BACKGROUND:Bone marrow stromal stem cels transplanted into infracted cardiac tissue can inhibit and reduce myocardial apoptosis, but whether this effect is correlated with improvement in cardiac function is stil unclear. OBJECTIVE:To study the early effect of bone marrow stromal stem cels transplanted into the ischemic myocardium on the cardiac function. METHODS: Models of acute myocardial infarction were established by ligation of the left anterior descending branch, while no ligation was done in the sham group. In the transplantation group, rat bone marrow stromal stem cels (0.1 mL, 2×106 RESULTS AND CONCLUSION:At 3 days after cel transplantation, myocardial apoptosis was more evident in the infarct and ischemic zones of the model group than the sham group; the number of apoptotic myocardial cels was significantly lower in the infarct and ischemic zones of the transplantation group than the model group. Compared with the sham group, the mean arterial blood pressure and left ventricular systolic pressure were ) were injected into five sites on the edge of infarcted myocardial tissues at 30 minutes after myocardial infarction. In the sham group and model group, the same volume of normal saline was injected into the myocardial tissues. Three days after cel transplantation, hemodynamic monitoring, echocardiography, TUNEL assay were employed to detect myocardial apoptosis. significantly reduced, the left ventricular end diastolic pressure was increased, and the left ventricular ejection fraction and shortened fraction were significantly lowered in the model and transplantation groups (P < 0.05), but there was no difference between the model and transplantation groups (P > 0.05). These findings indicate that myocardial apoptosis can be reduced but the cardiac function cannot be improved in acute myocardial infarction rats at early stage after bone marrow stromal stem cels transplantation.