兔骨髓间充质干细胞自体移植及血管新生修复梗死心肌的实验研究

Autologous transplantation of bone marrow mesenchymal stem cells and neovascularization repair infarcted myocardium:an experimental study

目的 了解骨髓间充质干细胞 (MSCs)在心肌梗死的缺血心肌微环境中转化为心肌细胞并改善心功能的可行性。方法 结扎兔左前降支 (LAD)制作急性心肌梗死(AMI)模型 ,骨穿抽取骨髓 ,分离培养扩增骨髓间充质干细胞。术后 2周进行心肌梗死瘢痕内移植 5溴脱氧尿嘧啶(BrdU)标记的骨髓间充质干细胞 ,对照组注射培养基。AMI术前、AMI术后 3d及移植后 4周做超声心动图检测心功能 ,移植后 4周从右颈总动脉插管至左心室测左室压力变化 ,随后处死动物模型 ,取左室标本做冰冻切片 ,采用免疫荧光方法检测BrdU鉴定植入细胞并检测Ⅷ因子相关抗原以测量毛细血管密度。结果 细胞移植组左室切片中可见BrdU染色阳性细胞即植入细胞 ,对照组未见BrdU染色阳性细胞。Ⅷ因子阳性内皮细胞计数表明细胞移植组毛细血管密度大于对照组 (P <0 0 5 )。超声心动图检查证实MSCs移植后 4周左室收缩末期直径 (LVESD)、舒张末期直径 (LVEDD)均小于对照组 (分别为P <0 0 1及P <0 0 5 ) ,小轴缩短率 (ΔD % )、射血分数 (EF)均大于对照组 (均P <0 0 1)。结论 兔缺血心肌内注射骨髓间充质干细胞可依赖组织微环境转化为心肌细胞修复梗死心肌 ,可能伴有移植区域新生血管形成 ,能显著改善心功能 ,可用于心肌梗死的治疗。

Objectives To investigate the feasibility that bone marrow mesenchymal stem cells (MSCs) differentiate into cardiomyocytes in ischemic myocardium microenvironment and improve heart function. Methods The left anterodecending arteries (LAD) of adult rabbits were ligated so as to establish animal models of acute myocardial infarction. Animals were randomly divided into 2 groups. Mesenchymal stem cells were isolated from bone marrow and were cultured. 2 weeks later the expanded MSCs labeled with BrdU were injected into the scar tissue. The heart function of each rabbit was measured by echocardiography and hemodynamics. Specimens were taken 4 weeks after implantation. Histologic sections of left ventricular were stained by immunofluorescent and examined under fluorescent microscope to identify the transplanted MSCs and factor Ⅷ + endothelial cells. Capillary density was expressed as factor Ⅷ + endothelial cells per high power field. Results The implanted cells were found in the MSCs groups and not in the control group. The capillary density of MSCs group was bigger than that of control group ( P <0 05). Compared with control group, 4 weeks after transplantation MSCs group resulted in shorter LVESD ( P <0 01), LVEDD ( P <0 05) and higher EF ( P <0 01). Conclusions Autologous bone marrow mesenchymal stem cells can differentiate into cardiomyocytes in vivo and maybe form new vasculars to repair infarcted myocardium and improve the heart function. Bone marrow MSCs transplantation can use to therapy acute myocardial infarction.