The impact of bone marrow mesenchymal stem cells combined with VEGF gene transplantation on cardiomyocyte apoptosis in a porcine AMI model

Objective To observe the impacts of bone marrow mesenchymal stem cells(MSCs) combined with vascular endothelial growth factor(VEGF) gene transplantation on cardiomyocyte apoptosis and expressions of apoptosis-association protein Bcl-2,Bax and Caspase-3 and explore the potential mechanisms in a porcine acute myocardial infarction(AMI) model.Methods The bone marrow MSCs were isolated and cultured in vitro and transferred with adenovirus-mediated VEGF(Ad.VEGF) gene.The porcine AMI model was established by balloon closure method.The minipigs were randomly divided into four groups(n = 4 each) for different aim after one week:groupⅠ(intracoronary infusion of 100 μl auto-MSCs transferred with Ad.VEGF gene),groupⅡ(intracoronary infusion of 100 μl auto-MSCs non-transferred with Ad.VEGF gene),group Ⅲ(intracoronary infusion of 50 μl auto-VEGF plasmid) and group Ⅳ(intracoronary infusion of 100 μl phosphate buffer solution as a control).Four weeks later,the heart function was determined by echocardiography in vivo,then the minipigs were killed and the hearts were dissected for measuring cardiomyocyte apoptosis and the expressions of apoptosis-association protein in vitro.The cardiomyocyte apoptosios was measured by TdT-mediated dUTP nick end labeling(TUNEL) method,and the cardiomyocyte apoptosis index(AI) was calculated.The expression levels of Bcl-2,Bax and Caspase-3 protein in cardiomyocyte were measured by immunohistochemical method.Results(1) Echocardiogram showed that ejection fraction(EF) and left ventricular fractional shortening rate(FS) were significantly improved compared with before intervention in groups Ⅰ,Ⅱ and Ⅲ(P 0.01 or P 0.05),and the improvement of heart function in group Ⅰwas the most obvious(P 0.01).The heart function remained unchanged before and after intervention in group Ⅳ(P 0.05).(2) The results of TUNEL showed that the AI value and the expression levels of Bax and Caspase-3 proteins in cardiomyocytes were all the lowest(P 0.01 or P 0.05),and the expression level of Bcl-2 protein was the highest(P 0.05) in group Ⅰcompared with the other groups.Conclusions Bone marrow MSCs combined with VEGF gene transplantation to porcine AMI region has the effects of promoting angiogenesis,decreasing cardiomyocyte apoptosis,inhibiting expressions of Bax and Caspase-3,enhancing the expressions of Bcl-2 and thus improving heart function.