促进慢性缺血脑组织内新生血管的形成能够改善脑血流灌注并降低脑卒中风险，但调控脑血管新生的机制尚不明确。我们前期研究发现：miR-126-5p可在体外促进常氧状态下人脑微血管内皮细胞的增殖成管，以及PI3K/Akt/eNOS作为下游通路参与调控大鼠脑内血管新生。结合DLK1可能作为miR-126-5p的靶基因参与血管新生的调控，我们提出假设：miR-126-5p可通过靶向抑制DLK1的表达，降低后者对PI3K/Akt通路的抑制，进而上调内皮细胞eNOS的表达，最终促进血管新生。本项目是前期研究的延续，拟采用双荧光素酶报告明确miR-126-5p的下游靶基因，并以mRNA干扰为干预手段，通过体外细胞学实验以及慢性脑缺血大鼠局部脑血管新生的体内研究，来明确并验证miR-126-5p促进脑血管新生的作用和分子机制，同时探索DLK1的下游调控通路，为慢性缺血性脑血管病临床疗效的提高寻找新的治疗靶点。

Promoting the angiogenesis in chronic ischemic brain tissue can improve cerebral blood perfusion and reduce the risk of stroke, but the mechanism for regulating cerebral angiogenesis is not clear. Our previous study found that miR-126-5p can promote the proliferation and tube formation of human brain microvascular endothelial cells under normoxia in vitro. At the same time, PI3K/Akt/eNOS was involved in the formation of neonatal cerebral blood vessels as a downstream pathway. Combining with that miR-126-5p may participate the molecular regulation of angiogenesis directly through inhibiting DLK1. We hypothesize that miR-126-5p can targetedly inhibitie DLK1 expression, and then reduce the inhibition of PI3K/Akt pathway from DLK1 , and then up-regulate the expression of eNOS in endothelial cells, thereby promote angiogenesis. This project is a continuation of the previous research, and it is intended to use dual luciferase reporter to determine the target mRNA of miR-126-5p, and to use mRNA interference as an intervention method. Through cell biology experiments in vitro , combined with regional angiogenesis experiments on chronic cerebral ischemia rats models in vivo, we are planning to determine the effect and molecular mechanism of miR-126-5p in promoting cerebral angiogenesis, to explore the downstream regulatory pathway of DLK1, and to find new therapeutic targets for the improvement of clinical efficacy of chronic ischemic cerebrovascular diseases.