Background The necrosis of a large number of myocardial cells after acute myocardial infarction (AMI) results in a decrease of cardiac function and ventricle remodeling.Stem cell transplantation could improve cardiac function after AMI,but the involving mechanisms have not been completely understood.The present study aimed to investigate the effects of transplantation of autologous bone marrow mononuclear cells (BM-MNC) and rnesenchymal stem cells (MSCs) via the coronary artery on the ventricle remodeling after AMI as well as the mechanisms of the effects of transplantation of different stem cells on ventricle remodeling.Methods A total of 36 male pigs were enrolled in this study,which were divided into 4 groups: control group,simple infarct model group,BM-MNC transplantation group,and MSCs transplantation group.At 90 minutes when a miniature porcine model with AMI was established,transplantation of autologous BM-MNC ((4.7±1.7)×107) and MSCs ((6.2±1.6)×105) was performed in the coronary artery via a catheter.Ultrasound,electron microscope,immunohistochemical examination and real time reverse transcdptase-polymerase chain reaction were used respectively to observe cardiac fun~ons,counts of blood vessels of cardiac muscle,cardiac muscle nuclear factor (NF)-KB,myocardial cell apoptosis,and the expression of the mRNA of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in cardiac muscles.Multivariate Logistic regression was used to analyze the correlation factors of left ventricular end-diastolic diameter (EDD).Results The number of blood vessels in the infarct zone and around its border in the BM-MNC transplantation group was more than those in the infarct model group and MSCs group (P=0.0001) and there was less myocardial cell apoptosis in the stem cell transplantation group than that in the infarct model group (all P