentralID PMC3173214

  • Adipose tissue-derived stem cells display a proangiogenic phenotype on 3D scaffolds. Journal of biomedical materials research. Part A Neofytou, E. A., Chang, E., Patlola, B., Joubert, L., Rajadas, J., Gambhir, S. S., Cheng, Z., Robbins, R. C., Beygui, R. E. 2011; 98 (3): 383-393


    Ischemic heart disease is the leading cause of death worldwide. Recent studies suggest that adipose tissue-derived stem cells (ASCs) can be used as a potential source for cardiovascular tissue engineering due to their ability to differentiate along the cardiovascular lineage and to adopt a proangiogenic phenotype. To understand better ASCs' biology, we used a novel 3D culture device. ASCs' and b.END-3 endothelial cell proliferation, migration, and vessel morphogenesis were significantly enhanced compared to 2D culturing techniques. ASCs were isolated from inguinal fat pads of 6-week-old GFP+/BLI+ mice. Early passage ASCs cells (P3-P4), PKH26-labeled murine b.END-3 cells or a co-culture of ASCs and b.END-3 cells were seeded at a density of 1 × 10(5) on three different surface configurations: (a) a 2D surface of tissue culture plastic, (b) Matrigel, and (c) a highly porous 3D scaffold fabricated from inert polystyrene. VEGF expression, cell proliferation, and tubulization, were assessed using optical microscopy, fluorescence microscopy, 3D confocal microscopy, and SEM imaging (n = 6). Increased VEGF levels were seen in conditioned media harvested from co-cultures of ASCs and b.END-3 on either Matrigel or a 3D matrix. Fluorescence, confocal, SEM, bioluminescence revealed improved cell, proliferation, and tubule formation for cells seeded on the 3D polystyrene matrix. Collectively, these data demonstrate that co-culturing ASCs with endothelial cells in a 3D matrix environment enable us to generate prevascularized tissue-engineered constructs. This can potentially help us to surpass the tissue thickness limitations faced by the tissue engineering community today.

    View details for DOI 10.1002/jbm.a.33113

    View details for PubMedID 21630430

  • Adipose tissue-derived stem cells display a proangiogenic phenotype on 3D scaffolds JOURNAL OF BIOMEDICAL MATERIALS RESEARCH PART A Neofytou, E. A., Chang, E., Patloia, B., Joubert, L., Rajadas, J., Gambhir, S. S., Cheng, Z., Robbins, R. C., Beygui, R. E. 2011; 98A (3): 383-393
  • Advanced contrast nanoagents for photoacoustic molecular imaging, cytometry, blood test and photothermal theranostics CONTRAST MEDIA & MOLECULAR IMAGING de la Zerda, A., Kim, J., Galanzha, E. I., Gambhir, S. S., Zharov, V. P. 2011; 6 (5): 346-369


    Various nanoparticles have raised significant interest over the past decades for their unique physical and optical properties and biological utilities. Here we summarize the vast applications of advanced nanoparticles with a focus on carbon nanotube (CNT)-based or CNT-catalyzed contrast agents for photoacoustic (PA) imaging, cytometry and theranostics applications based on the photothermal (PT) effect. We briefly review the safety and potential toxicity of the PA/PT contrast nanoagents, while showing how the physical properties as well as multiple biological coatings change their toxicity profiles and contrasts. We provide general guidelines needed for the validation of a new molecular imaging agent in living subjects, and exemplify these guidelines with single-walled CNTs targeted to α(v) β(3) , an integrin associated with tumor angiogenesis, and golden carbon nanotubes targeted to LYVE-1, endothelial lymphatic receptors. An extensive review of the potential applications of advanced contrast agents is provided, including imaging of static targets such as tumor angiogenesis receptors, in vivo cytometry of dynamic targets such as circulating tumor cells and nanoparticles in blood, lymph, bones and plants, methods to enhance the PA and PT effects with transient and stationary bubble conjugates, PT/PA Raman imaging and multispectral histology. Finally, theranostic applications are reviewed, including the nanophotothermolysis of individual tumor cells and bacteria with clustered nanoparticles, nanothrombolysis of blood clots, detection and purging metastasis in sentinel lymph nodes, spectral hole burning and multiplex therapy with ultrasharp rainbow nanoparticles.

    View details for DOI 10.1002/cmmi.455

    View details for Web of Science ID 000300110400003

    View details for PubMedID 22025336

    View details for PubMedCentralID PMC4282188

  • Preclinical Evaluation of Raman Nanoparticle Biodistribution for their Potential Use in Clinical Endoscopy Imaging SMALL Zavaleta, C. L., Hartman, K. B., Miao, Z., James, M. L., Kempen, P., Thakor, A. S., Nielsen, C. H., Sinclair, R., Cheng, Z., Gambhir, S. S. 2011; 7 (15): 2232-2240


    Raman imaging offers unsurpassed sensitivity and multiplexing capabilities. However, its limited depth of light penetration makes direct clinical translation challenging. Therefore, a more suitable way to harness its attributes in a clinical setting would be to couple Raman spectroscopy with endoscopy. The use of an accessory Raman endoscope in conjunction with topically administered tumor-targeting Raman nanoparticles during a routine colonoscopy could offer a new way to sensitively detect dysplastic lesions while circumventing Raman's limited depth of penetration and avoiding systemic toxicity. In this study, the natural biodistribution of gold surface-enhanced Raman scattering (SERS) nanoparticles is evaluated by radiolabeling them with (64) Cu and imaging their localization over time using micropositron emission tomography (PET). Mice are injected either intravenously (IV) or intrarectally (IR) with approximately 100 microcuries (μCi) (3.7 megabecquerel (MBq)) of (64) Cu-SERS nanoparticles and imaged with microPET at various time points post injection. Quantitative biodistribution data are obtained as % injected dose per gram (%ID g(-1)) from each organ, and the results correlate well with the corresponding microPET images, revealing that IV-injected mice have significantly higher uptake (p < 0.05) in the liver (5 h = 8.96% ID g(-1); 24 h = 8.27% ID g(-1)) than IR-injected mice (5 h = 0.09% ID g(-1); 24 h = 0.08% ID g(-1)). IR-injected mice show localized uptake in the large intestine (5 h = 10.37% ID g(-1); 24 h = 0.42% ID g(-1)) with minimal uptake in other organs. Raman imaging of excised tissues correlate well with biodistribution data. These results suggest that the topical application of SERS nanoparticles in the mouse colon appears to minimize their systemic distribution, thus avoiding potential toxicity and supporting the clinical translation of Raman spectroscopy as an endoscopic imaging tool.

    View details for DOI 10.1002/smll.201002317

    View details for Web of Science ID 000294361200015

    View details for PubMedID 21608124

  • Bioluminescence resonance energy transfer (BRET) imaging of protein-protein interactions within deep tissues of living subjects PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Dragulescu-Andrasi, A., Chan, C. T., De, A., Massoud, T. F., Gambhir, S. S. 2011; 108 (29): 12060-12065


    Identifying protein-protein interactions (PPIs) is essential for understanding various disease mechanisms and developing new therapeutic approaches. Current methods for assaying cellular intermolecular interactions are mainly used for cells in culture and have limited use for the noninvasive assessment of small animal disease models. Here, we describe red light-emitting reporter systems based on bioluminescence resonance energy transfer (BRET) that allow for assaying PPIs both in cell culture and deep tissues of small animals. These BRET systems consist of the recently developed Renilla reniformis luciferase (RLuc) variants RLuc8 and RLuc8.6, used as BRET donors, combined with two red fluorescent proteins, TagRFP and TurboFP635, as BRET acceptors. In addition to the native coelenterazine luciferase substrate, we used the synthetic derivative coelenterazine-v, which further red-shifts the emission maxima of Renilla luciferases by 35 nm. We show the use of these BRET systems for ratiometric imaging of both cells in culture and deep-tissue small animal tumor models and validate their applicability for studying PPIs in mice in the context of rapamycin-induced FK506 binding protein 12 (FKBP12)-FKBP12 rapamycin binding domain (FRB) association. These red light-emitting BRET systems have great potential for investigating PPIs in the context of drug screening and target validation applications.

    View details for DOI 10.1073/pnas.1100923108

    View details for Web of Science ID 000292876900069

    View details for PubMedID 21730157

    View details for PubMedCentralID PMC3141927

  • Pilot Pharmacokinetic and Dosimetric Studies of F-18-FPPRGD2: A PET Radiopharmaceutical Agent for Imaging alpha(v)beta(3) Integrin Levels RADIOLOGY Mittra, E. S., Goris, M. L., Iagaru, A. H., Kardan, A., Burton, L., Berganos, R., Chang, E., Liu, S., Shen, B., Chin, F. T., Chen, X., Gambhir, S. S. 2011; 260 (1): 182-191


    To assess the safety, biodistribution, and dosimetric properties of the positron emission tomography (PET) radiopharmaceutical agent fluorine 18 ((18)F) FPPRGD2 (2-fluoropropionyl labeled PEGylated dimeric RGD peptide [PEG3-E{c(RGDyk)}2]), which is based on the dimeric arginine-glycine-aspartic acid (RGD) peptide sequence and targets α(v)β(3) integrin, in the first volunteers imaged with this tracer.The protocol was approved by the institutional review board, and written informed consent was obtained from all participants. Five healthy volunteers underwent whole-body combined PET-computed tomography 0.5, 1.0, 2.0, and 3.0 hours after tracer injection (mean dose, 9.5 mCi ± 3.4 [standard deviation] [351.5 MBq ± 125.8]; mean specific radioactivity, 1200 mCi/mmol ± 714 [44.4 GBq/mmol ± 26.4]). During this time, standard vital signs, electrocardiographic (ECG) readings, and blood sample values (for chemistry, hematologic, and liver function tests) were checked at regular intervals and 1 and 7 days after the injection. These data were used to evaluate tracer biodistribution and dosimetric properties, time-activity curves, and the stability of laboratory values. Significant changes in vital signs and laboratory values were evaluated by using a combination of population-averaged generalized estimating equation regression and exact paired Wilcoxon tests.The administration of (18)F-FPPRGD2 was well tolerated, with no marked effects on vital signs, ECG readings, or laboratory values. The tracer showed the same pattern of biodistribution in all volunteers: primary clearance through the kidneys (0.360 rem/mCi ± 0.185 [0.098 mSv/MBq ± 0.050]) and bladder (0.862 rem/mCi ± 0.436 [0.233 mSv/MBq ± 0.118], voiding model) and uptake in the spleen (0.250 rem/mCi ± 0.168 [0.068 mSv/MBq ± 0.046]) and large intestine (0.529 rem/mCi ± 0.236 [0.143 mSv/MBq ± 0.064]). The mean effective dose of (18)F-FPPRGD2 was 0.1462 rem/mCi ± 0.0669 (0.0396 mSv/MBq ± 0.0181). With an injected dose of 10 mCi (370 MBq) and a 1-hour voiding interval, a patient would be exposed to an effective radiation dose of 1.5 rem (15 mSv). Above the diaphragm, there was minimal uptake in the brain ventricles, salivary glands, and thyroid gland. Time-activity curves showed rapid clearance from the vasculature, with a mean 26% ± 17 of the tracer remaining in the circulation at 30 minutes and most of the activity occurring in the plasma relative to cells (mean whole blood-plasma ratio, 0.799 ± 0.096).(18)F-FPPRGD2 has desirable pharmacokinetic and biodistribution properties. The primary application is likely to be PET evaluation of oncologic patients-especially those with brain, breast, or lung cancer. Specific indications may include tumor staging, identifying patients who would benefit from antiangiogenesis therapy, and separating treatment responders from nonresponders early.

    View details for DOI 10.1148/radiol.11101139

    View details for Web of Science ID 000291932300021

    View details for PubMedID 21502381

  • Synthesis and Radioluminescence of PEGylated Eu3+-doped Nanophosphors as Bioimaging Probes ADVANCED MATERIALS Sun, C., Pratx, G., Carpenter, C. M., Liu, H., Cheng, Z., Gambhir, S. S., Xing, L. 2011; 23 (24): H195-H199

    View details for DOI 10.1002/adma.201100919

    View details for Web of Science ID 000293046600018

    View details for PubMedID 21557339

    View details for PubMedCentralID PMC4145869

  • Nanoparticle PEGylation for imaging and therapy NANOMEDICINE Jokerst, J. V., Lobovkina, T., Zare, R. N., Gambhir, S. S. 2011; 6 (4): 715-728


    Nanoparticles are an essential component in the emerging field of nanomedical imaging and therapy. When deployed in vivo, these materials are typically protected from the immune system by polyethylene glycol (PEG). A wide variety of strategies to coat and characterize nanoparticles with PEG has established important trends on PEG size, shape, density, loading level, molecular weight, charge and purification. Strategies to incorporate targeting ligands are also prevalent. This article presents a background to investigators new to stealth nanoparticles, and suggests some key considerations needed prior to designing a nanoparticle PEGylation protocol and characterizing the performance features of the product.

    View details for DOI 10.2217/NNM.11.19

    View details for Web of Science ID 000292994300019

    View details for PubMedID 21718180

  • Potent, tumor-specific gene expression in an orthotopic hepatoma rat model using a Survivin-targeted, amplifiable adenoviral vector GENE THERAPY Ahn, B., Ronald, J. A., Kim, Y. I., Katzenberg, R., Singh, A., Paulmurugan, R., Ray, S., Hofmann, L. V., Gambhir, S. S. 2011; 18 (6): 606-612


    Ideal cancer gene therapies should have high tumor specificity and efficacy, and allow systemic administration to target metastases. We recently developed a bi-directional, two-step transcriptional amplification (TSTA) system driven by the tumor-specific Survivin promoter (pSurv) to amplify the correlated expression of both the reporter gene firefly luciferase (FL) and therapeutic gene tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Here, we compare the specificity and potency of an adenovirus carrying this system (Ad-pSurv-TSTA-TRAIL-FL) to a nonspecific vector (Ad-pCMV-FL) in an orthotopic hepatocellular carcinoma (HCC) rat model after systemic administration. At 24 h after injection of Ad-pCMV-FL, bioluminescence imaging revealed a trend (P=0.30) towards greater FL expression in liver versus tumor. In striking contrast, Ad-pSurv-TSTA-TRAIL-FL showed increased FL activity within the tumor compared with the liver (P<0.01), a strong trend towards reduced liver expression compared with Ad-pCMV-FL (P=0.07), and importantly, similar FL levels within tumor compared with Ad-pCMV-FL (P=0.32). Hence, this vector shows potent, tumor-specific transgene expression even after extensive liver transduction and may be of significant value in avoiding hepatotoxicity in HCC patients. Future studies will explore the benefits of tumor-specific TRAIL expression in this model, the potential to target metastases and the extension of this vector for the treatment of other Survivin-positive tumors is warranted.

    View details for DOI 10.1038/gt.2011.5

    View details for Web of Science ID 000291438900010

    View details for PubMedID 21307888

    View details for PubMedCentralID PMC4154811

  • Therapeutic treatment of critical limb ischemia using human induced pluripotent stem cell-derived endothelial cells Huang, N. F., Jalil, R. A., Lee, J., Jame, S., Nguyen, H. N., De, A., Gambhir, S., Reijo-Pera, R., Cooke, J. P. SAGE PUBLICATIONS LTD. 2011: 221–21
  • Engineering and Visualization of Bacteria for Targeting Infarcted Myocardium MOLECULAR THERAPY Le, U. N., Kim, H., Kwon, J., Kim, M. Y., Nguyen, V. H., Jiang, S. N., Lee, B., Hong, Y., Shin, M. G., Rhee, J. H., Bom, H., Ahn, Y., Gambhir, S. S., Choy, H. E., Min, J. 2011; 19 (5): 951-959


    Optimization of the specific affinity of cardiac delivery vector could significantly improve the efficiency of gene/protein delivery, yet no cardiac vectors to date have sufficient target specificity for myocardial infarction (MI). In this study, we explored bacterial tropism for infarcted myocardium based on our previous observations that certain bacteria are capable of targeting the hypoxic regions in solid tumors. Out of several Escherichia coli or Salmonella typhimurium strains, the S. typhimurium defective in the synthesis of ppGpp (ΔppGpp S. typhimurium) revealed accumulation and selective proliferation in the infarcted myocardium without spillover to noncardiac tissue. The Salmonellae that were engineered to express a variant of Renilla luciferase gene (RLuc8), under the control of the E. coli arabinose operon promoter (P(BAD)), selectively targeted and delivered RLuc8 in the infarcted myocardium only upon injection of L-arabinose. An examination of the infarct size before and after infection, and estimations of C-reactive protein (CRP) and procalcitonin indicated that intravenous injection of ΔppGpp S. typhimurium did not induce serious local or systemic immune reactions. This current proof-of-principle study demonstrates for the first time the capacity of Salmonellae to target infarcted myocardium and to serve as a vehicle for the selective delivery of therapeutic agents in MI.

    View details for DOI 10.1038/mt.2011.25

    View details for Web of Science ID 000290146200021

    View details for PubMedID 21364539

  • Early Diagnosis of Ovarian Carcinoma: Is a Solution in Sight? RADIOLOGY Lutz, A. M., Willmann, J. K., Drescher, C. W., Ray, P., Cochran, F. V., Urban, N., Gambhir, S. S. 2011; 259 (2): 329-345


    Ovarian cancer is the most lethal of the gynecologic malignancies. Because ovarian cancer symptoms are subtle and nonspecific, the diagnosis is often delayed until the disease is well advanced. Overall 5-year survival is a rather dismal 50% but can be improved to greater than 90% if the disease is confined to the ovary at the time of diagnosis (generally in fewer than 25% of patients). Effective screening tools are currently not available. Owing to the rather low incidence of the disease in the general population, potential screening tests must provide very high specificity to avoid unnecessary interventions in false-positive cases. This article reviews currently available serum biomarkers and imaging tests for the early detection of ovarian cancer and provides an outlook on the potential improvements in these noninvasive diagnostic tools that may lead to successful implementation in a screening program. Supplemental material:

    View details for DOI 10.1148/radiol.11090563

    View details for Web of Science ID 000289667300006

    View details for PubMedID 21502390

  • "Same Day" Ex-vivo Regional Gene Therapy: A Novel Strategy to Enhance Bone Repair MOLECULAR THERAPY Virk, M. S., Sugiyama, O., Park, S. H., Gambhir, S. S., Adams, D. J., Drissi, H., Lieberman, J. R. 2011; 19 (5): 960-968


    Ex-vivo regional gene therapy with bone marrow cells (BMCs) overexpressing bone morphogenetic protein-2 (BMP-2) has demonstrated efficacy in healing critical sized bone defects in preclinical studies. The purpose of this preclinical study was to compare the osteoinductive potential of a novel "same day" ex-vivo regional gene therapy versus a traditional two-step approach, which involves culture expansion of the donor cells before implantation. In the "same day" strategy buffy coat cells were harvested from the rat bone marrow, transduced with a lentiviral vector-expressing BMP-2 for 1 hour and implanted into a rat femoral defect in the same sitting. There was no significant difference (P = 0.22) with respect to the radiographic healing rates between the femoral defects treated with the "same day" strategy (13/13; 100%) versus the traditional two-step approach (11/14; 78%). However, the femoral defects treated with the "same day" strategy induced earlier radiographic bone healing (P = 0.004) and higher bone volume (BV) [micro-computed tomography (micro-CT); P < 0.001]. The "same day" strategy represents a significant advance in the field of ex-vivo regional gene therapy because it offers a solution to limitations associated with the culture expansion process required in the traditional ex vivo approach. This strategy should be cost-effective when adapted for human use.

    View details for DOI 10.1038/mt.2011.2

    View details for Web of Science ID 000290146200022

    View details for PubMedID 21343916

  • Multimodality Imaging of beta-Cells in Mouse Models of Type 1 and 2 Diabetes DIABETES Yong, J., Rasooly, J., Dang, H., Lu, Y., Middleton, B., Zhang, Z., Hon, L., Namavari, M., Stout, D. B., Atkinson, M. A., Tian, J., Gambhir, S. S., Kaufman, D. L. 2011; 60 (5): 1383-1392


    β-Cells that express an imaging reporter have provided powerful tools for studying β-cell development, islet transplantation, and β-cell autoimmunity. To further expedite diabetes research, we generated transgenic C57BL/6 "MIP-TF" mice that have a mouse insulin promoter (MIP) driving the expression of a trifusion (TF) protein of three imaging reporters (luciferase/enhanced green fluorescent protein/HSV1-sr39 thymidine kinase) in their β-cells. This should enable the noninvasive imaging of β-cells by charge-coupled device (CCD) and micro-positron emission tomography (PET), as well as the identification of β-cells at the cellular level by fluorescent microscopy.MIP-TF mouse β-cells were multimodality imaged in models of type 1 and type 2 diabetes.MIP-TF mouse β-cells were readily identified in pancreatic tissue sections using fluorescent microscopy. We show that MIP-TF β-cells can be noninvasively imaged using microPET. There was a correlation between CCD and microPET signals from the pancreas region of individual mice. After low-dose streptozotocin administration to induce type 1 diabetes, we observed a progressive reduction in bioluminescence from the pancreas region before the appearance of hyperglycemia. Although there have been reports of hyperglycemia inducing proinsulin expression in extrapancreatic tissues, we did not observe bioluminescent signals from extrapancreatic tissues of diabetic MIP-TF mice. Because MIP-TF mouse β-cells express a viral thymidine kinase, ganciclovir treatment induced hyperglycemia, providing a new experimental model of type 1 diabetes. Mice fed a high-fat diet to model early type 2 diabetes displayed a progressive increase in their pancreatic bioluminescent signals, which were positively correlated with area under the curve-intraperitoneal glucose tolerance test (AUC-IPGTT).MIP-TF mice provide a new tool for monitoring β-cells from the single cell level to noninvasive assessments of β-cells in models of type 1 diabetes and type 2 diabetes.

    View details for DOI 10.2337/db10-0907

    View details for Web of Science ID 000290349700004

    View details for PubMedID 21441442

  • The Fate and Toxicity of Raman-Active Silica-Gold Nanoparticles in Mice SCIENCE TRANSLATIONAL MEDICINE Thakor, A. S., Luong, R., Paulmurugan, R., Lin, F. I., Kempen, P., Zavaleta, C., Chu, P., Massoud, T. F., Sinclair, R., Gambhir, S. S. 2011; 3 (79)


    Raman spectroscopy is an optical imaging method that is based on the Raman effect, the inelastic scattering of a photon when energy is absorbed from light by a surface. Although Raman spectroscopy is widely used for chemical and molecular analysis, its clinical application has been hindered by the inherently weak nature of the Raman effect. Raman-silica-gold-nanoparticles (R-Si-Au-NPs) overcome this limitation by producing larger Raman signals through surface-enhanced Raman scattering. Because we are developing these particles for use as targeted molecular imaging agents, we examined the acute toxicity and biodistribution of core polyethylene glycol (PEG)-ylated R-Si-Au-NPs after different routes of administration in mice. After intravenous administration, PEG-R-Si-Au-NPs were removed from the circulation by macrophages in the liver and spleen (that is, the reticuloendothelial system). At 24 hours, PEG-R-Si-Au-NPs elicited a mild inflammatory response and an increase in oxidative stress in the liver, which subsided by 2 weeks after administration. No evidence of significant toxicity was observed by measuring clinical, histological, biochemical, or cardiovascular parameters for 2 weeks. Because we are designing targeted PEG-R-Si-Au-NPs (for example, PEG-R-Si-Au-NPs labeled with an affibody that binds specifically to the epidermal growth factor receptor) to detect colorectal cancer after administration into the bowel lumen, we tested the toxicity of the core nanoparticle after administration per rectum. We observed no significant bowel or systemic toxicity, and no PEG-R-Si-Au-NPs were detected systemically. Although additional studies are required to investigate the long-term effects of PEG-R-Si-Au-NPs and their toxicity when carrying the targeting moiety, the results presented here support the idea that PEG-R-Si-Au-NPs can be safely used in living subjects, especially when administered rectally.

    View details for DOI 10.1126/scitranslmed.3001963

    View details for Web of Science ID 000292976700004

    View details for PubMedID 21508310

  • FDG-PET/CT in Cancers of the Head and Neck: What is the Definition of Whole Body Scanning? MOLECULAR IMAGING AND BIOLOGY Iagaru, A., Mittra, E. S., Gambhir, S. S. 2011; 13 (2): 362-367


    The role of 2-deoxy-2-[F-18]fluoro-D-glucose-positron emission tomography (FDG-PET) was studied in a variety of cancers, including head and neck squamous cell carcinomas (HNSCC) and nasopharyngeal carcinomas (NPC), with several presentations indicating that for these clinical entities a "whole-body" (i.e., eyes to thighs) may yield little additional information. Therefore, we were prompted to review our experience with PET/computed tomography (CT) in the management of patients with HNSCC and NPC.This is a retrospective study of 133 patients with HNSCC, 23-90 years old (average: 58.2 ± 12.7) and 26 patients with NPC, ages 16-75 (average: 47.3 ± 17.1), who had whole body PET/CT at our institution from Jan 2003 to Nov 2006. Reinterpretation of the imaging studies for accuracy and data analysis from medical records was performed. Lesions identified on PET/CT below the level of the adrenal glands were recorded and tabulated.Lesions were identified below the adrenal glands in seven patients (5.2%) with HNSCC. These included hepatic and osseous metastases from HNSCC in two patients (1.5%), a new renal cancer (0.75%), a new pancreatic cancer (0.75%), a new colon cancer (0.75%) and findings proven benign on follow-up (focal colon uptake in one patient and an inflammatory inguinal lymph node in another patient; 1.5%). Lesions were identified below the adrenal glands in three patients (11.5%) with NPC. These included osseous metastases from NPC in two patients (7.7%) and findings proven benign on follow-up (focal colon uptake in one patient; 3.84%).This study suggests that whole body PET/CT imaging in HNSCC has a relatively low yield (3%, 95% CI: 1.33-8.42) of significant findings below the level of the adrenal glands. Therefore, implementing a more limited protocol (through the level of adrenal glands), especially in low-risk cases of HNSCC, may be considered. However, whole body PET/CT imaging in NPC may have a significant yield (7.7%, 95% CI: 1.02-25.26) of medically relevant findings below the level of the adrenal glands. Thus, the whole body (i.e., vertex to thighs) PET/CT scan of NPC patients appears to be the appropriate imaging protocol for this population. This recommendation requires further evaluation and validation in larger prospective studies.

    View details for DOI 10.1007/s11307-010-0343-8

    View details for Web of Science ID 000288177700021

    View details for PubMedID 20495879

  • Molecular Imaging Using Light-Absorbing Imaging Agents and a Clinical Optical Breast Imaging System-a Phantom Study MOLECULAR IMAGING AND BIOLOGY van de Ven, S. M., Mincu, N., Brunette, J., Ma, G., Khayat, M., Ikeda, D. M., Gambhir, S. S. 2011; 13 (2): 232-238


    The aim of the study was to determine the feasibility of using a clinical optical breast scanner with molecular imaging strategies based on modulating light transmission.Different concentrations of single-walled carbon nanotubes (SWNT; 0.8-20.0 nM) and black hole quencher-3 (BHQ-3; 2.0-32.0 µM) were studied in specifically designed phantoms (200-1,570 mm(3)) with a clinical optical breast scanner using four wavelengths. Each phantom was placed in the scanner tank filled with optical matching medium. Background scans were compared to absorption scans, and reproducibility was assessed.All SWNT phantoms were detected at four wavelengths, with best results at 684 nm. Higher concentrations (≥8.0 µM) were needed for BHQ-3 detection, with the largest contrast at 684 nm. The optical absorption signal was dependent on phantom size and concentration. Reproducibility was excellent (intraclass correlation 0.93-0.98).Nanomolar concentrations of SWNT and micromolar concentrations of BHQ-3 in phantoms were reproducibly detected, showing the potential of light absorbers, with appropriate targeting ligands, as molecular imaging agents for clinical optical breast imaging.

    View details for DOI 10.1007/s11307-010-0356-3

    View details for Web of Science ID 000288177700006

    View details for PubMedID 20532642

  • Reproducibility study of [F-18]FPP(RGD)(2) uptake in murine models of human tumor xenografts EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Chang, E., Liu, S., Gowrishankar, G., Yaghoubi, S., Wedgeworth, J. P., Chin, F., Berndorff, D., Gekeler, V., Gambhir, S. S., Cheng, Z. 2011; 38 (4): 722-730


    An (18)F-labeled PEGylated arginine-glycine-aspartic acid (RGD) dimer {[(18)F]FPP(RGD)(2)} has been used to image tumor α(v)β(3) integrin levels in preclinical and clinical studies. Serial positron emission tomography (PET) studies may be useful for monitoring antiangiogenic therapy response or for drug screening; however, the reproducibility of serial scans has not been determined for this PET probe. The purpose of this study was to determine the reproducibility of the integrin α(v)β(3)-targeted PET probe, [(18)F]FPP(RGD)(2,) using small animal PET.Human HCT116 colon cancer xenografts were implanted into nude mice (n = 12) in the breast and scapular region and grown to mean diameters of 5-15 mm for approximately 2.5 weeks. A 3-min acquisition was performed on a small animal PET scanner approximately 1 h after administration of [(18)F]FPP(RGD)(2) (1.9-3.8 MBq, 50-100 μCi) via the tail vein. A second small animal PET scan was performed approximately 6 h later after reinjection of the probe to assess for reproducibility. Images were analyzed by drawing an ellipsoidal region of interest (ROI) around the tumor xenograft activity. Percentage injected dose per gram (%ID/g) values were calculated from the mean or maximum activity in the ROIs. Coefficients of variation and differences in %ID/g values between studies from the same day were calculated to determine the reproducibility.The coefficient of variation (mean±SD) for %ID(mean)/g and %ID(max)/g values between [(18)F]FPP(RGD)(2) small animal PET scans performed 6 h apart on the same day were 11.1 ± 7.6% and 10.4 ± 9.3%, respectively. The corresponding differences in %ID(mean)/g and %ID(max)/g values between scans were -0.025 ± 0.067 and -0.039 ± 0.426. Immunofluorescence studies revealed a direct relationship between extent of α(ν)β(3) integrin expression in tumors and tumor vasculature with level of tracer uptake. Mouse body weight, injected dose, and fasting state did not contribute to the variability of the scans; however, consistent scanning parameters were necessary to ensure accurate studies, in particular, noting tumor volume, as well as making uniform: the time of imaging after injection and the ROI size. Reanalysis of ROI placement displayed variability for %ID(mean)/g of 6.6 ± 3.9% and 0.28 ± 0.12% for %ID(max)/g.[(18)F]FPP(RGD)(2) small animal PET mouse tumor xenograft studies are reproducible with relatively low variability.

    View details for DOI 10.1007/s00259-010-1672-1

    View details for Web of Science ID 000288255500015

    View details for PubMedID 21125268

  • Multiparametric MRI reveals early response patterns to antiangiogenic therapy in primary breast cancer HUGHES, N. P., Mehta, S., Adams, R. F., Gambhir, S. S., Padhani, A. R., Harris, A. L. SOC NUCLEAR MEDICINE INC. 2011: 668–69
  • Molecular imaging of the Epidermal Growth Factor Receptor in rodent colon via Affibody-functionalized surface enhanced Raman scattering (SERS) nanoparticles 241st National Meeting and Exposition of the American-Chemical-Society (ACS) Jokerst, J. V., Miao, Z., Thakor, A. S., Cheng, Z., Gambhir, S. S. AMER CHEMICAL SOC. 2011
  • MYC Phosphorylation, Activation, and Tumorigenic Potential in Hepatocellular Carcinoma Are Regulated by HMG-CoA Reductase CANCER RESEARCH Cao, Z., Fan-Minogue, H., Bellovin, D. I., Yevtodiyenko, A., Arzeno, J., Yang, Q., Gambhir, S. S., Felsher, D. W. 2011; 71 (6): 2286-2297


    MYC is a potential target for many cancers but is not amenable to existing pharmacologic approaches. Inhibition of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA reductase) by statins has shown potential efficacy against a number of cancers. Here, we show that inhibition of HMG-CoA reductase by atorvastatin (AT) blocks both MYC phosphorylation and activation, suppressing tumor initiation and growth in vivo in a transgenic model of MYC-induced hepatocellular carcinoma (HCC) as well as in human HCC-derived cell lines. To confirm specificity, we show that the antitumor effects of AT are blocked by cotreatment with the HMG-CoA reductase product mevalonate. Moreover, by using a novel molecular imaging sensor, we confirm that inhibition of HMG-CoA reductase blocks MYC phosphorylation in vivo. Importantly, the introduction of phosphorylation mutants of MYC at Ser62 or Thr58 into tumors blocks their sensitivity to inhibition of HMG-CoA reductase. Finally, we show that inhibition of HMG-CoA reductase suppresses MYC phosphorylation through Rac GTPase. Therefore, HMG-CoA reductase is a critical regulator of MYC phosphorylation, activation, and tumorigenic properties. The inhibition of HMG-CoA reductase may be a useful target for the treatment of MYC-associated HCC as well as other tumors.

    View details for DOI 10.1158/0008-5472.CAN-10-3367

    View details for Web of Science ID 000288381300028

    View details for PubMedID 21262914

  • Affibody-Functionalized Gold-Silica Nanoparticles for Raman Molecular Imaging of the Epidermal Growth Factor Receptor SMALL Jokerst, J. V., Miao, Z., Zavaleta, C., Cheng, Z., Gambhir, S. S. 2011; 7 (5): 625-633


    The affibody functionalization of fluorescent surface-enhanced Raman scattering gold-silica nanoparticles as multimodal contrast agents for molecular imaging specific to epidermal growth factor receptor (EGFR) is reported. This nanoparticle bioconjugate reports EGFR-positive A431 tumors with a signal nearly 35-fold higher than EGFR-negative MDA-435S tumors. The low-level EGFR expression in adjacent healthy tissue is 7-fold lower than in the positive tumors. Validation via competitive inhibition reduces the signal by a factor of six, and independent measurement of EGFR via flow cytometry correlates at R(2) = 0.92.

    View details for DOI 10.1002/smll.201002291

    View details for Web of Science ID 000288081900013

    View details for PubMedID 21302357

  • Affibody-based nanoprobes for HER2-expressing cell and tumor imaging BIOMATERIALS Gao, J., Chen, K., Miao, Z., Ren, G., Chen, X., Gambhir, S. S., Cheng, Z. 2011; 32 (8): 2141-2148


    This article reports the affibody-based nanoprobes specifically target and image human epidermal growth factor receptor type 2 (HER2)-expressing cells and tumors. The affibody molecules are a promising class of targeting ligands with simple, robust, and precise structure and high affinity. Using near-infrared (NIR) quantum dots (QDs) and iron oxide (IO) nanoparticles as two representative nanomaterials, we designed anti-HER2 affibody molecules with a N-terminus cysteine residue (Cysteine-Z(HER2:342)) and precisely conjugated with maleimide-functionalized nanoparticles to make nanoparticle-affibody conjugates. The in vitro and in vivo study showed the conjugates are highly specific to target and image HER2-expressing cells and tumors. This work indicated the nanoparticle-affibody conjugates may be excellent candidates as targeting probes for molecular imaging and diagnosis.

    View details for DOI 10.1016/j.biomaterials.2010.11.053

    View details for Web of Science ID 000287061400015

    View details for PubMedID 21147502

  • Use of DNA Microarray and Small Animal Positron Emission Tomography in Preclinical Drug Evaluation of RAF265, a Novel B-Raf/VEGFR-2 lInhibitor NEOPLASIA Tseng, J. R., Stuart, D., Aardalen, K., Kaplan, A., Aziz, N., Hughes, N. P., Gambhir, S. S. 2011; 13 (3): 266-U108


    Positron emission tomography (PET) imaging has become a useful tool for assessing early biologic response to cancer therapy and may be particularly useful in the development of new cancer therapeutics. RAF265, a novel B-Raf/vascular endothelial growth factor receptor-2 inhibitor, was evaluated in the preclinical setting for its ability to inhibit the uptake of PET tracers in the A375M(B-Raf(V600E)) human melanoma cell line. RAF265 inhibited 2-deoxy-2-[(18)F]fluoro-d-glucose (FDG) accumulation in cell culture at 28 hours in a dose-dependent manner. RAF265 also inhibited FDG accumulation in tumor xenografts after 1 day of drug treatment. This decrease persisted for the remaining 2 weeks of treatment. DNA microarray analysis of treated tumor xenografts revealed significantly decreased expression of genes regulating glucose and thymidine metabolism and revealed changes in apoptotic genes, suggesting that the imaging tracers FDG, 3-deoxy-3-[(18)F]fluorothymidine, and annexin V could serve as potential imaging biomarkers for RAF265 therapy monitoring. We concluded that RAF265 is highly efficacious in this xenograft model of human melanoma and decreases glucose metabolism as measured by DNA microarray analysis, cell culture assays, and small animal FDG PET scans as early as 1 day after treatment. Our results support the use of FDG PET in clinical trials with RAF265 to assess early tumor response. DNA microarray analysis and small animal PET studies may be used as complementary technologies in drug development. DNA microarray analysis allows for analysis of drug effects on multiple pathways linked to cancer and can suggest corresponding imaging tracers for further analysis as biomarkers of tumor response.

    View details for DOI 10.1593/neo.101466

    View details for Web of Science ID 000288905900008

    View details for PubMedID 21390189

    View details for PubMedCentralID PMC3050869

  • Noninvasive Monitoring of Placenta-Specific Transgene Expression by Bioluminescence Imaging PLOS ONE Fan, X., Ren, P., Dhal, S., Bejerano, G., Goodman, S. B., Druzin, M. L., Gambhir, S. S., Nayak, N. R. 2011; 6 (1)


    Placental dysfunction underlies numerous complications of pregnancy. A major obstacle to understanding the roles of potential mediators of placental pathology has been the absence of suitable methods for tissue-specific gene manipulation and sensitive assays for studying gene functions in the placentas of intact animals. We describe a sensitive and noninvasive method of repetitively tracking placenta-specific gene expression throughout pregnancy using lentivirus-mediated transduction of optical reporter genes in mouse blastocysts.Zona-free blastocysts were incubated with lentivirus expressing firefly luciferase (Fluc) and Tomato fluorescent fusion protein for trophectoderm-specific infection and transplanted into day 3 pseudopregnant recipients (GD3). Animals were examined for Fluc expression by live bioluminescence imaging (BLI) at different points during pregnancy, and the placentas were examined for tomato expression in different cell types on GD18. In another set of experiments, blastocysts with maximum photon fluxes in the range of 2.0E+4 to 6.0E+4 p/s/cm(2)/sr were transferred. Fluc expression was detectable in all surrogate dams by day 5 of pregnancy by live imaging, and the signal increased dramatically thereafter each day until GD12, reaching a peak at GD16 and maintaining that level through GD18. All of the placentas, but none of the fetuses, analyzed on GD18 by BLI showed different degrees of Fluc expression. However, only placentas of dams transferred with selected blastocysts showed uniform photon distribution with no significant variability of photon intensity among placentas of the same litter. Tomato expression in the placentas was limited to only trophoblast cell lineages.These results, for the first time, demonstrate the feasibility of selecting lentivirally-transduced blastocysts for uniform gene expression in all placentas of the same litter and early detection and quantitative analysis of gene expression throughout pregnancy by live BLI. This method may be useful for a wide range of applications involving trophoblast-specific gene manipulations in utero.

    View details for DOI 10.1371/journal.pone.0016348

    View details for Web of Science ID 000286522300037

    View details for PubMedID 21283713

  • Oxidative Stress Mediates the Effects of Raman-Active Gold Nanoparticles in Human Cells SMALL Thakor, A. S., Paulmurugan, R., Kempen, P., Zavaleta, C., Sinclair, R., Massoud, T. F., Gambhir, S. S. 2011; 7 (1): 126-136


    Polyethylene glycol (PEG)ylated Raman-active gold nanoparticles (PEG-R-AuNPs) consist of an interchangeable Raman organic molecule layer held onto a gold nanocore by a silica shell. PEG-R-AuNPs have been shown preclinically to increase the sensitivity and specificity of Raman spectroscopy, with picomolar sensitivity and multiplexing capabilities. Although clinical trials are being designed to use functionalized PEG-R-AuNPs in various applications (e.g., to target dysplastic bowel lesions during colonoscopy), the effects of these nanoparticles on human cells remain unknown. The occurrence and mechanisms underlying any potential cytotoxicity induced by these nanoparticles (0-1000 PEG-R-AuNPs/cell) are investigated in immortalized human HeLa and HepG2 cell lines at several time points (0-48 h) after exposure. Using fluorometric assays, cell viability (MTT), reactive oxygen species (ROS) generation (dichlorofluorescein diacetate), protein oxidation (protein carbonyl content), and total cellular antioxidant concentrations the concentrations (metmyoblobin-induced oxidation of ABTS) are assessed. Analysis of lipid oxidation using an enzyme immunoassay (8-isoprostane concentrations), gene expression of antioxidant enzymes using quantitative reverse transcription polymerase chain reactions, and the intracellular location of PEG-R-AuNPs using transmission electron microscopy is also undertaken. PEG-R-AuNPs cause no cytotoxicity in either HeLa or HepG2 cells in the acute setting as ROS generation is balanced by antioxidant enzyme upregulation. Following prolonged exposures (48 h) at relatively high concentrations (1000 PEG-R-AuNPs/cell), nanoparticles are found within vesicles inside cells. Under these conditions, a minimal amount of cytotoxicity is seen in both cell lines owing to increases in cellular oxidative stress, most likely due to ROS overwhelming the antioxidant defenses. Evidence of oxidative stress-induced damage includes increased lipid and protein oxidation. Although further in vivo toxicity studies are necessary, these initial encouraging results show that PEG-R-AuNPs cause minimal toxicity in human cells in the acute setting, which bodes well for potential future applications of these nanoparticles in living subjects.

    View details for DOI 10.1002/smll.201001466

    View details for Web of Science ID 000285794100015

    View details for PubMedID 21104804

  • Radiolabeling of a Saxitoxin derivative for PET-MRI imaging of pain Hoehne, A., Parsons, W. H., Behera, D., Shen, B., Gambhir, S. S., Du Bois, J., Biswal, S., Chin, F. T. WILEY-BLACKWELL. 2011: S2–S2
  • A Hybrid Least Squares and Principal Component Analysis Algorithm for Raman Spectroscopy 33rd Annual International Conference of the IEEE Engineering-in-Medicine-and-Biology-Society (EMBS) Van de Sompel, D., Garai, E., Zavaleta, C., Gambhir, S. S. IEEE. 2011: 6971–6974


    The least squares fitting algorithm is the most commonly used algorithm in Raman spectroscopy. In this paper, however, we show that it is sensitive to variations in the background signal when the signal of interest is weak. To address this problem, we propose a novel algorithm to analyze measured spectra in Raman spectroscopy. The method is a hybrid least squares and principal component analysis algorithm. It explicitly accounts for any variations expected in the reference spectra used in the signal decomposition. We compare the novel algorithm to the least squares method with a low-order polynomial residual model, and demonstrate the novel algorithm's superior performance by comparing quantitative error metrics. Our experiments use both simulated data and data acquired from an in vitro solution of Raman-enhanced gold nanoparticles.

    View details for Web of Science ID 000298810005123

    View details for PubMedID 22255942

  • [F-18]YF3 nanoprobes: a novel synthetic strategy for F-18-labeled imaging agents Xiong Liqin, L. Q., Shen Bin, B., Gambhir, S. S., Chin, F. T., Rao Jianghong, J. H. WILEY-BLACKWELL. 2011: S77–S77
  • [F-18]FTC-146 for imaging sigma-1 receptors in squirrel monkey brain using PET/MRI James, M. L., Shen, B., Nielsen, C. H., Buckmaster, C. L., Berganos, R. A., Zavaleta, C., Lyons, D., McCurdy, C. R., Gambhir, S. S., Chin, F. T. WILEY-BLACKWELL. 2011: S317–S317
  • F-18-Cyanobenzolthiol ([F-18]CBT): A novel F-18-prosthetic group for labeling peptide or protein Shen Bin, B., Jeon, J., Gambhir, S. S., Rao, J., Chin, F. T. WILEY-BLACKWELL. 2011: S503–S503
  • Longitudinal, Noninvasive Imaging of T-Cell Effector Function and Proliferation in Living Subjects CANCER RESEARCH Patel, M. R., Chang, Y., Chen, I. Y., Bachmann, M. H., Yan, X., Contag, C. H., Gambhir, S. S. 2010; 70 (24): 10141-10149


    Adoptive immunotherapy is evolving to assume an increasing role in treating cancer. Most imaging studies in adoptive immunotherapy to date have focused primarily on locating tumor-specific T cells rather than understanding their effector functions. In this study, we report the development of a noninvasive imaging strategy to monitor T-cell activation in living subjects by linking a reporter gene to the Granzyme B promoter (pGB), whose transcriptional activity is known to increase during T-cell activation. Because pGB is relatively weak and does not lead to sufficient reporter gene expression for noninvasive imaging, we specifically employed 2 signal amplification strategies, namely the Two Step Transcription Amplification (TSTA) strategy and the cytomegalovirus enhancer (CMVe) strategy, to maximize firefly luciferase reporter gene expression. Although both amplification strategies were capable of increasing pGB activity in activated primary murine splenocytes, only the level of bioluminescence activity achieved with the CMVe strategy was adequate for noninvasive imaging in mice. Using T cells transduced with a reporter vector containing the hybrid pGB-CMVe promoter, we were able to optically image T-cell effector function longitudinally in response to tumor antigens in living mice. This methodology has the potential to accelerate the study of adoptive immunotherapy in preclinical cancer models.

    View details for DOI 10.1158/0008-5472.CAN-10-1843

    View details for Web of Science ID 000285334200016

    View details for PubMedID 21159636

  • Near-infrared fluorescent nanoprobes for cancer molecular imaging: status and challenges TRENDS IN MOLECULAR MEDICINE He, X., Gao, J., Gambhir, S. S., Cheng, Z. 2010; 16 (12): 574-583


    Near-infrared fluorescence (NIRF) imaging promises to improve cancer imaging and management; advances in nanomaterials allow scientists to combine new nanoparticles with NIRF imaging techniques, thereby fulfilling this promise. Here, we present a synopsis of current developments in NIRF nanoprobes, their use in imaging small living subjects, their pharmacokinetics and toxicity, and finally their integration into multimodal imaging strategies. We also discuss challenges impeding the clinical translation of NIRF nanoprobes for molecular imaging of cancer. Whereas utilization of most NIRF nanoprobes remains at a proof-of-principle stage, optimizing the impact of nanomedicine in cancer patient diagnosis and management will probably be realized through persistent interdisciplinary amalgamation of diverse research fields.

    View details for DOI 10.1016/j.molmed.2010.08.006

    View details for Web of Science ID 000285727200004

    View details for PubMedID 20870460

  • PET Imaging of Tumor Neovascularization in a Transgenic Mouse Model with a Novel Cu-64-DOTA-Knottin Peptide CANCER RESEARCH Nielsen, C. H., Kimura, R. H., Withofs, N., Tran, P. T., Miao, Z., Cochran, J. R., Cheng, Z., Felsher, D., Kjaer, A., Willmann, J. K., Gambhir, S. S. 2010; 70 (22): 9022-9030


    Due to the high mortality of lung cancer, there is a critical need to develop diagnostic procedures enabling early detection of the disease while at a curable stage. Targeted molecular imaging builds on the positive attributes of positron emission tomography/computed tomography (PET/CT) to allow for a noninvasive detection and characterization of smaller lung nodules, thus increasing the chances of positive treatment outcome. In this study, we investigate the ability to characterize lung tumors that spontaneously arise in a transgenic mouse model. The tumors are first identified with small animal CT followed by characterization with the use of small animal PET with a novel 64Cu-1,4,7,10-tetra-azacylododecane-N,N',N'',N'''-tetraacetic acid (DOTA)-knottin peptide that targets integrins upregulated during angiogenesis on the tumor associated neovasculature. The imaging results obtained with the knottin peptide are compared with standard 18F-fluorodeoxyglucose (FDG) PET small animal imaging. Lung nodules as small as 3 mm in diameter were successfully identified in the transgenic mice by small animal CT, and both 64Cu-DOTA-knottin 2.5F and FDG were able to differentiate lung nodules from the surrounding tissues. Uptake and retention of the 64Cu-DOTA-knottin 2.5F tracer in the lung tumors combined with a low background in the thorax resulted in a statistically higher tumor to background (normal lung) ratio compared with FDG (6.01±0.61 versus 4.36±0.68; P<0.05). Ex vivo biodistribution showed 64Cu-DOTA-knottin 2.5F to have a fast renal clearance combined with low nonspecific accumulation in the thorax. Collectively, these results show 64Cu-DOTA-knottin 2.5F to be a promising candidate for clinical translation for earlier detection and improved characterization of lung cancer.

    View details for DOI 10.1158/0008-5472.CAN-10-1338

    View details for Web of Science ID 000284213300008

    View details for PubMedID 21062977

  • Cancer stem cells from human breast tumors are involved in spontaneous metastases in orthotopic mouse models PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Liu, H., Patel, M. R., Prescher, J. A., Patsialou, A., Qian, D., Lin, J., Wen, S., Chang, Y., Bachmann, M. H., Shimono, Y., Dalerba, P., Adorno, M., Lobo, N., Bueno, J., Dirbas, F. M., Goswami, S., Somlo, G., Condeelis, J., Contag, C. H., Gambhir, S. S., Clarke, M. F. 2010; 107 (42): 18115-18120


    To examine the role of breast cancer stem cells (BCSCs) in metastasis, we generated human-in-mouse breast cancer orthotopic models using patient tumor specimens, labeled with optical reporter fusion genes. These models recapitulate human cancer features not captured with previous models, including spontaneous metastasis in particular, and provide a useful platform for studies of breast tumor initiation and progression. With noninvasive imaging approaches, as few as 10 cells of stably labeled BCSCs could be tracked in vivo, enabling studies of early tumor growth and spontaneous metastasis. These advances in BCSC imaging revealed that CD44(+) cells from both primary tumors and lung metastases are highly enriched for tumor-initiating cells. Our metastatic cancer models, combined with noninvasive imaging techniques, constitute an integrated approach that could be applied to dissect the molecular mechanisms underlying the dissemination of metastatic CSCs (MCSCs) and to explore therapeutic strategies targeting MCSCs in general or to evaluate individual patient tumor cells and predict response to therapy.

    View details for DOI 10.1073/pnas.1006732107

    View details for Web of Science ID 000283184800050

    View details for PubMedID 20921380

    View details for PubMedCentralID PMC2964232

  • Dynamic Visualization of RGD-Quantum Dot Binding to Tumor Neovasculature and Extravasation in Multiple Living Mouse Models Using Intravital Microscopy SMALL Smith, B. R., Cheng, Z., De, A., Rosenberg, J., Gambhir, S. S. 2010; 6 (20): 2222-2229

    View details for DOI 10.1002/smll.201001022

    View details for Web of Science ID 000283890500003

    View details for PubMedID 20862677

  • 3-D Deep Penetration Photoacoustic Imaging with a 2-D CMUT Array. Proceedings. IEEE Ultrasonics Symposium Ma, T., Kothapalli, S. R., Vaithilingam, S., Oralkan, O., Kamaya, A., Wygant, I. O., Zhuang, X., Gambhir, S. S., Jeffrey, R. B., Khuri-Yakub, B. T. 2010; 2010: 375-377


    In this work, we demonstrate 3-D photoacoustic imaging of optically absorbing targets embedded as deep as 5 cm inside a highly scattering background medium using a 2-D capacitive micromachined ultrasonic transducer (CMUT) array with a center frequency of 5.5 MHz. 3-D volumetric images and 2-D maximum intensity projection images are presented to show the objects imaged at different depths. Due to the close proximity of the CMUT to the integrated frontend circuits, the CMUT array imaging system has a low noise floor. This makes the CMUT a promising technology for deep tissue photoacoustic imaging.

    View details for PubMedID 22977296

    View details for PubMedCentralID PMC3438520

  • [F-18]FPPRGD2 PET/CT Imaging of Integrin Expression in Healthy Volunteers 23rd Annual Congress of the European-Association-of-Nuclear-Medicine (EANM) Mittra, E., Iagaru, A., Goris, M. L., Chin, F., Chen, X., Gambhir, S. S. SPRINGER. 2010: S287–S287
  • Combined F-18 Fluoride and F-18 FDG PET/CT Scan for Evaluation of Malignancy: Beyond the Pilot Phase Study 23rd Annual Congress of the European-Association-of-Nuclear-Medicine (EANM) Iagaru, A., Mittra, E., Dick, D. W., Gambhir, S. S. SPRINGER. 2010: S200–S200
  • A Comparison Between Time Domain and Spectral Imaging Systems for Imaging Quantum Dots in Small Living Animals MOLECULAR IMAGING AND BIOLOGY de la Zerda, A., Bodapati, S., Teed, R., Schipper, M. L., Keren, S., Smith, B. R., Ng, J. S., Gambhir, S. S. 2010; 12 (5): 500-508


    We quantified the performance of time-domain imaging (TDI) and spectral imaging (SI) for fluorescence imaging of quantum dots (QDs) in three distinct imaging instruments: eXplore Optix (TDI, Advanced Research Technologies Inc.), Maestro (SI, CRi Inc.), and IVIS-Spectrum (SI, Caliper Life Sciences Inc.).The instruments were compared for their sensitivity in phantoms and living mice, multiplexing capabilities (ability to resolve the signal of one QD type in the presence of another), and the dependence of contrast and spatial resolution as a function of depth.In phantoms, eXplore Optix had an order of magnitude better sensitivity compared to the SI systems, detecting QD concentrations of ~40 pM in vitro. Maestro was the best instrument for multiplexing QDs. Reduction of contrast and resolution as a function of depth was smallest with eXplore Optix for depth of 2-6 mm, while other depths gave comparable results in all systems. Sensitivity experiments in living mice showed that the eXplore Optix and Maestro systems outperformed the IVIS-Spectrum.TDI was found to be an order of magnitude more sensitive than SI at the expense of speed and very limited multiplexing capabilities. For deep tissue QD imaging, TDI is most applicable for depths between 2 and 6 mm, as its contrast and resolution degrade the least at these depths.

    View details for DOI 10.1007/s11307-009-0290-4

    View details for Web of Science ID 000282273200006

    View details for PubMedID 20012220

  • Classical Hodgkin Lymphoma in First Complete Remission: Is There a Role for F-18 FDG PET/CT Surveillance? 23rd Annual Congress of the European-Association-of-Nuclear-Medicine (EANM) Lagaru, A., Maeda, L. S., Lin, F. I., Hoppe, R. T., Rosenberg, S. A., Gambhir, S. S., Advani, R. H. SPRINGER. 2010: S212–S213
  • Tumor Measurements by F-18-FDG PET: How Accurate are they? 23rd Annual Congress of the European-Association-of-Nuclear-Medicine (EANM) Mittra, E., Iagaru, A., Gambhir, S. S. SPRINGER. 2010: S330–S331
  • Noninvasive molecular imaging of c-Myc activation in living mice PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Fan-Minogue, H., Cao, Z., Paulmurugan, R., Chan, C. T., Massoud, T. F., Felsher, D. W., Gambhir, S. S. 2010; 107 (36): 15892-15897


    The cytoplasmic Myc protein (c-Myc) regulates various human genes and is dysregulated in many human cancers. Phosphorylation mediates the protein activation of c-Myc and is essential for the function of this transcription factor in normal cell behavior and tumor growth. To date, however, the targeting of Myc as a therapeutic approach for cancer treatment has been achieved primarily at the nonprotein level. We have developed a molecular imaging sensor for noninvasive imaging of c-Myc activity in living subjects using a split Firefly luciferase (FL) complementation strategy to detect and quantify the phosphorylation-mediated interaction between glycogen synthase kinase 3beta (GSK3beta) and c-Myc. This sensor system consists of two fusion proteins, GSK 35-433-CFL and NFL-c-Myc, in which specific fragments of GSK3beta and c-Myc are fused with C-terminal and N-terminal fragments of the split FL, respectively. The sensor detects phosphorylation-specific GSK3beta-c-Myc interaction, the imaging signal of which correlates with the steady-state and temporal regulation of c-Myc phosphorylation in cell culture. The sensor also detects inhibition of c-Myc activity via differential pathways, allowing noninvasive monitoring of c-Myc-targeted drug efficacy in intact cells and living mice. Notably, this drug inhibition is detected before changes in tumor size are apparent in mouse xenograft and liver tumor models. This reporter system not only provides an innovative way to investigate the role of functional c-Myc in normal and cancer-related biological processes, but also facilitates c-Myc-targeted drug development by providing a rapid quantitative approach to assessing cancer response to therapy in living subjects.

    View details for DOI 10.1073/pnas.1007443107

    View details for Web of Science ID 000281637800049

    View details for PubMedID 20713710

    View details for PubMedCentralID PMC2936612

  • Biodistribution of Neural Stem Cells After Intravascular Therapy for Hypoxic-Ischemia STROKE Pendharkar, A. V., Chua, J. Y., Andres, R. H., Wang, N., Gaeta, X., Wang, H., De, A., Choi, R., Chen, S., Rutt, B. K., Gambhir, S. S., Guzman, R. 2010; 41 (9): 2064-2070


    Intravascular transplantation of neural stem cells represents a minimally invasive therapeutic approach for the treatment of central nervous system diseases. The cellular biodistribution after intravascular injection needs to be analyzed to determine the ideal delivery modality. We studied the biodistribution and efficiency of targeted central nervous system delivery comparing intravenous and intra-arterial (IA) administration of neural stem cells after brain ischemia.Mouse neural stem cells were transduced with a firefly luciferase reporter gene for bioluminescence imaging (BLI). Hypoxic-ischemia was induced in adult mice and reporter neural stem cells were transplanted IA or intravenous at 24 hours after brain ischemia. In vivo BLI was used to track transplanted cells up to 2 weeks after transplantation and ex vivo BLI was used to determine single organ biodistribution.Immediately after transplantation, BLI signal from the brain was 12 times higher in IA versus intravenous injected animals (P<0.0001). After IA injection, 69% of the total luciferase activity arose from the brain early after transplantation and 93% at 1 week. After intravenous injection, 94% of the BLI signal was detected in the lungs (P=0.004) followed by an overall 94% signal loss at 1 week, indicating lack of cell survival outside the brain. Ex vivo single organ analysis showed a significantly higher BLI signal in the brain than in the lungs, liver, and kidneys at 1 week (P<0.0001) and 2 weeks in IA (P=0.007).IA transplantation results in superior delivery and sustained presence of neural stem cells in the ischemic brain in comparison to intravenous infusion.

    View details for DOI 10.1161/STROKEAHA.109.575993

    View details for Web of Science ID 000281503000037

    View details for PubMedID 20616329

  • DYNAMIC CONTRAST-ENHANCED MRI REVEALS CORE SIGNALLING PATHWAYS IN BREAST CANCER 1st British Breast Cancer Research Conference Mehta, S., HUGHES, N. P., Buffa, F. M., Adams, R. F., Gambhir, S. S., Harris, A. L. PERGAMON-ELSEVIER SCIENCE LTD. 2010: 13–13
  • Facile synthesis, silanization and biodistribution of biocompatible quantum dots Ma, N., Marshall, A. F., Gambhir, S., Rao, J. AMER CHEMICAL SOC. 2010
  • Design, Synthesis, and Imaging of an Activatable Photoacoustic Probe JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Levi, J., Kothapalli, S. R., Ma, T., Hartman, K., Khuri-Yakub, B. T., Gambhir, S. S. 2010; 132 (32): 11264-11269


    Photoacoustic tomography is a rapidly growing imaging modality that can provide images of high spatial resolution and high contrast at depths up to 5 cm. We report here the design, synthesis, and evaluation of an activatable probe that shows great promise for enabling detection of the cleaved probe in the presence of high levels of nonactivated, uncleaved probe, a difficult task to attain in absorbance-based modality. Before the cleavage by its target, proteolytic enzyme MMP-2, the probe, an activatable cell-penetrating peptide, Ceeee[Ahx]PLGLAGrrrrrK, labeled with two chromophores, BHQ3 and Alexa750, shows photoacoustic signals of similar intensity at the two wavelengths corresponding to the absorption maxima of the chromophores, 675 and 750 nm. Subtraction of the images taken at these two wavelengths makes the probe effectively photoacoustically silent, as the signals at these two wavelengths essentially cancel out. After the cleavage, the dye associated with the cell-penetrating part of the probe, BHQ3, accumulates in the cells, while the other dye diffuses away, resulting in photoacoustic signal seen at only one of the wavelengths, 675 nm. Subtraction of the photoacoustic images at two wavelengths reveals the location of the cleaved (activated) probe. In the search for the chromophores that are best suited for photoacoustic imaging, we have investigated the photoacoustic signals of five chromophores absorbing in the near-infrared region. We have found that the photoacoustic signal did not correlate with the absorbance and fluorescence of the molecules, as the highest photoacoustic signal arose from the least absorbing quenchers, BHQ3 and QXL 680.

    View details for DOI 10.1021/0104000a

    View details for Web of Science ID 000280861300058

    View details for PubMedID 20698693

  • [F-18]FTC-146: A novel and highly selective PET ligand for visualizing sigma-1 receptors in living subjects 8th International Symposium on Functional Neuroreceptor Mapping of the Living Brain James, M. L., Shen, B., Zavaleta, C., Berganos, R. A., Mesangeau, C., Shaikh, J., Gambhir, S. S., Matsumoto, R. R., McCurdy, C. R., Chin, F. T. ACADEMIC PRESS INC ELSEVIER SCIENCE. 2010: S123–S124
  • A molecularly engineered split reporter for imaging protein-protein interactions with positron emission tomography NATURE MEDICINE Massoud, T. F., Paulmurugan, R., Gambhir, S. S. 2010; 16 (8): 921-U123


    Improved techniques to noninvasively image protein-protein interactions (PPIs) are essential. We molecularly engineered a positron emission tomography (PET)-based split reporter (herpes simplex virus type 1 thymidine kinase), cleaved between Thr265 and Ala266, and used this in a protein-fragment complementation assay (PCA) to quantify PPIs in mammalian cells and to microPET image them in living mice. An introduced point mutation (V119C) markedly enhanced thymidine kinase complementation in PCAs, on the basis of rapamycin modulation of FKBP12-rapamycin-binding domain (FRB) and FKBP12 (FK506 binding protein), the interaction of hypoxia-inducible factor-1alpha with the von Hippel-Lindau tumor suppressor, and in an estrogen receptor intramolecular protein folding assay. Applications of this unique split thymidine kinase are potentially far reaching, including, for example, considerably more accurate monitoring of immune and stem cell therapies, allowing for fully quantitative and tomographic PET localization of PPIs in preclinical small- and large-animal models of disease.

    View details for DOI 10.1038/nm.2185

    View details for Web of Science ID 000280649200033

    View details for PubMedID 20639890

  • Antiangiogenic Cancer Therapy: Monitoring with Molecular US and a Clinically Translatable Contrast Agent (BR55) RADIOLOGY Pysz, M. A., Foygel, K., Rosenberg, J., Gambhir, S. S., Schneider, M., Willmann, J. K. 2010; 256 (2): 519-527


    To develop and test human kinase insert domain receptor (KDR)-targeted microbubbles (MBs) (MB(KDR)) for imaging KDR at the molecular level and for monitoring antiangiogenic therapy in a human colon cancer xenograft tumor model in mice.Animal studies were approved by the Institutional Administrative Panel on Laboratory Animal Care. A heterodimeric peptide that binds to human KDR with low nanomolar affinity (K(D) = 0.5 nmol/L) was coupled onto the surface of perfluorobutane-containing lipid-shelled MBs (MB(KDR)). Binding specificity of MB(KDR) to human KDR and cross-reactivity with murine vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2) were tested in cell culture under flow shear stress conditions (at 100 sec(-1)). In vivo binding specificity of MB(KDR) to VEGFR2 was tested in human LS174T colon cancer xenografts in mice with a 40-MHz ultrasonographic (US) transducer. Targeted contrast material-enhanced US imaging signal by using MB(KDR) was longitudinally measured during 6 days in tumors with (n = 6) and without (n = 6) antiangiogenic treatment (anti-VEGF antibody). Ex vivo VEGFR2 staining and microvessel density analysis were performed. Significant differences were evaluated (t, Mann-Whitney, or Wilcoxon test).Cell culture experiments showed four times greater binding specificity of MB(KDR) to human KDR and cross-reactivity to murine VEGFR2 (P < or = .01). In vivo imaging signal was more than three times higher (P = .01) with MB(KDR) compared with control MBs and decreased significantly (approximately fourfold lower, P = .03) following in vivo receptor blocking with anti-VEGFR2 antibody. One day after initiation of antiangiogenic therapy, imaging signal was significantly decreased (approximately 46% lower, P = .02) in treated versus untreated tumors; it remained significantly lower (range, 46%-84% decreased; P = .038) during the following 5 days. Microvessel density was significantly reduced (P = .04) in treated (mean, 7.3 microvessels per square millimeter +/- 4.7 [standard deviation]) versus untreated tumors (mean, 22.0 microvessels per square millimeter +/- 9.4); VEGFR2 expression was significantly decreased (>50% lower, P = .03) in treated tumors.Human MB(KDR) allow in vivo imaging and longitudinal monitoring of VEGFR2 expression in human colon cancer xenografts.

    View details for DOI 10.1148/radiol.10091858

    View details for Web of Science ID 000280272100023

    View details for PubMedID 20515975

  • Facile Synthesis, Silanization, and Biodistribution of Biocompatible Quantum Dots SMALL Ma, N., Marshall, A. F., Gambhir, S. S., Rao, J. 2010; 6 (14): 1520-1528


    A facile strategy for the synthesis of silica-coated quantum dots (QDs) for in vivo imaging is reported. All the QD synthesis and silanization steps are conducted in water and methanol under mild conditions without involving any organometallic precursors or high-temperature, oxygen-free environments. The as-prepared silica-coated QDs possess high quantum yields and are extremely stable in mouse serum. In addition, the silanization method developed here produces nanoparticles with small sizes that are difficult to achieve via conventional silanization methods. The silica coating helps to prevent the exposure of the QD surface to the biological milieu and therefore increases the biocompatibility of QDs for in vivo applications. Interestingly, the silica-coated QDs exhibit a different biodistribution pattern from that of commercially available Invitrogen QD605 (carboxylate) with a similar size and emission wavelength. The Invitrogen QD605 exhibits predominant liver (57.2% injected dose (ID) g(-1)) and spleen (46.1% ID g(-1)) uptakes 30 min after intravenous injection, whereas the silica-coated QDs exhibit much lower liver (16.2% ID g(-1)) and spleen (3.67% ID g(-1)) uptakes but higher kidney uptake (8.82% ID g(-1)), blood retention (15.0% ID g(-1)), and partial renal clearance. Overall, this straightforward synthetic strategy paves the way for routine and customized synthesis of silica-coated QDs for biological use.

    View details for DOI 10.1002/smll.200902409

    View details for Web of Science ID 000280633900011

    View details for PubMedID 20564726

  • Indirect imaging of cardiac-specific transgene expression using a bidirectional two-step transcriptional amplification strategy GENE THERAPY Chen, I. Y., Gheysens, O., Ray, S., Wang, Q., Padmanabhan, P., Paulmurugan, R., Loening, A. M., Rodriguez-Porcel, M., Willmann, J. K., Sheikh, A. Y., Nielsen, C. H., Hoyt, G., Contag, C. H., Robbins, R. C., Biswal, S., Wu, J. C., Gambhir, S. S. 2010; 17 (7): 827-838


    Transcriptional targeting for cardiac gene therapy is limited by the relatively weak activity of most cardiac-specific promoters. We have developed a bidirectional plasmid vector, which uses a two-step transcriptional amplification (TSTA) strategy to enhance the expression of two optical reporter genes, firefly luciferase (fluc) and Renilla luciferase (hrluc), driven by the cardiac troponin T (cTnT) promoter. The vector was characterized in vitro and in living mice using luminometry and bioluminescence imaging to assess its ability to mediate strong, correlated reporter gene expression in a cardiac cell line and the myocardium, while minimizing expression in non-cardiac cell lines and the liver. In vitro, the TSTA system significantly enhanced cTnT-mediated reporter gene expression with moderate preservation of cardiac specificity. After intramyocardial and hydrodynamic tail vein delivery of an hrluc-enhanced variant of the vector, long-term fluc expression was observed in the heart, but not in the liver. In both the cardiac cell line and the myocardium, fluc expression correlated well with hrluc expression. These results show the vector's ability to effectively amplify and couple transgene expression in a cardiac-specific manner. Further replacement of either reporter gene with a therapeutic gene should allow non-invasive imaging of targeted gene therapy in living subjects.

    View details for DOI 10.1038/gt.2010.30

    View details for Web of Science ID 000279614600002

    View details for PubMedID 20237511

    View details for PubMedCentralID PMC2900530

  • Molecular imaging: current status and emerging strategies CLINICAL RADIOLOGY Pysz, M. A., Gambhir, S. S., Willmann, J. K. 2010; 65 (7): 500-516


    In vivo molecular imaging has a great potential to impact medicine by detecting diseases in early stages (screening), identifying extent of disease, selecting disease- and patient-specific treatment (personalized medicine), applying a directed or targeted therapy, and measuring molecular-specific effects of treatment. Current clinical molecular imaging approaches primarily use positron-emission tomography (PET) or single photon-emission computed tomography (SPECT)-based techniques. In ongoing preclinical research, novel molecular targets of different diseases are identified and, sophisticated and multifunctional contrast agents for imaging these molecular targets are developed along with new technologies and instrumentation for multi-modality molecular imaging. Contrast-enhanced molecular ultrasound (US) with molecularly-targeted contrast microbubbles is explored as a clinically translatable molecular imaging strategy for screening, diagnosing, and monitoring diseases at the molecular level. Optical imaging with fluorescent molecular probes and US imaging with molecularly-targeted microbubbles are attractive strategies as they provide real-time imaging, are relatively inexpensive, produce images with high spatial resolution, and do not involve exposure to ionizing irradiation. Raman spectroscopy/microscopy has emerged as a molecular optical imaging strategy for ultrasensitive detection of multiple biomolecules/biochemicals with both in vivo and ex vivo versatility. Photoacoustic imaging is a hybrid of optical and US techniques involving optically-excitable molecularly-targeted contrast agents and quantitative detection of resulting oscillatory contrast agent movement with US. Current preclinical findings and advances in instrumentation, such as endoscopes and microcatheters, suggest that these molecular imaging methods have numerous potential clinical applications and will be translated into clinical use in the near future.

    View details for DOI 10.1016/j.crad.2010.03.011

    View details for Web of Science ID 000280379900002

    View details for PubMedID 20541650

  • Reply to: The diagnostic accuracy of F-18-FDG PET in cutaneous malignant melanoma EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Delgado-Bolton, R. C., Jimenez-Requena, F., Fernandez-Perez, C., Gambhir, S. S., Schwimmer, J., Perez-Vazquez, J. M., Carreras-Delgado, J. L. 2010; 37 (7): 1436-1437
  • Implantable semiconductor biosensor for continuous in vivo sensing of far-red fluorescent molecules OPTICS EXPRESS O'Sullivan, T., Munro, E. A., Parashurama, N., Conca, C., Gambhir, S. S., Harris, J. S., Levi, O. 2010; 18 (12): 12513-12525


    We have fabricated miniature implantable fluorescence sensors for continuous fluorescence sensing applications in living subjects. These monolithically integrated GaAs-based sensors incorporate a 675 nm vertical-cavity surface-emitting laser (VCSEL), a GaAs PIN photodiode, and a fluorescence emission filter. We demonstrate high detection sensitivity for Cy5.5 far-red dye (50 nanoMolar) in living tissue, limited by the intrinsic background autofluorescence. These low cost, sensitive and scalable sensors are promising for long-term continuous monitoring of molecular dynamics for biomedical studies in freely moving animals.

    View details for Web of Science ID 000278527700052

    View details for PubMedID 20588377

  • Cu-64-Labeled Affibody Molecules for Imaging of HER2 Expressing Tumors MOLECULAR IMAGING AND BIOLOGY Cheng, Z., De Jesus, O. P., Kramer, D. J., De, A., Webster, J. M., Gheysens, O., Levi, J., Namavari, M., Wang, S., Park, J. M., Zhang, R., Liu, H., Lee, B., Syud, F. A., Gambhir, S. S. 2010; 12 (3): 316-324


    The development of molecular probes based on novel engineered protein constructs is under active investigation due to the great potential of this generalizable strategy for imaging a variety of tumor targets.In this report, human epidermal growth factor receptor type 2 (HER2)-binding Affibody molecules were radiolabeled with (64)Cu and their imaging ability was further evaluated in tumor mice models to understand the promise and limitations of such probes. The anti-HER2 Affibody molecules in monomeric (Z(HER2:477)) and dimeric [(Z(HER2:477))(2)] forms were site specifically modified with the maleimide-functionalized chelator, 1,4,7,10-tetraazacyclododecane-1,4,7-tris(acetic acid)-10-acetate mono (N-ethylmaleimide amide) (Mal-DOTA). The resulting DOTA-Affibody conjugates were radiolabeled with (64)Cu and evaluated in nude mice bearing subcutaneous SKOV3 tumors. Biodistribution experiments showed that tumor uptake values of (64)Cu-DOTA-Z(HER2:477) and (64)Cu-DOTA-(Z(HER2:477))(2) were 6.12 +/- 1.44% and 1.46 +/- 0.50% ID/g, respectively, in nude mice (n = 3 each) at 4 h postinjection. Moreover, (64)Cu-labeled monomer exhibited significantly higher tumor/blood ratio than that of radiolabeled dimeric counterpart at all time points examined in this study. MicroPET imaging of (64)Cu-DOTA-Z(HER2:477) in SKOV3 tumor mice clearly showed good and specific tumor localization. This study demonstrates that (64)Cu-labeled Z(HER2:477) is a promising targeted molecular probe for imaging HER2 receptor expression in living mice. Further work is needed to improve the excretion properties, hence dosimetry and imaging efficacy, of the radiometal-based probe.

    View details for DOI 10.1007/s11307-009-0256-6

    View details for Web of Science ID 000277375300010

    View details for PubMedID 19779897

  • Antioxidants Improve Early Survival of Cardiomyoblasts After Transplantation to the Myocardium MOLECULAR IMAGING AND BIOLOGY Rodriguez-Porcel, M., Gheysens, O., Paulmurugan, R., Chen, I. Y., Peterson, K. M., Willmann, J. K., Wu, J. C., Zhu, X., Lerman, L. O., Gambhir, S. S. 2010; 12 (3): 325-334


    We tested the hypothesis that modulation of the microenvironment (using antioxidants) will increase stem cell survival in hypoxia and after transplantation to the myocardium.Rat cardiomyoblasts were stably transfected with a reporter gene (firefly luciferase) for bioluminescence imaging (BLI). First, we examined the role of oxidative stress in cells under hypoxic conditions. Subsequently, stem cells were transplanted to the myocardium of rats using high-resolution ultrasound, and their survival was monitored daily using BLI.Under hypoxia, oxidative stress was increased together with decreased cell survival compared to control cells, both of which were preserved by antioxidants. In living subjects, oxidative stress blockade increased early cell survival after transplantation to the myocardium, compared to untreated cells/animals.Modulation of the local microenvironment (with antioxidants) improves stem cell survival. Increased understanding of the interaction between stem cells and their microenvironment will be critical to advance the field of regenerative medicine.

    View details for DOI 10.1007/s11307-009-0274-4

    View details for Web of Science ID 000277375300011

    View details for PubMedID 20013064

  • Ultrahigh Sensitivity Carbon Nanotube Agents for Photoacoustic Molecular Imaging in Living Mice NANO LETTERS de la Zerda, A., Liu, Z., Bodapati, S., Teed, R., Vaithilingam, S., Khuri-Yakub, B. T., Chen, X., Dai, H., Gambhir, S. S. 2010; 10 (6): 2168-2172


    Photoacoustic imaging is an emerging modality that overcomes to a great extent the resolution and depth limitations of optical imaging while maintaining relatively high-contrast. However, since many diseases will not manifest an endogenous photoacoustic contrast, it is essential to develop exogenous photoacoustic contrast agents that can target diseased tissue(s). Here we present a novel photoacoustic contrast agent, Indocyanine Green dye-enhanced single walled carbon nanotube (SWNT-ICG). We conjugated this contrast agent with cyclic Arg-Gly-Asp (RGD) peptides to molecularly target the alpha(v)beta(3) integrins, which are associated with tumor angiogenesis. Intravenous administration of this tumor-targeted contrast agent to tumor-bearing mice showed significantly higher photoacoustic signal in the tumor than in mice injected with the untargeted contrast agent. The new contrast agent gave a markedly 300 times higher photoacoustic contrast in living tissues than previously reported SWNTs, leading to subnanomolar sensitivities. Finally, we show that the new contrast agent can detect approximately 20 times fewer cancer cells than previously reported SWNTs.

    View details for DOI 10.1021/nl100890d

    View details for Web of Science ID 000278449200033

    View details for PubMedID 20499887

  • Radiation-Luminescence-Excited Quantum Dots for in vivo Multiplexed Optical Imaging SMALL Liu, H., Zhang, X., Xing, B., Han, P., Gambhir, S. S., Cheng, Z. 2010; 6 (10): 1087-1091

    View details for DOI 10.1002/smll.200902408

    View details for Web of Science ID 000278629300004

    View details for PubMedID 20473988

  • Assessing delivery and quantifying efficacy of small interfering ribonucleic acid therapeutics in the skin using a dual-axis confocal microscope JOURNAL OF BIOMEDICAL OPTICS Ra, H., Gonzalez-Gonzalez, E., Smith, B. R., Gambhir, S. S., Kino, G. S., Solgaard, O., Kaspar, R. L., Contag, C. H. 2010; 15 (3)


    Transgenic reporter mice and advances in imaging instrumentation are enabling real-time visualization of cellular mechanisms in living subjects and accelerating the development of novel therapies. Innovative confocal microscope designs are improving their utility for microscopic imaging of fluorescent reporters in living animals. We develop dual-axis confocal (DAC) microscopes for such in vivo studies and create mouse models where fluorescent proteins are expressed in the skin for the purpose of advancing skin therapeutics and transdermal delivery tools. Three-dimensional image volumes, through the different skin compartments of the epidermis and dermis, can be acquired in several seconds with the DAC microscope in living mice, and are comparable to histologic analyses of reporter protein expression patterns in skin sections. Intravital imaging with the DAC microscope further enables visualization of green fluorescent protein (GFP) reporter gene expression in the skin over time, and quantification of transdermal delivery of small interfering RNA (siRNA) and therapeutic efficacy. Visualization of transdermal delivery of nucleic acids will play an important role in the development of innovative strategies for treating skin pathologies.

    View details for DOI 10.1117/1.3432627

    View details for Web of Science ID 000280642900042

    View details for PubMedID 20615029

  • Embryonic Stem Cell-Derived Endothelial Cells Engraft Into the Ischemic Hindlimb and Restore Perfusion ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY Huang, N. F., Niiyama, H., Peter, C., De, A., Natkunam, Y., Fleissner, F., Li, Z., Rollins, M. D., Wu, J. C., Gambhir, S. S., Cooke, J. P. 2010; 30 (5): 984-U224


    We examined the effect of delivery modality on the survival, localization, and functional effects of exogenously administered embryonic stem cells (ESCs) or endothelial cells derived from them (ESC-ECs) in the ischemic hindlimb.Murine ESCs or ESC-ECs were stably transduced with a construct for bioluminescence imaging (BLI) and fluorescent detection. In a syngeneic murine model of limb ischemia, ESCs or ESC-ECs were delivered by intramuscular (IM), intrafemoral artery (IA), or intrafemoral vein injections (n=5 in each group). For 2 weeks, cell survival and localization were tracked by BLI and confirmed by immunohistochemistry, and functional improvement was assessed by laser Doppler perfusion. BLI showed that ESCs localized to the ischemic limb after IM or IA, but not after intrafemoral vein administration. Regardless of the route of administration, ESCs were detected outside the hindlimb circulation in the spleen or lungs. ESCs did not improve limb perfusion and generated teratomas. In contrast, ESC-ECs delivered by all 3 modalities localized to the ischemic limb, as assessed by BLI. Most surprisingly, ESC-EC injected intrafemoral vein eventually localized to the ischemic limb after initially lodging in the pulmonary circulation. Immunohistochemical studies confirmed the engraftment of ESC-ECs into the limb vasculature after 2 weeks. Notably, ESC-ECs were not detected in the spleen or lungs after 2 weeks, regardless of route of administration. Furthermore, ESC-ECs significantly improved limb perfusion and neovascularization compared with the parental ESCs or the vehicle control group.In contrast to parental ESCs, ESC-ECs preferentially localized in the ischemic hindlimb by IA, IM, and intrafemoral vein delivery. ESC-ECs engrafted into the ischemic microvasculature, enhanced neovascularization, and improved limb perfusion.

    View details for DOI 10.1161/ATVBAHA.110.202796

    View details for Web of Science ID 000276677700015

    View details for PubMedID 20167654

    View details for PubMedCentralID PMC2874560

  • Cetuximab-Based Immunotherapy and Radioimmunotherapy of Head and Neck Squamous Cell Carcinoma CLINICAL CANCER RESEARCH Niu, G., Sun, X., Cao, Q., Courter, D., Koong, A., Le, Q., Gambhir, S. S., Chen, X. 2010; 16 (7): 2095-2105


    To show the relationship between antibody delivery and therapeutic efficacy in head and neck cancers, in this study we evaluated the pharmacokinetics and pharmacodynamics of epidermal growth factor receptor (EGFR)-targeted immunotherapy and radioimmunotherapy by quantitative positron emission tomography (PET) imaging.EGFR expression on UM-SCC-22B and SCC1 human head and neck squamous cell cancer (HNSCC) cells were determined by flow cytometry and immunostaining. Tumor delivery and distribution of cetuximab in tumor-bearing nude mice were evaluated with small animal PET using (64)Cu-DOTA-cetuximab. The in vitro toxicity of cetuximab to HNSCC cells was evaluated by MTT assay. The tumor-bearing mice were then treated with four doses of cetuximab at 10 mg/kg per dose, and tumor growth was evaluated by caliper measurement. FDG PET was done after the third dose of antibody administration to evaluate tumor response. Apoptosis and tumor cell proliferation after cetuximab treatment were analyzed by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling and Ki-67 staining. Radioimmunotherapy was done with (90)Y-DOTA-cetuximab.EGFR expression on UM-SCC-22B cells is lower than that on SCC1 cells. However, the UM-SCC-22B tumors showed much higher (64)Cu-DOTA-cetuximab accumulation than the SCC1 tumors. Cetuximab-induced apoptosis in SCC1 tumors and tumor growth was significantly inhibited, whereas an agonistic effect of cetuximab on UM-SCC-22B tumor growth was observed. After cetuximab treatment, the SCC1 tumors showed decreased FDG uptake, and the UM-SCC-22B tumors had increased FDG uptake. UM-SCC-22B tumors are more responsive to (90)Y-DOTA-cetuximab treatment than SCC1 tumors, partially due to the high tumor accumulation of the injected antibody.Cetuximab has an agonistic effect on the growth of UM-SCC-22B tumors, indicating that tumor response to cetuximab treatment is not necessarily related to EGFR expression and antibody delivery efficiency, as determined by PET imaging. Although PET imaging with antibodies as tracers has limited function in patient screening, it can provide guidance for targeted therapy using antibodies as delivery vehicles.

    View details for DOI 10.1158/1078-0432.CCR-09-2495

    View details for Web of Science ID 000278595800013

    View details for PubMedID 20215534

  • Molecular imaging of biological gene delivery vehicles for targeted cancer therapy: beyond viral vectors. Nuclear medicine and molecular imaging Min, J., Nguyen, V. H., Gambhir, S. S. 2010; 44 (1): 15-24


    Cancer persists as one of the most devastating diseases in the world. Problems including metastasis and tumor resistance to chemotherapy and radiotherapy have seriously limited the therapeutic effects of present clinical treatments. To overcome these limitations, cancer gene therapy has been developed over the last two decades for a broad spectrum of applications, from gene replacement and knockdown to vaccination, each with different requirements for gene delivery. So far, a number of genes and delivery vectors have been investigated, and significant progress has been made with several gene therapy modalities in clinical trials. Viral vectors and synthetic liposomes have emerged as the vehicles of choice for many applications. However, both have limitations and risks that restrict gene therapy applications, including the complexity of production, limited packaging capacity, and unfavorable immunological features. While continuing to improve these vectors, it is important to investigate other options, particularly nonviral biological agents such as bacteria, bacteriophages, and bacteria-like particles. Recently, many molecular imaging techniques for safe, repeated, and high-resolution in vivo imaging of gene expression have been employed to assess vector-mediated gene expression in living subjects. In this review, molecular imaging techniques for monitoring biological gene delivery vehicles are described, and the specific use of these methods at different steps is illustrated. Linking molecular imaging to gene therapy will eventually help to develop novel gene delivery vehicles for preclinical study and support the development of future human applications.

    View details for DOI 10.1007/s13139-009-0006-3

    View details for PubMedID 24899933

  • Rosiglitazone Increases Myocardial Glucose Metabolism in Insulin-Resistant Cardiomyopathy JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY Kao, D. P., Witteles, R. M., Quon, A., Wu, J. C., Gambhir, S. S., Fowler, M. B. 2010; 55 (9): 926-927

    View details for DOI 10.1016/j.jacc.2009.08.085

    View details for Web of Science ID 000274865100015

    View details for PubMedID 20185047

  • Targeted Contrast-Enhanced Ultrasound Imaging of Tumor Angiogenesis with Contrast Microbubbles Conjugated to Integrin-Binding Knottin Peptides JOURNAL OF NUCLEAR MEDICINE Willmann, J. K., Kimura, R. H., Deshpande, N., Lutz, A. M., Cochran, J. R., Gambhir, S. S. 2010; 51 (3): 433-440


    Targeted contrast-enhanced ultrasound imaging is increasingly being recognized as a powerful imaging tool for the detection and quantification of tumor angiogenesis at the molecular level. The purpose of this study was to develop and test a new class of targeting ligands for targeted contrast-enhanced ultrasound imaging of tumor angiogenesis with small, conformationally constrained peptides that can be coupled to the surface of ultrasound contrast agents.Directed evolution was used to engineer a small, disulfide-constrained cystine knot (knottin) peptide that bound to alpha(v)beta(3) integrins with a low nanomolar affinity (Knottin(Integrin)). A targeted contrast-enhanced ultrasound imaging contrast agent was created by attaching Knottin(Integrin) to the shell of perfluorocarbon-filled microbubbles (MB-Knottin(Integrin)). A knottin peptide with a scrambled sequence was used to create control microbubbles (MB-Knottin(Scrambled)). The binding of MB-Knottin(Integrin) and MB-Knottin(Scrambled) to alpha(v)beta(3) integrin-positive cells and control cells was assessed in cell culture binding experiments and compared with that of microbubbles coupled to an anti-alpha(v)beta(3) integrin monoclonal antibody (MB(alphavbeta3)) and microbubbles coupled to the peptidomimetic agent c(RGDfK) (MB(cRGD)). The in vivo imaging signals of contrast-enhanced ultrasound with the different types of microbubbles were quantified in 42 mice bearing human ovarian adenocarcinoma xenograft tumors by use of a high-resolution 40-MHz ultrasound system.MB-Knottin(Integrin) attached significantly more to alpha(v)beta(3) integrin-positive cells (1.76 +/- 0.49 [mean +/- SD] microbubbles per cell) than to control cells (0.07 +/- 0.006). Control MB-Knottin(Scrambled) adhered less to alpha(v)beta(3) integrin-positive cells (0.15 +/- 0.12) than MB-Knottin(Integrin). After blocking of integrins, the attachment of MB-Knottin(Integrin) to alpha(v)beta(3) integrin-positive cells decreased significantly. The in vivo ultrasound imaging signal was significantly higher after the administration of MB-Knottin(Integrin) than after the administration of MB(alphavbeta3) or control MB-Knottin(Scrambled). After in vivo blocking of integrin receptors, the imaging signal after the administration of MB-Knottin(Integrin) decreased significantly (by 64%). The imaging signals after the administration of MB-Knottin(Integrin) were not significantly different in the groups of tumor-bearing mice imaged with MB-Knottin(Integrin) and with MB(cRGD). Ex vivo immunofluorescence confirmed integrin expression on endothelial cells of human ovarian adenocarcinoma xenograft tumors.Integrin-binding knottin peptides can be conjugated to the surface of microbubbles and used for in vivo targeted contrast-enhanced ultrasound imaging of tumor angiogenesis. Our results demonstrate that microbubbles conjugated to small peptide-targeting ligands provide imaging signals higher than those provided by a large antibody molecule.

    View details for DOI 10.2967/jnumed.109.068007

    View details for Web of Science ID 000275133100026

    View details for PubMedID 20150258

  • Evaluation of a Cu-64-Labeled Cystine-Knot Peptide Based on Agouti-Related Protein for PET of Tumors Expressing alpha(v)beta(3) Integrin JOURNAL OF NUCLEAR MEDICINE Jiang, L., Kimura, R. H., Miao, Z., Silverman, A. P., Ren, G., Liu, H., Li, P., Gambhir, S. S., Cochran, J. R., Cheng, Z. 2010; 51 (2): 251-258


    Recently, a truncated form of the agouti-related protein (AgRP), a 4-kDa cystine-knot peptide of human origin, was used as a scaffold to engineer mutants that bound to alpha(v)beta(3) integrin with high affinity and specificity. In this study, we evaluated the potential of engineered integrin-binding AgRP peptides for use as cancer imaging agents in living subjects.Engineered AgRP peptides were prepared by solid-phase peptide synthesis and were folded in vitro and purified by reversed-phase high-performance liquid chromatography. Competition assays were used to measure the relative binding affinities of engineered AgRP peptides for integrin receptors expressed on the surface of U87MG glioblastoma cells. The highest-affinity mutant, AgRP clone 7C, was site-specifically conjugated with 1,4,7,10-tetra-azacyclododecane-N,N',N''N'''-tetraacetic acid (DOTA). The resulting bioconjugate, DOTA-AgRP-7C, was radiolabeled with (64)Cu for biodistribution analysis and small-animal PET studies in mice bearing U87MG tumor xenografts. In addition to serum stability, the in vivo metabolic stability of (64)Cu-DOTA-AgRP-7C was assessed after injection and probe recovery from mouse kidney, liver, tumor, and urine.AgRP-7C and DOTA-AgRP-7C bound with high affinity to integrin receptors expressed on U87MG cells (half maximal inhibitory concentration values, 20 +/- 4 and 14 +/- 2 nM, respectively). DOTA-AgRP-7C was labeled with (64)Cu with high radiochemical purity (>99%). In biodistribution and small-animal PET studies, (64)Cu-DOTA-AgRP-7C displayed rapid blood clearance, good tumor uptake and retention (2.70 +/- 0.93 percentage injected dose per gram [%ID/g] and 2.37 +/- 1.04 %ID/g at 2 and 24 h, respectively), and high tumor-to-background tissue ratios. The integrin-binding specificity of (64)Cu-DOTA-AgRP-7C was confirmed in vitro and in vivo by showing that a large molar excess of the unlabeled peptidomimetic c(RGDyK) could block probe binding and tumor uptake. Serum stability and in vivo metabolite assays demonstrated that engineered AgRP peptides are sufficiently stable for in vivo molecular imaging applications.A radiolabeled version of the engineered AgRP peptide 7C showed promise as a PET agent for tumors that express the alpha(v)beta(3) integrin. Collectively, these results validate AgRP-based cystine-knot peptides for use in vivo as molecular imaging agents and provide support for the general use of AgRP as a scaffold to develop targeting peptides, and hence diagnostics, against other tumor receptors.

    View details for DOI 10.2967/jnumed.109.069831

    View details for Web of Science ID 000274152800028

    View details for PubMedID 20124048

  • Photoacoustic ocular imaging OPTICS LETTERS de la Zerda, A., Paulus, Y. M., Teed, R., Bodapati, S., Dollberg, Y., Khuri-Yakub, B. T., Blumenkranz, M. S., Moshfeghi, D. M., Gambhir, S. S. 2010; 35 (3): 270-272


    We developed a photoacoustic ocular imaging device and demonstrated its utility in imaging the deeper layers of the eye including the retina, choroid, and optic nerve. Using safe laser intensity, the photoacoustic system was able to visualize the blood distribution of an enucleated pig's eye and an eye of a living rabbit. Ultrasound images, which were simultaneously acquired, were overlaid on the photoacoustic images to visualize the eye's anatomy. Such a system may be used in the future for early detection and improved management of neovascular ocular diseases, including wet age-related macular degeneration and proliferative diabetic retinopathy.

    View details for Web of Science ID 000274196100001

    View details for PubMedID 20125691

  • A Dual-Labeled Knottin Peptide for PET and Near-Infrared Fluorescence Imaging of Integrin Expression in Living Subjects. Bioconjugate chemistry 2010


    Previously, we used directed evolution to engineer mutants of the Ecballium elaterium trypsin inhibitor (EETI-II) knottin that bind to alpha(v)beta(3) and alpha(v)beta(5) integrin receptors with low nanomolar affinity, and showed that Cy5.5- or (64)Cu-DOTA-labeled knottin peptides could be used to image integrin expression in mouse tumor models using near-infrared fluorescence (NIRF) imaging or positron emission tomography (PET). Here, we report the development of a dual-labeled knottin peptide conjugated to both NIRF and PET imaging agents for multimodality imaging in living subjects. We created an orthogonally protected peptide-based linker for stoichiometric coupling of (64)Cu-DOTA and Cy5.5 onto the knottin N-terminus and confirmed that conjugation did not affect binding to alpha(v)beta(3) and alpha(v)beta(5) integrins. NIRF and PET imaging studies in tumor xenograft models showed that Cy5.5 conjugation significantly increased kidney uptake and retention compared to the knottin peptide labeled with (64)Cu-DOTA alone. In the tumor, the dual-labeled (64)Cu-DOTA/Cy5.5 knottin peptide showed decreased wash-out leading to significantly better retention (p < 0.05) compared to the (64)Cu-DOTA-labeled knottin peptide. Tumor uptake was significantly reduced (p < 0.05) when the dual-labeled knottin peptide was coinjected with an excess of unlabeled competitor and when tested in a tumor model with lower levels of integrin expression. Finally, plots of tumor-to-background tissue ratios for Cy5.5 versus (64)Cu uptake were well-correlated over several time points post injection, demonstrating pharmacokinetic cross validation of imaging labels. This dual-modality NIRF/PET imaging agent is promising for further development in clinical applications where high sensitivity and high resolution are desired, such as detection of tumors located deep within the body and image-guided surgical resection.

    View details for DOI 10.1021/bc9003102

    View details for PubMedID 20131753

  • A red-shifted Renilla luciferase for transient reporter-gene expression NATURE METHODS Loening, A. M., Dragulescu-Andrasi, A., Gambhir, S. S. 2010; 7 (1): 5-6

    View details for DOI 10.1038/nmeth0110-05

    View details for Web of Science ID 000273128300003

    View details for PubMedID 20038949

  • Optical Imaging with Radioactive Probes PLoS One Liu, H., Ren G, Miao Z, Zhang X, Tang X, Han P, Gambhir SS, Cheng Z 2010; 5 (3): E9470
  • Meta-analysis of the Performance of [18F] FDG-PET in Cutaneous Melanoma. European Journal of Nuclear Medicine and Molecular Imaging JImenez-Requena F, Delgado-Bolton R, Fernandez-Perez C, Gambhir SS, Schwimmer J, Perez-Vazquez J, Carreras-Delgado J. 2010; 37(2): 284-300
  • Combined F-18-FDG and Fluoride Approach in PET/CT Imaging: Is There a Clinical Future? REPLY JOURNAL OF NUCLEAR MEDICINE Iagaru, A., Mittra, E., Goris, M. L., Gambhir, S. S. 2010; 51 (1): 166-167
  • A Novel Method of Monitoring Placenta-Specific Transgene Expression Throughout Pregnancy by Noninvasive Bioluminescence Imaging 43rd Annual Meeting of the Society-for-the-Study-of-Reproduction Fan, X., Ren, P., Dhal, S., Goodman, S. B., Gambhir, S. S., Druzin, M. L., Nayak, N. R. SOC STUDY REPRODUCTION. 2010: 144–145
  • Functional and Transcriptional Characterization of Human Embryonic Stem Cell-Derived Endothelial Cells for Treatment of Myocardial Infarction PLOS ONE Li, Z., Wilson, K. D., Smith, B., Kraft, D. L., Jia, F., Huang, M., Xie, X., Robbins, R. C., Gambhir, S. S., Weissman, I. L., Wu, J. C. 2009; 4 (12)


    Differentiation of human embryonic stem cells into endothelial cells (hESC-ECs) has the potential to provide an unlimited source of cells for novel transplantation therapies of ischemic diseases by supporting angiogenesis and vasculogenesis. However, the endothelial differentiation efficiency of the conventional embryoid body (EB) method is low while the 2-dimensional method of co-culturing with mouse embryonic fibroblasts (MEFs) require animal product, both of which can limit the future clinical application of hESC-ECs. Moreover, to fully understand the beneficial effects of stem cell therapy, investigators must be able to track the functional biology and physiology of transplanted cells in living subjects over time.In this study, we developed an extracellular matrix (ECM) culture system for increasing endothelial differentiation and free from contaminating animal cells. We investigated the transcriptional changes that occur during endothelial differentiation of hESCs using whole genome microarray, and compared to human umbilical vein endothelial cells (HUVECs). We also showed functional vascular formation by hESC-ECs in a mouse dorsal window model. Moreover, our study is the first so far to transplant hESC-ECs in a myocardial infarction model and monitor cell fate using molecular imaging methods.Taken together, we report a more efficient method for derivation of hESC-ECs that express appropriate patterns of endothelial genes, form functional vessels in vivo, and improve cardiac function. These studies suggest that hESC-ECs may provide a novel therapy for ischemic heart disease in the future.

    View details for DOI 10.1371/journal.pone.0008443

    View details for Web of Science ID 000273180200002

    View details for PubMedID 20046878

    View details for PubMedCentralID PMC2795856

  • Efficacy of F-18-FDG PET/CT in the evaluation of patients with recurrent cervical carcinoma EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Mittra, E., El-Maghraby, T., Rodriguez, C. A., Quon, A., McDougall, I. R., Gambhir, S. S., Iagaru, A. 2009; 36 (12): 1952-1959


    Only a limited number of studies have evaluated the efficacy of 18F-FDG PET/CT for recurrent cervical carcinoma, which this study seeks to expand upon.This is a retrospective study of 30 women with cervical carcinoma who had a surveillance PET/CT after initial therapy. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were calculated using a 2 × 2 contingency table with pathology results (76%) or clinical follow-up (24%) as the gold standard. The Wilson score method was used to perform 95% confidence interval estimations.The sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of PET/CT for the detection of local recurrence at the primary site were 93, 93, 93, 86, and 96%, respectively. The same values for the detection of distant metastases were 96, 95, 95, 96, and 95%, respectively. Seventy-one percent of the scans performed in symptomatic patients showed true-positive findings. In comparison, 44% of scans performed in asymptomatic patients showed true-positive findings. But, all patients subsequently had a change in their management based on the PET/CT findings such that the effect was notable. The maximum standardized uptake value ranged from 5 to 28 (average: 13 ± 7) in the primary site and 3 to 23 (average: 8 ± 4) in metastases which were significantly different (p = 0.04).This study demonstrates favorable efficacy of 18F-FDG PET/CT for identification of residual/recurrent cervical cancer, as well as for localization of distant metastases.

    View details for DOI 10.1007/s00259-009-1206-x

    View details for Web of Science ID 000271979300004

    View details for PubMedID 19585114

  • Development and intra-institutional and inter-institutional validation of a comprehensive new hepatobiliary software: part 1-liver and gallbladder function NUCLEAR MEDICINE COMMUNICATIONS Krishnamurthy, G. T., Krishnamurthy, S., Gambhir, S. S., Rodrigues, C., Rosenberg, J., Schiepers, C., Buxton-Thomas, M. 2009; 30 (12): 934-944


    To develop a software tool for quantification of liver and gallbladder function, and to assess the repeatability and reproducibility of measurements made with it.The software tool developed with the JAVA programming language uses the JAVA2 Standard Edition framework. After manual selection of the regions of interest on a 99mTc hepatic iminodiacetic acid study, the program calculates differential hepatic bile flow, basal duodeno-gastric bile reflux (B-DGBR), hepatic extraction fraction (HEF) of both the lobes with deconvolutional analysis and excretion half-time with nonlinear least squares fit. Gallbladder ejection fraction, ejection period (EP), ejection rate (ER), and postcholecystokinin (CCK) DGBR are calculated after stimulation with CCK-8. To assess intra-observer repeatability and intra-observer reproducibility, measurements from 10 normal participants were analyzed twice by three nuclear medicine technologists at the primary center. To assess inter-site reproducibility, measurements from a superset of 24 normal participants were also assessed once by three observers at the primary center and single observer at three other sites.For the 24 control participants, mean+/-SD of hepatic bile flow into gallbladder was 63.87+/-28.7%, HEF of the right lobe 100+/-0%, left lobe 99.43+2.63%, excretion half-time of the right lobe 21.50+6.98 min, left lobe 28.3+/-11.3 min. Basal DGBR was 1.2+/-1.0%. Gallbladder ejection fraction was 80+/-11%, EP 15.0+/-3.0 min, ER 5.8+/-1.6%/min, and DGBR-CCK 1.3+/-2.3%. Left and right lobe HEF was virtually identical across readers. All measures showed high repeatability except for gallbladder bile flow, basal DGBR, and EP, which exhibited marginal repeatability. Ejection fraction exhibited high reproducibility. There was high concordance among the three primary center observers except for basal DGBR, EP, and ER. Concordance between the primary site and one of the other sites was high, one was fair, and one was poor.New United States Food and Drug Administration-approved personal computer-based Krishnamurthy Hepato-Biliary Software for quantification of the liver and gallbladder function shows promise for consistently repeatable and reproducible results both within and between institutions, and may help to promote universal standardization of data acquisition and analysis in nuclear hepatology.

    View details for DOI 10.1097/MNM.0b013e32832ed34a

    View details for Web of Science ID 000272116100006

    View details for PubMedID 19858769

  • Embryonic Stem Cell-Derived Endothelial Cells Engraft Into the Ischemic Hindlimb and Restore Perfusion 82nd National Conference and Exhibitions and Scientific Sessions of the American-Heart-Association Huang, N. F., Niiyama, H., Peter, C., De, A., Natkunam, Y., Fleissner, F., Li, Z., Rollins, M. D., Wu, J. C., Gambhir, S. S., Cooke, J. P. LIPPINCOTT WILLIAMS & WILKINS. 2009: S1152–S1152
  • A Novel Molecular Imaging Sensor of Cellular Oxidative Stress 82nd National Conference and Exhibitions and Scientific Sessions of the American-Heart-Association Peterson, K. M., Chen, I. Y., Simari, R. D., Gambhir, S. S., Lerman, A., Rodriguez-Porcel, M. LIPPINCOTT WILLIAMS & WILKINS. 2009: S1025–S1025
  • Matrix-insensitive protein assays push the limits of biosensors in medicine NATURE MEDICINE Gaster, R. S., Hall, D. A., Nielsen, C. H., Osterfeld, S. J., Yu, H., Mach, K. E., Wilson, R. J., Murmann, B., Liao, J. C., Gambhir, S. S., Wang, S. X. 2009; 15 (11): 1327-U130


    Advances in biosensor technologies for in vitro diagnostics have the potential to transform the practice of medicine. Despite considerable work in the biosensor field, there is still no general sensing platform that can be ubiquitously applied to detect the constellation of biomolecules in diverse clinical samples (for example, serum, urine, cell lysates or saliva) with high sensitivity and large linear dynamic range. A major limitation confounding other technologies is signal distortion that occurs in various matrices due to heterogeneity in ionic strength, pH, temperature and autofluorescence. Here we present a magnetic nanosensor technology that is matrix insensitive yet still capable of rapid, multiplex protein detection with resolution down to attomolar concentrations and extensive linear dynamic range. The matrix insensitivity of our platform to various media demonstrates that our magnetic nanosensor technology can be directly applied to a variety of settings such as molecular biology, clinical diagnostics and biodefense.

    View details for DOI 10.1038/nm.2032

    View details for Web of Science ID 000271543700023

    View details for PubMedID 19820717

  • Three-Dimensional Photoacoustic Imaging Using a Two-Dimensional CMUT Array IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL Vaithilingam, S., Ma, T., Furukawa, Y., Wygant, I. O., Zhuang, X., de la Zerda, A., Oralkan, O., Kamaya, A., Gambhir, S. S., Jeffrey, R. B., Khuri-Yakub, B. T. 2009; 56 (11): 2411-2419


    In this paper, we describe using a 2-D array of capacitive micromachined ultrasonic transducers (CMUTs) to perform 3-D photoacoustic and acoustic imaging. A tunable optical parametric oscillator laser system that generates nanosecond laser pulses was used to induce the photoacoustic signals. To demonstrate the feasibility of the system, 2 different phantoms were imaged. The first phantom consisted of alternating black and transparent fishing lines of 180 mum and 150 mum diameter, respectively. The second phantom comprised polyethylene tubes, embedded in chicken breast tissue, filled with liquids such as the dye indocyanine green, pig blood, and a mixture of the 2. The tubes were embedded at a depth of 0.8 cm inside the tissue and were at an overall distance of 1.8 cm from the CMUT array. Two-dimensional cross-sectional slices and 3-D volume rendered images of pulse-echo data as well as photoacoustic data are presented. The profile and beamwidths of the fishing line are analyzed and compared with a numerical simulation carried out using the Field II ultrasound simulation software. We investigated using a large aperture (64 x 64 element array) to perform photoacoustic and acoustic imaging by mechanically scanning a smaller CMUT array (16 x 16 elements). Two-dimensional transducer arrays overcome many of the limitations of a mechanically scanned system and enable volumetric imaging. Advantages of CMUT technology for photoacoustic imaging include the ease of integration with electronics, ability to fabricate large, fully populated 2-D arrays with arbitrary geometries, wide-bandwidth arrays and high-frequency arrays. A CMUT based photoacoustic system is proposed as a viable alternative to a piezoelectric transducer based photoacoustic systems.

    View details for DOI 10.1109/TUFFC.2009.1329

    View details for Web of Science ID 000271478600010

    View details for PubMedID 19942528

  • Whole-body, real-time preclinical imaging of quantum dot fluorescence with time-gated detection JOURNAL OF BIOMEDICAL OPTICS May, A., Bhaumik, S., Gambhir, S. S., Zhan, C., Yazdanfar, S. 2009; 14 (6)


    We describe a wide-field preclinical imaging system optimized for time-gated detection of quantum dot fluorescence emission. As compared to continuous wave measurements, image contrast was substantially improved by suppression of short-lifetime background autofluorescence. Real-time (8 frames/s) biological imaging of subcutaneous quantum dot injections is demonstrated simultaneously in multiple living mice.

    View details for DOI 10.1117/1.3269675

    View details for Web of Science ID 000274267900004

    View details for PubMedID 20059235

  • PET of Malignant Melanoma Using F-18-Labeled Metallopeptides JOURNAL OF NUCLEAR MEDICINE Ren, G., Liu, Z., Miao, Z., Liu, H., Subbarayan, M., Chin, F. T., Zhang, L., Gambhir, S. S., Cheng, Z. 2009; 50 (11): 1865-1872


    Melanocortin type 1 receptor (MC1R), also known as alpha-melanocyte-stimulating hormone (alpha-MSH) receptor, is an attractive molecular target for melanoma imaging and therapy. An (18)F-labeled linear alpha-MSH peptide ((18)F-FB-Ac-Nle-Asp-His-d-Phe-Arg-Trp-Gly-Lys-NH(2) [NAPamide]) shows promising melanoma imaging properties but with only moderate tumor uptake and retention. A transition metal rhenium-cyclized alpha-MSH peptide, ReO[Cys(3,4,10),d-Phe(7),Arg(11)]alpha-MSH(3-13) (ReCCMSH(Arg(11))), has shown high in vitro binding affinity to MC1R and excellent in vivo melanoma-targeting profiles when labeled with radiometals. Therefore, we hypothesized that ReCCMSH(Arg(11)) could be a good platform for the further development of an (18)F-labeled probe for PET of MC1R-positive malignant melanoma.In this study, the metallopeptide Ac-d-Lys-ReCCMSH(Arg(11)) was synthesized using conventional solid-phase peptide synthesis chemistry and a rhenium cyclization reaction. The resulting peptides were then labeled with N-succinimidyl-4-(18)F-fluorobenzoate ((18)F-SFB). The (18)F-labeled metallopeptides were further tested for their in vitro receptor binding affinities, in vivo biodistribution, and PET imaging properties.Both isomers of Ac-d-Lys-ReCCMSH(Arg(11)), named as RMSH-1 and RMSH-2, were purified and identified by high-performance liquid chromatography. The binding affinities of RMSH-1 and RMSH-2 and their respective (19)F-SFB-conjugated peptides ((19)F-FB-RMSH-1 and (19)F-FB-RMSH-2) were all determined to be within nanomolar range. Both (18)F-labeled metallopeptides showed good tumor uptake in the B16F10 murine model, with high MC1R expression, but much lower uptake in the A375M human melanoma xenografted in mice, indicating low MC1R expression. (18)F-FB-RMSH-1, when compared with (18)F-FB-RMSH-2, displayed more favorable in vivo performance in terms of slightly higher tumor uptakes and much lower accumulations in the kidney and liver at 2 h after injection. Small-animal PET of (18)F-FB-RMSH-1 and -2 in mice bearing B16F10 tumors at 1 and 2 h showed good tumor imaging quality. As expected, much lower tumor uptakes and poorer tumor-to-normal organ contrasts were observed for the A375M model than for the B16F10 model. (18)F-FB-RMSH-1 and -2 showed higher tumor uptake and better tumor retention than did (18)F-FB-NAPamide.Specific in vivo targeting of (18)F-FB-RMSH-1 to malignant melanoma was successfully achieved in preclinical models with high MC1R expression. Thus, the radiofluorinated metallopeptide (18)F-FB-RMSH-1 is a promising molecular probe for PET of MC1R-positive tumors.

    View details for DOI 10.2967/jnumed.109.062877

    View details for Web of Science ID 000272554100021

    View details for PubMedID 19837749

  • F-18-FDG Uptake in Lung, Breast, and Colon Cancers: Molecular Biology Correlates and Disease Characterization JOURNAL OF NUCLEAR MEDICINE Jadvar, H., Alavi, A., Gambhir, S. S. 2009; 50 (11): 1820-1827


    It is hoped that in the not too distant future, noninvasive imaging-based molecular interrogation and characterization of tumors can improve our fundamental understanding of the dynamic biologic behavior of cancer. For example, the new dimension of diagnostic information that is provided by (18)F-FDG PET has led to improved clinical decision making and management changes in a substantial number of patients with cancer. In this context, the aim of this review is to bring together and summarize the current data on the correlation between the underlying molecular biology and the clinical observations of tumor (18)F-FDG accumulation in 3 major human cancers: lung, breast, and colon.

    View details for DOI 10.2967/jnumed.108.054098

    View details for Web of Science ID 000272554100015

    View details for PubMedID 19837767

  • A strategy for blood biomarker amplification and localization using ultrasound PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA D'Souza, A. L., Tseng, J. R., Pauly, K. B., Guccione, S., Rosenberg, J., Gambhir, S. S., Glazer, G. M. 2009; 106 (40): 17152-17157


    Blood biomarkers have significant potential applications in early detection and management of various diseases, including cancer. Most biomarkers are present in low concentrations in blood and are difficult to discriminate from noise. Furthermore, blood measurements of a biomarker do not provide information about the location(s) where it is produced. We hypothesize a previously undescribed strategy to increase the concentration of biomarkers in blood as well as localize the source of biomarker signal using ultrasound energy directly applied to tumor cells. We test and validate our hypothesis in cell culture experiments and mouse tumor xenograft models using the human colon cancer cell line LS174T, while measuring the biomarker carcinoembryonic antigen (CEA) before and after the use of ultrasound to liberate the biomarker from the tumor cells. The results demonstrate that the application of low-frequency ultrasound to tumor cells causes a significant release of tumor biomarker, which can be measured in the blood. Furthermore, we establish that this release is specific to the direct application of the ultrasound to the tumor, enabling a method for localization of biomarker production. This work shows that it is possible to use ultrasound to amplify and localize the source of CEA levels in blood of tumor-bearing mice and will allow for a previously undescribed way to determine the presence and localization of disease more accurately using a relatively simple and noninvasive strategy.

    View details for DOI 10.1073/pnas.0903437106

    View details for Web of Science ID 000270537500053

    View details for PubMedID 19805109

    View details for PubMedCentralID PMC2749842

  • A novel multimodal approach to track neural progenitor cells in vivo 24th International Symposium on Cerebral Blood Flow and Metabolism/9th International Conference on Quantification of Brain Function with PET Pendharkar, A., De, A., Wang, H., Gaeta, X., Wang, N., Chua, J. Y., Andres, R., Chen, X., Gambhir, S. S., Guzman, R. NATURE PUBLISHING GROUP. 2009: S472–S473
  • Creatine modulates survival, migration and differentiation in neural stem cells 24th International Symposium on Cerebral Blood Flow and Metabolism/9th International Conference on Quantification of Brain Function with PET Andres, R. H., Pendharkar, A., Guzman, R., De, A., Bliss, T. M., MacMillan, E., Svendsen, C., Gambhir, S. S., Widmer, H., Wallimann, T. NATURE PUBLISHING GROUP. 2009: S562–S562
  • A Novel Estrogen Receptor Intramolecular Folding-based Titratable Transgene Expression System MOLECULAR THERAPY Paulmurugan, R., Padmanabhan, P., Ahn, B., Ray, S., Willmann, J. K., Massoud, T. F., Biswal, S., Gambhir, S. S. 2009; 17 (10): 1703-1711


    The use of regulated gene expression systems is important for successful gene therapy applications. In this study, ligand-induced structural change in the estrogen receptor (ER) was used to develop a novel ER intramolecular folding-based transcriptional activation system. The system was studied using ER-variants of different lengths, flanked on either side by the GAL4-DNA-binding domain and the VP16-transactivation domain (GAL4(DBD)-ER-VP16). The ER ligands of different types showed efficient ligand-regulated transactivation. We also characterized a bidirectional transactivation system based on the ER and demonstrated its utility in titrating both reporter and therapeutic gene expression. The ligand-regulated transactivation system developed by using a mutant form of the ER (G521T, lacking affinity for the endogenous ligand 17beta-estradiol, whereas maintaining affinity for other ligands) showed efficient activation by the ligand raloxifene in living mice without significant interference from the circulating endogenous ligand. The ligand-regulated transactivation system was used to test the therapeutic efficiency of the tumor suppressor protein p53 in HepG2 (p53(+/+)) and SKBr3 (p53(-/-)/mutant-p53(+/+)) cells in culture and tumor xenografts in living mice. The multifunctional capabilities of this system should be useful for gene therapy applications, to study ER biology, to evaluate gene regulation, ER ligand screening, and ER ligand biocharacterization in cells and living animals.

    View details for DOI 10.1038/mt.2009.171

    View details for Web of Science ID 000270851900008

    View details for PubMedID 19654568

  • Melanin-Targeted Preclinical PET Imaging of Melanoma Metastasis JOURNAL OF NUCLEAR MEDICINE Ren, G., Miao, Z., Liu, H., Jiang, L., Limpa-Amara, N., Mahmood, A., Gambhir, S. S., Cheng, Z. 2009; 50 (10): 1692-1699


    Dialkylamino-alkyl-benzamides possess an affinity for melanin, suggesting that labeling of such benzamides with (18)F could potentially produce melanin-targeted PET probes able to identify melanotic melanoma metastases in vivo with high sensitivity and specificity.In this study, N-[2-(diethylamino)ethyl]-4-(18)F-fluorobenzamide ((18)F-FBZA) was synthesized via a 1-step conjugation reaction. The sigma-receptor binding affinity of (19)F-FBZA was determined along with the in vitro cellular uptake of radiofluorinated (18)F-FBZA in B16F10 cells. In vivo distribution and small-animal PET studies were conducted on mice bearing B16F10 melanoma, A375M amelanotic melanoma, and U87MG tumors, and comparative studies were performed with (18)F-FDG PET in the melanoma models.In vitro, uptake of (18)F-FBZA was significantly higher in B16F10 cells treated with l-tyrosine (P < 0.001). In vivo, (18)F-FBZA displayed significant tumor uptake; at 2 h, 5.94 +/- 1.83 percentage injected dose (%ID) per gram was observed in B16F10 tumors and only 0.75 +/- 0.09 %ID/g and 0.56 +/- 0.13 %ID/g was observed in amelanotic A375M and U87MG tumors, respectively. Lung uptake was significantly higher in murine lungs bearing melanotic B16F10 pulmonary metastases than in normal murine lungs (P < 0.01). Small-animal PET clearly identified melanotic lesions in both primary and pulmonary metastasis B16F10 tumor models. Coregistered micro-CT with small-animal PET along with biopsies further confirmed the presence of tumor lesions in the mouse lungs.(18)F-FBZA specifically targets primary and metastatic melanotic melanoma lesions with high tumor uptake and may have translational potential.

    View details for DOI 10.2967/jnumed.109.066175

    View details for Web of Science ID 000272553600023

    View details for PubMedID 19759116

  • A 2-Helix Small Protein Labeled with Ga-68 for PET Imaging of HER2 Expression JOURNAL OF NUCLEAR MEDICINE Ren, G., Zhang, R., Liu, Z., Webster, J. M., Miao, Z., Gambhir, S. S., Syud, F. A., Cheng, Z. 2009; 50 (9): 1492-1499


    Affibody molecules are a class of scaffold proteins being developed into a generalizable approach to targeting tumors. Many 3-helix-based Affibody proteins have shown excellent in vivo properties for tumor imaging and therapy. By truncating one alpha-helix that is not responsible for receptor recognition in the Affibody and maturating the protein affinity through synthetic strategies, we have successfully identified in our previous research several small 2-helix proteins with excellent binding affinities to human epidermal growth factor receptor type 2 (HER2). With preferential properties such as faster blood clearance and tumor accumulation, lower immunogenic potential, and facile and economically viable synthetic schemes, we hypothesized that these 2-helix protein binders could become excellent molecular imaging probes for monitoring HER2 expression and modulation.In this study, a 2-helix small protein, MUT-DS, was chemically modified with a metal chelator, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). DOTA-MUT-DS was then site-specifically radiolabeled with an important PET radionuclide, (68)Ga. The resulting radiolabeled anti-HER2 2-helix molecule was further evaluated as a potential molecular probe for small-animal PET HER2 imaging in a SKOV3 tumor mouse model.The 2-helix DOTA-MUT-DS showed high HER2-binding affinity (dissociation constant, 4.76 nM). The radiolabeled probe displayed high stability in mouse serum and specificity toward HER2 in cell cultures. Biodistribution and small-animal PET studies further showed that (68)Ga-DOTA-MUT-DS had rapid and high SKOV3 tumor accumulation and quick clearance from normal organs. The specificity of (68)Ga-DOTA-MUT-DS for SKOV3 tumors was confirmed by monitoring modulation of HER2 protein on treatment of tumor mice with heat shock protein 90 inhibitor 17-N,N-dimethyl ethylene diamine-geldanamycin in vivo.This proof-of-concept research clearly demonstrated that synthetic 2-helix (68)Ga-DOTA-MUT-DS is a promising PET probe for imaging HER2 expression in vivo. The Affibody-derived small 2-helix protein scaffold has great potential for developing targeting agents for a variety of tumor-associated biomarkers.

    View details for DOI 10.2967/jnumed.109.064287

    View details for Web of Science ID 000272548900023

    View details for PubMedID 19690041

  • Efficacy of F-18-FDG PET/CT for Breast Cancer Mittra, E., Quon, A., Gambhir, S. S., Iagaru, A. SPRINGER. 2009: S176–S176
  • Combined F-18 Fluoride and F-18 FDG PET/CT Scan for Evaluation of Malignancy Lagaru, A., Mittra, E., Dick, D., Quon, A., Goris, M. L., Gambhir, S. S. SPRINGER. 2009: S214–S214
  • Prospective Evaluation of Tc-99m-MDP Scintigraphy, F-18 NaF PET/CT and F-18 FDG PET/CT for Detection of Skeletal Metastases Iagaru, A., Mittra, E., Dick, D., Gambhir, S. S. SPRINGER. 2009: S187–S187
  • Chemical tools for imaging glycosylation in vivo Chang, P. V., Prescher, J. A., Foss, C. A., Ray, P., Gambhir, S. S., Pomper, M. G., Bertozzi, C. R. AMER CHEMICAL SOC. 2009
  • Visualizing Implanted Tumors in Mice with Magnetic Resonance Imaging Using Magnetotactic Bacteria CLINICAL CANCER RESEARCH Benoit, M. R., Mayer, D., Barak, Y., Chen, I. Y., Hu, W., Cheng, Z., Wang, S. X., Spielman, D. M., Gambhir, S. S., Matin, A. 2009; 15 (16): 5170-5177


    To determine if magnetotactic bacteria can target tumors in mice and provide positive contrast for visualization using magnetic resonance imaging.The ability of the magnetotactic bacterium, Magnetospirillum magneticum AMB-1 (referred to from here as AMB-1), to confer positive magnetic resonance imaging contrast was determined in vitro and in vivo. For the latter studies, AMB-1 were injected either i.t. or i.v. Bacterial growth conditions were manipulated to produce small (approximately 25-nm diameter) magnetite particles, which were observed using transmission electron microscopy. Tumor targeting was confirmed using 64Cu-labeled bacteria and positron emission tomography and by determination of viable cell counts recovered from different organs and the tumor.We show that AMB-1 bacteria with small magnetite particles generate T1-weighted positive contrast, enhancing in vivo visualization by magnetic resonance imaging. Following i.v. injection of 64Cu-labeled AMB-1, positron emission tomography imaging revealed increasing colonization of tumors and decreasing infection of organs after 4 hours. Viable cell counts showed that, by day 6, the bacteria had colonized tumors but were cleared completely from other organs. Magnetic resonance imaging showed a 1.22-fold (P = 0.003) increased positive contrast in tumors on day 2 and a 1.39-fold increase (P = 0.0007) on day 6.Magnetotactic bacteria can produce positive magnetic resonance imaging contrast and colonize mouse tumor xenografts, providing a potential tool for improved magnetic resonance imaging visualization in preclinical and translational studies to track cancer.

    View details for DOI 10.1158/1078-0432.CCR-08-3206

    View details for Web of Science ID 000269024900019

    View details for PubMedID 19671860

  • Multiplexed imaging of surface enhanced Raman scattering nanotags in living mice using noninvasive Raman spectroscopy PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Zavaleta, C. L., Smith, B. R., Walton, I., Doering, W., Davis, G., Shojaei, B., Natan, M. J., Gambhir, S. S. 2009; 106 (32): 13511-13516


    Raman spectroscopy is a newly developed, noninvasive preclinical imaging technique that offers picomolar sensitivity and multiplexing capabilities to the field of molecular imaging. In this study, we demonstrate the ability of Raman spectroscopy to separate the spectral fingerprints of up to 10 different types of surface enhanced Raman scattering (SERS) nanoparticles in a living mouse after s.c. injection. Based on these spectral results, we simultaneously injected the five most intense and spectrally unique SERS nanoparticles i.v. to image their natural accumulation in the liver. All five types of SERS nanoparticles were successfully identified and spectrally separated using our optimized noninvasive Raman imaging system. In addition, we were able to linearly correlate Raman signal with SERS concentration after injecting four spectrally unique SERS nanoparticles either s.c. (R(2) = 0.998) or i.v. (R(2) = 0.992). These results show great potential for multiplexed imaging in living subjects in cases in which several targeted SERS probes could offer better detection of multiple biomarkers associated with a specific disease.

    View details for DOI 10.1073/pnas.0813327106

    View details for Web of Science ID 000268877300066

    View details for PubMedID 19666578

  • Cys-diabody Quantum Dot Conjugates (ImmunoQdots) for Cancer Marker Detection BIOCONJUGATE CHEMISTRY Barat, B., Sirk, S. J., McCabe, K. E., Li, J., Lepin, E. J., Remenyi, R., Koh, A. L., Olafsen, T., Gambhir, S. S., Weiss, S., Wu, A. M. 2009; 20 (8): 1474-1481


    The present work demonstrates the use of small bivalent engineered antibody fragments, cys-diabodies, for biological modification of nanoscale particles such as quantum dots (Qdots) for detection of target antigens. Novel bioconjugated quantum dots known as immunoQdots (iQdots) were developed by thiol-specific oriented coupling of tumor specific cys-diabodies, at a position away from the antigen binding site to amino PEG CdSe/ZnS Qdots. Initially, amino PEG Qdot 655 were coupled with reduced anti-HER2 cys-diabody by amine-sulfhydryl-reactive linker [N-ε-maleimidocaproyloxy] succinimide ester (EMCS) to produce anti-HER2 iQdot 655. Spectral characterization of the conjugate revealed that the spectrum was symmetrical and essentially identical to unconjugated Qdot. Specific receptor binding activity of anti-HER2 iQdot 655 was confirmed by flow cytometry on HER2 positive and negative cells. Immunofluorescence results showed homogeneous surface labeling of the cell membrane with Qdot 655 conjugate. In addition, cys-diabodies specific for HER2, as well as prostate stem cell antigen (PSCA), were conjugated successfully with amino PEG Qdot 800. All of these iQdots retain the photoluminescence properties of the unconjugated Qdot 800 as well as the antigen binding specificity of the cys-diabody as demonstrated by flow cytometry. Simultaneous detection of two tumor antigens on LNCaP/PSCA prostate cancer cells (which express PSCA and HER2) in culture was possible using two iQdots, anti-HER2 iQdot 655 and anti-PSCA iQdot 800. Thus, these iQdots are potentially useful as optical probes for sensitive, multiplexed detection of surface markers on tumor cells. The present thiol-specific conjugation method demonstrates a general approach for site-specific oriented coupling of cys-diabodies to a wide variety of nanoparticles without disturbing the antigen binding site and maintaining small size compared to intact antibody.

    View details for DOI 10.1021/bc800421f

    View details for Web of Science ID 000269042100006

    View details for PubMedID 19642689

  • BRET3: a red-shifted bioluminescence resonance energy transfer (BRET)-based integrated platform for imaging protein-protein interactions from single live cells and living animals FASEB JOURNAL De, A., Ray, P., Loening, A. M., Gambhir, S. S. 2009; 23 (8): 2702-2709


    Taking advantage of the bioluminescence resonance energy transfer (BRET) phenomenon, we report the development of a highly photon-efficient, self-illuminating fusion protein combining a mutant red fluorescent protein (mOrange) and a mutant Renilla reniformis luciferase (RLuc8). This new BRET fusion protein (BRET3) exhibits severalfold improvement in light intensity in comparison with existing BRET fusion proteins. BRET3 also exhibits the most red-shifted light output (564-nm peak wavelength) of any reported bioluminescent protein that utilizes its natural substrate coelenterazine, a benefit of which is demonstrated at various tissue depths in small animals. The imaging utility of BRET3 at the single-cell level is demonstrated using an intramolecular sensor incorporating two mammalian target of rapamycin pathway proteins (FKBP12 and FRB) that dimerize only in the presence of rapamycin. With its increased photon intensity, red-shifted light output, and good spectral resolution (approximately 85 nm), BRET3 shows improved spatial and temporal resolution for measuring intracellular events in single cells and in living small animal models. The development of further BRET3-based assays will allow imaging of protein-protein interactions using a single assay directly scalable from intact living cells to small living subjects, allowing accelerated drug discovery.

    View details for DOI 10.1096/fj.08-118919

    View details for Web of Science ID 000268836700038

    View details for PubMedID 19351700

  • Simulations of Virtual PET/CT 3-D Bronchoscopy Imaging Using a Physical Porcine Lung-Heart Phantom MOLECULAR IMAGING AND BIOLOGY Yerushalmi, D., Mullick, R., Quon, A., Fahrig, R., Pelc, N. J., Fann, J. I., Gambhir, S. S. 2009; 11 (4): 275-282


    We present a systematic approach for studying positron emission tomography-computed tomography (PET/CT) 3-D virtual fly-through endoscopy and for assessing the accuracy of this technology for visualizing and detecting endobronchial lesions as a function of focal lesion morphology and activity.Capsules designed to simulate endobronchial lesions were filled with activity and introduced into a porcine lung-heart phantom. PET/CT images were acquired, reconstructed, and volume rendered as 3-D fly-through and fly-around visualizations. Anatomical positioning of lesions seen on the 3-D-volume-rendered PET/CT images was compared to the actual position of the capsules.Lesion size was observed to be highly sensitive to PET threshold parameter settings and careful opacity and color transfer function parameter assignment.We have demonstrated a phantom model for studies of PET/CT 3-D virtual fly-through bronchoscopy and have applied this model for understanding the effect of PET thresholding on the visualization and detection of lesions.

    View details for DOI 10.1007/s11307-009-0201-8

    View details for Web of Science ID 000266830700010

    View details for PubMedID 19434462

  • Role of Oxidative Stress in Stem Cell Survival 10th Annual Conference on Arteriosclerosis, Thrombosis and Vascular Biology Peterson, K. M., Abdelrhaman, A., Gambhir, S. S., Rodriguez-Porcel, M. G. LIPPINCOTT WILLIAMS & WILKINS. 2009: E88–E88
  • Imaging Gene Expression in Human Mesenchymal Stem Cells: From Small to Large Animals RADIOLOGY Willmann, J. K., Paulmurugan, R., Rodriguez-Porcel, M., Stein, W., Brinton, T. J., Connolly, A. J., Nielsen, C. H., Lutz, A. M., Lyons, J., Ikeno, F., Suzuki, Y., Rosenberg, J., Chen, I. Y., Wu, J. C., Yeung, A. C., Yock, P., Robbins, R. C., Gambhir, S. S. 2009; 252 (1): 117-127


    To evaluate the feasibility of reporter gene imaging in implanted human mesenchymal stem cells (MSCs) in porcine myocardium by using clinical positron emission tomography (PET)-computed tomography (CT) scanning.Animal protocols were approved by the Institutional Administrative Panel on Laboratory Animal Care. Transduction of human MSCs by using different doses of adenovirus that contained a cytomegalovirus (CMV) promoter driving the mutant herpes simplex virus type 1 thymidine kinase reporter gene (Ad-CMV-HSV1-sr39tk) was characterized in a cell culture. A total of 2.25 x 10(6) transduced (n = 5) and control nontransduced (n = 5) human MSCs were injected into the myocardium of 10 rats, and reporter gene expression in human MSCs was visualized with micro-PET by using the radiotracer 9-(4-[fluorine 18]-fluoro-3-hydroxymethylbutyl)-guanine (FHBG). Different numbers of transduced human MSCs suspended in either phosphate-buffered saline (PBS) (n = 4) or matrigel (n = 5) were injected into the myocardium of nine swine, and gene expression was visualized with a clinical PET-CT. For analysis of cell culture experiments, linear regression analyses combined with a t test were performed. To test differences in radiotracer uptake between injected and remote myocardium in both rats and swine, one-sided paired Wilcoxon tests were performed. In swine experiments, a linear regression of radiotracer uptake ratio on the number of injected transduced human MSCs was performed.In cell culture, there was a viral dose-dependent increase of gene expression and FHBG accumulation in human MSCs. Human MSC viability was 96.7% (multiplicity of infection, 250). Cardiac FHBG uptake in rats was significantly elevated (P < .0001) after human MSC injection (0.0054% injected dose [ID]/g +/- 0.0007 [standard deviation]) compared with that in the remote myocardium (0.0003% ID/g +/- 0.0001). In swine, myocardial radiotracer uptake was not elevated after injection of up to 100 x 10(6) human MSCs (PBS group). In the matrigel group, signal-to-background ratio increased to 1.87 after injection of 100 x 10(6) human MSCs and positively correlated (R(2) = 0.97, P < .001) with the number of administered human MSCs.Reporter gene imaging in human MSCs can be translated to large animals. The study highlights the importance of co-administering a "scaffold" for increasing intramyocardial retention of human MSCs.

    View details for DOI 10.1148/radiol.2513081616

    View details for Web of Science ID 000268362900015

    View details for PubMedID 19366903

    View details for PubMedCentralID PMC2702468

  • Tumor Metabolic Phenotypes on F-18 FDG PET REPLY JOURNAL OF NUCLEAR MEDICINE Iagaru, A. H., Gambhir, S. S., Goris, M. L. 2009; 50 (6): 1011-1012
  • Engineered Two-Helix Small Proteins for Molecular Recognition CHEMBIOCHEM Webster, J. M., Zhang, R., Gambhir, S. S., Cheng, Z., Syud, F. A. 2009; 10 (8): 1293-1296


    Less is more: By starting with a high-affinity HER2-binding 3-helix affibody molecule, we successfully developed 2-helix small protein binders with 5 nM affinities by using a combination of several different strategies. Our efforts clearly suggest that 2-helix small proteins against important tumor targets can be obtained by rational protein design and engineering.

    View details for DOI 10.1002/cbic.200900062

    View details for Web of Science ID 000266561500003

    View details for PubMedID 19422008

  • Comparison of Optical Bioluminescence Reporter Gene and Superparamagnetic Iron Oxide MR Contrast Agent as Cell Markers for Noninvasive Imaging of Cardiac Cell Transplantation MOLECULAR IMAGING AND BIOLOGY Chen, I. Y., Greve, J. M., Gheysens, O., Willmann, J. K., Rodriguez-Porcel, M., Chu, P., Sheikh, A. Y., Faranesh, A. Z., Paulmurugan, R., Yang, P. C., Wu, J. C., Gambhir, S. S. 2009; 11 (3): 178-187


    In this study, we compared firefly luciferase (Fluc) reporter gene and superparamagnetic iron oxide (Feridex) as cell markers for longitudinal monitoring of cardiomyoblast graft survival using optical bioluminescence imaging (BLI) and magnetic resonance imaging (MRI), respectively.Rats (n = 31) underwent an intramyocardial injection of cardiomyoblasts (2 x 10(6)) labeled with Fluc, Feridex, or no marker (control) or an injection of Feridex alone (75 microg). Afterward, rats were serially imaged with BLI or MRI and killed at different time points for histological analysis.BLI revealed a drastically different cell survival kinetics (half-life = 2.65 days over 6 days) than that revealed by MRI (half-life = 16.8 days over 80 days). Injection of Feridex alone led to prolonged tissue retention of Feridex (> or =16 days) and persistent MR signal (> or =42 days).Fluc BLI reporter gene imaging is a more accurate gauge of transplanted cell survival as compared to MRI of Feridex-labeled cells.

    View details for DOI 10.1007/s11307-008-0182-z

    View details for Web of Science ID 000265686900005

    View details for PubMedID 19034584

    View details for PubMedCentralID PMC4155941

  • A Potent, Imaging Adenoviral Vector Driven by the Cancer-selective Mucin-1 Promoter That Targets Breast Cancer Metastasis CLINICAL CANCER RESEARCH Huyn, S. T., Burton, J. B., Sato, M., Carey, M., Gambhir, S. S., Wu, L. 2009; 15 (9): 3126-3134


    With breast cancer, early detection and proper staging are critical, and will often influence both the treatment regimen and the therapeutic outcome for those affected with this disease. Improvements in these areas will play a profound role in reducing mortality from breast cancer.In this work we developed a breast cancer-targeted serotype 5 adenoviral vector, utilizing the tumor-specific mucin-1 promoter in combination with the two-step transcriptional amplification system, a system used to augment the activity of weak tissue-specific promoters.We showed the strong specificity of this tumor-selective adenovirus to express the luciferase optical imaging gene, leading to diagnostic signals that enabled detection of sentinel lymph node metastasis of breast cancer. Furthermore, we were able to target hepatic metastases following systemic administration of this mucin-1 selective virus.Collectively, we showed that the amplified mucin-1 promoter-driven vector is able to deliver to and selectively express a desirable transgene in metastatic lesions of breast tumors. This work has strong clinical relevance to current diagnostic staging approaches, and could add to targeted therapeutic strategies to advance the fight against breast cancer.

    View details for DOI 10.1158/1078-0432.CCR-08-2666

    View details for Web of Science ID 000265712100022

    View details for PubMedID 19366829

  • Molecular Imaging of Phosphorylation Events for Drug Development MOLECULAR IMAGING AND BIOLOGY CHAN, C. T., Paulmurugan, R., Reeves, R. E., Solow-Cordero, D., Gambhir, S. S. 2009; 11 (3): 144-158


    Protein phosphorylation mediated by protein kinases controls numerous cellular processes. A genetically encoded, generalizable split firefly luciferase (FL)-assisted complementation system was developed for noninvasive monitoring phosphorylation events and efficacies of kinase inhibitors in cell culture and in small living subjects by optical bioluminescence imaging.An Akt sensor (AST) was constructed to monitor Akt phosphorylation and the effect of different PI-3K and Akt inhibitors. Specificity of AST was determined using a non-phosphorylable mutant sensor containing an alanine substitution (ASA).The PI-3K inhibitor LY294002 and Akt kinase inhibitor perifosine led to temporal- and dose-dependent increases in complemented FL activities in 293T human kidney cancer cells stably expressing AST (293T/AST) but not in 293T/ASA cells. Inhibition of endogenous Akt phosphorylation and kinase activities by perifosine also correlated with increase in complemented FL activities in 293T/AST cells but not in 293T/ASA cells. Treatment of nude mice bearing 293T/AST xenografts with perifosine led to a 2-fold increase in complemented FL activities compared to that of 293T/ASA xenografts. Our system was used to screen a small chemical library for novel modulators of Akt kinase activity.This generalizable approach for noninvasive monitoring of phosphorylation events will accelerate the discovery and validation of novel kinase inhibitors and modulators of phosphorylation events.

    View details for DOI 10.1007/s11307-008-0187-7

    View details for Web of Science ID 000265686900002

    View details for PubMedID 19048345

    View details for PubMedCentralID PMC4154800

  • Novel Strategy for a Cocktail F-18-Fluoride and F-18-FDG PET/CT Scan for Evaluation of Malignancy: Results of the Pilot-Phase Study JOURNAL OF NUCLEAR MEDICINE Iagaru, A., Mittra, E., Yaghoubi, S. S., Dick, D. W., Quon, A., Goris, M. L., Gambhir, S. S. 2009; 50 (4): 501-505


    (18)F-FDG PET/CT is used for detecting cancer and monitoring cancer response to therapy. However, because of the variable rates of glucose metabolism, not all cancers are identified reliably. Sodium (18)F was previously used for bone imaging and can be used as a PET/CT skeletal tracer. The combined administration of (18)F and (18)F-FDG in a single PET/CT study for cancer detection has not been reported to date.This is a prospective pilot study (November 2007-November 2008) of 14 patients with proven malignancy (6 sarcoma, 3 prostate cancer, 2 breast cancer, 1 colon cancer, 1 lung cancer, and 1 malignant paraganglioma) who underwent separate (18)F PET/CT and (18)F-FDG PET/CT and combined (18)F/(18)F-FDG PET/CT scans for the evaluation of malignancy (a total of 3 scans each). There were 11 men and 3 women (age range, 19-75 y; average, 50.4 y).Interpretation of the combined (18)F/(18)F-FDG PET/CT scans compared favorably with that of the (18)F-FDG PET/CT (no lesions missed) and the (18)F PET/CT scans (only 1 skull lesion seen on an (18)F PET/CT scan was missed on the corresponding combined scan). Through image processing, the combined (18)F/(18)F-FDG scan yielded results for bone radiotracer uptake comparable to those of the (18)F PET/CT scan performed separately.Our pilot-phase prospective trial demonstrates that the combined (18)F/(18)F-FDG administration followed by a single PET/CT scan is feasible for cancer detection. This combined method opens the possibility for improved patient care and reduction in health care costs.

    View details for DOI 10.2967/jnumed.108.058339

    View details for Web of Science ID 000272487200003

    View details for PubMedID 19289439

  • Human adipose tissue-derived mesenchymal stromal cells as vehicles for tumor bystander effect: a model based on bioluminescence imaging GENE THERAPY Vilalta, M., Degano, I. R., Bago, J., Aguilar, E., Gambhir, S. S., Rubio, N., Blanco, J. 2009; 16 (4): 547-557


    Human adipose tissue mesenchymal stromal cells (AMSCs) share common traits, including similar differentiation potential and cell surface markers, with their bone marrow counterparts. Owing to their general availability, higher abundance and ease of isolation AMSCs may be convenient autologous delivery vehicles for localized tumor therapy. We demonstrate a model for tumor therapy development based on the use of AMSCs expressing renilla luciferase and thymidine kinase, as cellular vehicles for ganciclovir-mediated bystander killing of firefly luciferase expressing tumors, and noninvasive bioluminescence imaging to continuously monitor both, tumor cells and AMSCs. We show that the therapy delivering AMSCs survive long time within tumors, optimize the ratio of AMSCs to tumor cells for therapy, and asses the therapeutic effect in real time. Treatment of mice bearing prostate tumors plus therapeutic AMSCs with the prodrug ganciclovir induced bystander killing effect, reducing the number of tumor cells to 1.5 % that of control tumors. Thus, AMSCs could be useful vehicles to deliver localized therapy, with potential for clinical application in inoperable tumors and surgical borders after tumor resection. This approach, useful to evaluate efficiency of therapeutic models, should facilitate the selection of cell types, dosages, therapeutic agents and treatment protocols for cell-based therapies of specific tumors.

    View details for DOI 10.1038/gt.2008.176

    View details for Web of Science ID 000265021400012

    View details for PubMedID 19092860

  • Engineered Knottin Peptides: A New Class of Agents for Imaging Integrin Expression in Living Subjects CANCER RESEARCH Kimura, R. H., Cheng, Z., Gambhir, S. S., Cochran, J. R. 2009; 69 (6): 2435-2442


    There is a critical need for molecular imaging agents to detect cell surface integrin receptors that are present in human cancers. Previously, we used directed evolution to engineer knottin peptides that bind with high affinity ( approximately 10 to 30 nmol/L) to integrin receptors that are overexpressed on the surface of tumor cells and the tumor neovasculature. To evaluate these peptides as molecular imaging agents, we site-specifically conjugated Cy5.5 or (64)Cu-1,4,7,10-tetra-azacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA) to their N termini, and used optical and positron emission tomography (PET) imaging to measure their uptake and biodistribution in U87MG glioblastoma murine xenograft models. NIR fluorescence and microPET imaging both showed that integrin binding affinity plays a strong role in the tumor uptake of knottin peptides. Tumor uptake at 1 hour postinjection for two high-affinity (IC(50), approximately 20 nmol/L) (64)Cu-DOTA-conjugated knottin peptides was 4.47% +/- 1.21% and 4.56% +/- 0.64% injected dose/gram (%ID/g), compared with a low-affinity knottin peptide (IC(50), approximately 0.4 mumol/L; 1.48 +/- 0.53%ID/g) and c(RGDyK) (IC(50), approximately 1 mumol/L; 2.32 +/- 0.55%ID/g), a low-affinity cyclic pentapeptide under clinical development. Furthermore, (64)Cu-DOTA-conjugated knottin peptides generated lower levels of nonspecific liver uptake ( approximately 2%ID/g) compared with c(RGDyK) ( approximately 4%ID/g) 1 hour postinjection. MicroPET imaging results were confirmed by in vivo biodistribution studies. (64)Cu-DOTA-conjugated knottin peptides were stable in mouse serum, and in vivo metabolite analysis showed minimal degradation in the blood or tumor upon injection. Thus, engineered integrin-binding knottin peptides show great potential as clinical diagnostics for a variety of cancers.

    View details for DOI 10.1158/0008-5472.CAN-08-2495

    View details for Web of Science ID 000264541300037

    View details for PubMedID 19276378

  • Stem Cell-Mediated Accelerated Bone Healing Observed with in Vivo Molecular and Small Animal Imaging Technologies in a Model of Skeletal Injury JOURNAL OF ORTHOPAEDIC RESEARCH Lee, S., Padmanabhan, P., Ray, P., Gambhir, S. S., Doyle, T., Contag, C., Goodman, S. B., Biswal, S. 2009; 27 (3): 295-302


    Adult stem cells are promising therapeutic reagents for skeletal regeneration. We hope to validate by molecular imaging technologies the in vivo life cycle of adipose-derived multipotent cells (ADMCs) in an animal model of skeletal injury. Primary ADMCs were lentivirally transfected with a fusion reporter gene and injected intravenously into mice with bone injury or sham operation. Bioluminescence imaging (BLI), [(18)F]FHBG (9-(fluoro-hydroxy-methyl-butyl-guanine)-micro-PET, [(18)F]Fluoride ion micro-PET and micro-CT were performed to monitor stem cells and their effect. Bioluminescence microscopy and immunohistochemistry were done for histological confirmation. BLI showed ADMC's traffic from the lungs then to the injury site. BLI microscopy and immunohistochemistry confirmed the ADMCs in the bone defect. Micro-CT measurements showed increased bone healing in the cell-injected group compared to the noninjected group at postoperative day 7 (p < 0.05). Systemically administered ADMC's traffic to the site of skeletal injury and facilitate bone healing, as demonstrated by molecular and small animal imaging. Molecular imaging technologies can validate the usage of adult adipose tissue-derived multipotent cells to promote fracture healing. Imaging can in the future help establish therapeutic strategies including dosage and administration route.

    View details for DOI 10.1002/jor.20736

    View details for Web of Science ID 000263307200003

    View details for PubMedID 18752273

  • A Novel Method for Direct Site-Specific Radiolabeling of Peptides Using [F-18]FDG BIOCONJUGATE CHEMISTRY Namavari, M., Cheng, Z., Zhang, R., De, A., Levi, J., Hoerner, J. K., Yaghoubi, S. S., Syud, F. A., Gambhir, S. S. 2009; 20 (3): 432-436


    We have used the well-accepted and easily available 2-[(18)F]fluoro-2-deoxyglucose ([(18)F]FDG) positron emission tomography (PET) tracer as a prosthetic group for synthesis of (18)F-labeled peptides. We herein report the synthesis of [(18)F]FDG-RGD ((18)F labeled linear RGD) and [(18)F]FDG-cyclo(RGD(D)YK) ((18)F labeled cyclic RGD) as examples of the use of [(18)F]FDG. We have successfully prepared [(18)F]FDG-RGD and [(18)F]FDG-cyclo(RGD(D)YK) in 27.5% and 41% radiochemical yields (decay corrected) respectively. The receptor binding affinity study of FDG-cyclo(RGD(D)YK) for integrin alpha(v)beta(3), using alpha(v)beta(3) positive U87MG cells confirmed a competitive displacement with (125)I-echistatin as a radioligand. The IC(50) value for FDG-cyclo(RGD(D)YK) was determined to be 0.67 +/- 0.19 muM. High-contrast small animal PET images with relatively moderate tumor uptake were observed for [(18)F]FDG-RGD and [(18)F]FDG-cyclo(RGD(D)YK) as PET probes in xenograft models expressing alpha(v)beta(3) integrin. In conclusion, we have successfully used [(18)F]FDG as a prosthetic group to prepare (18)F]FDG-RGD and [(18)F]FDG-cyclic[RGD(D)YK] based on a simple one-step radiosynthesis. The one-step radiosynthesis methodology consists of chemoselective oxime formation between an aminooxy-functionalized peptide and [(18)F]FDG. The results have implications for radiolabeling of other macromolecules and would lead to a very simple strategy for routine preclinical and clinical use.

    View details for DOI 10.1021/bc800422b

    View details for Web of Science ID 000264389800005

    View details for PubMedID 19226160

  • Development of a breast cancer brain metastases model to study I-131 radioablative therapy. 31st Annual Meeting of the San Antonio Breast Cancer Symposium Renier, C., De, A., Hou, L., Dunkel, J., Sun, A., Prugpichailers, T., Gambhir, S. S., Tse, V., Wapnir, I. L. AMER ASSOC CANCER RESEARCH. 2009: 159S–160S
  • Protein-Functionalized Synthetic Antiferromagnetic Nanoparticles for Biomolecule Detection and Magnetic Manipulation ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Fu, A., Hu, W., Xu, L., Wilson, R. J., Yu, H., Osterfeld, S. J., Gambhir, S. S., Wang, S. X. 2009; 48 (9): 1620-1624


    Direct protein functionalization provides synthetic antiferromagnetic nanoparticles with high chemical specificity and multifunctionality. These nanoparticle-protein conjugates function as improved magnetic labels for biological detection experiments, and exhibit tunable responses to a small external magnetic field gradient, thus allowing the observation of distinctive single nanoparticle motion.

    View details for DOI 10.1002/anie.200803994

    View details for Web of Science ID 000263642300018

    View details for PubMedID 19156803

  • Human adipose tissue-derived menesenchymal stromal cells as vehicles for tumor bystander effect: A model based on bioluminescence imaging Gene Therapy Vilalta M, Degano I, Bago J, Aguilar E, Gambhir SS, Rubio N, Blanco J 2009; 16 (4): 547-557
  • Controlling the selection stringency of phage display using a microfluidic device LAB ON A CHIP Liu, Y., Adams, J. D., Turner, K., Cochran, F. V., Gambhir, S. S., Soh, H. T. 2009; 9 (8): 1033-1036


    We report the utilization of microfluidic technology to phage selection and demonstrate that accurate control of washing stringency in our microfluidic magnetic separator (MMS) directly impacts the diversity of isolated peptide sequences. Reproducible generation of magnetic and fluidic forces allows controlled washing conditions that enable rapid convergence of selected peptide sequences. These findings may provide a foundation for the development of automated microsystems for rapid in vitro directed evolution of affinity reagents.

    View details for DOI 10.1039/b820985e

    View details for Web of Science ID 000264978800001

    View details for PubMedID 19350081

  • Endogenous NIS expression in triple negative breast cancers Annals of Surgical Oncology Renier C, Yao C, Goris M, Ghosh M, Katznelson L, Nowles K, Gambhir SS, Wapnir I 2009; 16 (4): 962-968
  • Effects of Creatine on Survival, Migration, and Differentiation of Neural Stem Cells 16th Annual Meeting of the American-Society-for-Neural-Therapy-and-Repair Andres, R. H., PENDHARKAR, A. V., Guzman, R., De, A., Bliss, T. M., McMillan, E., Svendsen, C. N., Gambhir, S. S., Widmer, H. R., Wallimann, T., Steinberg, G. K. COGNIZANT COMMUNICATION CORP. 2009: 208–
  • Lymphoid tissue-specific homing of bone marrow-derived dendritic cells Blood Creusot R, Yaghoubi S, Chang P, Chia J, Contag C, Gambhir SS, Fathman C 2009; 113 (26): 6638-47
  • Embryonic stem cell-derived endothelial cells for treatment of hindlimb ischemia. Journal of visualized experiments : JoVE Huang, N. F., Niiyama, H., De, A., Gambhir, S. S., Cooke, J. P. 2009


    Peripheral arterial disease (PAD) results from narrowing of the peripheral arteries that supply oxygenated blood and nutrients to the legs and feet, This pathology causes symptoms such as intermittent claudication (pain with walking), painful ischemic ulcerations, or even limb-threatening gangrene. It is generally believed that the vascular endothelium, a monolayer of endothelial cells that invests the luminal surface of all blood and lymphatic vessels, plays a dominant role in vascular homeostasis and vascular regeneration. As a result, stem cell-based regeneration of the endothelium may be a promising approach for treating PAD. In this video, we demonstrate the transplantation of embryonic stem cell (ESC)-derived endothelial cells for treatment of unilateral hindimb ischemia as a model of PAD, followed by non-invasive tracking of cell homing and survival by bioluminescence imaging. The specific materials and procedures for cell delivery and imaging will be described. This protocol follows another publication in describing the induction of hindlimb ischemia by Niiyama et al.

    View details for DOI 10.3791/1034

    View details for PubMedID 19229180

    View details for PubMedCentralID PMC2781824

  • Noninvasive detection of therapeutic cytolytic T cells with F-18-FHBG PET in a patient with glioma NATURE CLINICAL PRACTICE ONCOLOGY Yaghoubi, S. S., Jensen, M. C., Satyamurthy, N., Budhiraja, S., Paik, D., Czernin, J., Gambhir, S. S. 2009; 6 (1): 53-58


    A 57-year-old man had been diagnosed with grade IV glioblastoma multiforme and was enrolled in a trial of adoptive cellular immunotherapy. The trial involved infusion of ex vivo expanded autologous cytolytic CD8+ T cells (CTLs), genetically engineered to express the interleukin 13 zetakine gene (which encodes a receptor protein that targets these T cells to tumor cells) and the herpes simplex virus 1 thymidine kinase (HSV1 tk) suicide gene, and PET imaging reporter gene.MRI, whole-body and brain PET scan with (18)F-radiolabelled 9-[4-fluoro-3-(hydroxymethyl)butyl]guanine ((18)F-FHBG) to detect CTLs that express HSV1 tk, and safety monitoring after injection of (18)F-FHBG.MRI detected grade III-IV glioblastoma multiforme plus two tumors recurrences that developed after resection of the initial tumor.Surgical resection of primary glioblastoma tumor, enrollment in CTL therapy trial, reresection of glioma recurrences, infusion of approximately 1 x 10(9) CTLs into the site of tumor reresection, and (18)F-FHBG PET scan to detect infused CTLs.

    View details for DOI 10.1038/ncponc1278

    View details for Web of Science ID 000261845300011

    View details for PubMedID 19015650

    View details for PubMedCentralID PMC3526373

  • A novel high-sensitivity rapid acquisition single photon cardiac imaging camera Journal of Nuclear Medicine Gambhir SS, Berman D, Ziffer J, Nagler M, Sandler M, Patton J, Hutton B, Sharir T, Haim S 2009; 50 (4): 635-643
  • An Engineered Knottin Peptide Labeled with [18F] for PET Imaging of Integrin Expression. Bioconjugate Chemistry Miao Z, Ren G, Liu H, Kimura R, Jiang L, Cochran J, Gambhir SS, Cheng Z. 2009; 20(12): 2342-2347
  • Particle Size, Surface Coating, and PEGylation Influence the Biodistribution of Quantum Dots in Living Mice SMALL Schipper, M. L., Iyer, G., Koh, A. L., Cheng, Z., Ebenstein, Y., Aharoni, A., Keren, S., Bentolila, L. A., Li, J., Rao, J., Chen, X., Banin, U., Wu, A. M., Sinclair, R., Weiss, S., Gambhir, S. S. 2009; 5 (1): 126-134


    This study evaluates the influence of particle size, PEGylation, and surface coating on the quantitative biodistribution of near-infrared-emitting quantum dots (QDs) in mice. Polymer- or peptide-coated 64Cu-labeled QDs 2 or 12 nm in diameter, with or without polyethylene glycol (PEG) of molecular weight 2000, are studied by serial micropositron emission tomography imaging and region-of-interest analysis, as well as transmission electron microscopy and inductively coupled plasma mass spectrometry. PEGylation and peptide coating slow QD uptake into the organs of the reticuloendothelial system (RES), liver and spleen, by a factor of 6-9 and 2-3, respectively. Small particles are in part renally excreted. Peptide-coated particles are cleared from liver faster than physical decay alone would suggest. Renal excretion of small QDs and slowing of RES clearance by PEGylation or peptide surface coating are encouraging steps toward the use of modified QDs for imaging living subjects.

    View details for DOI 10.1002/smll.200800003

    View details for Web of Science ID 000262895300019

    View details for PubMedID 19051182

    View details for PubMedCentralID PMC3084659

  • AUTOMATED RADIOSYNTHESIS OF [F-18]EF-5 FOR IMAGING HYPOXIA IN HUMAN Chin, F. T., Subbarayan, M., Sorger, J., Gambhir, S. S., Graves, E. E. WILEY-BLACKWELL. 2009: S274–S274
  • Trafficking Mesenchymal Stem Cell Engraftment and Differentiation in Tumor-Bearing Mice by Bioluminescence Imaging STEM CELLS Wang, H., Cao, F., De, A., Cao, Y., Contag, C., Gambhir, S. S., Wu, J. C., Chen, X. 2009; 27 (7): 1548-1558


    The objective of the study was to track the distribution and differentiation of mesenchymal stem cells (MSCs) in tumor-bearing mice. The 4T1 murine breast cancer cells were labeled with renilla luciferase-monomeric red fluorescence protein (rLuc-mRFP) reporter gene. The MSCs labeled with firefly luciferase-enhanced green fluorescence protein (fLuc-eGFP) reporter gene (MSCs-R) were isolated from L2G85 transgenic mice that constitutively express fLuc-eGFP reporter gene. To study the tumor tropism of MSCs, we established both subcutaneous and lung metastasis models. In lung metastasis tumor mice, we injected MSCs-R intravenously either on the same day or 4 days after 4T1 tumor cell injection. In subcutaneous tumor mice, we injected MSCs-R intravenously 7 days after subcutaneous 4T1 tumor inoculation. The tumor growth was monitored by rLuc bioluminescence imaging (BLI). The fate of MSCs-R was monitored by fLuc BLI. The localization of MSCs-R in tumors was examined histologically. The osteogenic and adipogenic differentiation of MSCs-R was investigated by alizarin red S and oil red O staining, respectively. The mechanism of the dissimilar differentiation potential of MSCs-R under different tumor microenvironments was investigated. We found that the 4T1 cells were successfully labeled with rLuc-mRFP. The MSCs-R isolated from L2G85 transgenic mice constitutively express fLuc-eGFP reporter gene. When injected intravenously, MSCs-R survived, proliferated, and differentiated in tumor sites but not elsewhere. The localization of GFP(+) MSCs-R in tumor lesions was confirmed ex vivo. In conclusion, the MSCs-R can selectively localize, survive, and proliferate in both subcutaneous tumor and lung metastasis as evidenced by noninvasive bioluminescence imaging and ex vivo validation. The MSCs-R migrated to lung tumor differentiated into osteoblasts, whereas the MSCs-R targeting subcutaneous tumor differentiated into adipocytes.

    View details for DOI 10.1002/stem.81

    View details for Web of Science ID 000268257100011

    View details for PubMedID 19544460

    View details for PubMedCentralID PMC4161123

  • Multimodality Molecular Imaging of Transplanted Neural Progenitor Cells 16th Annual Meeting of the American-Society-for-Neural-Therapy-and-Repair PENDHARKAR, A. V., De, A., Wang, H., Gaeta, X., Wang, N., Andres, R. H., Chen, X., Gambhir, S. S., Guzman, R. COGNIZANT COMMUNICATION CORP. 2009: 230–31
  • F-18-FDG PET/CT evaluation of patients with ovarian carcinoma NUCLEAR MEDICINE COMMUNICATIONS Iagaru, A. H., Mittra, E. S., McDougall, I. R., Quon, A., Gambhir, S. S. 2008; 29 (12): 1046-1051


    The role of F-FDG PET has been studied in ovarian carcinoma, but its sensitivity and specificity calculations are based on dedicated PET acquisition, not PET/CT in the majority of the published studies. Therefore, we were prompted to review our experience with PET/CT in the management of patients with ovarian carcinoma.This is a retrospective study of 43 women with ovarian carcinoma, 27-80 years old (average: 53.9+/-7.8), who had whole-body PET/CT at our institution from 1 January 2003 to 31 August 2006. We reviewed the patients' outcomes from medical records and compared them to the interpretation of the PET/CT scans. Sensitivity and specificity were calculated using a 2 x 2 table with pathology results (79.1% of the patients) or clinical follow-up (20.9% of the cases) as the 'gold standard'. Confidence interval (CI) estimations were performed using the Wilson score method.All patients had advanced stage ovarian cancer and the study was requested for re-staging. A total of 60 scans were performed: 30 patients had one scan, nine patients had two scans and four patients had three scans. The administered doses of F-FDG ranged from 381.1 to 769.6 MBq (average: 569.8+/-73.3). PET/CT had a sensitivity of 88.4% (95% CI: 75.1-95.4) and a specificity of 88.2% (95% CI: 64.4-97.9) for detection of ovarian cancer. The SUV max of the detected lesions ranged from 3 to 27 (average: 9.4+/-5.9). The CA-125 tumor marker ranged from 3 to 935 kU/ml (average: 265.2) in patients with positive scans and 4-139 kU/ml (average: 17.1) in patients with negative scans. This difference was statistically significant (P value: 0.0242).This study confirms the good results of F-FDG PET/CT for identification of residual/recurrent ovarian cancer, as well as for distant metastases localization. PET/CT should be an integral part in evaluation of patients with high-risk ovarian cancer or rising values of tumor markers (CA-125), prior to selection of the most appropriate therapy.

    View details for DOI 10.1097/MNM.0b013e32831089cb

    View details for Web of Science ID 000261164200004

    View details for PubMedID 18987524

  • Uptake kinetics and biodistribution of C-14-D-luciferin-a radiolabeled substrate for the firefly luciferase catalyzed bioluminescence reaction: impact on bioluminescence based reporter gene imaging EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Berger, F., Paulmurugan, R., Bhaumik, S., Gambhir, S. S. 2008; 35 (12): 2275-2285


    Firefly luciferase catalyzes the oxidative decarboxylation of D: -luciferin to oxyluciferin in the presence of cofactors, producing bioluminescence. This reaction is used in optical bioluminescence-based molecular imaging approaches to detect the expression of the firefly luciferase reporter gene. Biokinetics and distribution of the substrate most likely have a significant impact on levels of light signal and therefore need to be investigated.Benzene ring (14)C(U)-labeled D-luciferin was utilized. Cell uptake and efflux assays, murine biodistribution, autoradiography and CCD-camera based optical bioluminescence imaging were carried out to examine the in vitro and in vivo characteristics of the tracer in cell culture and in living mice respectively.Radiolabeled and unlabeled D-luciferin revealed comparable levels of light emission when incubated with equivalent amounts of the firefly luciferase enzyme. Cell uptake assays in pCMV-luciferase-transfected cells showed slow trapping of the tracer and relatively low uptake values (up to 22.9-fold higher in firefly luciferase gene-transfected vs. nontransfected cells, p = 0.0002). Biodistribution studies in living mice after tail-vein injection of (14)C-D-luciferin demonstrated inhomogeneous tracer distribution with early predominant high radioactivity levels in kidneys (10.6% injected dose [ID]/g) and liver (11.9% ID/g), followed at later time points by the bladder (up to 81.3% ID/g) and small intestine (6.5% ID/g), reflecting the elimination routes of the tracer. Kinetics and uptake levels profoundly differed when using alternate injection routes (intravenous versus intraperitoneal). No clear trapping of (14)C-D-luciferin in firefly luciferase-expressing tissues could be observed in vivo.The data obtained with (14)C-D-luciferin provide insights into the dynamics of D: -luciferin cell uptake, intracellular accumulation, and efflux. Results of the biodistribution and autoradiographic studies should be useful for optimizing and adapting optical imaging protocols to specific experimental settings when utilizing the firefly luciferase and D: -luciferin system.

    View details for DOI 10.1007/s00259-008-0870-6

    View details for Web of Science ID 000261654000015

    View details for PubMedID 18661130

  • Noninvasive Imaging of Therapeutic Gene Expression Using a Bidirectional Transcriptional Amplification Strategy MOLECULAR THERAPY Ray, S., Paulmurugan, R., Patel, M. R., Ahn, B. C., Wu, L., Carey, M., Gambhir, S. S. 2008; 16 (11): 1848-1856


    Promoters that limit transgene expression to tumors play a vital role in cancer gene therapy. Although tumor specific, the human Survivin promoter (pSurv) elicits low levels of transcription. A bidirectional two-step transcriptional amplification (TSTA) system was designed to enhance expression of the therapeutic gene (TG) tumor necrosis factor-alpha-related apoptosis-inducing ligand (TRAIL or TR) and the reporter gene firefly luciferase (FL) from pSurv. An adenoviral vector carrying the enhanced targeting apparatus (Ad-pSurv-TR-G8-FL) was tested for efficiency and specificity of gene expression in cells and in living animals. Compared to the one-step systems (Ad-pSurv-FL or Ad-pSurv-TR), the bidirectional TSTA system showed tenfold higher expression of both the therapeutic and the reporter gene and their expression correlated in cells (R(2) = 0.99) and in animals (R(2) = 0.67). Noninvasive quantitative monitoring of magnitude and time variation of TRAIL gene expression was feasible by bioluminescence imaging of the transcriptionally linked FL gene in xenograft tumors following intratumoral adenoviral injection. Moreover, the TSTA adenovirus maintained promoter specificity in nontarget tissues following tail vein administration. These studies demonstrate the potential of the bidirectional TSTA system to achieve high levels of gene expression from a weak promoter, while preserving specificity and the ability to image expression of the TG noninvasively.

    View details for DOI 10.1038/mt.2008.180

    View details for Web of Science ID 000260472600015

    View details for PubMedID 18766175

  • Transcriptional and Functional Profiling of Human Embryonic Stem Cell-Derived Cardiomyocytes PLOS ONE Cao, F., Wagner, R. A., Wilson, K. D., Xie, X., Fu, J., Drukker, M., Lee, A., Li, R. A., Gambhir, S. S., Weissman, I. L., Robbins, R. C., Wu, J. C. 2008; 3 (10)


    Human embryonic stem cells (hESCs) can serve as a potentially limitless source of cells that may enable regeneration of diseased tissue and organs. Here we investigate the use of human embryonic stem cell-derived cardiomyocytes (hESC-CMs) in promoting recovery from cardiac ischemia reperfusion injury in a mouse model. Using microarrays, we have described the hESC-CM transcriptome within the spectrum of changes that occur between undifferentiated hESCs and fetal heart cells. The hESC-CMs expressed cardiomyocyte genes at levels similar to those found in 20-week fetal heart cells, making this population a good source of potential replacement cells in vivo. Echocardiographic studies showed significant improvement in heart function by 8 weeks after transplantation. Finally, we demonstrate long-term engraftment of hESC-CMs by using molecular imaging to track cellular localization, survival, and proliferation in vivo. Taken together, global gene expression profiling of hESC differentiation enables a systems-based analysis of the biological processes, networks, and genes that drive hESC fate decisions, and studies such as this will serve as the foundation for future clinical applications of stem cell therapies.

    View details for DOI 10.1371/journal.pone.0003474

    View details for Web of Science ID 000265126100005

    View details for PubMedID 18941512

    View details for PubMedCentralID PMC2565131

  • Noninvasive Raman spectroscopy in living mice for evaluation of tumor targeting with carbon nanotubes NANO LETTERS Zavaleta, C., de la Zerda, A., Liu, Z., Keren, S., Cheng, Z., Schipper, M., Chen, X., Dai, H., Gambhir, S. S. 2008; 8 (9): 2800-2805


    An optimized noninvasive Raman microscope was used to evaluate tumor targeting and localization of single walled carbon nanotubes (SWNTs) in mice. Raman images were acquired in two groups of tumor-bearing mice. The control group received plain-SWNTs, whereas the experimental group received tumor targeting RGD-SWNTs intravenously. Raman imaging commenced over the next 72 h and revealed increased accumulation of RGD-SWNTs in tumor ( p < 0.05) as opposed to plain-SWNTs. These results support the development of a new preclinical Raman imager.

    View details for DOI 10.1021/nl801362a

    View details for Web of Science ID 000259140200034

    View details for PubMedID 18683988

  • F-18-FDG-PET/CT evaluation of response to treatment in lymphoma: when is the optimal time for the first re-evaluation scan? HELLENIC JOURNAL OF NUCLEAR MEDICINE Iagaru, A., Wang, Y., Mari, C., Quon, A., Goris, M. L., Horning, S., Gambhir, S. S. 2008; 11 (3): 153-156


    Assessing the response to treatment as soon after treatment initiation is one of the key reasons for imaging lymphoma patients. The optimal time after initiating treatment for assessing response to treatment has yet to be determined. Therefore, we were prompted to review our experience with serial (18)F-FDG PET/CT in patients undergoing treatment for Hodgkin's disease (HD) and non Hodgkin's lymphoma (NHL). This is a retrospective study (Feb 2003 - Oct 2004) of 20 patients, 11 men and 9 women, with age range of 7-75 years with diagnosis of HD (10) and NHL (10), who had PET/CT at our institution prior, during and at the completion of therapy. Restaging PET/CT was done after 2 cycles of chemotherapy in 10 patients (group A) and after 4 cycles of chemotherapy in 10 pts (group B). A total of 60 scans were reviewed. The DeltaSUV from baseline to first PET/CT was on average 67.6% in group A and 75.1% in group B. This had no statistical significance (P value: 0.31). The DeltaSUV from baseline to post-therapy PET/CT was on average 72.9% in group A and 79.8% in group B. This difference also had no statistical significance (P value: 0.24). The correlation coefficient was 0.98 in group A and 0.80 in group B. Results of PET/CT after 2 cycles of chemotherapy did not statistically differ from the results of PET/CT after 4 cycles of chemotherapy. These results need to be confirmed in larger, prospective, randomized trials.

    View details for Web of Science ID 000262093600003

    View details for PubMedID 19081857

  • Carbon nanotubes as photoacoustic molecular imaging agents in living mice NATURE NANOTECHNOLOGY de la Zerda, A., Zavaleta, C., Keren, S., Vaithilingam, S., Bodapati, S., Liu, Z., Levi, J., Smith, B. R., Ma, T., Oralkan, O., Cheng, Z., Chen, X., Dai, H., Khuri-Yakub, B. T., Gambhir, S. S. 2008; 3 (9): 557-562


    Photoacoustic imaging of living subjects offers higher spatial resolution and allows deeper tissues to be imaged compared with most optical imaging techniques. As many diseases do not exhibit a natural photoacoustic contrast, especially in their early stages, it is necessary to administer a photoacoustic contrast agent. A number of contrast agents for photoacoustic imaging have been suggested previously, but most were not shown to target a diseased site in living subjects. Here we show that single-walled carbon nanotubes conjugated with cyclic Arg-Gly-Asp (RGD) peptides can be used as a contrast agent for photoacoustic imaging of tumours. Intravenous administration of these targeted nanotubes to mice bearing tumours showed eight times greater photoacoustic signal in the tumour than mice injected with non-targeted nanotubes. These results were verified ex vivo using Raman microscopy. Photoacoustic imaging of targeted single-walled carbon nanotubes may contribute to non-invasive cancer imaging and monitoring of nanotherapeutics in living subjects.

    View details for DOI 10.1038/nnano.2008.231

    View details for Web of Science ID 000259013100014

    View details for PubMedID 18772918

  • Cancer screening: A mathematical model relating secreted blood biomarker levels to tumor sizes PLOS MEDICINE Lutz, A. M., Willmann, J. K., Cochran, F. V., Ray, P., Gambhir, S. S. 2008; 5 (8): 1287-1297


    Increasing efforts and financial resources are being invested in early cancer detection research. Blood assays detecting tumor biomarkers promise noninvasive and financially reasonable screening for early cancer with high potential of positive impact on patients' survival and quality of life. For novel tumor biomarkers, the actual tumor detection limits are usually unknown and there have been no studies exploring the tumor burden detection limits of blood tumor biomarkers using mathematical models. Therefore, the purpose of this study was to develop a mathematical model relating blood biomarker levels to tumor burden.Using a linear one-compartment model, the steady state between tumor biomarker secretion into and removal out of the intravascular space was calculated. Two conditions were assumed: (1) the compartment (plasma) is well-mixed and kinetically homogenous; (2) the tumor biomarker consists of a protein that is secreted by tumor cells into the extracellular fluid compartment, and a certain percentage of the secreted protein enters the intravascular space at a continuous rate. The model was applied to two pathophysiologic conditions: tumor biomarker is secreted (1) exclusively by the tumor cells or (2) by both tumor cells and healthy normal cells. To test the model, a sensitivity analysis was performed assuming variable conditions of the model parameters. The model parameters were primed on the basis of literature data for two established and well-studied tumor biomarkers (CA125 and prostate-specific antigen [PSA]). Assuming biomarker secretion by tumor cells only and 10% of the secreted tumor biomarker reaching the plasma, the calculated minimally detectable tumor sizes ranged between 0.11 mm(3) and 3,610.14 mm(3) for CA125 and between 0.21 mm(3) and 131.51 mm(3) for PSA. When biomarker secretion by healthy cells and tumor cells was assumed, the calculated tumor sizes leading to positive test results ranged between 116.7 mm(3) and 1.52 x 10(6) mm(3) for CA125 and between 27 mm(3) and 3.45 x 10(5) mm(3) for PSA. One of the limitations of the study is the absence of quantitative data available in the literature on the secreted tumor biomarker amount per cancer cell in intact whole body animal tumor models or in cancer patients. Additionally, the fraction of secreted tumor biomarkers actually reaching the plasma is unknown. Therefore, we used data from published cell culture experiments to estimate tumor cell biomarker secretion rates and assumed a wide range of secretion rates to account for their potential changes due to field effects of the tumor environment.This study introduced a linear one-compartment mathematical model that allows estimation of minimal detectable tumor sizes based on blood tumor biomarker assays. Assuming physiological data on CA125 and PSA from the literature, the model predicted detection limits of tumors that were in qualitative agreement with the actual clinical performance of both biomarkers. The model may be helpful in future estimation of minimal detectable tumor sizes for novel proteomic biomarker assays if sufficient physiologic data for the biomarker are available. The model may address the potential and limitations of tumor biomarkers, help prioritize biomarkers, and guide investments into early cancer detection research efforts.

    View details for DOI 10.1371/journal.pmed.0050170

    View details for Web of Science ID 000258739200018

    View details for PubMedID 18715113

  • A generalizable strategy for imaging pre-mRNA levels in living subjects using spliceosome-mediated RNA trans-splicing JOURNAL OF NUCLEAR MEDICINE Walls, Z. F., Puttaraju, M., Temple, G. F., Gambhir, S. S. 2008; 49 (7): 1146-1154


    Molecular imaging of gene expression is currently hindered by the lack of a generalizable platform for probe design. For any gene of interest, a probe that targets protein levels must often be generated empirically. Targeting gene expression at the level of mRNA, however, would allow probes to be built on the basis of sequence information alone. Presented here is a class of generalizable probes that can image pre-mRNA in a sequence-specific manner, using signal amplification and a facile method of delivery.Pre-trans-splicing molecules (PTMs) were engineered to capitalize on the phenomenon of spliceosome-mediated RNA trans-splicing. Using a modular binding domain that confers specificity by base-pair complementarity to the target pre-mRNA, PTMs were designed to target a chimeric target mini gene and trans-splice the Renilla luciferase gene onto the end of the target. PTMs and target genes were transfected in cell culture and assessed by luciferase assay, reverse-transcriptase polymerase chain reaction, Western blot, and rapid analysis of 5' cDNA ends. PTMs and target genes were also assessed in vivo by hydrodynamic delivery in mice.Efficiency and specificity of the trans-splicing reaction were found to vary depending on the binding domain length and structure. Specific trans-splicing was observed in living animals (P = 0.0862, Kruskal-Wallis test).Described here is a model system used to demonstrate the feasibility of spliceosome-mediated RNA trans-splicing for imaging gene expression at the level of pre-mRNA using optical imaging techniques in living animals. The experiments reported here show proof of principle for a generalizable imaging probe against RNA that can amplify signal on detection and be delivered using existing gene delivery methodology.

    View details for DOI 10.2967/jnumed.107.047662

    View details for Web of Science ID 000257599700021

    View details for PubMedID 18552150

  • Direct site-specific radiolabeling of an affibody protein with 4-[F-18]fluorobenzaldehyde via oxime chemistry MOLECULAR IMAGING AND BIOLOGY Namavari, M., De Jesus, O. P., Cheng, Z., De, A., Kovacs, E., Levi, J., Zhang, R., Hoerner, J. K., Grade, H., Syud, F. A., Gambhir, S. S. 2008; 10 (4): 177-181
  • Direct site-specific radiolabeling of an Affibody protein with 4-[18F]fluorobenzaldehyde via oxime chemistry. Molecular imaging and biology Namavari, M., Padilla De Jesus, O., Cheng, Z., De, A., Kovacs, E., Levi, J., Zhang, R., Hoerner, J. K., Grade, H., Syud, F. A., Gambhir, S. S. 2008; 10 (4): 177-181


    In this study, we introduce a methodology for preparing 18F-labeled Affibody protein, specifically 18F-Anti-HER2 dimeric Affibody (14 kDa), for in vivo imaging of HER2neu with positron emission tomography (PET).We have used 4-[18F]fluorobenzaldehyde as a synthon to prepare 18F-Anti-HER2 Affibody. Aminooxy-functionalized Affibody (Anti-HER2-ONH2) was incubated with 4-[18F]fluorobenzaldehyde in ammonium acetate buffer at pH 4 in the presence of methanol at 70 degrees C for 15 min. The resulting 18F-labeled Affibody molecule was evaluated as a PET probe in xenograft models expressing HER2.We have successfully prepared 18F-Anti-HER2 dimeric Affibody (14 kDa), N-(4-[18F]fluorobenzylidine)oxime-Anti-HER2 Affibody, [18F]FBO-Anti-HER2, in 26-30% radiochemical yields (decay corrected). High-contrast small-animal PET images with relatively moderate tumor uptake (1.79 +/- 0.40% ID/g) were observed for the 18F-Anti-HER2 Affibody.Site-specific 18F-labeled Affibody against HER2 has been synthesized via chemoselective oxime formation between an aminooxy-functionalized Affibody and 18F-fluorobenzaldehyde. The results have implications for radiolabeling of other affibodies and macromolecules and should also be important for advancing Affibody imaging with PET.

    View details for DOI 10.1007/s11307-008-0142-7

    View details for PubMedID 18481153

  • A human estrogen receptor (ER)alpha mutation with differential responsiveness to nonsteroidal ligands: Novel approaches for studying mechanism of ER action MOLECULAR ENDOCRINOLOGY Paulmurugan, R., Tamrazi, A., Katzenellenbogen, J. A., Katzenellenbogen, B. S., Gambhir, S. S. 2008; 22 (7): 1552-1564


    Estrogens, acting through the estrogen receptors (ERs), play crucial roles in regulating the function of reproductive and other systems under physiological and pathological conditions. ER activity in regulating target genes is modulated by the binding of both steroidal and synthetic nonsteroidal ligands, with ligand binding inducing ERs to adopt various conformations that control their interactions with transcriptional coregulators. Previously, we developed an intramolecular folding sensor with a mutant form of ERalpha (ER(G521T)) that proved to be essentially unresponsive to the endogenous ligand 17beta-estradiol, yet responded very well to certain synthetic ligands. In this study, we have characterized this G521T-ER mutation in terms of the potency and efficacy of receptor response toward several steroidal and nonsteroidal ligands in two different ways: directly, by ligand effects on mutant ER conformation (by the split-luciferase complementation system), and indirectly, by ligand effects on mutant ER transactivation. Full-length G521T-ER shows no affinity for estradiol and does not activate an estrogen-responsive reporter gene. The synthetic pyrazole agonist ligand propyl-pyrazole-triol is approximately 100-fold more potent than estradiol in inducing intramolecular folding and reporter gene transactivation with the mutant ER, whereas both ligands have high potency on wild-type ER. This estradiol-unresponsive mutant ER can also specifically highlight the agonistic property of the selective ER modulator, 4-hydroxytamoxifen, by reporter gene transactivation, even in the presence of estradiol, and it can exert a dominant-negative effect on estrogen-stimulated wild-type ER. This system provides a model for ER-mutants that show differential ligand responsiveness to gene activation to gain insight into the phenomenon of hormone resistance observed in endocrine therapies of ER-positive breast cancers.

    View details for DOI 10.1210/me.2007-0570

    View details for Web of Science ID 000257144500004

    View details for PubMedID 18451095

  • Molecular imaging of cancer: From molecules to humans - Introduction JOURNAL OF NUCLEAR MEDICINE Gambhir, S. S. 2008; 49: 1S-4S

    View details for DOI 10.2967/jnumed.108.053751

    View details for Web of Science ID 000256491100001

    View details for PubMedID 18523062

  • Molecular Imaging of Hypoxia-Inducible Factor 1 alpha and von Hippel-Lindau Interaction in Mice MOLECULAR IMAGING Choi, C. Y., Chau, D. A., Paulmurugan, R., Sutphin, P. D., Le, Q., Koong, A. C., Zundel, W., Gambhir, S. S., Giaccia, A. J. 2008; 7 (3): 139-146


    Tumor hypoxia plays a crucial role in tumorigenesis. Under hypoxia, hypoxia-inducible factor 1 alpha (HIF-1 alpha) regulates activation of genes promoting malignant progression. Under normoxia, HIF-1 alpha is hydroxylated on prolines 402 and 564 and is targeted for ubiquitin-mediated degradation by interacting with the von Hippel-Lindau protein complex (pVHL). We have developed a novel method of studying the interaction between HIF-1 alpha and pVHL using the split firefly luciferase complementation-based bioluminescence system in which HIF-1 alpha and pVHL are fused to amino-terminal and carboxy-terminal fragments of the luciferase, respectively. We demonstrate that hydroxylation-dependent interaction between the HIF-1 alpha and pVHL leads to complementation of the two luciferase fragments, resulting in bioluminescence in vitro and in vivo. Complementation-based bioluminescence is diminished when mutant pVHLs with decreased affinity for binding HIF-1 alpha are used. This method represents a new approach for studying interaction of proteins involved in the regulation of protein degradation.

    View details for DOI 10.2310/7290.2008.00017

    View details for Web of Science ID 000260954700004

    View details for PubMedID 19123984

  • Cell-free metabolic engineering promotes high-level production of bioactive Gaussia princeps luciferase METABOLIC ENGINEERING Goerke, A. R., Loening, A. M., Gambhir, S. S., Swartz, J. R. 2008; 10 (3-4): 187-200


    Due to its small size and intense luminescent signal, Gaussia princeps luciferase (GLuc) is attractive as a potential imaging agent in both cell culture and small animal research models. However, recombinant GLuc production using in vivo techniques has only produced small quantities of active luciferase, likely due to five disulfide bonds being required for full activity. Cell-free biology provides the freedom to control both the catalyst and chemical compositions in biological reactions, and we capitalized on this to produce large amounts of highly active GLuc in cell-free reactions. Active yields were improved by mutating the cell extract source strain to reduce proteolysis, adjusting reaction conditions to enhance oxidative protein folding, further activating energy metabolism, and encouraging post-translational activation. This cell-free protein synthesis procedure produced 412mug/mL of purified GLuc, relative to 5mug/mL isolated for intracellular Escherichia coli expression. The cell-free product had a specific activity of 4.2x10(24)photons/s/mol, the highest reported activity for any characterized luciferase.

    View details for DOI 10.1016/j.ymben.2008.04.001

    View details for Web of Science ID 000261595600006

    View details for PubMedID 18555198

  • Imaging of VEGF receptor in a rat myocardial infarction model using PET JOURNAL OF NUCLEAR MEDICINE Rodriguez-Porcel, M., Cai, W., Gheysens, O., Willmann, J. K., Chen, K., Wang, H., Chen, I. Y., He, L., Wu, J. C., Li, Z., Mohamedali, K. A., Kim, S., Rosenblum, M. G., Chen, X., Gambhir, S. S. 2008; 49 (4): 667-673


    Myocardial infarction (MI) leads to left ventricular (LV) remodeling, which leads to the activation of growth factors such as vascular endothelial growth factor (VEGF). However, the kinetics of a growth factor's receptor expression, such as VEGF, in the living subject has not yet been described. We have developed a PET tracer (64Cu-DOTA-VEGF121 [DOTA is 1,4,7,10-tetraazadodecane-N,N',N'',N'''-tetraacetic acid]) to image VEGF receptor (VEGFR) expression after MI in the living subject.In Sprague-Dawley rats, MI was induced by ligation of the left coronary artery and confirmed by ultrasound (n = 8). To image and study the kinetics of VEGFRs, 64Cu-DOTA-VEGF121 PET scans were performed before MI induction (baseline) and on days 3, 10, 17, and 24 after MI. Sham-operated animals served as controls (n = 3).Myocardial origin of the 64Cu-DOTA-VEGF121 signal was confirmed by CT coregistration and autoradiography. VEGFR specificity of the 64Cu-DOTA-VEGF121 probe was confirmed by in vivo use of a 64Cu-DOTA-VEGFmutant. Baseline myocardial uptake of 64Cu-DOTA-VEGF121 was minimal (0.30 +/- 0.07 %ID/g [percentage injected dose per gram of tissue]); it increased significantly after MI (day 3, 0.97 +/- 0.05 %ID/g; P < 0.05 vs. baseline) and remained elevated for 2 wk (up to day 17 after MI), after which time it returned to baseline levels.We demonstrate the feasibility of imaging VEGFRs in the myocardium. In summary, we imaged and described the kinetics of 64Cu-DOTA-VEGF121 uptake in a rat model of MI. Studies such as the one presented here will likely play a major role when studying pathophysiology and assessing therapies in different animal models of disease and, potentially, in patients.

    View details for DOI 10.2967/jnumed.107.040576

    View details for Web of Science ID 000254813600028

    View details for PubMedID 18375924

    View details for PubMedCentralID PMC2853914

  • Configurations of a two-tiered amplified gene expression system in adenoviral vectors designed to improve the specificity of in vivo prostate cancer imaging GENE THERAPY Sato, M., Figueiredo, M. L., Burton, J. B., Johnson, M., Chen, M., Powell, R., Gambhir, S. S., Carey, M., Wu, L. 2008; 15 (8): 583-593


    Effective treatment for recurrent, disseminated prostate cancer is notably limited. We have developed adenoviral vectors with a prostate-specific two-step transcriptional amplification (TSTA) system that would express therapeutic genes at a robust level to target metastatic disease. The TSTA system employs the prostate-specific antigen (PSA) promoter/enhancer to drive a potent synthetic activator, which in turn activates the expression of the therapeutic gene. In this study, we explored different configurations of this bipartite system and discovered that physical separation of the two TSTA components into E1 and E3 regions of adenovirus was able to enhance androgen regulation and cell-discriminatory expression. The TSTA vectors that express imaging reporter genes were assessed by noninvasive imaging technologies in animal models. The improved selectivity of the E1E3 configured vector was reflected in silenced ectopic expression in the lung. Significantly, the enhanced specificity of the E1E3 vector enabled the detection of lung metastasis of prostate cancer. An E1E3 TSTA vector that expresses the herpes simplex virus thymidine kinase gene can effectively direct positron emission tomography (PET) imaging of the tumor. The prostate-targeted gene delivery vectors with robust and cell-specific expression capability will advance the development of safe and effective imaging guided therapy for recurrent metastatic stages of prostate cancer.

    View details for DOI 10.1038/gt.2008.19

    View details for Web of Science ID 000254561200004

    View details for PubMedID 18305574

  • Initial evaluation of F-18-fluorothymidine (FLT) PET/CT scanning for primary pancreatic cancer EUROPEAN JOURNAL OF NUCLEAR MEDICINE AND MOLECULAR IMAGING Quon, A., Chang, S. T., Chin, F., Kamaya, A., Dick, D. W., Loo, B. W., Gambhir, S. S., Koong, A. C. 2008; 35 (3): 527-531


    The aim of this study was to evaluate the potential of (18)F-fluorothymidine (FLT) PET/CT for imaging pancreatic adenocarcinoma.This was a pilot study of five patients (four males, one female) with newly diagnosed and previously untreated pancreatic adenocarcinoma. Patients underwent FLT PET/CT, (18)F-fluorodeoxyglucose (FDG) PET/CT, and contrast-enhanced CT scanning before treatment. The presence of cancer was confirmed by histopathological analysis at the time of scanning in all five patients. The degree of FLT and FDG uptake at the primary tumor site was assessed using visual interpretation and semi-quantitative SUV analyses.The primary tumor size ranged from 2.5 x 2.8 cm to 3.5 x 7.0 cm. The SUV of FLT uptake within the primary tumor ranged from 2.1 to 3.1. Using visual interpretation, the primary cancer could be detected from background activity in two of five patients (40%) on FLT PET/CT. By comparison, FDG uptake was higher in each patient with a SUV range of 3.4 to 10.8, and the primary cancer could be detected from background in all five patients (100%).In this pilot study of five patients with primary pancreatic adenocarcinoma, FLT PET/CT scanning showed poor lesion detectability and relatively low levels of radiotracer uptake in the primary tumor.

    View details for DOI 10.1007/s00259-007-0630-z

    View details for Web of Science ID 000254402800010

    View details for PubMedID 17960376

  • Perspectives of molecular imaging and radioimmunotherapy in lymphoma RADIOLOGIC CLINICS OF NORTH AMERICA Iagaru, A., Goris, M. L., Gambhir, S. S. 2008; 46 (2): 243-252


    Successful treatment of Hodgkin lymphomas and non-Hodgkin lymphomas depends on accurate staging and prognostic estimations, as well as evaluation of response to therapy as early after initiation as possible. We focus on several aspects of molecular imaging and therapy that affect the management of patients who have lymphoma. First, we review prior use of gallium-67 citrate for evaluation of lymphoma patients, mainly from a historical perspective, since it was the mainstream lymphoma functional imaging tracer for decades. Next, we review current clinical uses of 18F Fluoro-2-Deoxyglucose (18F FDG) PET and PET/CT for evaluation of lymphoma patients and use of radioimmunotherapy in lymphoma. Finally, we discuss advances in molecular imaging that may herald the next generation of PET radiotracers after 18F FDG.

    View details for DOI 10.1016/j.rcl.2008.03.007

    View details for Web of Science ID 000258543500006

    View details for PubMedID 18619379

  • Noninvasive molecular neuroimaging using reporter genes: Part II, experimental, current, and future applications AMERICAN JOURNAL OF NEURORADIOLOGY Massoud, T. F., Singh, A., Gambhir, S. S. 2008; 29 (3): 409-418


    In this second article, we review the various strategies and applications that make use of reporter genes for molecular imaging of the brain in living subjects. These approaches are emerging as valuable tools for monitoring gene expression in diverse applications in laboratory animals, including the study of gene-targeted and trafficking cells, gene therapies, transgenic animals, and more complex molecular interactions within the central nervous system. Further development of more sensitive and selective reporters, combined with improvements in detection technology, will consolidate the position of in vivo reporter gene imaging as a versatile technique for greater understanding of intracellular biologic processes and underlying molecular neuropathology and will potentially establish a future role in the clinical management of patients with neurologic diseases.

    View details for DOI 10.3174/ajnr.A0863

    View details for Web of Science ID 000254066700002

    View details for PubMedID 18272565

  • Monitoring of the biological response to murine Hindlimb ischemia with Cu-64-labeled vascular endothelial growth factor-121 positron emission tomography CIRCULATION Willmann, J. K., Chen, K., Wang, H., Paulmurugan, R., Rollins, M., Cai, W., Wang, D. S., Chen, I. Y., Gheysens, O., Rodriguez-Porcel, M., Chen, X., Gambhir, S. S. 2008; 117 (7): 915-922


    Vascular endothelial growth factor-121 (VEGF121), an angiogenic protein secreted in response to hypoxic stress, binds to VEGF receptors (VEGFRs) overexpressed on vessels of ischemic tissue. The purpose of this study was to evaluate 64Cu-VEGF121 positron emission tomography for noninvasive spatial, temporal, and quantitative monitoring of VEGFR2 expression in a murine model of hindlimb ischemia with and without treadmill exercise training.64Cu-labeled VEGF121 and a VEGF mutant were tested for VEGFR2 binding specificity in cell culture. Mice (n=58) underwent unilateral ligation of the femoral artery, and postoperative tissue ischemia was assessed with laser Doppler imaging. Longitudinal VEGFR2 expression in exercised and nonexercised mice was quantified with 64Cu-VEGF121 positron emission tomography at postoperative day 8, 15, 22, and 29 and correlated with postmortem gamma-counting. Hindlimbs were excised for immunohistochemistry, Western blotting, and microvessel density measurements. Compared with the VEGF mutant, VEGF121 showed specific binding to VEGFR2. Perfusion in ischemic hindlimbs fell to 9% of contralateral hindlimb on postoperative day 1 and recovered to 82% on day 29. 64Cu-VEGF121 uptake in ischemic hindlimbs increased significantly (P < 0.001) from a control level of 0.61+/-0.17% ID/g (percentage of injected dose per gram) to 1.62+/-0.35% ID/g at postoperative day 8, gradually decreased over the following 3 weeks (0.59+/-0.14% ID/g at day 29), and correlated with gamma-counting (R2 = 0.99). Compared with nonexercised mice, 64Cu-VEGF121 uptake was increased significantly (P < or = 0.0001) in exercised mice (at day 15, 22, and 29) and correlated with VEGFR2 levels as obtained by Western blotting (R2 = 0.76). Ischemic hindlimb tissue stained positively for VEGFR2. In exercised mice, microvessel density was increased significantly (P<0.001) compared with nonexercised mice.64Cu-VEGF121 positron emission tomography allows longitudinal spatial and quantitative monitoring of VEGFR2 expression in murine hindlimb ischemia and indirectly visualizes enhanced angiogenesis stimulated by treadmill exercise training.

    View details for DOI 10.1161/CIRCULATIONAHA.107.733220

    View details for Web of Science ID 000253428100008

    View details for PubMedID 18250264

    View details for PubMedCentralID PMC4157592

  • Reporter gene imaging following percutaneous delivery in swine - Moving toward clinical applications JOURNAL OF THE AMERICAN COLLEGE OF CARDIOLOGY Rodriguez-Porcel, M., Brinton, T. J., Chen, I. Y., Gheysens, O., Lyons, J., Ikeno, F., Willmann, J. K., Wu, L., Wu, J. C., Yeung, A. C., Yock, P., Gambhir, S. S. 2008; 51 (5): 595-597

    View details for DOI 10.1016/j.jacc.2007.08.063

    View details for Web of Science ID 000252908600013

    View details for PubMedID 18237691

  • Noninvasive molecular neuroimaging using reporter genes: Part I, principles revisited AMERICAN JOURNAL OF NEURORADIOLOGY Massoud, T. F., Singh, A., Gambhir, S. S. 2008; 29 (2): 229-234


    In this first article, we review the basic principles of using reporter genes for molecular imaging of the brain in living subjects. This approach is emerging as a valuable tool for monitoring gene expression in diverse applications in laboratory animals, including the study of gene-targeted and trafficking cells, gene therapies, transgenic animals, and more complex molecular interactions within the central nervous system. Further development of more sensitive and selective reporters, combined with improvements in detection technology, will consolidate the position of in vivo reporter gene imaging as a versatile method for greater understanding of intracellular biologic processes and underlying molecular neuropathology and will potentially establish a future role in the clinical management of patients with neurologic diseases.

    View details for DOI 10.3174/ajnr.A0864

    View details for Web of Science ID 000253345200011

    View details for PubMedID 18024575

  • US imaging of tumor angiogenesis with microbubbles targeted to vascular endothelial growth factor receptor type 2 in mice RADIOLOGY Willmann, J. K., Paulmurugan, R., Chen, K., Gheysens, O., Rodriguez-Porcel, M., Lutz, A. M., Chen, I. Y., Chen, X., Gambhir, S. S. 2008; 246 (2): 508-518


    To prospectively evaluate contrast material-enhanced ultrasonography (US) with microbubbles targeted to vascular endothelial growth factor receptor type 2 (VEGFR2) for imaging tumor angiogenesis in two murine tumor models.Animal protocols were approved by the Institutional Administrative Panel on Laboratory Animal Care. A US contrast agent, consisting of encapsulated gaseous microbubbles, was developed specifically to bind to VEGFR2 (by using anti-VEGFR2 antibodies and biotin-streptavidin interaction) which is up-regulated on endothelial cells of tumor blood vessels. VEGFR2-targeted microbubbles (MB(V)), control microbubbles (MB(C)), and nonlabeled microbubbles (MB(N)) were tested for binding specificity on cells expressing VEGFR2 (mouse angiosarcoma SVR cells) and control cells (mouse skeletal myoblast C2C12 cells). Expression of mouse VEGFR2 in culture cells was tested with immunocytochemical and Western blot analysis. Contrast-enhanced US imaging with MB(V) and MB(C) was performed in 28 tumor-bearing nude mice (mouse angiosarcoma, n = 18; rat malignant glioma, n = 10). Differences were calculated by using analysis of variance.In cell culture, adherence of MB(V) on SVR cells (2.1 microbubbles per SVR cell) was significantly higher than adherence of control microbubbles (0.01-0.10 microbubble per SVR cell; P < .001) and significantly more MB(V) attached to SVR cells than to C2C12 cells (0.15 microbubble per C2C12 cell; P < .001). In vivo, contrast-enhanced US imaging showed significantly higher average video intensity when using MB(V) compared with MB(C) for angiosarcoma and malignant glioma tumors (P < .001). Results of immunohistochemical analysis confirmed VEGFR2 expression on vascular endothelial cells of both tumor types.US imaging with contrast microbubbles targeted to VEGFR2 allows noninvasive visualization of VEGFR2 expression in tumor vessels in mice.

    View details for DOI 10.1148/radio1.2462070536

    View details for Web of Science ID 000252796300021

    View details for PubMedID 18180339

  • 90Y Ibritumomal therapy in refractory non-Hodgkins lymphoma: Observations from 111 in-ibritumomab pre-treatment imaging Journal of Nuclear Medicine Iagaru A, Gambhir SS, Goris M 2008; 49 (11): 1809-1812
  • Molecular Imaging of Cancer: From Molecules to Humans. Introduction. Molecular Imaging of Cancer: From Molecules to Humans. Introduction. Gambhir, S. 2008; 49: 1S-4S
  • Use of Bioluminescent Imaging to Assay the Transplantation of Immortalized Human Fetal Hepatocytes Into Mice CELL TRANSPLANTATION Choi, M. S., Catana, A. M., Wu, J., Kim, Y. S., Yoon, S. J., Borowsky, A. D., Gambhir, S. S., Gupta, S., Zern, M. A. 2008; 17 (8): 899-909


    Noninvasive serial monitoring of the fate of transplanted cells would be invaluable to evaluate the potential therapeutic use of human hepatocyte transplantation. Therefore, we assessed the feasibility of bioluminescent imaging using double or triple fusion lentiviral vectors in a NOD-SCID mouse model transplanted with immortalized human fetal hepatocytes. Lentiviral vectors driven by the CMV promoter were constructed carrying reporter genes: firefly luciferase and green fluorescence protein with or without herpes simplex virus type 1 thymidine kinase. Human fetal hepatocytes immortalized by telomerase reconstitution (FH-hTERT) were successfully transduced with either of these fusion vectors. Two million stably transduced cells selected by fluorescence-activated cell sorting were injected into the spleens of NOD-SCID mice pretreated with methylcholanthrene and monocrotaline. The transplanted mice were serially imaged with a bioluminescence charged-coupled device camera after D-luciferin injection. Bioluminescence signal intensity was highest on day 3 (6.10 +/- 2.02 x 10(5) p/s/cm2/sr, mean +/- SEM), but decreased to 2.26 +/- 1.54 x 10(5) and 7.47 +/- 3.09 x 10(4) p/s/cm2/sr on day 7 and 10, respectively (p = 0.001). ELISA for human albumin in mice sera showed that levels were similar to those of control mice on day 2 (3.25 +/- 0.92 vs. 2.84 +/- 0.59 ng/ml, mean +/- SEM), peaked at 18.04 +/- 3.11 ng/ml on day 7, and decreased to 8.93 +/- 1.40 and 3.54 +/- 0.87 ng/ml on day 14 and 21, respectively (p = 0.02). Real-time quantitative RT-PCR showed gene expression levels of human albumin, alpha1-antitrypsin, and transferrin in mouse liver were 60.7 +/- 6.5%, 26.0 +/- 1.4%, and 156.8 +/- 62.4% of those of primary human adult hepatocytes, respectively, and immunohistochemistry revealed cells with human albumin and alpha1-antitrypsin expression in the mouse liver. In conclusion, our study demonstrated that bioluminescent imaging appears to be a sensitive, noninvasive modality for serial monitoring of transplanted hepatic stem cells.

    View details for Web of Science ID 000261489600003

    View details for PubMedID 19069633

  • Molecular imaging of PET reporter gene expression. Handbook of experimental pharmacology Min, J., Gambhir, S. S. 2008: 277-303


    Multimodality molecular imaging continues to rapidly expand and is impacting many areas of biomedical research as well as patient management. Reporter-gene assays have emerged as a very general strategy for indirectly monitoring various intracellular events. Furthermore, reporter genes are being used to monitor gene/cell therapies, including the location(s), time variation, and magnitude of gene expression. This chapter reviews reporter gene technology and its major pre-clinical and clinical applications to date. The future appears quite promising for the continued expansion of the use of reporter genes in many evolving biomedically related arenas.

    View details for DOI 10.1007/978-3-540-77496-9_12

    View details for PubMedID 18626607

  • Dual targeted contrast agent for US assessment of tumor angiogenesis in vivo Radiology Willmann J, Lutz A, Paulmurugan R, Patel M, Chu P, Rosenberg J, Gambhir SS 2008; 248 (3): 936-944
  • Preclinical efficacy of the c-met inhibitor CE-355621 in a U87 MG mouse xenograft model evaluated by F-18-FDG small-animal PET JOURNAL OF NUCLEAR MEDICINE Tseng, J. R., Kang, K. W., Dandekar, M., Yaghoubi, S., Lee, J. H., Christensen, J. G., Muir, S., Vincent, P. W., Michaud, N. R., Gambhir, S. S. 2008; 49 (1): 129-134


    The purpose of this study was to evaluate the efficacy of CE-355621, a novel antibody against c-Met, in a subcutaneous U87 MG xenograft mouse model using (18)F-FDG small-animal PET.CE-355621 or control vehicle was administered intraperitoneally into nude mice (drug-treated group, n = 12; control group, n = 14) with U87 MG subcutaneous tumor xenografts. Drug efficacy was evaluated over 2 wk using (18)F-FDG small-animal PET and compared with tumor volume growth curves.The maximum %ID/g (percentage injected dose per gram of tissue) of (18)F-FDG accumulation in mice treated with CE-355621 remained essentially unchanged over 2 wk, whereas the %ID/g of the control tumors increased 66% compared with the baseline. Significant inhibition of (18)F-FDG accumulation was seen 3 d after drug treatment, which was earlier than the inhibition of tumor volume growth seen at 7 d after drug treatment.CE-355621 is an efficacious novel antineoplastic chemotherapeutic agent that inhibits (18)F-FDG accumulation earlier than tumor volume changes in a mouse xenograft model. These results support the use of (18)F-FDG PET to assess early tumor response for CE-355621.

    View details for DOI 10.2967/jnumed.106.038836

    View details for Web of Science ID 000252391700026

    View details for PubMedID 18077531

    View details for PubMedCentralID PMC4161137

  • Molecular imaging of the efficacy of heat shock protein 90 inhibitors in living subjects CANCER RESEARCH Chan, C. T., Paulmurugan, R., Gheysens, O. S., Kim, J., Chiosis, G., Gambhir, S. S. 2008; 68 (1): 216-226


    Heat shock protein 90 alpha (Hsp90 alpha)/p23 and Hsp90 beta/p23 interactions are crucial for proper folding of proteins involved in cancer and neurodegenerative diseases. Small molecule Hsp90 inhibitors block Hsp90 alpha/p23 and Hsp90 beta/p23 interactions in part by preventing ATP binding to Hsp90. The importance of isoform-selective Hsp90 alpha/p23 and Hsp90 beta/p23 interactions in determining the sensitivity to Hsp90 was examined using 293T human kidney cancer cells stably expressing split Renilla luciferase (RL) reporters. Interactions between Hsp90 alpha/p23 and Hsp90 beta/p23 in the split RL reporters led to complementation of RL activity, which was determined by bioluminescence imaging of intact cells in cell culture and living mice using a cooled charge-coupled device camera. The three geldanamycin-based and seven purine-scaffold Hsp90 inhibitors led to different levels of inhibition of complemented RL activities (10-70%). However, there was no isoform selectivity to both classes of Hsp90 inhibitors in cell culture conditions. The most potent Hsp90 inhibitor, PU-H71, however, led to a 60% and 30% decrease in RL activity (14 hr) in 293T xenografts expressing Hsp90 alpha/p23 and Hsp90 beta/p23 split reporters respectively, relative to carrier control-treated mice. Molecular imaging of isoform-specific Hsp90 alpha/p23 and Hsp90 beta/p23 interactions and efficacy of different classes of Hsp90 inhibitors in living subjects have been achieved with a novel genetically encoded reporter gene strategy that should help in accelerating development of potent and isoform-selective Hsp90 inhibitors.

    View details for DOI 10.1158/0008-5472.CAN-07-2268

    View details for Web of Science ID 000252072100029

    View details for PubMedID 18172314

    View details for PubMedCentralID PMC4146344

  • I-123 MIBG mapping with intraoperative gamma probe for recurrent neuroblastoma MOLECULAR IMAGING AND BIOLOGY Iagaru, A., Peterson, D., Quon, A., Dutta, S., Twist, C., Daghighian, F., Gambhir, S. S., Albanese, C. 2008; 10 (1): 19-23


    Intraoperative gamma probe guidance has become widely utilized for sentinel lymph node dissection in patients with breast cancer and melanoma, using (99m)Tc sulfur colloid. However, new indications are possible and need to continue to be investigated. We report the use during a wedge liver biopsy of a new hand-held gamma probe designed for (123)I intraoperative guidance. The patient studied is a 5-year-old boy with history of stage 4 high-risk neuroblastoma. Anatomic imaging (CT, MRI), (99m)Tc bone scintigraphy and 2-deoxy-2-[F-18]fluoro-d-glucose-positron emission tomography/computed tomography (FDG-PET/CT) were negative, but the (123)I MIBG scintigraphy suggested recurrent liver disease. A decision was made to biopsy these lesions to obtain histopathological confirmation. Intraoperative gamma probe mapping of the liver identified areas with signal above the background, but these were prove to be hemosiderin deposits on histo-pathology examination.

    View details for DOI 10.1007/s11307-007-0116-1

    View details for Web of Science ID 000252107800002

    View details for PubMedID 17975716

  • Molecular Imaging of Reporter Gene Expression in Prostate Cancer: An Overview. Seminars in Nuclear Medicine Singh A, Massoud T, Deroose C, Gambhir SS 2008; 39(1): 9-19


    Cancer, with more than 10 million new cases a year worldwide, is the third leading cause of death in developed countries. One critical requirement during cancer progression is angiogenesis, the formation of new blood vessels. Structural and functional imaging of tumor vasculature has been studied using various imaging modalities such as magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound. Molecular imaging, a key component of the 21st-century cancer-patient management strategy, takes advantage of these traditional imaging techniques and introduces molecular probes to determine the expression of indicative molecular markers at different stages of cancer development. In this chapter, we will focus on two tumor vasculature-related targets: integrin alpha(v)beta(3) and vascular endothelial growth factor receptor (VEGFR). For imaging of integrin alpha(v)beta(3) on the tumor vasculature, only nanoparticle-based probes will be discussed. VEGFR imaging will be discussed in depth, and we will give a detailed example of positron emission tomography (PET) imaging of VEGFR expression using radio-labeled VEGF(121) protein. Future clinical translation will be critical for maximum patient benefit from these agents. To achieve this goal, multidisciplinary approaches and cooperative efforts from many individuals, institutions, industries, and organizations are needed to quickly translate multimodality tumor vasculature imaging into multiple facets of cancer patient management.

    View details for DOI 10.1016/S0076-6879(08)03007-3

    View details for Web of Science ID 000260774900007

    View details for PubMedID 19022059

  • Applications of lentiviral vectors in non-invasive molecular imaging Methods in Molecular Biology De A, Yaghoubi S, Gambhir SS 2008; 433 (1): 177-202
  • Ovarian cancer early detection claims are biased Clinical Center Researh McIntosh M, Anderson G, Drescher C, Hanash S, Urban N, Brown P, Gambhir SS, Coukos G, Laird P, Nelson B, Palmer C 2008; 14 (22): 7574
  • Monitoring caspase-3 activation with a multimodality imaging sensor in living subjects Clinical Cancer Research Ray P, De A, Patel M, Gambhir SS 2008; 14 (18): 5801-5809
  • Targeted microbubbles for imaging tumor angiogenesis: Assessment of whole body biodistribution with dynamic micro-PET in mice Radiology Willmann J, Cheng Z, Davis C, Lutz A, Schipper M, Nielsen C, Gambhir SS 2008; 249: 212-219
  • Uptake Kinetics and Biodistribution of (14)C-D:-Luciferin-a Radiolabeled Substrate for the Firefly Luciferase Catalyzed Bioluminescence Reaction: Impact on Bioluminescence Based Reporter Gene Imaging European Journal of Nuclear Medicine and Molecular Imaging Berger, F., Paulmurugan, R, Bhaumik, S, Gambhir, SS 2008
  • A comparison between a time domain and continuous wave small animal optical imaging system IEEE TRANSACTIONS ON MEDICAL IMAGING Keren, S., Gheysens, O., Levin, C. S., Gambhir, S. S. 2008; 27 (1): 58-63


    We present a phantom study to evaluate the performance of the eXplore Optix (Advanced Research Technologies-GE Healthcare), the first commercially available time-domain tomography system for small animal fluorescence imaging, and compare its capabilities with the widely used IVIS 200 (Xenogen Corporation-Caliper) continuous wave planar imaging system. The eXplore Optix, based on point-wise illumination and collection scheme, is found to be a log order more sensitive with significantly higher detection depth and spatial resolution as compared with the wide-area illumination IVIS 200 under the conditions tested. A time-resolved detection system allows the eXplore Optix to measure the arrival time distribution of fluorescence photons. This enables fluorescence lifetime measurement, absorption mapping, and estimation of fluorescent inclusion depth, which in turn is used by a reconstruction algorithm to calculate the volumetric distribution of the fluorophore concentration. An increased acquisition time and lack of ability to image multiple animals simultaneously are the main drawbacks of the eXplore Optix as compared with the IVIS 200.

    View details for DOI 10.1109/TMI.2007.902800

    View details for Web of Science ID 000252098300007

    View details for PubMedID 18270062

  • BRET-Based method for detection of specific RNA species BIOCONJUGATE CHEMISTRY Walls, Z. F., Gambhir, S. S. 2008; 19 (1): 178-184


    RNA detection and quantitation is a common necessity in modern molecular biology research. Most methods, however, are complex and/or time-intensive. Presented here is a BRET (bioluminescene resonance energy transfer)-based method that can accomplish the task of RNA identification quickly and easily. By conjugating BRET enzymes to two different oligonucleotides that are complementary to the same target sequence, probes were developed that could detect RNA using a solution-based assay. This assay was optimized for spacer length between the binding sites (found to be 10 nucleotides), and sensitivity was determined to be 1 microg for a specific species of RNA within a mixed population. Specificity of the assay was assessed using in vitro transcribed cRNA and found to be statistically siginificant ( p = 3.11 x 10 (-6), ANOVA, multiple range test). This assay represents a possibility for a less technically demanding, streamlined alternative to canonical RNA assays.

    View details for DOI 10.1021/bc700278n

    View details for Web of Science ID 000252520300024

    View details for PubMedID 18072724

  • Comparison between adenoviral and retroviral vectors for the transduction of the thymidine kinase PET reporter gene in rat mesenchymal stem cells Journal of Nuclear Medicine Roelants V, Labar D, DeMeester C, Havaux X, Tabilio A, Gambhir SS, Dilanni M, Bertrand L, Vanoverschelde J 2008; 49 (11): 1836-1844
  • Crystal structures of the luciferase and green fluorescent protein from Renilla reniformis JOURNAL OF MOLECULAR BIOLOGY Loening, A. M., Fenn, T. D., Gambhir, S. S. 2007; 374 (4): 1017-1028


    Due to its ability to emit light, the luciferase from Renilla reniformis (RLuc) is widely employed in molecular biology as a reporter gene in cell culture experiments and small animal imaging. To accomplish this bioluminescence, the 37-kDa enzyme catalyzes the degradation of its substrate coelenterazine in the presence of molecular oxygen, resulting in the product coelenteramide, carbon dioxide, and the desired photon of light. We successfully crystallized a stabilized variant of this important protein (RLuc8) and herein present the first structures for any coelenterazine-using luciferase. These structures are based on high-resolution data measured to 1.4 A and demonstrate a classic alpha/beta-hydrolase fold. We also present data of a coelenteramide-bound luciferase and reason that this structure represents a secondary conformational form following shift of the product out of the primary active site. During the course of this work, the structure of the luciferase's accessory green fluorescent protein (RrGFP) was also determined and shown to be highly similar to that of Aequorea victoria GFP.

    View details for DOI 10.1016/j.jmb.2007.09.078

    View details for Web of Science ID 000251700900015

    View details for PubMedID 17980388

  • Regulatory and reimbursement challenges for molecular imaging RADIOLOGY Hoffman, J. M., Gambhir, S. S., Kelloff, G. J. 2007; 245 (3): 645-660


    Molecular imaging is being hailed as the next great advance for imaging. Since molecular imaging typically involves the use of specific imaging probes that are treated like drugs, they will require regulatory approval. As with any drug, molecular imaging probes and techniques will also require thorough assessment in clinical trials to show safety and efficacy. The timeline for the regulatory approval will be long and potentially problematic because of the mounting costs of obtaining final regulatory approval. The current article is a detailed review of the regulatory and reimbursement process that will be required for molecular imaging probes and techniques to become a widespread clinical reality. The role of molecular imaging in the therapeutic drug discovery process will also be reviewed, as this is where these exciting new techniques have the potential to revolutionize the drug discovery and development process and, it is hoped, make it less costly. [(18)F]fluoro-2-deoxy-2-D-glucose positron emission tomography, one of the first molecular imaging techniques to be widely used, will be used as an example to illustrate the process of obtaining eventual reimbursement for widespread clinical use.

    View details for DOI 10.1148/radiol.2453060737

    View details for Web of Science ID 000251070700006

    View details for PubMedID 18024447

  • Glia-dependent TGF-beta signaling, acting independently of the TH17 pathway, is critical for initiation of murine autoimmune encephalomyelitis JOURNAL OF CLINICAL INVESTIGATION Luo, J., Ho, P. P., Buckwalter, M. S., Hsu, T., Lee, L. Y., Zhang, H., Kim, D., Kim, S., Gambhir, S. S., Steinman, L., Wyss-Coray, T. 2007; 117 (11): 3306-3315


    Autoimmune encephalomyelitis, a mouse model for multiple sclerosis, is characterized by the activation of immune cells, demyelination of axons in the CNS, and paralysis. We found that TGF-beta1 synthesis in glial cells and TGF-beta-induced signaling in the CNS were activated several days before the onset of paralysis in mice with autoimmune encephalomyelitis. While early production of TGF-beta1 was observed in glial cells TGF-beta signaling was activated in neurons and later in infiltrating T cells in inflammatory lesions. Systemic treatment with a pharmacological inhibitor of TGF-beta signaling ameliorated the paralytic disease and reduced the accumulation of pathogenic T cells and expression of IL-6 in the CNS. Priming of peripheral T cells was not altered, nor was the generation of TH17 cells, indicating that this effect was directed within the brain, yet affected the immune system. These results suggest that early production of TGF-beta1 in the CNS creates a permissive and dangerous environment for the initiation of autoimmune inflammation, providing a rare example of the brain modulating the immune system. Importantly, inhibition of TGF-beta signaling may have benefits in the treatment of the acute phase of autoimmune CNS inflammation.

    View details for DOI 10.1172/JCI31763

    View details for Web of Science ID 000250676000023

    View details for PubMedID 17965773

    View details for PubMedCentralID PMC2040317

  • Dual-function probe for PET and near-infrared fluorescence imaging of tumor vasculature JOURNAL OF NUCLEAR MEDICINE Cai, W., Chen, K., Li, Z., Gambhir, S. S., Chen, X. 2007; 48 (11): 1862-1870


    To date, the in vivo imaging of quantum dots (QDs) has been mostly qualitative or semiquantitative. The development of a dual-function PET/near-infrared fluorescence (NIRF) probe can allow for accurate assessment of the pharmacokinetics and tumor-targeting efficacy of QDs.A QD with an amine-functionalized surface was modified with RGD peptides and 1,4,7,10-tetraazacyclodocecane-N,N',N'',N'''-tetraacetic acid (DOTA) chelators for integrin alpha(v)beta(3)-targeted PET/NIRF imaging. A cell-binding assay and fluorescence cell staining were performed with U87MG human glioblastoma cells (integrin alpha(v)beta(3)-positive). PET/NIRF imaging, tissue homogenate fluorescence measurement, and immunofluorescence staining were performed with U87MG tumor-bearing mice to quantify the probe uptake in the tumor and major organs.There are about 90 RGD peptides per QD particle, and DOTA-QD-RGD exhibited integrin alpha(v)beta(3)-specific binding in cell cultures. The U87MG tumor uptake of (64)Cu-labeled DOTA-QD was less than 1 percentage injected dose per gram (%ID/g), significantly lower than that of (64)Cu-labeled DOTA-QD-RGD (2.2 +/- 0.3 [mean +/- SD] and 4.0 +/- 1.0 %ID/g at 5 and 18 h after injection, respectively; n = 3). Taking into account all measurements, the liver-, spleen-, and kidney-to-muscle ratios for (64)Cu-labeled DOTA-QD-RGD were about 100:1, 40:1, and 1:1, respectively. On the basis of the PET results, the U87MG tumor-to-muscle ratios for DOTA-QD-RGD and DOTA-QD were about 4:1 and 1:1, respectively. Excellent linear correlation was obtained between the results measured by in vivo PET imaging and those measured by ex vivo NIRF imaging and tissue homogenate fluorescence (r(2) = 0.93). Histologic examination revealed that DOTA-QD-RGD targets primarily the tumor vasculature through an RGD-integrin alpha(v)beta(3) interaction, with little extravasation.We quantitatively evaluated the tumor-targeting efficacy of a dual-function QD-based probe with PET and NIRF imaging. This dual-function probe has significantly reduced potential toxicity and overcomes the tissue penetration limitation of optical imaging, allowing for quantitative targeted imaging in deep tissue.

    View details for DOI 10.2967/jnumed.107.043216

    View details for Web of Science ID 000252894900024

    View details for PubMedID 17942800

  • Molecular imaging techniques in body imaging RADIOLOGY Margolis, D. J., Hoffman, J. M., Herfkens, R. J., Jeffrey, R. B., Quon, A., Gambhir, S. S. 2007; 245 (2): 333-356


    Molecular imaging of the body involves new techniques to image cellular biochemical processes, which results in studies with high sensitivity, specificity, and signal-to-background. The most prevalently used molecular imaging technique in body imaging is currently fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET). FDG PET has become the method of choice for the staging and restaging of many of the most common cancers, including lymphoma, lung cancer, breast cancer, and colorectal cancer. FDG PET has also become extremely valuable in monitoring the response to therapeutic drugs in many cancers. New PET agents, such as fluorothymidine and acetate, have also shown promise in the evaluation of response to therapy and in the staging of prostate cancer. Magnetic resonance (MR) spectroscopy has shown promise in the evaluation of prostate cancer. Breast cancer evaluation benefits from advances in spectroscopic imaging and contrast-enhanced kinetic evaluation of vascular permeability, which is altered in neoplastic processes because of release of angiogenic factors. Superparamagnetic iron oxide (SPIO) particles represent the first of an expanding line of MR contrast agents that target specific cellular processes. SPIO particles have also been used in the evaluation of the cirrhotic liver and at MR lymphangiography.

    View details for DOI 10.1148/radiol.2452061117

    View details for Web of Science ID 000250343800007

    View details for PubMedID 17940297

  • Multimodality imaging of T-cell hybridoma trafficking in collagen-induced arthritic mice: image-based estimation of the number of cells accumulating in mouse paws JOURNAL OF BIOMEDICAL OPTICS Yaghoubi, S. S., Creusot, R. J., Ray, P., Fathman, C. G., Gambhir, S. S. 2007; 12 (6)


    Appropriate targeting of therapeutic cells is essential in adoptive cellular gene therapy (ACGT). Imaging cell trafficking in animal models and patients will guide development of ACGT protocols. Collagen type II (C-II)-specific T cell hybridomas are transduced with a lentivirus carrying a triple fusion reporter gene (TFR) construct consisting of a fluorescent reporter gene (RG), a bioluminescent RG (hRluc), and a positron emission tomography (PET) RG. Collagen-induced arthritic (CIA) mice are scanned with a bioluminescence imaging camera before and after implantation of various known cell quantities in their paws. Linear regression analysis yields equations relating two parameters of image signal intensity in mice paws to the quantity of hRluc expressing cells in the paws. Afterward, trafficking of intravenously injected cells is studied by quantitative analysis of bioluminescence images. Comparison of the average cell numbers does not demonstrate consistently higher accumulation of T-cell hybridomas in the paws with higher inflammation scores, and injecting more cells does not cause increased accumulation. MicroPET images illustrate above background signal in the inflamed paws and chest areas of CIA mice. The procedures described in this study can be used to derive equations for cells expressing other bioluminescent RGs and in other animal models.

    View details for DOI 10.1117/1.2821415

    View details for Web of Science ID 000252851100046

    View details for PubMedID 18163841

  • Design and evaluation of a variable aperture collimator for conformal radiotherapy of small animals using a microCT scanner MEDICAL PHYSICS Graves, E. E., Zhou, H., Chatterjee, R., Keall, P. J., Gambhir, S. S., Contag, C. H., Boyer, A. L. 2007; 34 (11): 4359-4367


    Treatment of small animals with radiation has in general been limited to planar fields shaped with lead blocks, complicating spatial localization of dose and treatment of deep-seated targets. In order to advance laboratory radiotherapy toward what is accomplished in the clinic, we have constructed a variable aperture collimator for use in shaping the beam of microCT scanner. This unit can image small animal subjects at high resolution, and is capable of delivering therapeutic doses in reasonable exposure times. The proposed collimator consists of two stages, each containing six trapezoidal brass blocks that move along a frame in a manner similar to a camera iris producing a hexagonal aperture of variable size. The two stages are offset by 30 degrees and adjusted for the divergence of the x-ray beam so as to produce a dodecagonal profile at isocenter. Slotted rotating driving plates are used to apply force to pins in the collimator blocks and effect collimator motion. This device has been investigated through both simulation and measurement. The collimator aperture size varied from 0 to 8.5 cm as the driving plate angle increased from 0 to 41 degrees. The torque required to adjust the collimator varied from 0.5 to 5 N x m, increasing with increasing driving plate angle. The transmission profiles produced by the scanner at isocenter exhibited a penumbra of approximately 10% of the collimator aperture width. Misalignment between the collimator assembly and the x-ray source could be identified on the transmission images and corrected by adjustment of the collimator location. This variable aperture collimator technology is therefore a feasible and flexible solution for adjustable shaping of radiation beams for use in small animal radiotherapy as well as other applications in which beam shaping is desired.

    View details for DOI 10.1118/1.2789498

    View details for Web of Science ID 000251145900029

    View details for PubMedID 18072501

  • Quantum dot imaging for embryonic stem cells BMC BIOTECHNOLOGY Lin, S., Xie, X., Patel, M. R., Yang, Y., Li, Z., Cao, F., Gheysens, O., Zhang, Y., Gambhir, S. S., Rao, J. H., Wu, J. C. 2007; 7


    Semiconductor quantum dots (QDs) hold increasing potential for cellular imaging both in vitro and in vivo. In this report, we aimed to evaluate in vivo multiplex imaging of mouse embryonic stem (ES) cells labeled with Qtracker delivered quantum dots (QDs).Murine embryonic stem (ES) cells were labeled with six different QDs using Qtracker. ES cell viability, proliferation, and differentiation were not adversely affected by QDs compared with non-labeled control cells (P = NS). Afterward, labeled ES cells were injected subcutaneously onto the backs of athymic nude mice. These labeled ES cells could be imaged with good contrast with one single excitation wavelength. With the same excitation wavelength, the signal intensity, defined as (total signal-background)/exposure time in millisecond was 11 +/- 2 for cells labeled with QD 525, 12 +/- 9 for QD 565, 176 +/- 81 for QD 605, 176 +/- 136 for QD 655, 167 +/- 104 for QD 705, and 1,713 +/- 482 for QD 800. Finally, we have shown that QD 800 offers greater fluorescent intensity than the other QDs tested.In summary, this is the first demonstration of in vivo multiplex imaging of mouse ES cells labeled QDs. Upon further improvements, QDs will have a greater potential for tracking stem cells within deep tissues. These results provide a promising tool for imaging stem cell therapy non-invasively in vivo.

    View details for DOI 10.1186/1472-6750-7-67

    View details for Web of Science ID 000252448600001

    View details for PubMedID 17925032

    View details for PubMedCentralID PMC2174930

  • Bisdeoxycoelenterazine derivatives for improvement of bioluminescence resonance energy transfer assays JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Levi, J., De, A., Cheng, Z., Gambhir, S. S. 2007; 129 (39): 11900-?

    View details for DOI 10.1021/ja073936h

    View details for Web of Science ID 000249887700013

    View details for PubMedID 17850082

  • Molecular imaging can accelerate anti-angiogenic drug development and testing NATURE CLINICAL PRACTICE ONCOLOGY Lagaru, A., Chen, X., Gambhir, S. S. 2007; 4 (10): 556-557

    View details for DOI 10.1038/ncponc0929

    View details for Web of Science ID 000249708800002

    View details for PubMedID 17726490

  • Osseous and soft tissue sarcomas: When can F-18 FDG PET/CT evaluation provide useful information? 20th Annual Congress of the European-Association-of-Nuclear-Medicine Iagaru, A., Quon, A., Jacobs, C., Marina, N., McDougall, I., Gambhir, S. S. SPRINGER. 2007: S152–S152
  • Differentiation, survival, and function of embryonic stem cell-derived endothelial cells for ischemic heart disease 79th Annual Scientific Session of the American-Heart-Association Li, Z., Wu, J. C., Sheikh, A. Y., Kraft, D., Cao, F., Xie, X., Patel, M., Gambhir, S. S., Robbins, R. C., Cooke, J. P., Wu, J. C. LIPPINCOTT WILLIAMS & WILKINS. 2007: I46–I54


    Embryonic stem (ES) cells are distinguished by their capacity for self-renewal and pluripotency. Here we characterize the differentiation of ES cell-derived endothelial cells (ESC-ECs), use molecular imaging techniques to examine their survival in vivo, and determine the therapeutic efficacy of ESC-ECs for restoration of cardiac function after ischemic injury.Murine ES cells were transfected with a construct composed of a vascular endothelial cadherin promoter driving enhanced green fluorescence protein (pVE-cadherin-eGFP). Differentiation of ES cells to ECs was detected by FACS analysis using Flk-1 (early EC marker at day 4) and VE-cadherin (late EC marker at day 8). After isolation, these ESC-ECs express endothelial cell markers similar to adult mouse lung endothelial cells, form vascular-like channels, and incorporate DiI-labeled acetylated low-density lipoprotein (DiI-Ac-LDL). For in vivo imaging, ES cells were transduced with an ubiquitin promoter driving firefly luciferase and monomeric red fluorescence protein (pUb-Fluc-mRFP). A robust correlation exists between Fluc signals and cell numbers by ex vivo imaging analysis (R2=0.98) and by in vitro enzyme assay (R2=0.94). Afterward, 5x10(5) ESC-ECs or PBS (as control) was injected into the hearts of mice undergoing LAD ligation (n=15 per group). Bioluminescence imaging showed longitudinal survival of transplanted ESC-ECs for approximately 8 weeks. Echocardiogram demonstrated significant functional improvement in the ESC-EC group compared with control (P=0.04). Finally, postmortem analysis confirmed increased presence of small capillaries and venules in the infarcted zones by CD31 staining.This is the first study to track the fate and function of transplanted ESC-ECs in the heart. With further validation, these ESC-ECs could become a valuable source of cell therapy for induction of angiogenesis in the treatment of myocardial ischemia.

    View details for DOI 10.1161/CIRCULATIONAHA.106.680561

    View details for Web of Science ID 000249364500007

    View details for PubMedID 17846325

    View details for PubMedCentralID PMC3657509

  • Molecular imaging: Integration of molecular imaging into the musculoskeletal imaging practice RADIOLOGY Biswal, S., Resnick, D. L., Hoffman, J. M., Gambhir, S. S. 2007; 244 (3): 651-671


    Chronic musculoskeletal diseases such as arthritis, malignancy, and chronic injury and/or inflammation, all of which may produce chronic musculoskeletal pain, often pose challenges for current clinical imaging methods. The ability to distinguish an acute flare from chronic changes in rheumatoid arthritis, to survey early articular cartilage breakdown, to distinguish sarcomatous recurrence from posttherapeutic inflammation, and to directly identify generators of chronic pain are a few examples of current diagnostic limitations. There is hope that a growing field known as molecular imaging will provide solutions to these diagnostic puzzles. These techniques aim to depict, noninvasively, specific abnormal cellular, molecular, and physiologic events associated with these and other diseases. For example, the presence and mobilization of specific cell populations can be monitored with molecular imaging. Cellular metabolism, stress, and apoptosis can also be followed. Furthermore, disease-specific molecules can be targeted, and particular gene-related events can be assayed in living subjects. Relatively recent molecular and cellular imaging protocols confirm important advances in imaging technology, engineering, chemistry, molecular biology, and genetics that have coalesced into a multidisciplinary and multimodality effort. Molecular probes are currently being developed not only for radionuclide-based techniques but also for magnetic resonance (MR) imaging, MR spectroscopy, ultrasonography, and the emerging field of optical imaging. Furthermore, molecular imaging is facilitating the development of molecular therapies and gene therapy, because molecular imaging makes it possible to noninvasively track and monitor targeted molecular therapies. Implementation of molecular imaging procedures will be essential to a clinical imaging practice. With this in mind, the goal of the following discussion is to promote a better understanding of how such procedures may help address specific musculoskeletal issues, both now and in the years ahead.

    View details for DOI 10.1148/radiol.2443060295

    View details for Web of Science ID 000248993500006

    View details for PubMedID 17709823

  • Fusion of Gaussia luciferase to an engineered anti-carcinoembryonic antigen (CEA) antibody for in vivo optical imaging MOLECULAR IMAGING AND BIOLOGY Venisnik, K. M., Olafsen, T., Gambhir, S. S., Wu, A. M. 2007; 9 (5): 267-277


    The bioluminescent protein Gaussia luciferase (GLuc) was fused to an anti-carcinoembryonic antigen (CEA) antibody fragment, the diabody, for in vivo optical tumor imaging. A 15-amino acid N-terminal truncation (GLDelta15) resulted in a brighter protein. Fusions of the anti-CEA diabody to full-length GLuc and GLDelta15 retained high affinity for the antigen, emitted light, and exhibited excellent enzymatic stability. In vivo optical imaging of tumor-bearing mice demonstrated specific targeting of diabody-GLDelta15 to CEA-positive xenografts, with a tumor/background ratio of 3.8 +/- 0.4 at four hours after tail-vein injection, compared to antigen-negative tumors at 1.3 +/- 0.1 (p = 0.001). MicroPET imaging using (124)I-diabody-GLDelta15 demonstrated specific uptake in the CEA-positive tumor (2.6% ID [injected dose]/g) compared to the CEA-negative tumor (0.4% ID/g) at 21 hours. Although further optimization of this fusion protein may be needed to improve in vivo performance, the diabody-GLDelta15 is a promising optical imaging probe for tumor detection in vivo.

    View details for DOI 10.1007/s11307-007-0101-8

    View details for Web of Science ID 000248865200003

    View details for PubMedID 17577599

  • MicroPET-based biodistribution of quantum dots in living mice JOURNAL OF NUCLEAR MEDICINE Schipper, M. L., Cheng, Z., Lee, S., Bentolila, L. A., Iyer, G., Rao, J., Chen, X., Wu, A. M., Weiss, S., Gambhir, S. S. 2007; 48 (9): 1511-1518


    This study evaluates the quantitative biodistribution of commercially available CdSe quantum dots (QD) in mice.(64)Cu-Labeled 800- or 525-nm emission wavelength QD (21- or 12-nm diameter), with or without 2,000 MW (molecular weight) polyethylene glycol (PEG), were injected intravenously into mice (5.55 MBq/25 pmol QD) and studied using well counting or by serial microPET and region-of-interest analysis.Both methods show rapid uptake by the liver (27.4-38.9 %ID/g) (%ID/g is percentage injected dose per gram tissue) and spleen (8.0-12.4 %ID/g). Size has no influence on biodistribution within the range tested here. Pegylated QD have slightly slower uptake into liver and spleen (6 vs. 2 min) and show additional low-level bone uptake (6.5-6.9 %ID/g). No evidence of clearance from these organs was observed.Rapid reticuloendothelial system clearance of QD will require modification of QD for optimal utility in imaging living subjects. Formal quantitative biodistribution/imaging studies will be helpful in studying many types of nanoparticles, including quantum dots.

    View details for DOI 10.2967/jnumed.107.040071

    View details for Web of Science ID 000252894700039

    View details for PubMedID 17704240

  • 2-Deoxy-2-[F-18]fluoro-D-glucose accumulation in ovarian carcinoma cell lines MOLECULAR IMAGING AND BIOLOGY Lutz, A. M., Ray, P., Willmann, J. K., Drescher, C., Gambhir, S. S. 2007; 9 (5): 260-266


    To evaluate 2-deoxy-2-[F-18]fluoro-D-glucose (FDG) accumulation in human ovarian carcinoma cell lines compared with control tumor cell lines known to accumulate FDG.FDG accumulation assays were performed in 15 different ovarian carcinoma cell lines at 1, 2, and 3 hours after incubation with 1 microCi of FDG. Results were compared with FDG accumulation in six different control tumor cell lines. 2-deoxy-2-[F-18]fluoro-D-glucose accumulation was expressed as counts per minute (cpm) in cells and normalized to initial cpm in medium and total protein content of cell lysates.FDG accumulation in all 15 ovarian carcinoma cell lines was equal to or higher than 0.0005 +/- 8.6 10(-5) cpm in cells/cpm in medium/mug protein at all three different time points. In two ovarian carcinoma cell lines (ES-2, poorly differentiated clear cell carcinoma, and OVCAR-3, poorly differentiated papillary adenocarcinoma), FDG accumulation was not statistically, significantly different compared to the control cell line with the highest FDG accumulation (LS 174T human colorectal adenocarcinoma) at two or more time points (P > or = 0.07). In 2 of 15 (13%) ovarian carcinoma cell lines (OVCAR5 epithelial carcinoma and SKOV3 clear cell carcinoma), FDG accumulation was lower than that in the control cell line with the lowest FDG accumulation (HT-29 human colorectal adenocarcinoma) at one or more time points (P < 0.05).Most human ovarian carcinoma cell lines showed comparable FDG accumulations with control cell lines known to accumulate FDG. This study lays the foundations for further comparisons with other ovarian cancer cell lines and for other positron emission tomography tracers.

    View details for DOI 10.1007/s11307-007-0105-4

    View details for Web of Science ID 000248865200002

    View details for PubMedID 17610017

  • An improved bioluminescence resonance energy transfer strategy for imaging intracellular events in single cells and living subjects CANCER RESEARCH De, A., Loening, A. M., Gambhir, S. S. 2007; 67 (15): 7175-7183


    Bioluminescence resonance energy transfer (BRET) is currently used for monitoring various intracellular events, including protein-protein interactions, in normal and aberrant signal transduction pathways. However, the BRET vectors currently used lack adequate sensitivity for imaging events of interest from both single living cells and small living subjects. Taking advantage of the critical relationship of BRET efficiency and donor quantum efficiency, we report generation of a novel BRET vector by fusing a GFP(2) acceptor protein with a novel mutant Renilla luciferase donor selected for higher quantum yield. This new BRET vector shows an overall 5.5-fold improvement in the BRET ratio, thereby greatly enhancing the dynamic range of the BRET signal. This new BRET strategy provides a unique platform to assay protein functions from both single live cells and cells located deep within small living subjects. The imaging utility of the new BRET vector is shown by constructing a sensor using two mammalian target of rapamycin pathway proteins (FKBP12 and FRB) that dimerize only in the presence of rapamycin. This new BRET vector should facilitate high-throughput sensitive BRET assays, including studies in single live cells and small living subjects. Applications will include anticancer therapy screening in cell culture and in small living animals.

    View details for DOI 10.1158/0008-5472.CAN-06-4623

    View details for Web of Science ID 000248529300018

    View details for PubMedID 17671185

  • Red-shifted Renilla reniformis luciferase variants for imaging in living subjects NATURE METHODS Loening, A. M., Wu, A. M., Gambhir, S. S. 2007; 4 (8): 641-643


    The use of R. reniformis luciferase (RLuc) as a reporter gene in small-animal imaging has been hampered by its 481 nm peaked emission spectrum, as blue wavelengths are strongly attenuated in biological tissues. To overcome this, we generated variants of RLuc with bathochromic (red) shifts of up to 66 nm (547 nm peak) that also had greater stability and higher light emission than native RLuc.

    View details for DOI 10.1038/NMETH1070

    View details for Web of Science ID 000248443900017

    View details for PubMedID 17618292

  • Cardiovascular molecular imaging RADIOLOGY Wu, J. C., Bengel, F. M., Gambhir, S. S. 2007; 244 (2): 337-355


    The goal of this review is to highlight how molecular imaging will impact the management and improved understanding of the major cardiovascular diseases that have substantial clinical impact and research interest. These topics include atherosclerosis, myocardial ischemia, myocardial viability, heart failure, gene therapy, and stem cell transplantation. Traditional methods of evaluation for these diseases will be presented first, followed by methods that incorporate conventional and molecular imaging approaches.

    View details for Web of Science ID 000248821400005

    View details for PubMedID 17592037

  • Oxygen sensitivity of reporter genes: Implications for preclinical imaging of tumor hypoxia MOLECULAR IMAGING Cecic, I., Chan, D. A., Sutphin, P. D., Ray, P., Gambhir, S. S., Giaccia, A. J., Gravcs, E. E. 2007; 6 (4): 219-228


    Reporter gene techniques have been applied toward studying the physiologic phenomena associated with tumor hypoxia, a negative prognostic indicator. The purpose of this study was to assess the potential adverse effects of hypoxic conditions on the effectiveness of four commonly used reporter genes: Renilla luciferase, monomeric red fluorescent protein, thymidine kinase, and lacZ. Tumor-forming A375 cells expressing a trifusion reporter consisting of Renilla luciferase, monomeric red fluorescent protein, and thymidine kinase were subjected to decreasing oxygen tensions and assayed for reporter expression and activity. A375 cells expressing beta-galactosidase were similarly exposed to hypoxia, with activity of the reporter monitored by cleavage of the fluorescent substrate 7-hydroxy-9H-(1,3-dichloro-9,9-dimethylacridin-2-one)-beta-galactoside (DDAOG). Generation of signal in in vivo tumor models expressing bioluminescent or beta-galactosidase reporters were also examined over the course of hypoxic stresses, either by tumor clamping or the antivascular agent 5,6-dimethylxanthenone-4-acetic acid (DMXAA). Our findings indicate that bioluminescent and fluorescent reporter activity are decreased under hypoxia despite minimal variations in protein production, whereas beta-galactosidase reporter activity per unit protein was unchanged. These results demonstrate that combining beta-galactosidase with the DDAOG optical probe may be a robust reporter system for the in vivo study of tumor hypoxia.

    View details for DOI 10.2310/7290.2007.00017

    View details for Web of Science ID 000249349100001

    View details for PubMedID 17711777

  • Molecular imaging: The vision and opportunity for radiology in the future RADIOLOGY Hoffman, J. M., Gambhir, S. S. 2007; 244 (1): 39-47


    Molecular imaging is being hailed as the next great advance for imaging. This introductory article in the molecular imaging series to be published over the next several months in Radiology sets the stage for the subsequent set of articles by providing relevant definitions and background information and traces the evolution of molecular imaging to its current state of research and clinical practice. It discusses in detail the evolution of molecular imaging and the role that the National Cancer Institute and the National Institutes of Health have had in the funding and development of many of the important molecular imaging research programs that are in existence today. The article also provides basic information about the complex biology of the cell and details of the pathogenesis of cancer and how molecular imaging will be critical for earlier detection and management of cancer in the future. The article lays the foundation for the subsequent articles in the series and describes how and why molecular imaging will be critical and integral for clinical care of patients in the future. The introductory article also discusses the relevance of molecular imaging to clinical radiology practice and why it is critical for the practicing radiologist to understand these evolving techniques, as they will be the future of imaging.

    View details for DOI 10.1148/radiol.2441060773

    View details for Web of Science ID 000247436500005

    View details for PubMedID 17507723

  • Small-animal PET of melanocortin 1 receptor expression using a F-18-labeled alpha-melanocyte-stimulating hormone analog JOURNAL OF NUCLEAR MEDICINE Cheng, Z., Zhang, L., Graves, E., Xiong, Z., Dandekar, M., Chen, X., Gambhir, S. S. 2007; 48 (6): 987-994


    (18)F-Labeled small synthetic peptides have emerged as attractive probes for imaging various molecular targets with PET. The alpha-melanocyte-stimulating hormone (alpha-MSH) receptor (melanocortin type 1 receptor [MC1R]) is overexpressed in most murine and human melanomas. It is a promising molecular target for diagnosis and therapy of melanomas. However, (18)F compounds have not been successfully developed for imaging the MC1R.In this study, an alpha-MSH analog, Ac-Nle-Asp-His-D-Phe-Arg-Trp-Gly-Lys-NH(2) (NAPamide), was radiolabeled with N-succinimidyl-4-(18)F-fluorobenzoate ((18)F-SFB). The resulting radiopeptide was evaluated as a potential molecular probe for small-animal PET of melanoma and MC1R expression in melanoma xenografted mouse models.The binding affinity of (19)F-SFB-conjugated NAPamide, (19)F-FB-NAPamide, was determined to be 7.2 +/- 1.2 nM (mean +/- SD) using B16/F10 cells and (125)I-(Tyr(2))-[Nle(4),D-Phe(7)]-alpha-MSH [(125)I-(Tyr(2))-NDP] as a radioligand. The biodistribution of (18)F-FB-NAPamide was then investigated in C57BL/6 mice bearing subcutaneous murine B16/F10 melanoma tumors with high expression of MC1Rs and Fox Chase Scid mice bearing human A375M melanoma with a relatively low number of MC1R receptors. Biodistribution experiments showed that tumor uptake values (percentage injected dose per gram of tumor [%ID/g]) of (18)F-FB-NAPamide were 1.19 +/- 0.11 %ID/g and 0.46 +/- 0.11 %ID/g, in B16/F10 and A375M xenografted melanoma at 1 h after injection, respectively. Furthermore, the B16/F10 tumor uptake was significantly inhibited by coinjection with excess alpha-MSH peptide (P < 0.05), indicating that (18)F-FB-NAPamide specifically recognizes the MC1R in living mice. Small-animal PET of (18)F-FB-NAPamide in mice bearing B16/F10 and A375M tumors at 1 h after tail vein injection revealed good B16/F10 tumor-to-background contrast and low A375M tumor-to-background ratios.(18)F-FB-NAPamide is a promising molecular probe for alpha-MSH receptor-positive melanoma PET and warrants further study.

    View details for DOI 10.2967/jnumed.107.039602

    View details for Web of Science ID 000247054800024

    View details for PubMedID 17504880

  • Evaluation of herpes simplex virus 1 thymidine kinase-mediated trapping of I-131 FIAU and prodrug activation of ganciclovir as a synergistic cancer radio/chemotherapy MOLECULAR IMAGING AND BIOLOGY Schipper, M. L., Goris, M. L., Gambhir, S. S. 2007; 9 (3): 110-116


    Evaluation of selective killing of Herpes Simplex Virus 1 thymidine kinase (HSV1-tk) expressing tumors by radiolabeled (131)I-fialuridine (FIAU), and of synergy between (131)I-FIAU and Ganciclovir (GCV).HSV1-tk-expressing cell lines and parental cell lines were exposed to (131)I-FIAU alone, GCV alone, or combinations. Activity and concentration were varied widely, concurrent and sequential administrations tested, and dose rate effects were studied.HSV1-tk-expressing cells accumulated up to 15.7-fold more (131)I-FIAU, were growth inhibited by 2 muCi/ml, or 5 muCi/ml (131)I-FIAU, and were inhibited by two log orders lower concentrations of GCV than parental cells. However, no synergy or additive effect was observed. Dose rate variations, or sequential treatment, did not alter outcome.Radioisotope therapy of HSV1-tk-expressing tumor cells with (131)I-FIAU is reported for the first time. Lack of synergy between (131)I-FIAU and GCV does not warrant further investigation of combination treatment with the two agents.

    View details for DOI 10.1007/s11307-007-0078-3

    View details for Web of Science ID 000246175500003

    View details for PubMedID 17294333

  • Integrating noninvasive molecular imaging into molecular medicine: an evolving paradigm TRENDS IN MOLECULAR MEDICINE Massoud, T. F., Gambhir, S. S. 2007; 13 (5): 183-191


    Molecular imaging is a rapidly emerging field, providing noninvasive visual quantitative representations of fundamental biological processes in intact living subjects. Fundamental biomedical research stands to benefit considerably from advances in molecular imaging, with improved molecular target selection, probe development and imaging instrumentation. The noninvasiveness of molecular imaging technologies will also provide benefit through improved patient care. Molecular imaging endpoints can be quantified, and therefore are particularly useful for translational research. Integration of the two disciplines of molecular imaging and molecular medicine, combined with systems-biology approaches to understanding disease complexity, promises to provide predictive, preventative and personalized medicine that will transform healthcare.

    View details for DOI 10.1016/j.molmed.2007.03.003

    View details for Web of Science ID 000247166100002

    View details for PubMedID 17403616

  • In vivo bioluminescence tumor imaging of RGD peptide-modified adenoviral vector encoding firefly luciferase reporter gene MOLECULAR IMAGING AND BIOLOGY Niu, G., Xiong, Z., Cheng, Z., Cai, W., Gambhir, S. S., Xing, L., Chen, X. 2007; 9 (3): 126-134


    The goal of this study is to demonstrate the feasibility of chemically modified human adenovirus (Ad) vectors for tumor retargeting.E1- and E3-deleted Ad vectors carrying firefly luciferase reporter gene under cytomegalovirus promoter (AdLuc) was surface-modified with cyclic arginine-glycine-aspartic acid (RGD) peptides through a bifunctional poly(ethyleneglycol) linker (RGD-PEG-AdLuc) for integrin alpha(v)beta(3) specific delivery. The Coxsackie and adenovirus viral receptor (CAR) and integrin alpha(v)beta(3) expression in various tumor cell lines was determined by reverse transcriptase PCR and fluorescence-activated cell sorting. Bioluminescence imaging was performed in vitro and in vivo to evaluate RGD-modified AdLuc infectivity.RGD-PEG-AdLuc abrogated the native CAR tropism and exhibited significantly enhanced transduction efficiency of integrin-positive tumors than AdLuc through intravenous administration.This approach provides a robust platform for site-specific gene delivery and noninvasive monitoring of the transgene delivery efficacy and homing.

    View details for DOI 10.1007/s11307-007-0079-2

    View details for Web of Science ID 000246175500005

    View details for PubMedID 17297551

    View details for PubMedCentralID PMC4165526

  • Fluorescent fructose derivatives for imaging breast cancer cells BIOCONJUGATE CHEMISTRY Levi, J., Cheng, Z., Gheysens, O., Patel, M., Chan, C. T., Wang, Y., Namavari, M., Gambhir, S. S. 2007; 18 (3): 628-634


    Breast cancer cells are known to overexpress Glut5, a sugar transporter responsible for the transfer of fructose across the cell membrane. Since Glut5 transporter is not significantly expressed in normal breast cells, fructose uptake can potentially be used to differentiate between normal and cancerous cells. Fructose was labeled with two fluorophores at the C-1 position: 7-nitro-1,2,3-benzadiazole (NBD) and Cy5.5. The labeling site was chosen on the basis of the presence and substrate specificity of the key proteins involved in the first steps of fructose metabolism. Using fluorescence microscopy, the uptake of the probes was studied in three breast cancer cell lines: MCF 7, MDA-MB-435, and MDA-MB-231. Both fluorescent fructose derivatives showed a very good uptake in all tested cell lines. The level of uptake was comparable to that of the corresponding glucose analogs, 2-NBDG and Cy5.5-DG. Significant uptake of 1-NBDF derivative was not observed in cells lacking Glut5 transporter, while the uptake of the 1-Cy5.5-DF derivative was independent of the presence of a fructose-specific transporter. While 1-NBDF showed Glut5-specific accumulation, the coupling of a large fluorophore such as Cy5.5 likely introduces big structural and electronic changes, leading to a fructose derivative that does not accurately describe the uptake of fructose in cells.

    View details for DOI 10.1021/bc060184s

    View details for Web of Science ID 000246485500005

    View details for PubMedID 17444608

    View details for PubMedCentralID PMC4145876

  • Cu-64-Labeled alpha-melanocyte-stimulating hormone analog for MicroPET imaging of melanocortin 1 receptor expression BIOCONJUGATE CHEMISTRY Cheng, Z., Xiong, Z., Subbarayan, M., Chen, X., Gambhir, S. S. 2007; 18 (3): 765-772


    The alpha-melanocyte-stimulating hormone (alpha-MSH) receptor (melanocortin type 1 receptor, or MC1R) plays an important role in the development and growth of melanoma cells. It was found that MC1R was overexpressed on most murine and human melanoma, making it a promising molecular target for melanoma imaging and therapy. Radiolabeled alpha-MSH peptide and its analogs that can specifically bind with MC1R have been extensively explored for developing novel agents for melanoma detection and radionuclide therapy. The goal of this study was to evaluate a 64Cu-labeled alpha-MSH analog, Ac-Nle-Asp-His-D-Phe-Arg-Trp-Gly-Lys(DOTA)-NH2 (DOTA-NAPamide), as a potential molecular probe for microPET imaging of melanoma and MC1R expression in melanoma xenografted mouse models. 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) conjugated NAPamide was synthesized and radiolabeled with 64Cu (t1/2=12 h) in NH4OAc (0.1 M; pH 5.5) buffered solution for 60 min at 50 degrees C. Cell culture studies reveal rapid and high uptake and internalization of 64Cu-DOTA-NAPamide in B16F10 cells. Over 90% of receptor-bound tracer is internalized at 3 h incubation. A cellular retention study demonstrates that the receptor-bound 64Cu-DOTA-NAPamide is slowly released from the B16F10 cells into the medium; 66% of the radioactivity is still associated with the cells even after 3 h incubation. The biodistribution of 64Cu-DOTA-NAPamide was then investigated in C57BL/6 mice bearing subcutaneous murine B16F10 melanoma tumors with high capacity of MC1R and Fox Chase Scid mice bearing human A375M melanoma with a relatively low number of MC1R receptors. Tumor uptake values of 64Cu-DOTA-NAPamide are found to be 4.63 +/- 0.45% and 2.49 +/- 0.31% ID/g in B16F10 and A375M xenografted melanoma at 2 h postinjection (pi), respectively. The B16F10 tumor uptake at 2 h pi is further inhibited to 2.29 +/- 0.24% ID/g, while A375M tumor uptake at 2 h pi remains 2.20 +/- 0.41% ID/g with a coinjection of excess alpha-MSH peptide. MicroPET imaging of 64Cu-DOTA-NAPamide in B16F10 tumor mice clearly shows good tumor localization. However, low A375M tumor uptake and poor tumor to normal tissue contrast were observed. This study demonstrates that 64Cu-DOTA-NAPamide is a promising molecular probe for alpha-MSH receptor positive melanoma PET imaging as well as MC1R expression imaging in living mice.

    View details for DOI 10.1021/bc060306g

    View details for Web of Science ID 000246485500021

    View details for PubMedID 17348700

  • Construction and validation of improved triple fusion reporter gene vectors for molecular imaging of living subjects CANCER RESEARCH Ray, P., Tsien, R., Gambhir, S. S. 2007; 67 (7): 3085-3093


    Multimodality imaging using several reporter genes and imaging technologies has become an increasingly important tool in determining the location(s), magnitude, and time variation of reporter gene expression in small animals. We have reported construction and validation of several triple fusion genes composed of a bioluminescent, a fluorescent, and a positron emission tomography (PET) reporter gene in cell culture and in living subjects. However, the bioluminescent and fluorescent components of fusion reporter proteins encoded by these vectors possess lesser activities when compared with the bioluminescent and fluorescent components of the nonfusions. In this study, we first created a mutant (mtfl) of a thermostable firefly luciferase (tfl) bearing the peroxisome localization signal to have greater cytoplasmic localization and improved access for its substrate, d-luciferin. Comparison between the three luciferases [mtfl, tfl, and firefly luciferase (fl)] both in cell culture and in living mice revealed that mtfl possessed 6- to 10-fold (in vitro) and 2-fold (in vivo) higher activity than fl. The improved version of the triple fusion vector carrying mtfl as the bioluminescent reporter component showed significantly (P < 0.05) higher bioluminescence than the previous triple fusion vectors. Of the three different red fluorescent reporter genes (jred, hcred, and mrfp1, isolated from jellyfish chromophore, coral Heteractis crispa, and coral Discosoma, respectively) evaluated, mrfp1 was able to preserve highest expression as a component of the triple fusion reporter gene for in vivo fluorescence imaging. A truncated version of wild-type herpes simplex virus 1 (HSV1) thymidine kinase gene (wttk) retained a higher expression level than the truncated mutant HSV1-sr39 TK (ttk) as the third reporter component of this improved triple fusion vector. Multimodality imaging of tumor-bearing mice using bioluminescence and microPET showed higher luciferase activity [(2.7 +/- 0.1 versus 1.9 +/- 0.1) x (10(6) p/s/cm(2)/sr)] but similar level of fluorine-18-labeled 2'-fluoro-2'-deoxyarabinofuranosyl-5-ethyluracil (18F-FEAU) uptake (1.37 +/- 0.15 versus 1.37 +/- 0.2) percentage injected dose per gram] by mtfl-mrfp1-wttk-expressing tumors compared with the fl-mrfp1-wttk-expressing tumors. Both tumors showed 4- to 5-fold higher accumulation (P < 0.05) of 18F-FEAU than fluorine-18-labeled 9-(4-fluoro-3-hydroxymethylbutyl)guanine. This improved triple fusion reporter vector will enable high sensitivity detection of lower numbers of cells from living animals using the combined bioluminescence, fluorescence, and microPET imaging techniques.

    View details for DOI 10.1158/0008-5472.CAN-06-2402

    View details for Web of Science ID 000245622900025

    View details for PubMedID 17409415

  • Reproducibility of F-18-FDG microPET studies in mouse tumor xenografts JOURNAL OF NUCLEAR MEDICINE Dandekar, M., Tseng, J. R., Gambhir, S. S. 2007; 48 (4): 602-607


    (18)F-FDG has been used to image mouse xenograft models with small-animal PET for therapy response. However, the reproducibility of serial scans has not been determined. The purpose of this study was to determine the reproducibility of (18)F-FDG small-animal PET studies.Mouse tumor xenografts were formed with B16F10 murine melanoma cells. A 7-min small-animal PET scan was performed 1 h after a 3.7- to 7.4-MBq (18)F-FDG injection via the tail vein. A second small-animal PET scan was performed 6 h later after reinjection of (18)F-FDG. Twenty-five sets of studies were performed. Mean injected dose per gram (%ID/g) values were calculated from tumor regions of interest. The coefficient of variation (COV) from studies performed on the same day was calculated to determine the reproducibility. Activity from the second scans performed after 6 h were adjusted by subtracting the estimated residual activity from the first (18)F-FDG injection. For 7 datasets, an additional scan immediately before the second injection was performed, and residual activity from this additional delayed scan was subtracted from the activity of the second injection. COVs of both subtraction methods were compared. Blood glucose values were measured at the time of injection and used to correct the %ID/g values.The COV for the mean %ID/g between (18)F-FDG small-animal PET scans performed on the same day 6 h apart was 15.4% +/- 12.6%. The delayed scan subtraction method did not produce any significant change in the COV. Blood glucose correction increased the COV. The injected dose, tumor size, and body weight did not appear to contribute to the variability of the scans.(18)F-FDG small-animal PET mouse xenograft studies were reproducible with moderately low variability. Therefore, serial small-animal PET studies may be performed with reasonable accuracy to measure tumor response to therapy.

    View details for DOI 10.2967/jnumed.106.036608

    View details for Web of Science ID 000245647000024

    View details for PubMedID 17401098

  • Detection of bone metastases: Assessment of integrated FDG PET/CT imaging RADIOLOGY Taira, A. V., Herfkens, R. J., Gambhir, S. S., Quon, A. 2007; 243 (1): 204-211


    To retrospectively evaluate the positive predictive value (PPV) of fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) in the identification of malignant bone lesions when the PET and CT findings are discordant and concordant.The study conformed to HIPAA standards, and the need for informed consent was waived by the institutional review board that approved the study. FDG PET/CT reports of 712 patients were reviewed to identify patients with malignant bone lesions. Fifty-nine patients (30 female and 29 male patients; age range, 10-82 years) with 113 lesions were analyzed. With use of confirmation from histopathologic examination or clinical follow-up, the PPVs of the integrated examination and of the stand-alone CT and PET components of the examination were calculated. The results were stratified according to cancer type, chemotherapy status, and number of bone lesions and were compared by using Fisher exact tests.Of 47 lesions with positive findings at both PET and CT, 46 were malignant and one was benign, for a PPV of 98%. Of 31 lesions with positive findings at PET and negative findings at CT, 19 were malignant and 12 were benign, for a PPV of 61%. Of 35 lesions with negative findings at PET and positive findings at CT, six were malignant and 29 were benign, for a PPV of 17%. Independently, the PPV of all lesions with positive findings at PET was significantly higher than that of all lesions with positive findings at CT. Chemotherapy status for lesions with positive findings at CT and the number of lesions per patient had a statistically significant effect on the PPV of examinations (P = .02 and P < .001, respectively).PET/CT has a very high PPV for bone metastases (98%) when the findings at PET and CT are concordant; however, in lesions with discordant PET and CT findings at the integrated examination, PPV is markedly diminished.

    View details for DOI 10.1148/radiol.2431052104

    View details for Web of Science ID 000245312500025

    View details for PubMedID 17392254

  • Combinatorial library screening for developing an improved split-firefly luciferase fragment-assisted complementation system for studying protein-protein interactions ANALYTICAL CHEMISTRY Paulmurugan, R., Gambhir, S. S. 2007; 79 (6): 2346-2353


    Split reporter-based bioluminescence imaging is a useful strategy for studying protein-protein as well as other intracellular interactions. We have used a combinatorial strategy to identify a novel split site for firefly luciferase with improved characteristics over previously published split sites. A combination of fragments with greater absolute signal with near-zero background signals was achieved by screening 115 different combinations. The identified fragments were further characterized by using five different interacting protein partners and an intramolecular folding strategy. Cell culture studies and imaging in living mice was performed to validate the new split sites. In addition, the signal generated by the newly identified combination of fragments (Nfluc 398/ Cfluc 394) was compared with different split luciferase fragments currently in use for studying protein-protein interactions and was shown to be markedly superior with a lower self-complementation signal and equal or higher postinteraction absolute signal. This study also identified many different combinations of nonoverlapping and overlapping firefly luciferase fragments that can be used for studying different cellular events such as subcellular localization of proteins, cell-cell fusion, and evaluating cell delivery vehicles, in addition to protein-protein interactions, both in cells and small living animals.

    View details for DOI 10.1021/ac062053q

    View details for Web of Science ID 000244867100020

    View details for PubMedID 17295448

  • In vivo optical bioluminescence imaging of collagen-supported cardiac cell grafts JOURNAL OF HEART AND LUNG TRANSPLANTATION Kutschka, I., Chen, I. Y., Kofidis, T., von Degenfeld, G., Sheikh, A. Y., Hendry, S. L., Hoyt, G., Pearl, J., Blau, H. M., Gambhir, S. S., Robbins, R. C. 2007; 26 (3): 273-280


    Histology-based survival assessment of cell grafts does not allow for in vivo follow-up. In this study we introduce two new experimental models for longitudinal in vivo survival studies of cardiac cell grafts using optical bioluminescence imaging.H9c2 cardiomyoblasts expressing both firefly luciferase (fluc) and green fluorescent protein (GFP) reporter genes were implanted into Lewis rats. In Model 1, H9c2-fluc-IRES-GFP cells (0.5 x 10(6)) were implanted into a cryoinjured abdominal wall muscle. Cells were injected using either liquid collagen (Matrigel [MG]) or phosphate-buffered saline (PBS) suspension. Cell survival was evaluated in vivo using bioluminescence imaging on days 1, 5 and 10 post-operatively. In model 2, rats underwent ligation of the left anterior descending (LAD) artery. The donor hearts were harvested, and the infarcted region was restored ex situ using 1 x 10(6) H9c2-fluc-IRES-GFP cells seeded in collagen matrix (Gelfoam [GF]) or suspended in PBS (n = 8/group). Hearts were then transplanted into the abdomen of syngeneic recipients. Optical bioluminescence imaging was performed on Days 1, 5, 8 and 14 post-operatively. After 4 weeks, immunohistologic studies were performed.For model 1, at day 5, bioluminescence signals were markedly higher for the H9c2/MG group (449 +/- 129 photons/second x 10(3)) compared with the H9c2/PBS group (137 +/- 82 photons/second x 10(3)) (p < 0.05). For model 2, bioluminescence signals were significantly (p < 0.04) higher in the H9c2/GF group compared with plain cell injection on days 5 (534 +/- 115 vs 219 +/- 34) and 8 (274 +/- 34 vs 180 +/- 23). Data were in accordance with GFP immunohistology.Optical bioluminescence is a powerful method for assessment of cardiac cell graft survival in vivo. Collagen matrices support early survival of cardiomyoblasts after transplantation into injured musculature.

    View details for Web of Science ID 000244979000010

    View details for PubMedID 17346630

  • Standardized uptake value atlas: Characterization of physiological 2-deoxy-2-[F-18]fluoro-D-glucose uptake in normal tissues MOLECULAR IMAGING AND BIOLOGY Wang, Y., Chiu, E., Rosenberg, J., Gambhir, S. S. 2007; 9 (2): 83-90


    The purpose of this study was to map the distribution of 2-deoxy-2-[18F]fluoro-D-glucose (FDG) uptake in organs of patients with no known abnormalities in those tissues.We measured maximum and mean standardized uptake values (SUV) from FDG-positron emission tomography (PET)/computed tomography (CT) obtained from 98 patients (48 males and 50 females).Significant uptake (mean SUVmean>2.5) was visualized in the cerebellum (8.0+/-2.2), soft palate (2.92+/-0.86), palatine tonsils (3.45+/-1.4), lingual tonsils (3.08+/-1.05), sublingual glands (3.3+/-1.5), and testes (2.57+/-0.56). Negative correlation for FDG uptake versus age was observed for the palatine tonsils, sublingual glands, and lungs (P<0.001).Better understanding of physiological uptake throughout the body is valuable for improved interpretive accuracy and should be useful for future semi-automated comparisons to a normal SUV database.

    View details for DOI 10.1007/s11307-006-0075-y

    View details for Web of Science ID 000244866700005

    View details for PubMedID 17225983

  • Impact of integrated PET/CT on variability of target volume delineation in rectal cancer TECHNOLOGY IN CANCER RESEARCH & TREATMENT Patel, D. A., Chang, S. T., Goodman, K. A., Quon, A., Thorndyke, B., Gambhir, S. S., McMillan, A., Loo, B. W., Koong, A. C. 2007; 6 (1): 31-36


    Several studies have demonstrated substantial variability among individual radiation oncologists in defining target volumes using computed tomography (CT). The objective of this study was to determine the impact of combined positron emission tomography and computed tomography (PET/CT) on inter-observer variability of target volume delineation in rectal cancer. We also compared the relative concordance of two PET imaging tracers, 18F-fluorodeoxyglucose (FDG) and 18F-fluorodeoxythymidine (FLT), against conventional computed tomography (CT). Six consecutive patients with locally advanced rectal cancer were enrolled onto an institutional protocol involving preoperative chemoradiotherapy and correlative studies including FDG- and FLT-PET scans acquired in the treatment position. Using these image data sets, four radiation oncologists independently delineated primary and nodal gross tumor volumes (GTVp and GTVn) for a hypothetical boost treatment. Contours were first defined based on CT alone with observers blinded to the PET images, then based on combined PET/CT. An inter-observer similarity index (SI), ranging from a value of 0 for complete disagreement to 1 for complete agreement of contoured voxels, was calculated for each set of volumes. For primary gross tumor volume (GTVp), the difference in estimated SI between CT and FDG was modest (CT SI = 0.77 vs. FDG SI = 0.81), but statistically significant (p = 0.013). The SI difference between CT and FLT for GTVp was also slight (FLT SI = 0.80) and marginally non-significant (p < 0.082). For nodal gross tumor volume, (GTVn), SI was significantly lower for CT based volumes with an estimated SI of 0.22 compared to an estimated SI of 0.70 for FDG-PET/CT (p < 0.0001) and an estimated SI of 0.70 for FLT-PET/CT (p < 0.0001). Boost target volumes in rectal cancer based on combined PET/CT results in lower inter-observer variability compared with CT alone, particularly for nodal disease. The use of FDG and FLT did not appear to be different from this perspective.

    View details for Web of Science ID 000244732600005

    View details for PubMedID 17241098

  • Multimodality imaging of tumor xenografts and metastases in mice with combined small-animal PET, small-animal CT, and bioluminescence imaging JOURNAL OF NUCLEAR MEDICINE Deroose, C. M., De, A., Loening, A. M., Chow, P. L., Ray, P., Chatziioannou, A. F., Gambhir, S. S. 2007; 48 (2): 295-303


    Recent developments have established molecular imaging of mouse models with small-animal PET and bioluminescence imaging (BLI) as an important tool in cancer research. One of the disadvantages of these imaging modalities is the lack of anatomic information. We combined small-animal PET and BLI technology with small-animal CT to obtain fusion images with both molecular and anatomic information.We used small-animal PET/CT and BLI to detect xenografts of different cell lines and metastases of a melanoma cell line (A375M-3F) that had been transduced with a lentiviral vector containing a trimodality imaging reporter gene encoding a fusion protein with Renilla luciferase, monomeric red fluorescent protein, and a mutant herpes simplex virus type 1 thymidine kinase.Validation studies in mouse xenograft models showed a good coregistration of images from both PET and CT. Melanoma metastases were detected by 18F-FDG PET, 9-[4-(18)F-fluoro-3-(hydroxymethyl)butyl]guanine (18F-FHBG) PET, CT, and BLI and confirmed by ex vivo assays of Renilla luciferase and mutant thymidine kinase expression. 18F-FHBG PET/CT allowed detection and localization of lesions that were not seen on CT because of poor contrast resolution and were not seen on 18F-FDG PET because of higher background uptake relative to 18F-FHBG.The combination of 18F-FHBG PET, small-animal CT, and BLI allows a sensitive and improved quantification of tumor burden in mice. This technique is potentially useful for the study of the biologic determinants of metastasis and for the evaluation of novel cancer treatments.

    View details for Web of Science ID 000244115600037

    View details for PubMedID 17268028

  • PET imaging of colorectal cancer in xenograft-bearing mice by use of an F-18-labeled T84.66 anti-carcinoembryonic antigen diabody JOURNAL OF NUCLEAR MEDICINE Cai, W., Olafsen, T., Zhang, X., Cao, Q., Gambhir, S. S., Williams, L. E., Wu, A. M., Chen, X. 2007; 48 (2): 304-310


    In this study, we investigated the 18F-labeled anti-carcinoembryonic antigen (CEA) T84.66 diabody, a genetically engineered noncovalent dimer of single-chain variable fragments, for small-animal PET imaging of CEA expression in xenograft-bearing mice.18F labeling of the anti-CEA T84.66 diabody (molecular mass, 55 kDa) was achieved with N-succinimidyl-4-18F-fluorobenzoate (18F-SFB). The biodistribution of the 18F-fluorobenzyl-T84.66 diabody (18F-FB-T84.66 diabody) was evaluated in athymic nude mice bearing subcutaneous LS 174T human colon carcinoma and C6 rat glioma tumors. Serial small-animal PET imaging studies were performed to further evaluate in vivo targeting efficacy and pharmacokinetics.Radiolabeling required 35 +/- 5 (mean +/- SD) min starting from 18F-SFB, and the tracer 18F-FB-T84.66 diabody was synthesized with a specific activity of 1.83 +/- 1.71 TBq/mmol. The decay-corrected radiochemical yield was 1.40% +/- 0.16% (n = 4), and the radiochemical purity was greater than 98%. The radioimmunoreactivity was 57.1% +/- 2.0%. The 18F-FB-T84.66 diabody showed rapid and high tumor uptake and fast clearance from the circulation in the LS 174T xenograft model, as evidenced by both small-animal PET imaging and biodistribution studies. High-contrast small-animal PET images were obtained as early as 1 h after injection of the 18F-FB-T84.66 diabody, and only a background level of activity accumulation was found in CEA-negative C6 tumors. The tracer exhibited predominantly renal clearance, with some activity in the liver and spleen at early time points.The 18F-labeled diabody represents a new class of tumor-specific probes for PET that are based on targeting cell surface antigen expression. The 18F-FB-T84.66 diabody can be used for high-contrast small-animal PET imaging of CEA-positive tumor xenografts. It may be translated to the clinic for PET of CEA-positive malignancies.

    View details for Web of Science ID 000244115600038

    View details for PubMedID 17268029

  • 2-deoxy-2-[F-18]fluoro-D-glucose positron emission tomography/computed tomography in the management of melanoma MOLECULAR IMAGING AND BIOLOGY Iagaru, A., Quon, A., Johnson, D., Gambhir, S. S., McDougall, I. R. 2007; 9 (1): 50-57


    2-Deoxy-2-[F-18]fluoro-D-glucose (FDG)-positron emission tomography (PET)/computed tomography (CT) is widely available as a powerful imaging modality, combining the ability to detect active metabolic processes and their morphologic features in a single exam. The role of FDG-PET is proven in a variety of cancers, including melanoma, but the estimates of sensitivity and specificity are based in the majority of the published studies on dedicated PET, not PET/CT. Therefore, we were prompted to review our experience with FDG-PET/CT in the management of melanoma.This is a retrospective study on 106 patients with melanoma (20-87 years old; average: 56.8 +/- 15.9), who had whole-body FDG-PET/CT at our institution from January 2003 to June 2005. Thirty-eight patients (35.9%) were women and 68 patients (64.1%) were men. Reinterpretation of the imaging studies for accuracy and data analysis from medical records were performed.All patients had the study for disease restaging. The primary tumor depth (Breslow's thickness) at initial diagnosis was available for 76 patients (71.7%) and ranged from 0.4 to 25 mm (average: 3.56 mm). The anatomic level of invasion in the skin (Clark's level) was determined for 70 patients (66%): 3, level II; 13, level III; 43, level IV; 11, level V. The administered dose of (18)F FDG ranged from 9.8 to 21.6 mCi (average: 15.4 +/- 1.8 mCi). FDG-PET/CT had a sensitivity of 89.3% [95% confidence interval (CI): 78.5-95] and a specificity of 88% (95% CI: 76.2-94.4) for melanoma detection.This study confirms the good results of FDG-PET/CT for residual/recurrent melanoma detection, as well as for distant metastases localization. PET/CT should be an integral part in evaluation of patients with high-risk melanoma, prior to selection of the most appropriate therapy.

    View details for DOI 10.1007/s11307-006-0065-0

    View details for Web of Science ID 000243545600007

    View details for PubMedID 17051322

  • Osseous and Soft Tissue Sarcomas: When Can F-18 FDG PET/CT Evaluation Provide Useful Information? Osseous and Soft Tissue Sarcomas: When Can F-18 FDG PET/CT Evaluation Provide Useful Information? Iagaru, A. 2007; 34 (2)
  • Endothelial progenitor cells from murine embryonic stem cells: isolation and transplantation for myocardial infarction Li, Z., Wu, J., Sheikh, A., Kraft, D., Cao, F., Xie, X., Patel, M., Gambhir, S., Robbins, R., Cooke, J., Wu, J. SAGE PUBLICATIONS LTD. 2007: 152–52
  • Development of a Bicistronic Vector for Multimodality Imaging of Estrogen Receptor Activity in a Breast Cancer Model; Preliminary Application. European Journal of Nuclear Medicine and Molecular Imaging Ottobrini L, Ciana P, Moresco R Lecchi M, Belloli S, Martelli C, Todde S, Fazio F, Gambhir SS, Maggi A, Lucignani G. 2007; 35(2): 365-378
  • Follicular Dendritic Sarcoma within a Focus of Castleman?s Disease. Serial FDG PET/CT in the follow up of Recurrence with Histopatholigic Confirmation. Revista Espanola Medicina Nuclear Journa Iagaru A, Mari C, Gambhir SS 2007; 26(1): 40-45
  • Reporter Gene Imaging of Protein-Protein Interactions in Living Subjects. Current Opinion in Biotechnology Massoud T, Paulmurugan R, De A, Ray P, Gambhir SS 2007; 18: 31-37
  • Noninvasive monitoring of ligand-dependent VEGF receptor-2 dimerization with split firefly luciferase 49th Annual Meeting of the American-Society-for-Therapeutic-Radiology-and-Oncology (ASTRO) Lee, P., Chan, C., Hua, A., Paulmurugan, R., Chan, D., Gambhir, S., Le, Q., Giaccia, A. ELSEVIER SCIENCE INC. 2007: S96–S97
  • Studying the biodistribution of positron emission tomography reporter probes in mice NATURE PROTOCOLS Yaghoubi, S. S., Berger, F., Gambhir, S. S. 2007; 2 (7): 1752-1755


    Positron emission tomography (PET) reporter probes (PRPs) are used to detect PET reporter gene (PRG) expression in living subjects. This article details protocols for analyzing the biodistribution of a PRP used to detect herpes simplex virus 1 thymidine kinase (HSV1-tk) or mutant HSV1-sr39tk PRG expression. However, the methods described are generalizable to other beta- or gamma/positron-emitting probes. Accumulation of PRPs in animal tissues can be determined by counting PRP activity of isolated tissues, whereas digital whole-body autoradiography (DWBA) provides high-resolution images of PRP biodistribution in 5- to 45-microm tissue slices of killed research animals at a single time point. Biodistribution assay results may be obtained in less than a week after beginning the assay, and DWBA image acquisitions can take up to 3 months depending on the probe's radioisotope.

    View details for DOI 10.1038/nprot.2007.228

    View details for Web of Science ID 000253139200020

    View details for PubMedID 17641641

  • Noninvasive imaging of molecular events with bioluminescent reporter genes in living subjects. Methods in molecular biology (Clifton, N.J.) Ray, P., Gambhir, S. S. 2007; 411: 131-144


    Bioluminescence imaging has become a very popular tool for noninvasive monitoring of fundamental biological and molecular processes in small living subjects. Luciferases are light-emitting enzymes that can generate light (known as bioluminescence) after reacting with specific substrates. The emitted light is used as a detection system for luciferase activity, which acts as a "reporter" for the activity of any regulatory elements that control its expression. These enzymes are isolated from various organisms, conveniently modified for expression in mammalian cells, and are extensively used in molecular biology and cell culture experiments. Recent advances in optical technology have opened a new dimension for in vivo application of luciferase enzymes in biomedical research. The most commonly utilized luciferases for in vivo bioluminescence are isolated from two very different sources: firefly luciferase (or beetle luciferase) and renilla luciferase (isolated from sea pansy). Although both these luciferases can produce light following interaction with the substrates, structurally and biochemically they are very different. Here we describe the methods and applications of firefly and renilla luciferases in molecular imaging using small animals.

    View details for DOI 10.1007/978-1-59745-549-7_10

    View details for PubMedID 18287643

  • Drug Delivery: Keeping Tabs on Nanocarriers. Nature Nanotechnology de la Zerda, A., Gambhir, SS 2007; 2: 745-746
  • F-18FDG PET/CT evaluation of osseous and soft tissue sarcomas CLINICAL NUCLEAR MEDICINE Iagaru, A., Quon, A., McDougall, T. R., Gambhir, S. S. 2006; 31 (12): 754-760


    Osseous and soft tissue sarcomas (OSTS) represent a histologic heterogeneous group of malignant tumors. Most of the current clinical data on the role of F-18 FDG PET in sarcomas come from patients studied with dedicated PET and less frequently with hardware fusion PET/CT. Therefore, we were prompted to review our experience with F-18 FDG PET/CT in OSTS.This is a retrospective study (January 2003-December 2005) of 44 patients with histologic diagnoses of OSTS who had F-18 FDG PET/CT at our institution. The group included 22 men and 22 women with an age range of 2 of 84 years (average, 37 +/- 20.2 years). The administered doses of F-18 FDG range 4.1 to 19.5 mCi (average, 14.3 +/- 3 mCi). Reinterpretation of the imaging studies for accuracy and data analysis from medical records was performed.The sensitivity and specificity of combined F-18 FDG PET/CT were 100% (95% confidence interval [CI] = 75.7-100) and 93.3% (95% CI = 78.7-98.1) for the primary OSTS, and 80% (95% CI = 58.4-91.9) and 86.4% (95% CI = 66.7-95.2) for metastases. When interpreted separately, CT outperformed PET for pulmonary metastases detection: CT was 76.5% sensitive and 88% specific, whereas PET was only 57.1% sensitive but 96.4% specific. For detection of other metastases, CT was 82.3% sensitive and 76% specific, with PET demonstrating 78.6% sensitivity and 92.8% specificity.Relatively similar results (except better specificity for PET and PET/CT) were noted when examining the rate of metastases detection, excluding pulmonary lesions. However, CT had a better detection rate for pulmonary metastases when compared with PET alone. A negative PET scan in the presence of suspicious CT findings in the chest cannot reliably exclude pulmonary metastases from OSTS.

    View details for Web of Science ID 000242481400004

    View details for PubMedID 17117068

  • Quantitative micro positron emission tomography (PET) imaging for the in vivo determination of pancreatic islet graft survival NATURE MEDICINE Kim, S., Doudet, D. J., Studenov, A. R., Nian, C., Ruth, T. J., Gambhir, S. S., McIntosh, C. H. 2006; 12 (12): 1423-1428


    Islet transplantation is an attractive approach for treating type-1 diabetes, but there is a massive loss of transplanted islets. It is currently only possible to estimate islet mass indirectly, through measurement of circulating C-peptide and insulin levels. This type of estimation, however, is not sufficiently sensitive or reproducible for follow-up of individuals who have undergone islet transplantation. Here we show that islet graft survival could be assessed for 1 month in diabetic NOD mice using 9-(4-[(18)F]-fluoro-3-hydroxymethylbutyl)guanine ([(18)F]FHBG)-positron emission tomography (PET) technology, the PET signal reflecting insulin secretory capacity of transplanted islets. Expression of the gene encoding viral interleukin-10 (vIL-10), was measurable in real time with PET scanning. Additionally, we addressed the clinical potential of this approach by visualizing transplanted islets in the liver, the preferred clinical transplantation site. We conclude that quantitative in vivo PET imaging is a valid method for facilitating the development of protocols for prolonging islet survival, with the potential for tracking human transplants.

    View details for DOI 10.1038/nm1458

    View details for Web of Science ID 000242618200024

    View details for PubMedID 17143277

  • Long-term monitoring of transplanted islets using positron emission tomography MOLECULAR THERAPY Lu, Y., Dang, H., Middleton, B., Campbell-Thompson, M., Atkinson, M. A., Gambhir, S. S., Tian, J., Kaufman, D. L. 2006; 14 (6): 851-856


    Islet transplantation can restore glucose homeostasis in those with type 1 diabetes; however, most recipients eventually lose graft function. A noninvasive method to monitor islets following transplantation would enable assessment of their survival and aid the development of therapeutics to prolong graft survival. Here, we show that recombinant lentivirus can be used to engineer human islets to express a positron emission tomography (PET) reporter gene. Following transplantation into mice, transduced islets could be imaged in vivo using microPET and a radiolabeled probe approved by the FDA for clinical use in humans. The magnitude of signal from engineered islets implanted into the axillary cavity reflected the implanted islet mass. Signals from implanted islets decreased by approximately one-half during the first few weeks following transplantation, which may reflect islet cell death shortly after transplantation. Thereafter, the magnitude of signals from the implanted islets remained fairly constant when the recipients were repetitively reimaged over 90 days. Histological analysis of the implants showed healthy islets with PET reporter-expressing cells distributed throughout the islet architecture. These studies suggest that PET imaging of lentivirus-transduced islets could provide a safe and feasible method for long-term monitoring of islet graft survival.

    View details for DOI 10.1016/j.ymthe.2006.08.007

    View details for Web of Science ID 000242723300011

    View details for PubMedID 16982215

  • Proteomic analysis of reporter genes for molecular imaging of transplanted embryonic stem cells PROTEOMICS Wu, J. C., Cao, F., Dutta, S., Xie, X., Kim, E., Chungfat, N., Gambhir, S., Mathewson, S., Connolly, A. J., Brown, M., Wang, E. W. 2006; 6 (23): 6234-6249


    Study of stem cells may reveal promising treatment for diseases. The fate and function of transplanted stem cells remain poorly defined. Recent studies demonstrate that reporter genes can monitor real-time survival of transplanted stem cells in living subjects. We examined the effects of a novel and versatile triple fusion (TF) reporter gene construction on embryonic stem (ES) cell function by proteomic analysis. Murine ES cells were stably transduced with a self-inactivating lentiviral vector containing fluorescence (firefly luciferase; Fluc), bioluminescence (monomeric red fluorescence protein; mRFP), and positron emission tomography (herpes simplex virus type 1 truncated thymidine kinase; tTK) reporter genes. Fluorescence-activated cell sorting (FACS) analysis isolated stably transduced populations. TF reporter gene effects on cellular function were evaluated by quantitative proteomic profiling of control ES cells versus ES cells stably expressing the TF construct (ES-TF). Overall, no significant changes in protein quantity were observed. TF reporter gene expression had no effect on ES cell viability, proliferation, and differentiation capability. Molecular imaging studies tracked ES-TF cell survival and proliferation in living animals. In summary, this is the first proteomic study, demonstrating the unique potential of reporter gene imaging for tracking ES cell transplantation non-invasively, repetitively, and quantitatively.

    View details for DOI 10.1002/pmic.200600150

    View details for Web of Science ID 000242879000011

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