Deformable hydrogel microparticles as delivery vehicles to the vascular wall

描述（由申请人提供）：血管靶向载体（VTC）通过非侵入性地提供显像剂或有效治疗剂的局部递送，为改善许多严重人类疾病（包括冠状动脉疾病（CAD））的诊断和治疗提供了独特的机会。CAD是世界上发病率和死亡率的主要原因。目前对CAD的治疗包括受影响动脉的外科搭桥术、经皮冠状动脉介入术和口服他汀类药物。这些治疗方法的改进是必要的，因为例如，50%的接受过积极的他汀类药物治疗的患者仍然会发生严重的冠状动脉事件。慢性炎症和相关过程（例如血管生成）涉及CAD的所有阶段，并且通过在血管壁上表达的与这些过程相关的生物分子导向CAD的VTC可以提供可行的非手术方法来预防或甚至逆转已建立的CAD。然而，通常被提出用作将治疗剂靶向至血管壁的载体的纳米颗粒（NP）最近已显示由于血流的红细胞核心中的高截留而不能有效地运输至血流中的血管壁。相反，微粒（MP），特别是直径在2 - 3 μ m范围内的微粒，在血流中有效地定位于血管壁。尽管如此，对于靶向疾病干预，NP仍然比MP具有高度吸引力，这是因为它们具有实现细胞内（例如，基因）和间质递送。或者总体目标是开发一种智能递送系统，以显着改善NP在血流中的转运，从而充分实现血管靶向NP（VTNP）用于疾病干预的潜力。 具体而言，我们提出开发具有可调几何形状、表面特性和可变形性的蛋白酶可降解水凝胶MP，以用作将载药的VTNP递送至与CAD相关的中至大血管中的血管壁的载体。提出的具体目的是：（1）制造和表征人血流中NP负载的蛋白酶可降解水凝胶MP的血流动力学，以及（2）评价蛋白酶诱导的负载VTNP的水凝胶MP的降解。我们假设，可以制造负载有VTNP的高度可变形和可降解的水凝胶MP，并且其尺寸范围将允许其从人血流定位到血管壁的高能力，并且水凝胶MP基质内的蛋白质可降解交联剂可以在与由发炎的内皮上调的疾病相关蛋白酶接触时有效地裂解以释放负载的VTNP。总体而言，我们系统地整合了MP的高血管壁定位效率和嵌入的NP的内化能力的优势，可以作为用于诊断和治疗CAD的靶向剂的更有效的策略。通过对血流动力学、血管结构和疾病特异性表位的理解而工程化的药物载体将提供优于其设计集中于单独靶向表位的当代载体的改善的体内功效。

DESCRIPTION (provided by applicant): Vascular-targeted carriers (VTCs) offer unique opportunities for improving diagnosis and treatment of many serious human ailments, including coronary artery disease (CAD), by non-invasively providing localized delivery of imaging agents or potent therapeutics. CAD is the leading cause of morbidity and mortality in the world. Current remedies for CAD include surgical bypass of the affected artery, percutaneous coronary interventions, and oral administration of statin drugs. Improvements in these treatments are necessary since, for instance, major coronary events can still occur in 50% of patients who have undergone aggressive statin therapy. Chronic inflammation and associated processes (e.g. angiogenesis) are involved at all stages of CAD, and VTCs directed to CAD via biomolecules expressed on the vascular wall in association with these processes may provide a viable, non-surgical approach to preventing or even reversing established CAD. However, nanoparticles (NPs) that are typically proposed for use as carriers in targeting therapeutics to the vascular wal have been recently shown to not effectively transport to the vascular wall in blood flow due to high entrapment in the red blood cell core of blood flow. Conversely, microparticles (MPs), particularly in the 2 - 3 �m diameter size range, effectively localize to the vascular wall in bloo flow. Nevertheless, NPs remain highly attractive over MPs for targeted disease intervention owing to their high potential for achieving intracellular (e.g., gene) and interstitial delivery. Or overall goal is to develop a smart delivery system to dramatically improve NP transport in blood flow, thus fully realizing the potential of vascular-targeted NPs (VTNPs) for disease intervention. Specifically, we propose to develop protease-degradable hydrogel MPs with tunable geometries, surface characteristics, and deformability to serve as carriers for the delivery of agent- loaded VTNPs to the vascular wall in medium to large blood vessels relevant in CAD. The proposed specific aims are: (1) to fabricate and characterize the hemodynamics of NP-loaded, protease-degradable hydrogel MPs in human blood flow, and (2) to evaluate protease-induced degradation of VTNP-loaded hydrogel MPs. We hypothesize that highly deformable and degradable hydrogel MPs loaded with VTNPs can be fabricated and in the size range that would allow for their high capacity to localize to the vascular wall from human blood flow and that protease-degradable cross-linkers within the hydrogel MPs matrix can be effectively cleaved to release loaded VTNPs upon contact with disease-associated proteases that are upregulated by the inflamed endothelium. Overall, our systematic integration of the advantages of the high vascular wall localization efficiency of MPs and the internalization capabilities of th embedded NPs can serve as a more effective strategy for targeting agent for diagnosis and treatment of CAD. Drug carriers engineered with the understanding of hemodynamics, vessel architecture, and disease-specific epitopes will offer improved in vivo efficacy over contemporary carriers whose design are focused on targeting epitope alone.