| Ischemic myocardial cells can be saved by traditional medicine or cardiac catheter, but once they are destroyed, they can not be repaired. Cell regeneration can replace and improve the biologic function of damaged cardium, which is one of the hottest questions in the field of cardiac disease recently. The plascitity of mesenchymal stem cells bring us the hope of myocardial regeneration. Many researches have comfirmed that cell regeneration can improve heart function and decrease the scar.The lastest studies confirm that the mesenchymal stem cells have the characteristics of moving to the damaged organs during the period of damaging, more cells can migrate to the infarct cardium in proper time and quality, so they have the purpose of improving the heart function. The past researches tell us that two weeks after myocardial infarction maybe the optimal regeneration time. Recently, the most commonly used approaches are the transplantations of stem cells into the damaged myocardium by via epicardium following chest-open, or via endocardium by cardiac catheters, or via coronary artery, or by intravenous injection. Of them, transplanting MSCs intravenously is well recognized as a simple, feasible and atraumatic approach, but whether it can work on heart function is still a problem to be confirmed. Transplating approach and time are the most important influencing factors, but the cell quantity is also a significant factor. Whether there are enough MSCs homing to infarct areas can directly impact on thearaputic efficacy.ObjectiveThe purpose of this study was to observed the protective effect of intravenous and via epicardium transplantation of bone marrow mesenchymal stem cells (MSCs) and the effect of different concentration of bone marrow stem cells (MSCs) by intravenous transplantation on heart function of acute myocardial infarction(AMI) rats.Methods and Results1. Myocardial infarction(MI)was created by occluding the left anterior descending artery (LAD) in SD rats. MSCs acquired from healthy rats were isolated, purified, amplificated and labeled with DAPI. Two weeks after MI, the labeled MSCs were transfused into MI rats through caudal vein (group A, n=10) or via epicardium (group B, n=10) while some culture medium was transfused into the control rats (group C, n=10) groups. Four weeks later, heart functions were evaluated and immunohistochemical analysis was performed. This result revealed the labeled cells were viable in the host hearts and immunochemical staining revealed that the engrafted stem cells expressed a-Actin. Left heart functions and infarct size in group A and group B were more obviously improved compared with those of control group.2. 2 weeks after MI, the labeled MSCs were transfused into AMI rats through caudal vein in dosage of 5×10~5 (A),1×10~6 (B),5×10~6 (C),1×10~7 (D) and culture medium of the same volume was transfused into control group. By the end of the four weeks, the heart functions were evaluated and immunohistochemical analysis was performed. The labeled cells were viable in the host hearts and immunochemical staining revealed that the engrafted stem cells expressed a-Actin. Compare with those of control group, the left ventricle function had no difference at A group (P>0.05) and were more obvious improvement at group B, C and D (P<0.05). Among the transplantation group, the C and D had greater improvement than B group (P<0.05).Conclusion1. Both intravenous and via epicardium transplantation of MSCs can migrate into the infracted areas and have some protective effect on rat heart of AMI by improved heart function..2. It may exist a certain dose-effect relationship between the engrafted cells and the improvement of heart function.
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