miR-155低表达内皮祖细胞对缺血性脑卒中小鼠血管再生的影响

Effect of endothelial progenitor cells with low miR-155 expression on the angiognesis of ischemic stroke rats

目的探讨miR-155低表达内皮祖细胞(EPCs)对缺血性脑卒中小鼠血管再生的影响。方法以线栓法建立C57BL6小鼠右侧大脑中动脉梗塞(MCAO)模型,提取分离小鼠循环血液及骨髓中EPCs,用流式细胞仪检测循环EPCs水平,qRT-PCR检测循环EPCs中miR-155的表达;体外培养EPCs,以慢病毒感染法沉默EPCs中的miR-155,以MTT法检测EPCs活性;通过尾静脉注射向脑卒中小鼠体内输注EPCs,检测脑微血管密度(CD31+)及用多普勒血流灌注仪检测脑血流灌注。结果与正常小鼠相比,缺血脑卒中小鼠循环EPCs水平显著下降(P<0.01),同时EPCs中miR-155表达水平显著升高(P<0.01);敲减EPCs中的miR-155,可显著增加EPCs的增殖活性(P<0.01);输注miR-155低表达EPCs后,脑缺血区微血管密度显著增加(P<0.01),并增加了缺血区脑血流灌注(P<0.01)。结论缺血性脑卒中病理条件下,EPCs中miR-155表达水平异常。输注miR-155低表达EPCs可以通过增加缺血区血管生成及脑血流灌注改善缺血性脑卒中小鼠缺血损伤。

Objective To investigate the effect of endothelial progenitor cells（EPCs） with low miR-155 expression on the angiogenesis of ischemic stroke rats. Methods C57 BL6 mouse were subjected to sham-surgery（control） or permanent cerebral artery occlusion（MCAO）. The circulating EPCs were extracted from the plasma of mice. The level of circulating EPCs was analyzed with flow cytometry,and the expression of miR-155 in EPCs was measured with qRT-PCR. EPCs were cultured in EGM-2 culture medium in vitro, and miR-155 in EPCs was silenced with lentivirus infection. MTT assay was used to measure the proliferation activity of EPCs. The EPCs were transferred into mice via tail intravenous injection. On day 3,cerebral microvascular density and cerebral blood flow were determined. Results Compared with normal mice, ischemic stroke rats had the level of circulating EPCs significantly decreased（P〈0.01） and the miR-155 expression in EPCs significantly increased（P〈0.01）; EPCs infusion increased the cerebral microvascular density（cMVD）（P〈0.01） and cerebral blood flow（CBF） in infarct area of the ischemic stroke mice. Moreover, silencing miR-155 enhanced the therapeutic efficacy of EPCs（P〈0.01）. Conclusion Under the pathological condition of ischemic stroke, miR-155 in circulating EPCs are abnormally expressed. The infusion of miR-155 low expressed EPCs can improve ischemia damage by increasing cMVD and CBF in infarct area of the ischemic stroke rats.