Abstract: Objective To investigate whether uninduced autologous bone-marrow mononuclear cell (ABM-MNC) could survive and differentiate into myocardial cells and endothelial cells in the infarcted heart. Methods 40 male big-ear Japanese rabbits were divided into two groups randomly: the transplanted group (n=20) and the control group (n=20). The model of acute myocardial infarction was made by left anterior descending artery ligation, which was confirmed by ECG. The cardiac function was evaluated by the echocardiography. 7 days later, BrdU labeled ABM-MNCs were injected into infarcted and marginal area myocardium in the transplanted group, while the control rabbits were injected with saline. 6 weeks later, the hearts were harvested for histology and immunohistochemistry evaluation. Results In the transplanted group, viable cells labeled with BrdU could be identified in the infarcted area, and myocytes and endothelial cells labeled with BrdU can also be found in the border area, these cells demonstrate myogenic differentiation with the expression of α-Actin by immunostaining. 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 the infarcted areas between two groups (P>0.05). At the 6 weeks after experiment, the cardiac function was improved in both groups, but the transplanted group improved more than that in the control group (P<0.05). Conclusion Autologous bone-marrow mononuclear cells injected into the infarcted myocardium could survive in both the infarcted and the border areas, differentiated into endothelial cells and other cells which have obtained the characters of myocytes, and increase the vessel density in border area, improved the cardiac function.

Key words: bone-marrow mononuclear cells, autologous, cell transplantation, myocardial infarction