内皮祖细胞移植治疗大鼠急性心肌梗死的实验研究

Experimental study of transplantation of rat endothelial progenitor cells for treatment of acute myocardial infarction

目的探讨大鼠内皮祖细胞(EPCs)移植于梗死心肌的增殖分化情况及对心功能的影响。方法分离培养大鼠EPCs,免疫荧光法检测其CD34+、CD133+和Flk-1+的表达。将SD大鼠冠状动脉左前降支结扎制造急性心肌梗死模型后,在梗死心肌处植入DAPI标记的EPCs(实验组)或M 199培养液(对照组)。移植后1周及4周,心脏超声检查心功能,并对梗死区心肌组织进行移植细胞形态学检查及毛细血管密度测定,逆转录聚合酶链反应及酶联免疫吸附测定梗死周边区血管内皮生长因子(VEGF)的表达。结果培养获得EPCs,其表型为CD34+、CD133+和Flk-1+。植入梗死区的EPCs可以分化为血管内皮细胞,实验组梗死心肌处血管密度较对照组明显增高(P<0.01),并且VEGF基因及蛋白表达在移植后1周均较对照组明显增高(P<0.01)。移植后4周,实验组大鼠左心室射血分数及左心室短轴缩短率较对照组明显提高(P<0.01);而移植后1周,两组大鼠超声检测心功能各指标变化不明显。结论同种异体EPCs移植到梗死心肌大鼠缺血心肌能分化为毛细血管内皮细胞,促进梗死后心肌血管新生,改善心功能。

Objective To investigate the proliferation and differentiation of rat endothelial progenitor cells （EPCs） implanted into ischemic myocardium, and observe the improvement of cardiac function. Methods EPCs of SD rats were isolated and cultured, hnmunofluorescence assays was used to detect the expression of CD34^＋, CD133^＋ and Flk-1^＋ EPCs labeled with DAPI （experimental group） or M199 medium （control group） were implanted into the ischemic myocarditan resulting from ligation of left descending branch of coronary artery. At 1 or 4 weeks after transplantation, echocardiography was used to examine the effects on heart function and specimens were taken from infarcted area for examining cell morphology and measuring capillary density. RT-PCR and ELISA assay were used to determine the expression level of vascular endothelial growth factor （VEGF）. Results EPCs were successfully isolated and cultured and its phenotypes were CD34^＋ , CD133^＋ and Flk-1^＋ . The labeled EPCs were successfully implanted into the ischemic area and differentiated into endothelial cells. The capillary density in infarcted area in experimental group increased compared with control group （ P 〈 0.01 ）. The levels of VEGF mRNA and protein expression at 1 week obviously increased in experimental group compared with control group （ P 〈 0.01 ）. Left ventricular function, including ejection fraction and fractional shortening, was improved in experimental group as compared with control group at 4 weeks （ P 〈 0.01 ）. Conclusion EPCs transplantation can accelerate angiogenesis in infarcted area after rat myocardial infarction and improve heart function.