Phage-based targeted imaging probes and their application to vascular diseases

描述（由申请人提供）：我们的总体目标是创建和测试基于蛋白笼纳米颗粒（pcn）的新一代细胞/组织靶向MRI造影剂。目的是显著提高体内血管疾病分子水平事件的检测和成像能力。该提案是一项多学科的努力，结合了心血管医学、血管生物学、MRI、病毒学、合成无机和纳米材料化学方面的成熟专业知识。基于体外和体内强有力的初步结果，我们的方法将结合使用噬菌体P22衣壳作为构建高性能多功能磁共振造影剂的生物模板。基于p22的蛋白质笼纳米颗粒（PCN）的内表面将用于在空间上限制一种独特的高分子高性能gd基T1造影剂家族。PCN的外部将用于细胞特异性靶向配体的多价展示，以及额外的体内选择和优化组织靶向和血液半衰期。这种方法的优点是对优化松弛性所需的物理参数进行了实质性的控制，同时结合了有效的组织靶向和在单个系统中进行体内发现的潜力。虽然这些平台可以应用于广泛的疾病，但这种应用的重点将是血管疾病（动脉粥样硬化）。该提议的具体目标是(i)开发基于蛋白质笼纳米颗粒的造影剂，优化其弛豫谱；（ii）将组织特异性靶向配体结合到PCN中，并在体内选择噬菌体以进行组织靶向和延长血液半衰期；（iii）在已建立的小鼠模型中翻译靶向蛋白质笼纳米颗粒以成像血管疾病。还将评估Gd毒性和P22免疫原性问题。针对新鲜人体组织直接筛选P22噬菌体文库为鉴定新的组织营养肽提供了另一种方法。使用最先进的设备创建和评估这些基于pcn的材料作为功能性磁共振造影剂，将为创建下一代高性能功能性磁共振造影剂的迭代过程提供快速和直接的反馈。这个项目是由三个有着大量合作历史的小组合作完成的；道格拉斯（密歇根州立大学），麦康奈尔（斯坦福大学）和特权（阿拉巴马大学）。其他成员包括Frank （NIH）、Dalman（斯坦福）、Tsao（斯坦福）、Contag（斯坦福）、Uchida（密歇根州立大学）和Zajac（阿拉巴马州），他们将作为合作者或顾问参与，共同为成功完成既定目标收集广泛的专业知识和经验。

DESCRIPTION (provided by applicant): Our overall goal is to create and test a new generation of cell/tissue- targeted MRI contrast agents based on protein cage nanoparticles (PCNs). The aim is to significantly increase the ability to detect and image molecular level events in vascular disease in vivo. This proposal is a multidisciplinary effort, combining established expertise in cardiovascular medicine, vascular biology, MRI, virology, synthetic inorganic and nano-materials chemistry. Based on strong preliminary results, both in vitro and in vivo, our approach will combine the use of bacteriophage P22 capsids as biotemplates for construction of high performance multifunctional MR contrast agents. The interior surface of the P22-based protein cage nanoparticles (PCN) will be used to spatially confine a unique family of polymeric high performance Gd-based T1 contrast agents. The exterior of the PCN will be used for multivalent display of cell-specific targeting ligands and additional in vivo selection and optimization of tissue targeting and blood half-life. The advantage of this approach is a substantial control over the physical parameters required to optimize relaxivity while at the same time incorporating effective tissue targeting and the potential for in vivo discovery in a single system. While these platforms can be applied to a broad range of diseases, the focus of this application will be on vascular disease (atherosclerosis). The specific objectives of this proposal are (i) the development of protein cage nanoparticle-based contrast agents with optimized relaxivity profiles and, (ii) the incorporation of tissue specific targeting ligands to the PCN and in vivo selection of phage for tissue targeting and extended blood half-life, and (iii) the translation of targeted protein cage nanoparticles to image vascular diseases in established mouse models. Issues of Gd toxicity and P22 immunogenicity will also be evaluated. Direct screening of the P22 phage library against fresh human tissue provides an alternative approach for identifying novel tissue-trophic peptides. Creation and evaluation of these PCN-based materials as functional MR contrast agents using state-of the-art facilities will provide rapid and direct feedback for an iterative process to create the next generation of high performance functional MRI contrast agents. The project is collaboration between three groups who have a history of substantial collaboration; Douglas (MSU), McConnell (Stanford University), and Privilege (University of Alabama). Others including Frank (NIH), Dalman (Stanford), Tsao (Stanford), Contag (Stanford), Uchida (MSU), and Zajac (Alabama) will participate as either collaborators or consultants and together this team gathers the breadth of expertise and experience necessary for the successful completion of the stated goals.