ABSTRACT
Objective To study the effects of heat shock treatment of rat bone marrow mesenehymal stem cells(MSCs),the apoptosis ratio of treated-cells under low serum condition and the treated-cells transplantation on left ventricular function in rats with myocardiaIinfarction.Methods MSC8 were heat-treated under 42℃for 30 min,then the heat shock protein-70(HSP-70)was detected bv Western blot.The apoptosis ratio of heat-treated MSCs under low serum condition was tested by Annexin kit.The treated-MSCs labeled with Dil were transplanted into infarcted myocardium and 8 weeks later,the cardiac function of rats in each group was evaluated by echocardiography and cardiac catheterization.Results The immunophenotype of heat-treated MSCs did not vary,Western blot confirmed a higher level expression of HSP-70 in the treated-MSCs group as compared with that in the control group.The early apoptosis ratio was lower in treated-MSCs measured by flow cytometry with annexin staining than that of MSCs when cultured with low serum medium.After 8 weeks,LVEF,LVSP,+dp/dtmax,and-dp/dtmax were significantly higher,and the LVEDP was significantly lowar in heat-treated MSCs transplantation group than that in the control group.Conclusions Heat shock pretreatment of MSCs enhances the tolerance of MSCs to low serum medium,whereas does not lcad to the change of the cell immunophenotype.Transplantation of heattreated MSCs might improve the cardiac function in a rat myocardialinfarction model.