Harnessing Platelet-Endothelial Interactions for Exosome Delivery

项目总结 研究表明，成体干细胞如间充质干细胞(MSCs)可以修复 心肌梗死(MI)或缺血/再灌注(I/R)损伤通过间接旁分泌机制而不是通过 分化和组织替换。在过去的十年里，外显体已经成为一种很有希望的无细胞生物。 治疗缺血性损伤的药物。几家基于exosome的治疗公司已经推出了早期阶段 临床试验。像大多数治疗学一样，迫切需要有效的交付策略来确保 足够数量的外切体到达受伤的组织。因为它们是纳米级天然脂双层 颗粒，一种选择是血管输送。然而，由于在很大程度上需要高剂量和重复给药 非靶点分布到单核巨噬细胞系统和其他器官，如肝、脾和 肺部。此外，MSC衍生的外切体(MSC-XO)需要与自然存在的外切体竞争 体液。MSC-XO的细胞结合和摄取也阻碍了治疗效果。新的方法是 将治疗性外切体运送到受损组织中的细胞所需。理想情况下，修饰的外切体应为1) 减少单核巨噬细胞系统的清除，2)结合损伤的血管，3)BE 损伤组织中靶细胞类型的有效摄取。现已证实急性心肌梗死可诱发 血管损伤和暴露的内皮下基质成分，包括胶原、纤维连接蛋白和血管性血友病 威勒布兰德因子(VWF)来募集血小板。血小板可结合并积聚在受损的血管系统上 在MI之后。我们没有对亲本细胞进行一般性修改或对外显子进行化学工程，而是使用了 血小板膜包裹外切体(以制造P-XO)并增加其巨噬细胞吞噬作用 细胞内化，以及它们靶向受损组织的能力。在这项拟议的研究中，我们计划 研究了P-XOS(AIM-1)的制备、表征及毒性。在那之后，我们将测试治疗 P-XOS对心脏损伤小鼠模型(AIM 2)和猪模型(AIM 3)的影响我们的研究将 为外切体的细胞内化机制、靶向特性和机制提供新的见解 P-XOS治疗的结果。总之，拟议的机械学和平移实验将提供一种 理解系统管理外显体的科学前提，同时提出新的方法 促进治疗性外切体的靶向性和治疗效果。

PROJECT SUMMARY Studies have demonstrated that adult stem cells such as mesenchymal stem cells (MSCs) repair myocardial infarction (MI) or ischemia/reperfusion (I/R) injury by indirect paracrine mechanisms rather than by differentiation and tissue replacement. In the past decade, exosomes have emerged as promising cell-free agents for treating ischemic injury. Several exosome-based therapeutic companies have launched early phase clinical trials. Like most therapeutics, there is an urgent need for effective delivery strategy to ensure a sufficient number of exosomes to reach the injured tissue. Since they are nanosized natural lipid bilayer particles, one option is vascular delivery. However, high and repeated dosing is needed due to a large degree of off-target distribution to the mononuclear phagocyte system and other organs, such as the liver, spleen and lungs. Moreover, MSC-derived exosomes (MSC-XOs) need to compete with naturally existing exosomes in body fluids. Cellular binding and uptake of MSC-XOs also hinder the therapeutic effects. Novel approaches are required to deliver therapeutic exosomes to cells in injured tissues. Ideally, modified exosomes should 1) reduce the clearance by the mononuclear phagocyte system, 2) bind to injured blood vessels, and 3) be efficiently uptake by target cell types in injured tissues. It has been established that acute MI can induce vascular damage and expose components of the subendothelial matrix including collagen, fibronectin and von Willebrand factor (vWF) to recruit platelets. Platelets can bind to and accumulate on injured vasculature following MI. Instead of generically modifying the parental cells or chemically engineering exosomes, we used platelet membranes to envelope exosomes (to make P-XOs) and increase their macropinocytosis-mediated cellular internalization, and their ability to target the injured tissue. In this proposed study, we plan to investigate the fabrication, characterization and toxicity of P-XOs (AIM 1). After that, we will test the therapeutic effect of P-XOs on a mouse model (AIM 2) and a porcine model (AIM 3) with cardiac injury. Our study will provide new insights on cellular internalization mechanism of exosomes, targeting properties and mechanism of the P-XOs treatment. Together, the proposed mechanistic and translational experiments will provide a scientific premise to understand system administrated exosomes while suggesting new approaches for promoting targeting and therapeutic effect of therapeutic exosomes.