[Ultrastructural changes of rat ischemic myocardium after bone marrow mesenchymal stem cell transplantation].

OBJECTIVE: To observe the ultrastructural changes of ischemic myocardium of rats after bone marrow mesenchymal stem cells (MSCs) transplantation. METHODS: Rat models of myocardial ischemia were established by ligating the descending anterior branch of the left coronary artery. The isolated and in vitro cultured MSCs labeled with 4' 6-diamidine-2-phenylindole (DAPI) were injected into the rats via the tail vein and the hearts of the rats were taken 1 week and 8 weeks after transplantation, respectively, for observation under fluorescence microscopy. The ultrastructural changes of the ischemic myocardium of the recipient rats were observed by transmission electron microscope. RESULTS: The third passage of cultured MSCs growing in colonies possessed good homogeneity. One week and 8 weeks after transplantation, DAPI-labeled cells were observed in the heart of the recipient rats, but not in the hearts of control rats. One week after transplantation, ultrastructural observation identified a small number of cells in the peripherals of the infarct area of the recipient rats with similar morphology to that of MSCs cultured in vitro. At 8 weeks,a large number of capillaries were seen in the ischemic myocardium on the peripheral of the infarct area. Ultrastructural observation also revealed some immature myocytes surviving in the ischemic region. CONCLUSION: MSCs is capable in vivo of homing to the ischemic myocardium via the blood circulation, and promote regeneration of the myocardium and blood vessels.