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Salerno S, Viviano M, Baglini E, Poggetti V, Giorgini D, Castagnoli J, Barresi E, Castellano S, Da Settimo F, Taliani S. TSPO Radioligands for Neuroinflammation: An Overview. Molecules 2024; 29:4212. [PMID: 39275061 PMCID: PMC11397380 DOI: 10.3390/molecules29174212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2024] [Revised: 08/30/2024] [Accepted: 09/03/2024] [Indexed: 09/16/2024] Open
Abstract
The translocator protein (TSPO) is predominately localized on the outer mitochondrial membrane in steroidogenic cells. In the brain, TSPO expression, low under normal conditions, results upregulated in response to glial cell activation, that occurs in neuroinflammation. As a consequence, TSPO has been extensively studied as a biomarker of such conditions by means of TSPO-targeted radiotracers. Although [11C]-PK11195, the prototypical TSPO radioligand, is still widely used for in vivo studies, it is endowed with severe limitations, mainly low sensitivity and poor amenability to quantification. Consequently, several efforts have been focused on the design of new radiotracers for the in vivo imaging of TSPO. The present review will provide an outlook on the latest advances in TSPO radioligands for neuroinflammation imaging. The final goal is to pave the way for (radio)chemists in the future design and development of novel effective and sensitive radiopharmaceuticals targeting TSPO.
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Affiliation(s)
- Silvia Salerno
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; (S.S.); (E.B.); (V.P.); (J.C.); (S.T.)
| | - Monica Viviano
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, Italy; (M.V.); (D.G.); (S.C.)
| | - Emma Baglini
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; (S.S.); (E.B.); (V.P.); (J.C.); (S.T.)
| | - Valeria Poggetti
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; (S.S.); (E.B.); (V.P.); (J.C.); (S.T.)
| | - Doralice Giorgini
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, Italy; (M.V.); (D.G.); (S.C.)
| | - Jacopo Castagnoli
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; (S.S.); (E.B.); (V.P.); (J.C.); (S.T.)
| | - Elisabetta Barresi
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; (S.S.); (E.B.); (V.P.); (J.C.); (S.T.)
| | - Sabrina Castellano
- Department of Pharmacy, University of Salerno, Via Giovanni Paolo II, 132, 84084 Fisciano, Italy; (M.V.); (D.G.); (S.C.)
| | - Federico Da Settimo
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; (S.S.); (E.B.); (V.P.); (J.C.); (S.T.)
| | - Sabrina Taliani
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy; (S.S.); (E.B.); (V.P.); (J.C.); (S.T.)
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Takamura Y, Kakuta H. In Vivo Receptor Visualization and Evaluation of Receptor Occupancy with Positron Emission Tomography. J Med Chem 2021; 64:5226-5251. [PMID: 33905258 DOI: 10.1021/acs.jmedchem.0c01714] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Positron emission tomography (PET) is useful for noninvasive in vivo visualization of disease-related receptors, for evaluation of receptor occupancy to determine an appropriate drug dosage, and for proof-of-concept of drug candidates in translational research. For these purposes, the specificity of the PET tracer for the target receptor is critical. Here, we review work in this area, focusing on the chemical structures of reported PET tracers, their Ki/Kd values, and the physical properties relevant to target receptor selectivity. Among these physical properties, such as cLogP, cLogD, molecular weight, topological polar surface area, number of hydrogen bond donors, and pKa, we focus especially on LogD and LogP as important physical properties that can be easily compared across a range of studies. We discuss the success of PET tracers in evaluating receptor occupancy and consider likely future developments in the field.
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Affiliation(s)
- Yuta Takamura
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
| | - Hiroki Kakuta
- Division of Pharmaceutical Sciences, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 1-1-1, Tsushima-naka, Kita-ku, Okayama 700-8530, Japan
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Wang L, Yao S, Tang R, Zhu H, Zhang L, Gong J, Chen Q, Collier TL, Xu H, Liang SH. A concisely automated synthesis of TSPO radiotracer [ 18 F]FDPA based on spirocyclic iodonium ylide method and validation for human use. J Labelled Comp Radiopharm 2020; 63:119-128. [PMID: 31895476 DOI: 10.1002/jlcr.3824] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 08/24/2019] [Accepted: 08/26/2019] [Indexed: 12/14/2022]
Abstract
Fluorine-18 labeled N,N-diethyl-2-(2-(4-(2-fluoroethoxy)phenyl)-5,7-dimethylpyrazolo[1,5-a]pyrimidin-3-yl)acetamide ([18 F]FDPA) is a potent and selective radiotracer for positron-emission tomography (PET) imaging of the translocator protein 18 kDa (TSPO). Our previous in vitro and in vivo evaluations have proven that this tracer is promising for further human translation. Our study addresses the need to streamline the automatic synthesis of this radiotracer to make it more accessible for widespread clinical evaluation and application. Here, we successfully demonstrate a one-step radiolabeling of [18 F]FDPA based on a novel spirocyclic iodonium ylide (SCIDY) precursor using tetra-n-butyl ammonium methanesulfonate (TBAOMs), which has demonstrated the highest radiochemical yields and molar activity from readily available [18 F]fluoride ion. The nucleophilic radiofluorination was completed on a GE TRACERlab FX2 N synthesis module, and the formulated [18 F]FDPA was obtained in nondecay corrected (n.d.c) radiochemical yields of 15.6 ± 4.2%, with molar activities of 529.2 ± 22.5 GBq/μmol (14.3 ± 0.6 Ci/μmol) at the end of synthesis (60 minutes, n = 3) and validated for human use. This methodology facilitates efficient synthesis of [18 F]FDPA in a commercially available synthesis module, which would be broadly applicable for routine production and widespread clinical PET imaging studies.
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Affiliation(s)
- Lu Wang
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, Guangzhou, China
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, Massachusetts
| | - Shaobo Yao
- Department of PET/CT Diagnostic, Tianjin Medical University General Hospital, Tianjin, China
| | - Ruikun Tang
- Department of Radiopharmaceuticals Quality Control, Guangzhou Atom Hightech Radiopharmaceutical Co. Ltd, Guangzhou, China
| | - Honghao Zhu
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Lingling Zhang
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Jian Gong
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Qiusong Chen
- Department of PET/CT Diagnostic, Tianjin Medical University General Hospital, Tianjin, China
| | - Thomas Lee Collier
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, Massachusetts
- Advion Inc., New York, USA
| | - Hao Xu
- Center of Cyclotron and PET Radiopharmaceuticals, Department of Nuclear Medicine and PET/CT-MRI Center, The First Affiliated Hospital of Jinan University, Guangzhou, China
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Department of Radiology, Harvard Medical School, Boston, Massachusetts
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Wang L, Cheng R, Fujinaga M, Yang J, Zhang Y, Hatori A, Kumata K, Yang J, Vasdev N, Du Y, Ran C, Zhang MR, Liang SH. A Facile Radiolabeling of [ 18F]FDPA via Spirocyclic Iodonium Ylides: Preliminary PET Imaging Studies in Preclinical Models of Neuroinflammation. J Med Chem 2017; 60:5222-5227. [PMID: 28530834 DOI: 10.1021/acs.jmedchem.7b00432] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A suitable TSPO PET ligand may visualize and quantify neuroinflammation in a living brain. Herein we report a 18F-ligand, [18F]2 ([18F]FDPA), is radiolabeled in high yield and high specific activity based on our spirocyclic iodonium ylide (SCIDY) strategy. [18F]2 demonstrated saturable specific binding to TSPO, substantially elevated brain uptake, and slow washout of bound PET signal in the preclinical models of brain neuroinflammation (cerebral ischemia and Alzheimer's disease).
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Affiliation(s)
- Lu Wang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Harvard Medical School , Boston, Massachusetts 02114, United States
| | - Ran Cheng
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Harvard Medical School , Boston, Massachusetts 02114, United States.,School of Pharmaceutical Science and Technology, Tianjin University , 92 Weijin Road, Nankai District, Tianjin, China
| | - Masayuki Fujinaga
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology , Chiba 263-8555, Japan
| | - Jian Yang
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital & Harvard Medical School , Boston, Massachusetts 02129, United States
| | - Yiding Zhang
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology , Chiba 263-8555, Japan
| | - Akiko Hatori
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology , Chiba 263-8555, Japan
| | - Katsushi Kumata
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology , Chiba 263-8555, Japan
| | - Jing Yang
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital & Harvard Medical School , Boston, Massachusetts 02129, United States
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Harvard Medical School , Boston, Massachusetts 02114, United States
| | - Yunfei Du
- School of Pharmaceutical Science and Technology, Tianjin University , 92 Weijin Road, Nankai District, Tianjin, China
| | - Chongzhao Ran
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital & Harvard Medical School , Boston, Massachusetts 02129, United States
| | - Ming-Rong Zhang
- Department of Radiopharmaceutics Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology , Chiba 263-8555, Japan
| | - Steven H Liang
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital & Harvard Medical School , Boston, Massachusetts 02114, United States
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Kawamura K, Shimoda Y, Yui J, Zhang Y, Yamasaki T, Wakizaka H, Hatori A, Xie L, Kumata K, Fujinaga M, Ogawa M, Kurihara Y, Nengaki N, Zhang MR. A useful PET probe [ 11C]BU99008 with ultra-high specific radioactivity for small animal PET imaging of I 2-imidazoline receptors in the hypothalamus. Nucl Med Biol 2016; 45:1-7. [PMID: 27835825 DOI: 10.1016/j.nucmedbio.2016.10.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 10/14/2016] [Accepted: 10/24/2016] [Indexed: 01/23/2023]
Abstract
INTRODUCTION A positron emission tomography (PET) probe with ultra-high specific radioactivity (SA) enables measuring high receptor specific binding in brain regions by avoiding mass effect of the PET probe itself. It has been reported that PET probe with ultra-high SA can detect small change caused by endogenous or exogenous ligand. Recently, Kealey et al. developed [11C]BU99008, a more potent PET probe for I2-imidazoline receptors (I2Rs) imaging, with a conventional SA (mean 76GBq/μmol) showed higher specific binding in the brain. Here, to detect small change of specific binding for I2Rs caused by endogenous or exogenous ligand in an extremely small region, such as hypothalamus in the brain, we synthesized and evaluated [11C]BU99008 with ultra-high SA as a useful PET probe for small-animal PET imaging of I2Rs. METHODS [11C]BU99008 was prepared by [11C]methylation of N-desmethyl precursor with [11C]methyl iodide. Biodistribution, metabolite analysis, and brain PET studies were conducted in rats. RESULTS [11C]BU99008 with ultra-high SA in the range of 5400-16,600GBq/μmol were successfully synthesized (n=7), and had appropriate radioactivity for in vivo study. In the biodistribution study, the mean radioactivity levels in all investigated tissues except for the kidney did not show significant difference between [11C]BU99008 with ultra-high SA and that with conventional SA. In the metabolite analysis, the percentage of unchanged [11C]BU99008 at 30min after the injection of probes with ultra-high and conventional SA was similar in rat brain and plasma. In the PET study of rats' brain, radioactivity level (AUC30-60 min) in the hypothalamus of rats injected with [11C]BU99008 with ultra-high SA (64 [SUV ∙ min]) was significantly higher than that observed for that with conventional SA (50 [SUV ∙ min]). The specific binding of [11C]BU99008 with ultra-high SA (86% of total binding) for I2R was higher than that of conventional SA (76% of total binding). CONCLUSION A PET study using [11C]BU99008 with ultra-high SA would thus contribute to the detection of small changes in or small regions with I2R expression and hence may be useful in elucidating new functions of I2R.
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Affiliation(s)
- Kazunori Kawamura
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan.
| | - Yoko Shimoda
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Joji Yui
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Yiding Zhang
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Tomoteru Yamasaki
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Hidekatsu Wakizaka
- Department of Medical Physics, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Akiko Hatori
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Lin Xie
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Katsushi Kumata
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Masayuki Fujinaga
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
| | - Masanao Ogawa
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan; SHI Accelerator Service Ltd., Tokyo 141-0032, Japan
| | - Yusuke Kurihara
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan; SHI Accelerator Service Ltd., Tokyo 141-0032, Japan
| | - Nobuki Nengaki
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan; SHI Accelerator Service Ltd., Tokyo 141-0032, Japan
| | - Ming-Rong Zhang
- Department of Radiopharmaceuticals Development, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba 263-8555, Japan
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Trapani A, Palazzo C, de Candia M, Lasorsa FM, Trapani G. Targeting of the Translocator Protein 18 kDa (TSPO): A Valuable Approach for Nuclear and Optical Imaging of Activated Microglia. Bioconjug Chem 2013; 24:1415-28. [DOI: 10.1021/bc300666f] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Adriana Trapani
- Department of Pharmacy and Drug
Sciences, University of Bari, Bari, 70125,
Italy
| | - Claudio Palazzo
- Department of Pharmacy and Drug
Sciences, University of Bari, Bari, 70125,
Italy
| | - Modesto de Candia
- Department of Pharmacy and Drug
Sciences, University of Bari, Bari, 70125,
Italy
| | | | - Giuseppe Trapani
- Department of Pharmacy and Drug
Sciences, University of Bari, Bari, 70125,
Italy
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A historical perspective on the specific activity of radiopharmaceuticals: What have we learned in the 35years of the ISRC? Nucl Med Biol 2013; 40:314-20. [DOI: 10.1016/j.nucmedbio.2012.12.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2012] [Revised: 11/30/2012] [Accepted: 12/20/2012] [Indexed: 11/19/2022]
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Kawamura K, Kimura Y, Yui J, Wakizaka H, Yamasaki T, Hatori A, Kumata K, Fujinaga M, Yoshida Y, Ogawa M, Nengaki N, Fukumura T, Zhang MR. PET study using [11C]FTIMD with ultra-high specific activity to evaluate I2-imidazoline receptors binding in rat brains. Nucl Med Biol 2012; 39:199-206. [DOI: 10.1016/j.nucmedbio.2011.07.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 06/29/2011] [Accepted: 07/26/2011] [Indexed: 10/17/2022]
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Lapi SE, Welch MJ. A historical perspective on the specific activity of radiopharmaceuticals: what have we learned in the 35 years of the ISRC? Nucl Med Biol 2012; 39:601-8. [PMID: 22261142 DOI: 10.1016/j.nucmedbio.2011.11.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Accepted: 11/12/2011] [Indexed: 11/30/2022]
Abstract
Specific activity (SA), defined as the amount of radioactivity per unit mass of a compound, is arguably one of the most important parameters in radiopharmaceutical development, particularly in quality control of carbon-11- and fluorine-18-labeled compounds. This review article will outline the progression of improvements in SA over the last few decades. The International Symposium of Radiopharmaceutical Chemistry abstracts were an excellent source of materials for this review and will be referenced throughout.
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Affiliation(s)
- Suzanne E Lapi
- Department of Radiology, Washington University, St. Louis, MO 63110, USA.
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Kobayashi N, Odaka K, Uehara T, Imanaka-Yoshida K, Kato Y, Oyama H, Tadokoro H, Akizawa H, Tanada S, Hiroe M, Fukumura T, Komuro I, Arano Y, Yoshida T, Irie T. Toward in vivo imaging of heart disease using a radiolabeled single-chain Fv fragment targeting tenascin-C. Anal Chem 2011; 83:9123-30. [PMID: 22074352 DOI: 10.1021/ac202159p] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Antibodies specific to a particular target molecule can be used as analytical reagents, not only for in vitro immunoassays but also for noninvasive in vivo imaging, e.g., immunoscintigraphies. In the latter case, it is important to reduce the size of antibody molecules in order to achieve suitable in vivo "diagnostic kinetics" and generate higher-resolution images. For these purposes, single-chain Fv fragments (scFvs; M(r) < 30 kDa) have greater potential than intact immunoglobulins (~150 kDa) or Fab (or Fab') fragments (~50 kDa). Our recent observation of enhanced tenascin-C (Tnc) expression at sites of cardiac repair after myocardial infarction prompted us to develop a radiolabeled scFv against Tnc for in vivo imaging of heart disease. We cloned the genes encoding the heavy and light chain variable domains of the mouse anti-Tnc monoclonal antibody 4F10, and combined them to create a single gene. The resulting scFv-4F10 gene was expressed in E. coli cells to produce soluble scFv proteins. scFv-4F10 has an affinity for Tnc (K(a) = 3.5 × 10(7) M(-1)), similar to the Fab fragment of antibody 4F10 (K(a) = 1.3 × 10(7) M(-1)) and high enough to be of practical use. A cysteine residue was then added to the C-terminus to achieve site-specific (111)In labeling via a chelating group. The resulting (111)In-labeled scFv was administered to a rat model of acute myocardial infarction. Biodistribution and quantitative autoradiographic studies indicated higher uptake of the radioactivity at the infarcted myocardium than the noninfarcted one. Single photon emission computed tomography (SPECT) provided in vivo cardiac images that coincided with the ex vivo observations. Our results will promote advances in diagnostic strategies for heart disease.
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Affiliation(s)
- Norihiro Kobayashi
- Kobe Pharmaceutical University, 4-19-1, Motoyama-Kitamachi, Higashinada-ku, Kobe 658-8558, Japan.
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Xie L, Yamasaki T, Ichimaru N, Yui J, Kawamura K, Kumata K, Hatori A, Nonomura N, Zhang MR, Li XK, Takahara S. [11C]DAC-PET for Noninvasively Monitoring Neuroinflammation and Immunosuppressive Therapy Efficacy in Rat Experimental Autoimmune Encephalomyelitis Model. J Neuroimmune Pharmacol 2011; 7:231-42. [DOI: 10.1007/s11481-011-9322-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2011] [Accepted: 10/17/2011] [Indexed: 11/30/2022]
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In vivo imaging and quantitative analysis of TSPO in rat peripheral tissues using small-animal PET with [18F]FEDAC. Nucl Med Biol 2010; 37:853-60. [DOI: 10.1016/j.nucmedbio.2010.04.183] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Revised: 04/19/2010] [Accepted: 04/19/2010] [Indexed: 11/23/2022]
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Yui J, Hatori A, Kawamura K, Yanamoto K, Yamasaki T, Ogawa M, Yoshida Y, Kumata K, Fujinaga M, Nengaki N, Fukumura T, Suzuki K, Zhang MR. Visualization of early infarction in rat brain after ischemia using a translocator protein (18 kDa) PET ligand [11C]DAC with ultra-high specific activity. Neuroimage 2010; 54:123-30. [PMID: 20705143 DOI: 10.1016/j.neuroimage.2010.08.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Revised: 07/23/2010] [Accepted: 08/04/2010] [Indexed: 10/19/2022] Open
Abstract
The aim of this study was to visualize early infarction in the rat brain after ischemia using a translocator protein (TSPO) (18 kDa) PET ligand [(11)C]DAC with ultra-high specific activity (SA) of 3670-4450 GBq/μmol. An infarction model of rat brain was prepared by ischemic surgery and evaluated 2 days after ischemia using small-animal PET and in vitro autoradiography. Early infarction with a small increase of TSPO expression in the brain was visualized using PET with high SA [(11)C]DAC (average 4060 GBq/μmol), but was not distinguished clearly with usually reported SA [(11)C]DAC (37 GBq/μmol). Infarction in the rat brain 4 days after ischemia was visualized using high and usually reported SAs [(11)C]DAC. Displacement experiments with unlabeled TSPO-selective AC-5216 or PK11195 diminished the difference in radioactivity between ipsilateral and contralateral sides, confirming that the increased uptake on the infracted brain was specific to TSPO. In vitro autoradiography with high SA [(11)C]DAC showed that the TSPO expression increased on early infarction in the rat brain. High SA [(11)C]DAC is a useful and sensitive biomarker for the visualization of early infarction and the characterization of TSPO expression which was slightly elevated in the infarcted brain using PET.
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Affiliation(s)
- Joji Yui
- Molecular Imaging Center, National Institute of Radiological Sciences, Inage-ku, Chiba, Japan
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