eNOS基因缺陷导致小鼠脑缺血损伤加重的内皮祖细胞机制研究

The treatment of stroke is still a global problem to date, and it is necessary to investigate new therapeautic strategies for stroke. It is reported that endothelial nitric oxide synthase (eNOS) deficiency aggravates cerebral ischemic injury in mice, but the mechanisms are not fully understood. Endothelial progenitor cells (EPC) participate in angiogenesis that correlates inversely with the severity of cerebral ischemic injury. Our previous studies demonstrated that EPCs were dysfunctional in eNOS gene knockout (eNOS-/-) mice. Accordingly, we hypothesize that EPCs dysfunction and/or number reduction induced by eNOS deficiency aggravate cerebral ischemic injury. To test this hypothesis, this project will perform following 4 aims: 1) to determine the relationship between the aggravated cerebral ischemic injury and EPC dysfunction and/or number reduction in eNOS-/- mice; 2) to investigate the mechanisms underlying a defect of EPC mobilization in eNOS-/- mice; 3) to investigate the mechanisms underlying the EPC dysfunction in eNOS-/- mice; 3) to investigate the effects of EPC transplantation on cerebral ischemic injury in mice. Clinical trials show that a higher EPC number is related with a better prognosis in stroke patients, and EPCs may serve as a therapeutic target of cardio-cerebrovascular diseases. Therefore, this project may provide a new therapeutic strategy for cardio-cerebrovascular diseases, such as stroke.

目前脑卒中的治疗依然是个世界性难题，探索新治疗方法有现实的意义。内皮型一氧化氮合酶(eNOS)基因缺陷可加重小鼠的脑缺血损伤，但其机制尚不完全明确。脑缺血损伤的严重程度与血管新生有关，而血管新生与内皮祖细胞(EPC)的数量和功能密切相关。我们发现eNOS基因敲除小鼠EPC的功能出现失常。基于此，我们推测：eNOS基因缺陷导致小鼠的EPC功能和/或数量受损，从而加重小鼠的脑缺血损伤。本项目拟通过下列实验来验证该假设：确定eNOS基因缺陷加重脑缺血损伤与其导致EPC数量和/或功能损害的关系；初步探索eNOS基因缺陷小鼠EPC动员能力受损的机制；阐明eNOS基因缺陷导致EPC功能受损的机制；研究EPC移植对脑缺血损伤的治疗作用。临床研究证实，外周血中EPC数量高的脑卒中患者预后比较好，EPC可作为治疗心脑血管疾病的新靶点，所以本项目的研究有可能为脑卒中等心脑血管系统疾病的治疗提供新的思路。

众所周知，寻求有效的手段防治脑卒中具有极其重要的临床意义。我们的实验结果证实，内皮型一氧化氮合酶(eNOS)基因缺陷可加重小鼠的脑缺血损伤。脑缺血损伤严重的eNOS-/-小鼠血管新生数量也减少，而且血管新生数量的减少与内皮祖细胞(EPC)数量减少和功能降低密切相关。此外，实验结果还表明，eNOS基因缺陷小鼠EPC动员能力受损与EPC中氧自由基水平升高和NO水平下降有关，并可诱导凝血酶敏感蛋白-1 (TSP-1)和凝血酶敏感蛋白-2 (TSP-2)表达的增加，增加的TSP-1和TSP-2导致EPC功能失常；经体外干预，功能得到改善的eNOS基因敲除小鼠EPC对脑缺血损伤的治疗效果得到提高。因此，EPC可作为治疗心脑血管疾病的新靶点，同时也为脑卒中等心脑血管系统疾病的治疗提供新的思路。