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ABSTRACT: A γ-AApeptide-based tracer for positron emission tomography imaging of integrin α(v)β(3) is reported. Despite its shorter sequence and linear nature, this tracer had comparable integrin α(v)β(3) binding affinity to the cyclic arginine-glycine-aspartic acid peptide but significantly higher resistance to enzymatic degradation and better stability.
Chemical Communications 08/2012; 48(63):7850-2. · 6.17 Impact Factor
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Hao Hong,
Yin Zhang,
Gregory W Severin, Yunan Yang,
Jonathan W Engle,
Gang Niu,
Robert J Nickles,
Xiaoyuan Chen,
Bryan R Leigh,
Todd E Barnhart,
Weibo Cai
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ABSTRACT: Metastatic breast cancer is incurable. The goal of this study was to develop a positron emission tomography (PET)/near-infrared fluorescent (NIRF) probe for imaging CD105 expression in breast cancer experimental lung metastasis. TRC105, a chimeric anti-CD105 antibody, was dual-labeled with a NIRF dye (IRDye 800CW) and (89)Zr to yield (89)Zr-Df-TRC105-800CW. Luciferase-transfected 4T1 murine breast cancer cells were injected intravenously into female mice to establish the tumor model. Bioluminescence imaging (BLI) was carried out to noninvasively monitor the lung tumor burden. PET imaging revealed that 4T1 lung tumor uptake of (89)Zr-Df-TRC105-800CW was 8.7 ± 1.4, 10.9 ± 0.5, and 9.7 ± 1.1% ID/g at 4, 24, and 48 h postinjection (n = 4), with excellent tumor contrast. Biodistribution studies, blocking, control studies with (89)Zr-Df-cetuximab-800CW, ex vivo BLI/PET/NIRF imaging, and histology all confirmed CD105 specificity of the tracer. Broad clinical potential of TRC105-based agents was shown in many tumor types, which also enabled early detection of small metastasis and intraoperative guidance for tumor removal.
Molecular Pharmaceutics 07/2012; · 4.78 Impact Factor
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ABSTRACT: A multifunctional unimolecular micelle made of a hyperbranched amphiphilic block copolymer was designed, synthesized, and characterized for cancer-targeted drug delivery and non-invasive positron emission tomography (PET) imaging in tumor-bearing mice. The hyperbranched amphiphilic block copolymer, Boltorn(®) H40-poly(L-glutamate-hydrazone-doxorubicin)-b-poly(ethylene glycol) (i.e., H40-P(LG-Hyd-DOX)-b-PEG), was conjugated with cyclo(Arg-Gly-Asp-D-Phe-Cys) peptides (cRGD, for integrin α(v)β(3) targeting) and macrocyclic chelators (1,4,7-triazacyclononane-N, N', N''-triacetic acid [NOTA], for (64)Cu-labeling and PET imaging) (i.e., H40-P(LG-Hyd-DOX)-b-PEG-OCH(3)/cRGD/NOTA, also referred to as H40-DOX-cRGD). The anti-cancer drug, doxorubicin (DOX) was covalently conjugated onto the hydrophobic segments of the amphiphilic block copolymer arms (i.e., PLG) via a pH-labile hydrazone linkage to enable pH-controlled drug release. The unimolecular micelles exhibited a uniform size distribution and pH-sensitive drug release behavior. cRGD-conjugated unimolecular micelles (i.e., H40-DOX-cRGD) exhibited a much higher cellular uptake in U87MG human glioblastoma cells due to integrin α(v)β(3)-mediated endocytosis than non-targeted unimolecular micelles (i.e., H40-DOX), thereby leading to a significantly higher cytotoxicity. In U87MG tumor-bearing mice, H40-DOX-cRGD-(64)Cu also exhibited a much higher level of tumor accumulation than H40-DOX-(64)Cu, measured by non-invasive PET imaging and confirmed by biodistribution studies and ex vivo fluorescence imaging. We believe that unimolecular micelles formed by hyperbranched amphiphilic block copolymers that synergistically integrate passive and active tumor-targeting abilities with pH-controlled drug release and PET imaging capabilities provide the basis for future cancer theranostics.
Biomaterials 04/2012; 33(11):3071-82. · 7.40 Impact Factor
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ABSTRACT: CD105 (endoglin) is an independent prognostic marker for poor prognosis in >10 solid tumor types, including breast cancer. The goal of this study was to develop a CD105-specific agent for both positron emission tomography (PET) and near-infrared fluorescence (NIRF) imaging, which can have potential clinical applications in diagnosis and imaged-guided surgery of breast cancer. TRC105, a chimeric anti-CD105 monoclonal antibody, was labeled with both a NIRF dye (i.e., 800CW) and (64)Cu to yield (64)Cu-NOTA-TRC105-800CW. Flow cytometry analysis revealed no difference in CD105 binding affinity/specificity between TRC105 and NOTA-TRC105-800CW. Serial PET imaging revealed that the 4T1 murine breast tumor uptake of (64)Cu-NOTA-TRC105-800CW was 5.2 ± 2.7, 11.0 ± 1.4, and 13.0 ± 0.4% ID/g at 4, 24, and 48 h postinjection respectively. Tumor uptake as measured by ex vivo NIRF imaging exhibited a good linear correlation with the % ID/g values obtained from PET (R = 0.74). Biodistribution data were consistent with the PET/NIRF findings. Blocking experiments, control studies with dual-labeled cetuximab (an isotype-matched control antibody), and histology confirmed the CD105 specificity of (64)Cu-NOTA-TRC105-800CW. Successful PET/NIRF imaging of CD105 expression warrants further investigation and clinical translation of dual-labeled TRC105-based imaging agents.
Molecular Pharmaceutics 03/2012; 9(3):645-53. · 4.78 Impact Factor
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Hao Hong,
Kai Yang,
Yin Zhang,
Jonathan W Engle,
Liangzhu Feng, Yunan Yang,
Tapas R Nayak,
Shreya Goel,
Jero Bean,
Charles P Theuer,
Todd E Barnhart,
Zhuang Liu,
Weibo Cai
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ABSTRACT: Herein we demonstrate that nanographene can be specifically directed to the tumor neovasculature in vivo through targeting of CD105 (i.e., endoglin), a vascular marker for tumor angiogenesis. The covalently functionalized nanographene oxide (GO) exhibited excellent stability and target specificity. Pharmacokinetics and tumor targeting efficacy of the GO conjugates were investigated with serial noninvasive positron emission tomography imaging and biodistribution studies, which were validated by in vitro, in vivo, and ex vivo experiments. The incorporation of an active targeting ligand (TRC105, a monoclonal antibody that binds to CD105) led to significantly improved tumor uptake of functionalized GO, which was specific for the neovasculature with little extravasation, warranting future investigation of these GO conjugates for cancer-targeted drug delivery and/or photothermal therapy to enhance therapeutic efficacy. Since poor extravasation is a major hurdle for nanomaterial-based tumor targeting in vivo, this study also establishes CD105 as a promising vascular target for future cancer nanomedicine.
ACS Nano 02/2012; 6(3):2361-70. · 10.77 Impact Factor
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ABSTRACT: The pivotal role of vascular endothelial growth factor (VEGF) in cancer is underscored by the approval of bevacizumab (Bev, a humanized anti-VEGF monoclonal antibody) for first line treatment of cancer patients. The aim of this study was to develop a dual-labeled Bev for both positron emission tomography (PET) and near-infrared fluorescence (NIRF) imaging of VEGF. Bev was conjugated to a NIRF dye (i.e. 800CW) and 2-S-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (p-SCN-Bn-NOTA) before (64)Cu-labeling. Flow cytometry analysis of U87MG human glioblastoma cells revealed no difference in VEGF binding affinity/specificity between Bev and NOTA-Bev-800CW. (64)Cu-labeling of NOTA-Bev-800CW was achieved with high yield. Serial PET imaging of U87MG tumor-bearing female nude mice revealed that tumor uptake of (64)Cu-NOTA-Bev-800CW was 4.6 ± 0.7, 16.3 ± 1.6, 18.1 ± 1.4 and 20.7 ± 3.7 %ID/g at 4, 24, 48 and 72 h post-injection respectively (n = 4), corroborated by in vivo/ex vivo NIRF imaging and biodistribution studies. Tumor uptake as measured by ex vivo NIRF imaging had a good linear correlation with the %ID/g values obtained from PET (R(2) = 0.93). Blocking experiments and histology both confirmed the VEGF specificity of (64)Cu-NOTA-Bev-800CW. The persistent, prominent, and VEGF-specific uptake of (64)Cu-NOTA-Bev-800CW in the tumor, observed by both PET and NIRF imaging, warrants further investigation and future clinical translation of such Bev-based imaging agents.
American journal of nuclear medicine and molecular imaging. 01/2012; 2(1):1-13.
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Yuling Xiao,
Hao Hong,
Vyara Z Matson,
Alireza Javadi,
Wenjin Xu, Yunan Yang,
Yin Zhang,
Jonathan W Engle,
Robert J Nickles,
Weibo Cai,
Douglas A Steeber,
Shaoqin Gong
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ABSTRACT: A multifunctional gold nanorod (GNR)-based nanoplatform for targeted anticancer drug delivery and positron emission tomography (PET) imaging of tumors was developed and characterized. An anti-cancer drug (i.e., doxorubicin (DOX)) was covalently conjugated onto PEGylated (PEG: polyethylene glycol) GNR nanocarriers via a hydrazone bond to achieve pH-sensitive controlled drug release. Tumor-targeting ligands (i.e., the cyclo(Arg-Gly-Asp-D-Phe-Cys) peptides, cRGD) and (64)Cu-chelators (i.e., 1,4,7-triazacyclononane-N, N', N''-triacetic acid (NOTA)) were conjugated onto the distal ends of the PEG arms to achieve active tumor-targeting and PET imaging, respectively. Based on flow cytometry analysis, cRGD-conjugated nanocarriers (i.e., GNR-DOX-cRGD) exhibited a higher cellular uptake and cytotoxicity than non-targeted ones (i.e., GNR-DOX) in vitro. However, GNR-DOX-cRGD and GNR-DOX nanocarriers had similar in vivo biodistribution according to in vivo PET imaging and biodistribution studies. Due to the unique optical properties of GNRs, this multifunctional GNR-based nanoplatform can potentially be optimized for combined cancer therapies (chemotherapy and photothermal therapy) and multimodality imaging (PET, optical, X-ray computed tomography (CT), etc.).
Theranostics. 01/2012; 2(8):757-68.
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Yin Zhang,
Hao Hong,
Gregory W Severin,
Jonathan W Engle, Yunan Yang,
Shreya Goel,
Alex J Nathanson,
Glenn Liu,
Robert J Nickles,
Bryan R Leigh,
Todd E Barnhart,
Weibo Cai
[show abstract]
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ABSTRACT: CD105 (endoglin) is an independent marker for poor prognosis in more than 10 solid tumor types. The goal of this study was to develop a CD105-specific agent for both positron emission tomography (PET) and near-infrared fluorescence (NIRF) imaging, which has potential clinical applications in the diagnosis and imaged-guided resection of solid tumors. TRC105, a chimeric anti-CD105 monoclonal antibody, was conjugated to a NIRF dye (800CW) and p-isothiocyanatobenzyl-desferrioxamine (Df-Bz-NCS) before (89)Zr-labeling. Another chimeric antibody, cetuximab, was used as an isotype-matched control. FACS analysis revealed no difference in CD105 binding affinity/specificity between TRC105 and Df-TRC105-800CW. Serial PET imaging revealed that the 4T1 tumor uptake of (89)Zr-Df-TRC105-800CW was 6.3 ± 1.9, 12.3 ± 1.3, and 11.4 ± 1.1 %ID/g at 4, 24, and 48 h post-injection (p.i.) respectively (n = 3), higher than all organs starting from 24 h p.i., which provided excellent tumor contrast. Tumor uptake as measured by both in vivo and ex vivo NIRF imaging had a linear correlation with the %ID/g values obtained from PET, corroborated by biodistribution studies. Blocking experiments, control studies with (89)Zr-Df-cetuximab-800CW, and histology all confirmed the CD105 specificity of (89)Zr-Df-TRC105-800CW. In conclusion, herein we report dual-modality PET and NIRF imaging of CD105 expression in a breast cancer model, where CD105-specific uptake of (89)Zr-Df-TRC105-800CW in the tumor was observed.
American Journal of Translational Research 01/2012; 4(3):333-46.
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ABSTRACT: High tumor microvessel density correlates with a poor prognosis in multiple solid tumor types. The clinical gold standard for assessing microvessel density is CD105 immunohistochemistry on paraffin-embedded tumor specimens. The goal of this study was to develop an (89)Zr-based PET tracer for noninvasive imaging of CD105 expression.
TRC105, a chimeric anti-CD105 monoclonal antibody, was conjugated to p-isothiocyanatobenzyl-desferrioxamine (Df-Bz-NCS) and labeled with (89)Zr. FACS analysis and microscopy studies were performed to compare the CD105 binding affinity of TRC105 and Df-TRC105. PET imaging, biodistribution, blocking, and ex-vivo histology studies were performed on 4T1 murine breast tumor-bearing mice to evaluate the pharmacokinetics and tumor-targeting of (89)Zr-Df-TRC105. Another chimeric antibody, cetuximab, was used as an isotype-matched control.
FACS analysis of HUVECs revealed no difference in CD105 binding affinity between TRC105 and Df-TRC105, which was further validated by fluorescence microscopy. (89)Zr labeling was achieved with high yield and specific activity. Serial PET imaging revealed that the 4T1 tumor uptake of (89)Zr-Df-TRC105 was 6.1 ± 1.2, 14.3 ± 1.2, 12.4 ± 1.5, 7.1 ± 0.9, and 5.2 ± 0.3 %ID/g at 5, 24, 48, 72, and 96 h after injection, respectively (n = 4), higher than all organs starting from 24 h after injection, which provided excellent tumor contrast. Biodistribution data as measured by gamma counting were consistent with the PET findings. Blocking experiments, control studies with (89)Zr-Df-cetuximab, and ex-vivo histology all confirmed the in vivo target specificity of (89)Zr-Df-TRC105.
We report here the first successful PET imaging of CD105 expression with (89)Zr as the radiolabel. Rapid, persistent, CD105-specific uptake of (89)Zr-Df-TRC105 in the 4T1 tumor was observed.
European Journal of Nuclear Medicine 09/2011; 39(1):138-48. · 4.53 Impact Factor
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Hao Hong,
Hélène A Benink,
Yin Zhang, Yunan Yang,
H Tetsuo Uyeda,
Jonathan W Engle,
Gregory W Severin,
Mark G McDougall,
Todd E Barnhart,
Dieter H Klaubert,
Robert J Nickles,
Frank Fan,
Weibo Cai
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ABSTRACT: Among the many molecular imaging techniques, reporter gene imaging has been a dynamic area of research. The HaloTag protein is a modified haloalkane dehalogenase which was designed to covalently bind to synthetic ligands (i.e. the HaloTag ligands [HTL]). Covalent bond formation between the HaloTag protein and the chloroal-kane within the HTL occurs rapidly under physiological conditions, which is highly specific and essentially irreversible. Over the years, HaloTag technology has been investigated for various applications such as in vitro/in vivo imaging, protein purification/trafficking, high-throughput assays, among others. The goal of this study is to explore the use of the HaloTag protein as a novel reporter gene for positron emission tomography (PET) imaging. By attaching a HaloTag -reactive chloroalkane to 1, 4, 7-triazacyclononane-N, N', N"-triacetic acid (NOTA) through hydrophilic linkers, the resulting NOTA-conjugated HTLs were labeled with (64)Cu and tested for PET imaging in living mice bearing 4T1-HaloTag-ECS tumors, which stably express the HaloTag protein on the cell surface. Significantly higher uptake of (64)Cu-NOTA-HTL-S (which contains a short hydrophilic linker) in the 4T1-HaloTag-ECS than the non-HaloTag-expressing 4T1 tumors was observed, which demonstrated the HaloTag specificity of (64)Cu-NOTA-HTL-S and warranted future investigation of the HaloTag protein as a PET reporter gene.
American Journal of Translational Research 08/2011; 3(4):392-403.
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ABSTRACT: Herein we demonstrate that intrinsically fluorescent zinc oxide (ZnO) nanowires (NWs) can be adopted for molecularly targeted imaging of cancer cells, after they are functionalized to render water solubility, biocompatibility, and low cellular toxicity. Optical imaging of integrin α(v)β(3) on U87MG human glioblastoma cells was achieved with RGD peptide-conjugated green fluorescent ZnO NWs, which opened up new avenues of research for investigating ZnO NW-based agents in tumor vasculature-targeted molecular imaging and drug delivery.
Nano Letters 08/2011; 11(9):3744-50. · 13.20 Impact Factor
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ABSTRACT: Angiogenesis is an indispensable process during tumor development. The currently accepted standard method for quantifying tumor angiogenesis is to assess microvessel density (MVD) based on CD105 staining, which is an independent prognostic factor for survival in patients with most solid tumor types. The goal of this study is to evaluate tumor angiogenesis in a mouse model by near-infrared fluorescence (NIRF) imaging of CD105 expression.
TRC105, a human/murine chimeric anti-CD105 monoclonal antibody, was conjugated to an NIRF dye (IRDye 800CW; Ex: 778 nm; Em: 806 nm). FACS analysis and microscopy studies were performed to compare the CD105 binding affinity of TRC105 and 800CW-TRC105. In vivo/ex vivo NIRF imaging, blocking studies, and ex vivo histology were performed on 4T1 murine breast tumor-bearing mice to evaluate the ability of 800CW-TRC105 to target tumor angiogenesis. Another chimeric antibody, cetuximab, was used as an isotype-matched control.
FACS analysis of human umbilical vein endothelial cells (HUVECs) revealed no difference in CD105 binding affinity between TRC105 and 800CW-TRC105, which was further validated by fluorescence microscopy. 800CW conjugation of TRC105 was achieved in excellent yield (> 85%), with an average of 0.4 800CW molecules per TRC105. Serial NIRF imaging after intravenous injection of 800CW-TRC105 revealed that the 4T1 tumor could be clearly visualized as early as 30 min post-injection. Quantitative region of interest (ROI) analysis showed that the tumor uptake peaked at about 16 h post-injection. Based on ex vivo NIRF imaging at 48 h post-injection, tumor uptake of 800CW-TRC105 was higher than most organs, thus providing excellent tumor contrast. Blocking experiments, control studies with 800CW-cetuximab and 800CW, as well as ex vivo histology all confirmed the in vivo target specificity of 800CW-TRC105.
This is the first successful NIRF imaging study of CD105 expression in vivo. Fast, prominent, persistent, and CD105-specific uptake of the probe during tumor angiogenesis was observed in a mouse model. 800CW-TRC105 may be used in the clinic for imaging tumor angiogenesis within the lesions close to the skin surface, tissues accessible by endoscopy, or during image-guided surgery.
European Journal of Nuclear Medicine 08/2011; 38(11):2066-76. · 4.53 Impact Factor
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ABSTRACT: In-depth understanding of the kinetics of the vapor deposition process is substantial for advancing this capable bottom-up nanostructure synthesis approach into a versatile large-scale nanomanufacturing technology. In this paper, we report a systematic study of the vapor deposition kinetics of ZnO nanomaterials under controlled atmosphere and properly refined deposition conditions. The experiments clearly evidenced the self-catalyzed growth of ZnO NWs via the formation of ZnO nanoflowers. This result illustrated how ZnO morphologies were associated with the discrepancy between oxidation rate and condensation rate of Zn. The capability of switching the NW morphologies and possibly mechanisms was demonstrated by kinetically controlling the deposition system. The high Zn composition during the deposition resulted in strongly luminescent NWs, which can be used for optical imaging applications. This research discovered a fundamental kinetics that governs the mechanisms and morphology selection of nanostructures in a non-catalyst growth system.
Journal of Materials Chemistry 05/2011; 21(25):9000-9008. · 5.97 Impact Factor
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Xiaoqiang Yang,
Hao Hong,
Jamison J Grailer,
Ian J Rowland,
Alireza Javadi,
Samuel A Hurley,
Yuling Xiao, Yunan Yang,
Yin Zhang,
Robert J Nickles,
Weibo Cai,
Douglas A Steeber,
Shaoqin Gong
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ABSTRACT: Multifunctional and water-soluble superparamagnetic iron oxide (SPIO) nanocarriers were developed for targeted drug delivery and positron emission tomography/magnetic resonance imaging (PET/MRI) dual-modality imaging of tumors with integrin α(v)β₃ expression. An anticancer drug was conjugated onto the PEGylated SPIO nanocarriers via pH-sensitive bonds. Tumor-targeting ligands, cyclo(Arg-Gly-Asp-d-Phe-Cys) (c(RGDfC)) peptides, and PET ⁶⁴Cu chelators, macrocyclic 1,4,7-triazacyclononane-N, N', N″-triacetic acid (NOTA), were conjugated onto the distal ends of the PEG arms. The effectiveness of the SPIO nanocarriers as an MRI contrast agent was evaluated via an in vitro r₂ MRI relaxivity measurement. cRGD-conjugated SPIO nanocarriers exhibited a higher level of cellular uptake than cRGD-free ones in vitro. Moreover, cRGD-conjugated SPIO nanocarriers showed a much higher level of tumor accumulation than cRGD-free ones according to non-invasive and quantitative PET imaging, and ex vivo biodistribution studies. Thus, these SPIO nanocarriers demonstrated promising properties for combined targeted anticancer drug delivery and PET/MRI dual-modality imaging of tumors.
Biomaterials 03/2011; 32(17):4151-60. · 7.40 Impact Factor
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ABSTRACT: Overexpression of CD105 (endoglin) correlates with poor prognosis in many solid tumor types. Tumor microvessel density (MVD) assessed by CD105 staining is the current gold standard for evaluating tumor angiogenesis in the clinic. The goal of this study was to develop a positron emission tomography (PET) tracer for imaging CD105 expression.
TRC105, a chimeric anti-CD105 monoclonal antibody, was conjugated to 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) and labeled with (64)Cu. FACS analysis and microscopy studies were performed to compare the CD105 binding affinity of TRC105 and DOTA-TRC105. PET imaging, biodistribution, blocking, and ex vivo histology studies were performed on 4T1 murine breast tumor-bearing mice to evaluate the ability of (64)Cu-DOTA-TRC105 to target tumor angiogenesis. Another chimeric antibody, cetuximab, was used as an isotype-matched control.
FACS analysis of human umbilical vein endothelial cells (HUVECs) revealed no difference in CD105 binding affinity between TRC105 and DOTA-TRC105, which was further validated by fluorescence microscopy. (64)Cu labeling was achieved with high yield and specific activity. Serial PET imaging revealed that the 4T1 tumor uptake of the tracer was 8.0 ± 0.5, 10.4 ± 2.8, and 9.7 ± 1.8%ID/g at 4, 24, and 48 h post-injection, respectively (n = 3), higher than most organs at late time points which provided excellent tumor contrast. Biodistribution data as measured by gamma counting were consistent with the PET findings. Blocking experiments, control studies with (64)Cu-DOTA-cetuximab, as well as ex vivo histology all confirmed the in vivo target specificity of (64)Cu-DOTA-TRC105.
This is the first successful PET imaging study of CD105 expression. Fast, prominent, persistent, and CD105-specific uptake of the tracer in the 4T1 tumor was observed. Further studies are warranted and currently underway.
European Journal of Nuclear Medicine 03/2011; 38(7):1335-43. · 4.53 Impact Factor
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ABSTRACT: Over the last decade, integrin αvβ3 has been studied with every single molecular imaging modality. Since no single modality is perfect and sufficient to obtain all the necessary information for a particular question, combination of certain molecular imaging modalities can offer synergistic advantages over any modality alone. This review will focus on multimodality imaging of integrin αvβ3 expression, where the contrast agent used can be detected by two or more imaging modalities, such as combinations of PET and optical, SPECT and fluorescence, PET and MRI, SPECT and MRI, and lastly, MRI and fluorescence. Most of these agents are based on certain type(s) of nanoparticles. Contrast agents that can be detected by more than two imaging modalities are expected to emerge in the future and a PET/MRI/fluorescence agent will likely find the most future biomedical/clinical applications. Big strides have been made over the last decade for imaging integrin αvβ3 expression and several PET/SPECT probes have been tested in human studies. For dualmodality and multimodality imaging applications, a number of proof-of-principle studies have been reported which opened up many new avenues for future research. The next decade will likely witness further growth and continued prosperity of molecular imaging studies focusing on integrin αvβ3, which can eventually impact patient management.
Theranostics. 01/2011;
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ABSTRACT: Since most solid tumor growth depends on angiogenesis, non-invasive imaging of tumor angiogenesis can allow for much earlier diagnosis and better prognosis of cancer, as well as more accurate treatment monitoring, which will eventually lead to personalized molecular medicine. CD105, also known as endoglin, is required for endo-thelial cell proliferation. The currently accepted standard method for quantifying tumor angiogenesis is to assess microvessel density based on CD105 staining, which has been shown to be an independent prognostic factor for survival in patients of almost all solid tumor types. In this review, we will summarize the progress to date on multimo-dality molecular imaging of CD105 expression during tumor angiogenesis which includes targeted contrast-enhanced ultrasound, molecular magnetic resonance, near-infrared fluorescence, single-photon emission computed tomography, and positron emission tomography. Although molecular imaging of CD105 expression is surprisingly understudied, non-invasive imaging of CD105 expression has already been achieved with every single molecular imaging modality. In the future, significant research effort should be directed towards non-invasive visualization of CD105 expression, such as quantitative imaging, the use of long-lived isotopes for antibody-based imaging, development of peptide, small molecule, or antibody fragment-based imaging agents, multimodality imaging of CD105 expression with a single agent, the application of nanotechnology, among others.
International journal of clinical and experimental medicine 01/2011; 4(1):32-42.
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ABSTRACT: INTRODUCTION Monitoring gene expression is crucial for studying the responses of gene therapy and clarifying gene function in various environments. Molecular imaging is a powerful tool for noninvasive visualization of gene expression. This article summarizes the current status of fluorescence and bioluminescence imaging (BLI) of gene expression in live cells and tissues, with the emphasis mainly on the early studies that pioneered the field. First, we describe fluorescence imaging of gene expression with a wide variety of fluorescent proteins. Next, we discuss the strategies for BLI of gene expression. Besides incorporating the reporter gene into the host DNA, mRNA-based BLI of gene expression is also briefly mentioned. Last, the construction of double- and triple-fusion reporter genes is presented. Because no single imaging modality is perfect and sufficient to obtain all of the necessary information for a given question, combinations of multiple molecular imaging modalities can offer synergistic advantages over any modality alone. Noninvasive optical imaging of gene expression has revolutionized biomedical research, and the progress made over the last decade should allow molecular imaging to play a major role in the field of gene therapy. For basic and preclinical research, optical imaging is indispensable for imaging gene expression. However, for clinical imaging of gene expression, positron emission tomography (PET) holds the greatest promise.
Cold Spring Harbor Protocols 01/2011; 2011(4):pdb.top103. · 4.63 Impact Factor
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ABSTRACT: Optimizing the in vivo stability of positron emission tomography (PET) tracers is of critical importance to cancer diagnosis. In the case of (64)Cu-labeled monoclonal antibodies (mAb), in vivo behavior and biodistribution is critically dependent on the performance of the bifunctional chelator used to conjugate the mAb to the radiolabel. This study compared the in vivo characteristics of (64)Cu-labeled TRC105 (a chimeric mAb that binds to both human and murine CD105), through two commonly used chelators: 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA) and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). Flow cytometry analysis confirmed that chelator conjugation of TRC105 did not affect its CD105 binding affinity or specificity. PET imaging and biodistribution studies in 4T1 murine breast tumor-bearing mice revealed that (64)Cu-NOTA-TRC105 exhibited better stability than (64)Cu-DOTA-TRC105 in vivo, which resulted in significantly lower liver uptake without compromising the tumor targeting efficiency. In conclusion, this study confirmed that NOTA is a superior chelator to DOTA for PET imaging with (64)Cu-labeled TRC105.
PLoS ONE 01/2011; 6(12):e28005. · 4.09 Impact Factor
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ABSTRACT: Over the last decade, integrin α(v)β(3) has been studied with every single molecular imaging modality. Since no single modality is perfect and sufficient to obtain all the necessary information for a particular question, combination of certain molecular imaging modalities can offer synergistic advantages over any modality alone. This review will focus on multimodality imaging of integrin α(v)β(3) expression, where the contrast agent used can be detected by two or more imaging modalities, such as combinations of PET and optical, SPECT and fluorescence, PET and MRI, SPECT and MRI, and lastly, MRI and fluorescence. Most of these agents are based on certain type(s) of nanoparticles. Contrast agents that can be detected by more than two imaging modalities are expected to emerge in the future and a PET/MRI/fluorescence agent will likely find the most future biomedical/clinical applications. Big strides have been made over the last decade for imaging integrin α(v)β(3) expression and several PET/SPECT probes have been tested in human studies. For dualmodality and multimodality imaging applications, a number of proof-of-principle studies have been reported which opened up many new avenues for future research. The next decade will likely witness further growth and continued prosperity of molecular imaging studies focusing on integrin α(v)β(3), which can eventually impact patient management.
Theranostics. 01/2011; 1:135-48.
