Mechanisms of endothelial repair after vascular injury

描述(由申请人提供)：该项目的长期目标是开发用于预防和治疗心血管疾病的新型内皮靶向疗法。循环内皮祖细胞的发现使人们对血管损伤后内皮修复和缺血组织血运重建的机制有了革命性的认识。然而，内皮祖细胞的有益影响的潜在机制却知之甚少。前列环素(PGI2)是血管内皮细胞释放的最重要的血管保护分子之一。值得注意的是，花生四烯酸代谢和PGI2的生物合成在调节内皮祖细胞再生功能中的作用还没有研究。在我们的初步研究中，我们发现PGI2的内在高生物合成是人内皮祖细胞的主要表型特征之一。此外，我们的研究表明，药物或遗传失活的PGI2显著损害内皮祖细胞的再生能力。因此，这一应用的一般假设是，在心血管系统中，内皮祖细胞中PGI2的生物合成是负责内皮祖细胞再生功能的重要机制。为了验证这一假说，我们提出了以下特定目标的研究：1)确定环氧合酶(COX)亚型在人内皮祖细胞中的表达和功能以及前列腺素类化合物的生物合成谱；2)确定PGI2在EPC再生功能中的作用；3)分析花生四烯酸代谢在衰老引起的EPC再生能力下降中的作用。实验将在从健康的年轻和老年志愿者的循环血液中分离出的EPC上进行。内皮祖细胞来源的PGI2在修复受损内皮细胞或血管生成中的作用将在体外和体内进行研究。通过建立裸小鼠颈总动脉线状损伤和后肢缺血模型，研究内皮祖细胞来源的PGI2在血管内皮细胞修复和血管重建中的作用。将对人内皮祖细胞进行基因修饰，以进一步从机制上了解花生四烯酸代谢在内皮祖细胞修复功能和衰老中的作用。拟议的研究将提供目前缺失的关于内皮祖细胞释放的前列腺素在心血管系统对损伤和衰老的反应中的作用的信息。了解这些机制将为开发预防和治疗心血管疾病的新的治疗方法奠定基础。公共卫生相关性：项目叙述内皮祖细胞(EPC)在包括心肌梗塞和中风在内的心血管疾病期间从骨髓中释放出来。它们的主要功能是修复受损的血管，恢复正常的心血管功能。目前，包括我们在内的许多实验室都致力于了解内皮祖细胞再生功能的机制。这项应用的长期目标是利用内皮祖细胞的治疗潜力。

DESCRIPTION (provided by applicant): The long-term goal of this project is to develop novel endothelium-targeted therapies for the prevention and treatment of cardiovascular disease. Discovery of circulating endothelial progenitor cells (EPCs) revolutionized understanding of the mechanisms responsible for endothelial repair after vascular injury and revascularization of ischemic tissues. However, the mechanisms underlying beneficial effects of EPCs are poorly understood. Prostacyclin (PGI2) is one of the most important vasoprotective molecules released from vascular endothelium. Strikingly, the role of arachidonic acid metabolism and biosynthesis of PGI2 in regulation of regenerative function of EPCs has not been studied. In our preliminary studies we identified intrinsically high biosynthesis of PGI2 as one of the major phenotypic characteristics of human EPCs. Furthermore, our studies indicate that pharmacological or genetic inactivation of PGI2 significantly impairs regenerative capacity of EPCs. Therefore, the general hypothesis of this application is that in the cardiovascular system, biosynthesis of PGI2 in EPCs is an essential mechanism responsible for the regenerative function of EPCs. To test this hypothesis we propose studies with the following specific aims: 1) determine expression and function of cyclooxygenase (COX) isoforms and profile of prostanoids biosynthesis in human EPCs, 2) define the role of PGI2 in regenerative functions of EPCs, and 3) analyze the role of arachidonic acid metabolism in aging-induced decline in regenerative capacity of EPCs. Experiments will be performed on EPCs isolated from circulating blood of healthy young and aged volunteers. The role of EPCs-derived PGI2 in repair injured endothelium or angiogenesis will be studied in vitro and in vivo. Established models of wire-induced injury of common carotid artery and hind limb ischemia in nude mice will be employed to determine the role of PGI2 derived from EPCs in endothelial repair and revascularization. Genetic modification of human EPCs will be carried out to gain further mechanistic insight into the role of arachidonic acid metabolism in reparative functions and aging of EPCs. The proposed studies will provide currently missing information regarding the role of prostanoids released from EPCs in response of the cardiovascular system to injury and aging. Understanding of these mechanisms will establish basis for development of novel therapeutic approaches to prevention and treatment of cardiovascular diseases. PUBLIC HEALTH RELEVANCE: Project Narrative Endothelial Progenitor Cells (EPCs) are released from the bone marrow during cardiovascular diseases including myocardial infarction and stroke. Their major function is to repair injured blood vessels and restore normal cardiovascular function. Currently, efforts of many laboratories, including ours, are focused on understanding the mechanisms responsible for regenerative function of EPCs. The long-term goal of this application is to harness therapeutic potential of EPCs.