Objective Explore the effect of mesenchymal stem cell transplantation on cardiac function in rats with adriamycin(Adr)-induced heart failure.Methods MSCs were isolated from 8-week old F344 rats and cultured in vitro.Cells at the third passage were identified with a flow cytometer and labeled with(5-Bromo-2'-Dexuuridine,BrdU)before transplantation.BrdU-labeled MSCs(3?106 cells)was transplanted into rats(the transplantation group and the sham transplantation group,respectively)via femoral vein.Four weeks after the transplantation,cardiac function was evaluated using physiological recorder.Hearts were harvested and analyzed by immunohistochemistry to identify the transplanted BrdU-labeled cells.Results Four weeks after transplantation:the mortality of transplantion group was 6.2%,significantly lower than 12.5% in sham transplantation group(P