Abstract: Objective To study the effects of marrow mesenchymal stem cells on heart functions and ventricular remodeling after myocardial infarction in rats. Methods Myocardial infarction was operated by ligation of the left anterior descending coronary artery ( LAD ) in adult SD rats. 4 and 8 weeks after MMSCs implantation, hemodynamic evaluations, left ventricular weight/body weight ratio and heart weight/body weight ratio were determined. HE staining was performed for double-blind counting the density of microvasculars and Van Gieson staining was used for measurements and calculation of the myocardial fibrillar collagen. Then we investigated the migration and evolution of MSCs in vivo by fluorescent microscope. Results First of all, HR were significantly decreased in transplantation MMSCs group. After transplantation 8 weeks, bodies weight in transplantation MMSCs group reached to control group's. At the same time, SBP, DBP and MBP, were significantly increased in transplantation MMSCs group. HR were significantly decreased in transplantation MMSCs group. Secondly, left ventricular weight/body weight ratio and heart weight/body weight ratio were significantly decreased after transplantation MMSCs 4 weeks. Then the ratio were significantly decreased after transplantation MMSCs 8 weeks. Thirdly, our results also demonstrated that the density of microvasculars were increased at the boundary of infarction site in the animals transplanted MMSCs. Finally, total volume of the myocardial fibrillar collagen was reduced in the MMSCs treated groups after MI. Conclusion Transplanting MMSCs can improve the ventricular remodeling and heart functions to acute MI rat models.

Key words: Myocardial infarction, Marrow mesenchymal stem cells, Ventricular remodeling, Enhanced green fluorescent protein