Mechanisms of endothelial repair after vascular injury

项目描述（由申请人提供）：该项目的长期目标是开发新的内皮靶向治疗方法，用于预防和治疗心血管疾病。循环内皮祖细胞（EPCs）的发现彻底改变了人们对血管损伤和缺血组织血运重建后内皮修复机制的理解。然而，EPCs有益作用的机制尚不清楚。前列环素（PGI2）是血管内皮释放的最重要的血管保护分子之一。引人注目的是，花生四烯酸代谢和PGI2的生物合成在EPCs再生功能调控中的作用尚未得到研究。在我们的初步研究中，我们发现PGI2的内在高生物合成是人类EPCs的主要表型特征之一。此外，我们的研究表明，PGI2的药理学或遗传失活显著损害EPCs的再生能力。因此，该应用的一般假设是，在心血管系统中，EPCs中PGI2的生物合成是EPCs具有再生功能的重要机制。为了验证这一假设，我们提出了以下研究目标：1)确定环氧化酶（COX）亚型的表达和功能以及人EPCs中prostanoids的生物合成谱；2)确定PGI2在EPCs再生功能中的作用；3)分析花生四烯酸代谢在衰老诱导的EPCs再生能力下降中的作用。实验将从健康青年和老年志愿者的循环血液中分离EPCs。epcs衍生的PGI2在修复受损内皮或血管生成中的作用将在体外和体内进行研究。建立裸鼠颈总动脉丝性损伤和后肢缺血模型，研究EPCs源性PGI2在内皮修复和血管重建中的作用。我们将对人类EPCs进行基因改造，以进一步了解花生四烯酸代谢在EPCs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EPCs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治疗方法奠定基础。内皮祖细胞（EPCs）在心血管疾病（包括心肌梗死和中风）期间从骨髓中释放。其主要功能是修复受损血管，恢复正常的心血管功能。目前，包括我们在内的许多实验室的努力都集中在了解内皮细胞再生功能的机制上。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.