RESPONSIVE MR AND PET AGENTS FOR BETA-CELL IMAGING

用于 β 细胞成像的灵敏 MR 和 PET 试剂

• 批准号: 7956979
• 负责人: XIAOFENG SUN
• 金额: $ 1.78万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7956979
• 关键词: Acetates; Animal Experiments; Animals; Arts; Attention; Beta Cell; Carbon Dioxide; Cell physiology; Cells; Chelating Agents; Chemistry; Citrate (si)-Synthase; Citric Acid Cycle; Clinical Investigator; Clinical Research; Collaborations; Communities; Complement component C1s; Complex; Computer Retrieval of Information on Scientific Projects Database; Cyclotrons; Detection; Development; Diagnostic Procedure; Disease; Early Diagnosis; Evaluation; Faculty; Floor; Funding; Generations; Glucose; Goals; Grant; Head; Heart; Housing; Hybrids; Hypoxia; Image; Imaging Techniques; Institution; Insulin-Dependent Diabetes Mellitus; Label; Laboratories; Libraries; Ligands; Location; Measures; Medical center; Metabolic; Metabolic Diseases; Metabolism; Metastatic Neoplasm to the Bone; Modality; Modeling; Molecular; Monitor; N-terminal; Non-Insulin-Dependent Diabetes Mellitus; Nuclear; Onset of illness; Oxidation-Reduction; Palliative Care; Pan Genus; Pancreas; Pathogenesis; Pattern; Peptides; Phage Display; Population; Positioning Attribute; Positron-Emission Tomography; Production; Pyruvate; Pyruvates; Radiation therapy; Radiochemistry; Rattus; Reporting; Research; Research Personnel; Resolution; Resources; Role; Route; Science; Sensitivity and Specificity; Series; Source; Techniques; Technology; Testing; The Sun; Tracer; Translating; United States National Institutes of Health; Work; base; bisphosphonate; clinical Diagnosis; cyclen; design; glucose sensor; imaging modality; imaging probe; in vivo; indexing; innovation; insulinoma; interest; islet; mathematical model; molecular imaging; novel; radiotracer; research study; square foot; type I and type II diabetes

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The development of non-invasive imaging methods for early diagnosis of beta cell associated metabolic diseases, including type 1 and type 2 diabetes (T1D and T2D), has recently drawn interest from the molecular imaging community and clinical investigators. Due to the challenges imposed by the location of the pancreas, the sparsely dispersed beta cell population within the pancreas, and the poor understanding of the pathogenesis of the diseases, clinical diagnosis of beta cell abnormalities is still limited. Current diagnostic methods are invasive, often inaccurate, and usually performed post-onset of the disease. The goal of this project is to merge the beta-cell metabolic strategies headed by Kathlynn Brown with state-of-the-art imaging agent technologies to create novel PET and MR agents for molecular imaging of the ¿-cell in vivo. Our goal is to develop imaging agents that not only target the pancreatic ¿-cell in vivo but also respond to ¿-cell metabolism by functional activation. Thus, our goal is to develop imaging agents that not only target the pancreatic ¿-cell in vivo but also respond to ¿-cell metabolism by functional activation. Before moving to animal experiments, we will initially develop a platform for both high resolution MR and PET imaging of cultured rat ¿-cells and isolated rat islets and use this technology to screen for entrapment of redox sensitive PET agents (64Cu-ATSM) and redox sensitive PARACEST agents (cyclen-based tetraamide complexes of Eu3+ or Tm3+) in ¿-cells. Proof of concept studies on agents that specifically target beta cells will be performed using multimeric peptides identified by phage display panning of insulinoma INS 832/1 cells and isolated rat islets. Given these peptides or others identified in Core B, we will develop an efficient labeling approach to attach either 18F or cyclen-based ligands to all targeting peptides to create MR (pH sensitive Gd3+-based agents, PARACEST-based Zn2+ and glucose sensors) and PET agents (both 18F and 64Cu) to measure a) ¿-cell mass and b) ¿-cell function. A final aim is to combine the technologies of aims 1 & 2 to create targeted & responsive MR and PET agents that not only report ¿-cell mass but also provide an imaging index of ¿-cell function. With the recent technical innovations of imaging modalities, molecular imaging is gaining more and more attention in the fields of basic biomedical sciences and clinical research and practice. Indeed, non-invasive imaging techniques are revolutionizing the understanding of diseases at the cellular and molecular levels. Among the current available imaging modalities, tomographic nuclear imaging approaches, especially positron emission tomography (PET), have demonstrated their significant importance and promising potential in applications of molecular imaging probes due to the superior sensitivity and specificity in diverse subjects, and the ability to quantitatively analyze the regions of interest. In collaboration with Dr. Dean Sherry, Dr. Sun's radiochemistry laboratory is interested in the design and in vivo evaluation of a series of hybrid agents featuring both radiometal bifunctional chelators and bisphosphonates (commonly used in the treatment of bone metastasis) for multi-modality (BLI/ MRI/SPECT/PET) detection of bone metastasis and the monitoring of radiotherapeutic/palliative treatment. Additionally, we are developing collaborations with the Advanced Imaging center to study intermediary metabolism by PET. One such project is to develop imaging agents that not only target the pancreatic b-cell in vivo but also respond to b-cell metabolism by functional activation. In this project, Drs. Sherry and Sun will create novel PET and MR agents for molecular imaging of the b-cell in vivo with state-of-the-art imaging agent technologies. Prior to animal experiments, a platform will be developed for both high resolution MR and PET imaging of isolated rat islets and this technology will be used to screen for entrapped hypoxia sensitive PET agents (64Cu-ATSM) and redox sensitive PARACEST agents (cyclen-based tetraamide complexes of Eu3+ or Tm3+) in b-cells. Proof of concept studies on agents that specifically target b-cells will be performed on isolated rat islets using a peptide (MSKSPEEGRATVQPSTQPHY) isolated from panning of glucose low-responding insulinoma INS 832/1 cells. With this, or similar peptides, either an 18F-labeled group or cyclen-based ligands will be added to the N-terminal amino position of all targeting peptides to create a library of targeted MR agents (both Gd3+ and PARACEST based) and targeted PET agents (both 18F and 64Cu) for measuring b-cell mass. In a related project, Dr. Sun's laboratory will synthesize [b-18F]-fluoropropionate as a tracer of pyruvate cycling for to test the hypothesis that [b-18F]-fluoropropionate will accumulate at significantly higher levels in ¿-cells than a-cells. If the technique works in isolated islet experiments, it will then be quickly translated to in vivo studies in small animals. This is a relatively easy hypothesis to test and, if proven correct, could provide a powerful, convenient way to image b-cell function by PET. The ultimate aim is to create targeted and responsive MR and PET agents that not only report b-cell mass but also provide an imaging index of b-cell function. It is noteworthy that the UT Southwestern Medical Center has planned to purchase a cyclotron to facilitate PET imaging studies and radiotracer developments. Construction is nearly complete on the Advanced Imaging Research Center (AIRC), which will house a 2,000 sq ft space on the first floor designated for a comprehensive PET chemistry laboratory. Once complete, Dr. Sun's laboratory will occupy this new space and begin to work closely with the faculty of the AIRC on in vivo metabolism. A novel project of potentially high impact is to administer [1-11C]acetate and [2-11C]acetate simultaneously in an attempt to tease out in vivo fluxes intersecting in the TCA cycle. Preliminary modeling by Dr. Jeffrey indicate that by placing the label in both the C1 and C2 positions of acetate, the temporal pattern of 11CO2 generation will be sufficiently sophisticated for mathematical modeling to reveal metabolic fluxes such as citrate synthase. Preliminary experiment will be performed in rat hearts perfused with [1-11C]acetate and [2-11C]acetate, and the perfusate will be analyzed via the gamma counts for hot CO2 production. Unfortunately a synthetic route for [2-11C]acetate has not been reported, therefore Dr. Sun will develop a synthetic route for [2-11C]acetate production prior to experimentation (one does exist for [1-11C]acetate). Obviously, Dr. Sun will extend his research with 18F and 11C to other metabolic substrates once the cyclotron is in place, giving PET chemistry an active role in the collaborative projects supported by this Research Resource grant.

该子项目是利用该技术的众多研究子项目之一 资源由 NIH/NCRR 资助的中心拨款提供。子项目和 研究者 (PI) 可能已从 NIH 的另一个来源获得主要资金， 因此可以在其他 CRISP 条目中表示。列出的机构是 对于中心来说，它不一定是研究者的机构。 用于早期诊断 β 细胞相关代谢疾病（包括 1 型和 2 型糖尿病（T1D 和 T2D））的非侵入性成像方法的开发最近引起了分子成像界和临床研究人员的兴趣。由于胰腺的位置、胰腺内β细胞群分布稀疏以及对疾病发病机制的了解不足，β细胞异常的临床诊断仍然有限。目前的诊断方法是侵入性的，通常不准确，并且通常在疾病发作后进行。该项目的目标是将凯瑟琳·布朗 (Kathlynn Brown) 领导的 β 细胞代谢策略与最先进的成像剂技术相结合，创造出用于体内 β 细胞分子成像的新型 PET 和 MR 试剂。我们的目标是开发不仅能靶向体内胰腺 Ν 细胞而且还能通过功能激活对 Ν 细胞代谢做出反应的显像剂。 因此，我们的目标是开发不仅能靶向体内胰腺 β 细胞而且还能通过功能激活对 β 细胞代谢做出反应的显像剂。 在进行动物实验之前，我们将首先开发一个对培养的大鼠 ¿-细胞和分离的大鼠胰岛进行高分辨率 MR 和 PET 成像的平台，并使用该技术来筛选 ¿ 细胞中氧化还原敏感的 PET 试剂 (64Cu-ATSM) 和氧化还原敏感的 PARACEST 试剂（Eu3+ 或 Tm3+ 的基于 Cyclen 的四酰胺复合物）的包埋。 将使用通过噬菌体展示淘选胰岛素瘤 INS 832/1 细胞和分离的大鼠胰岛鉴定的多聚肽，对特异性靶向 β 细胞的药物进行概念验证研究。 鉴于核心 B 中确定的这些肽或其他肽，我们将开发一种有效的标记方法，将 18F 或基于 Cyclen 的配体附着到所有靶向肽上，以创建 MR（基于 pH 敏感的 Gd3+ 试剂、基于 PARACEST 的 Zn2+ 和葡萄糖传感器）和 PET 试剂（18F 和 64Cu），以测量 a) ¿-细胞质量和 b) ¿-细胞功能。 最终目标是将目标 1 和 2 的技术结合起来，创建有针对性的响应性 MR 和 PET 试剂，不仅报告 细胞质量，还提供 细胞功能的成像指数。随着近年来成像方式的技术创新，分子成像在基础生物医学科学和临床研究与实践领域越来越受到关注。事实上，非侵入性成像技术正在彻底改变细胞和分子水平上对疾病的理解。在当前可用的成像方式中，断层核成像方法，特别是正电子发射断层扫描（PET），由于在不同受试者中具有卓越的灵敏度和特异性以及定量分析感兴趣区域的能力，已经证明了其在分子成像探针应用中的重要性和广阔前景。 孙博士的放射化学实验室与 Dean Sherry 博士合作，对一系列具有放射性金属双功能螯合剂和双膦酸盐（常用于治疗骨转移）的混合制剂的设计和体内评估感兴趣，用于骨转移的多模态（BLI/MRI/SPECT/PET）检测和放射治疗/姑息治疗的监测。此外，我们正在与高级成像中心开展合作，通过 PET 研究中间代谢。 其中一个项目是开发成像剂，不仅能靶向体内胰腺 b 细胞，还能通过功能激活对 b 细胞代谢做出反应。在这个项目中，博士。 Sherry 和 Sun 将利用最先进的成像剂技术开发新型 PET 和 MR 试剂，用于体内 b 细胞的分子成像。在动物实验之前，将开发一个平台，用于对离体大鼠胰岛进行高分辨率 MR 和 PET 成像，该技术将用于筛选 b 细胞中截留的缺氧敏感 PET 试剂 (64Cu-ATSM) 和氧化还原敏感 PARACEST 试剂（Eu3+ 或 Tm3+ 的基于 Cyclen 的四酰胺复合物）。 将使用从葡萄糖低反应胰岛素瘤 INS 832/1 细胞中分离的肽 (MSKSPEEGRATVQPSTQPHY) 在分离的大鼠胰岛上进行专门针对 b 细胞的药物的概念验证研究。 使用这种肽或类似的肽，18F标记基团或基于cyclen的配体将被添加到所有靶向肽的N端氨基位置，以创建靶向MR试剂（基于Gd3+和PARACEST）和靶向PET试剂（基于18F和64Cu）的库，用于测量b细胞质量。 在一个相关项目中，孙博士的实验室将合成[b-18F]-氟丙酸作为丙酮酸循环的示踪剂，以检验[b-18F]-氟丙酸在¿细胞中的积累水平明显高于a细胞的假设。 如果该技术在离体胰岛实验中有效，那么它将很快转化为小动物的体内研究。 这是一个相对容易测试的假设，如果被证明是正确的，可以提供一种强大、便捷的方法来通过 PET 对 b 细胞功能进行成像。最终目标是创建有针对性的响应性 MR 和 PET 试剂，不仅可以报告 b 细胞质量，还可以提供 b 细胞功能的成像指数。 值得注意的是，UT西南医学中心已计划购买一台回旋加速器，以促进PET成像研究和放射性示踪剂的开发。先进成像研究中心 (AIRC) 的建设已接近完成，该中心一楼将拥有 2,000 平方英尺的空间，指定用于综合 PET 化学实验室。建成后，孙博士的实验室将占据这个新空间，并开始与 AIRC 的教师在体内代谢方面密切合作。 一个具有潜在高影响力的新项目是同时施用[1-11C]乙酸盐和[2-11C]乙酸盐，试图梳理出TCA循环中交叉的体内通量。 Jeffrey 博士的初步建模表明，通过将标记放置在乙酸盐的 C1 和 C2 位置，11CO2 生成的时间模式将足够复杂，可用于数学建模以揭示柠檬酸合酶等代谢通量。 将在用[1-11C]乙酸盐和[2-11C]乙酸盐灌注的大鼠心脏中进行初步实验，并且将通过热CO2产生的伽马计数来分析灌注液。不幸的是，[2-11C]乙酸酯的合成路线尚​​未报道，因此孙博士将在实验前开发一条生产[2-11C]乙酸酯的合成路线（[1-11C]乙酸酯确实存在）。 显然，一旦回旋加速器到位，孙博士将把他对 18F 和 11C 的研究扩展到其他代谢底物，使 PET 化学在这项研究资源资助支持的合作项目中发挥积极作用。