The Role of Nitric Oxide Synthase in Circulating Progenitor Cell Function

描述(申请人提供)：我们建议确定内皮型一氧化氮合酶(ENOS)在年龄或疾病相关的人内皮祖细胞(EPC)功能障碍中的作用。衰老或积累不同的心血管危险因素的一个后果是血管内皮细胞的功能下降。这似乎与体外测量的EPC功能下降有关。在动物和人类体内移植内皮祖细胞被认为可以增强心肌梗死或外周缺血后功能性组织的保存/再生，这一点可能得到了我们自己的初步研究的支持。然而，EPC功能已被证明决定了组织修复的程度。培养中的EPC功能下降与EPC在心肌梗死后移植时帮助组织再生的能力下降有关。这就带来了这样一个问题：如果EPC本身的功能受损，那么体外扩张和重新输注患者自己的EPC可能是无效的。这一建议的主要假设是，在一些心血管风险较高的人群中，由于eNOS依赖的一氧化氮(NO)产生减少，EPC功能受损，而通过改造EPC使其过度表达eNOS，可以增强其功能。其具体目的是(1)评估EPC功能与心血管风险(包括年龄)高、低风险人群的EPC产生的eNOS依赖的NO之间是否存在相关性，(2)评估工程EPC过表达eNOS是否增强其在心血管疾病啮齿动物模型中改善功能的能力，以及(3)探讨NO在EPC功能中的机制作用。相关性：在血液中循环的祖细胞被认为参与血管的生长和维持。这些来自老年人或患有某些心血管疾病的人的祖细胞比健康的年轻人的祖细胞功能更差。这项研究将确定eNOS酶的缺陷是否是这一问题的部分原因，并将探索通过基因工程改造此类祖细胞以改善其功能的可能性，从而增加其有益效果。

DESCRIPTION (provided by applicant): We propose to determine the role of endothelial nitric oxide synthase (eNOS) in age- or disease-related dysfunction of human endothelial progenitor cells (EPCs). One consequence of aging or accumulating different cardiovascular risk factors is a decrease in the functional capabilities of the vascular endothelium. This appears to correlate with a decrease in EPC function as measured ex vivo. Transplantation of EPCs in both animals and humans has been suggested to enhance functional tissue preservation/regeneration after myocardial infarction or peripheral ischemia, a possibly that is supported by our own preliminary studies. However, EPC function has been shown to determine the extent of tissue recovery. Decreased EPC function in culture is associated with decreased ability of EPCs to aid in tissue regeneration when transplanted after myocardial infarction. This presents the problem that ex vivo expansion and re-infusion of a patient's own EPCs may be ineffective if the EPCs themselves are functionally impaired. The main hypothesis of this proposal is that EPC function is impaired in some populations with high cardiovascular risk as a result of reduced eNOS-dependent nitric oxide (NO) production, and that dysfunctional EPCs can be functionally enhanced by engineering them to overexpress eNOS. The specific aims are (1) to evaluate whether a correlation exists between EPC function and eNOS-dependent NO production in EPCs from populations with high versus low cardiovascular risk, including age, (2) to assess whether engineering EPCs to overexpress eNOS enhances their ability to improve function in rodent models of cardiovascular disease, and (3) to examine the mechanistic role of NO in EPC function. RELEVANCE: Progenitor cells that circulate in the blood are thought to participate in the growth and maintenance of blood vessels. Such progenitor cells from elderly individuals, or people who suffer from certain cardiovascular maladies, are less able to function than those from healthy young individuals. This research will determine if a deficiency in the enzyme eNOS is partially responsible for this problem, and will also explore the possibility of genetically engineering such progenitor cells to improve their function, thereby increasing their beneficial effects.