ObjectiveTo investigate the survival and differentiation of autologous bone-marrow mononuclear cell (ABM-MNCs) after transplanted to infarcted area and border area, and the effect of ABM-MNC on the cardiac function.Methods40 male big-ear Japanese rabbits were divided randomly into the transplanted group and control group with 20 animals in each group. Acute myocardial infarction model was made by ligating left anterior descending artery. 7 days later, Brdu labeled ABM-MNCs were injected into myocardium in the transplanted group, while the control rabbits were injected with saline. Six weeks later, tests of histology and immunohistochemistry were performed.ResultsViable cells labeled with Brdu can be identified in the infarcted area, and myocytes and endothelial cells labeled with Brdu can also be found in the border area, these cells demonstrated myogenic differentiation with the expression of α-actin by immunostaining. While, no cells labeled with Brdu were found in the control group. Moreover, the vessel density of the transplanted group in the borders of the infarction was higher than the control group (P<0.05), but there was no difference in infarcted area between two groups (P>0.05).At the 6 weeks after experiment, the cardiac function was improved in both groups, but there was a significant difference between two groups (P<0.05).ConclusionABM-MNCs injected into the infarcted myocardium can survive in both the infarcted and border areas, and differentiate into endothelial cells and other cells which are able to obtain the characters of myocytes, and increase the vessel density in border area, improve the cardiac function.