冠脉搭桥术后静脉桥血管再狭窄发病率高，早期干预至关重要但缺少有效手段。机械牵张所致桥血管炎症是关键因素。新近研究表明microRNA在桥血管再狭窄中起重要作用，可成为新的干预靶点。申请人在已完成的国自然研究中发现miR-551b-5p和转录因子EGR1在受机械牵张刺激的静脉内皮细胞中均高表达，EGR1引起炎症导致再狭窄，生物信息学分析EGR1可能是miR-551b-5p靶基因。故提出：“miR-551b-5p加重炎症导致桥血管再狭窄”假说。本项目拟观察患者再狭窄的静脉桥血管miR-551b-5p及炎症因子表达；RNA干扰构建miR-551b-5p沉默和过表达载体，观察受机械牵张刺激后细胞功能、靶基因和炎症因子表达变化；运用CRISPR/Cas9新技术制备基因敲除小鼠并复制静脉移植模型，观察miR-551b-5p敲除和抑制剂对静脉桥血管再狭窄的影响，进一步验证假说，提供早期干预靶点。

After coronary artery bypass graft,the incidence of vein graft failure is high. Early intervention is very important but the lack of effective methods. Vascular inflammation caused by mechanical stretch is the key factor. Recent studies indicated that microRNA is an important role and may be intervention target in the vein graft failure. In the finished project of Natural Science Foundation of China, we found that miR-551b-5p and EGR1 expression in endothelial cells are both up-regulated after mechanical stretch stimulation. EGR1 expression could promote inflammatory response, induce vein graft failure. And we found EGR1 may be the target gene of miR-551b-5p by using bioinformatic analysis. Therefore, we put forward the hypothesis:” miR-551b-5p promotes inflammation leading to vein graft failure”. This project aims to investigate miR-551b-5p and inflammatory factor expression in patients with vein graft failure; using RNA interference technique to build miR-551b-5p silence and overexpressed vector, then submitting to mechanical stetch, we observe the cell function, the target genes and inflammatory factors expression; using new CRISPR/Cas9 technique to prepare gene knockout mice and copy vein graft model, observing the effect of miR-551b-5p knockout and inhibitor in vein graft failure, providing early intervention targets.