骨髓间质干细胞移植后心肌梗死区的超微结构变化

目的观察骨髓间质干细胞(MSCs)移植后心肌梗死区的超微结构变化,探讨MSCs移植治疗急性心肌梗死(AMI)的可能机制。方法于冠状动脉左前降支结扎后1～2h,将5-溴脱氧尿核苷(BrdU)标记的MSCs注射至心肌梗死区,6周后采用免疫组化法鉴定宿主心肌内存活的MSCs,于透射电镜下观察心肌梗死区的超微结构。结果MSCs组梗死心肌内可见BrdU阳性细胞。电镜下,MSCs组可见幼稚的细胞:胞核大,染色质颗粒细而均匀,以常染色质为主,可见由肌微丝刚形成的小肌原节和发育程度不同的肌原纤维,部分与正常心肌形成缝隙连接。和MSCs组比较,AMI组可见肌纤维断裂、坏死严重,线粒体肿胀,内有黑色绒球状颗粒。结论MSCs移植能减轻心肌细胞坏死,并有可能通过分化为心肌细胞来修复梗死心肌。

Utrastructural changes of the infracted myocardium after mesenchymal stem cells transplantation

Objective To observe the ultrastructural changes of the infarcted myocardium after mesenchymal stem cells (MSCs) transplantation so as to investigate the underlying mechanisms of MSCs transplantation for myocardial infarction. Method MSCs labeled with bromodeoxyuridine(BrdU) were injected into the infarcted myocardium at 1~2 h after ligating the left anterior descending(LAD) coronary artery . 6 weeks after transplantation, MSCs surviving in infarcted myocardium were identified by Immunohistochemistry. Ultrastructural changes were observed by electron microscope. Result BrdU-positive cells were seen in the infarcted myocardium in MSCs group but not in AMI group. In MSCs group, some immature cells that form partly gap junction with normal myocardium were seen on the periphery of infarcted area with a big nucelus-to-cytoplasm ratio, small sarcomere and dissimilarly developed myofibril. Compared with the MSCs group, mitochondria swelling with decreasing crista and black grains like floccular process, cardiac muscle fibers breakage and fibrosis were more severe in the MI group. Conclusion MSCs transplantation can relieve myocardial cell necrosis and MSCs potentially differentiate into cadiocyte-like cell.