[Ameliorative effect of rat bone marrow mesenchymal stem cell transplantation on infracted heart function]

This study was purposed to investigate the effects of rat marrow mesenchymal stem cell (rMSC) transplantation on left ventricular (LV) function in a rat myocardial infarction model. Myocardial infarction was performed in male Lewis rats by ligating the proximal left coronary artery. Rats were randomly divided into 3 groups: sham operation group (only thoracotomy, n = 8), AMI group (DF12 injection, n = 10), rMSC group (Dil-Labeled rMSC transplantation). At 8 weeks later, the cardiac functions including left ventricular ejection fraction (LVEF), left ventricular end systolic pressure (LVESP), left ventricular end diastolic pressure (LVEDP), +dp/dtmax and -dp/dtmax were evaluated by echocardiography and cardiac catheterization. The presence and differentiation of engrafted cells were assessed. CD31 was detected by immunohistochemical staining to demonstrate neovascular formation. The results indicated that the cultured in vitro rMSC expressed CD90, CD44, CD105, CD54; did not express CD34, CD45, CD31, as compared with AMI group, rMSC group showed a significant increase of LVEF, LVESP, +dp/dtmax, -dp/dtmax and a significant decrease of LVEDP. Immunofluorescence demonstrated that some transplanted rMSCs were positive for myosin, suggesting that small number of transplanted rMSCs differentiated into cardiac-like cells. Immunostaining showed marked augmentation of capillary density in the rMSC group than that of AMI group. It is concluded that transplanted rMSCs can differentiate into cardiac-like cells and rMSC transplantation can improve LV function after myocardial infarction in rats.