Abstract: Objective: This study was designed to investigate the retainage rate, distribution, and emigration of the bone marrow mesenchymal stem cell (BMMSC) after transcoronary infusion and further evaluate the feasibility of BMMSCs injected into coronary artery. Method: BMMSCs were isolated, purified, expanded, and labelled with CM-DiI. In vitro study, the infarcted SD rat hearts were removed and perfused with Langendorff apparatus. The cells were injected into the aortic root and the fluid returning from the coronary system was collected and the labelled cells in the coronary effluent were quantitated with flowcytometry. At the same time left ventricle function was recorded to evaluate the safety of this approach. In vivo study, the cells were then injected into the briefly distally clamped ascending aorta through a catheter inserted through the left ventricle into the aortic root. The hearts were harvested at different time points after cell transplantation to obtain the direct evidence of distribution and emigration of the implanted cells. Results：In vitro study, we found that only 3-5% of transplanted cells returned into the right ventricle and more than 90% cells retained in the heart after injecting into the aortic root of Langendorff model of infarcted hearts of SD rats. Left ventricle function did not deteriorate after cell transplantation. In vivo study, the labelled cells were entrapped within the coronary capillary immediately after cell infusion, mainly in the normal area. After 24 hours some cells migrated through the capillary wall into interstitium of the heart. After 1 week later we could found that most survival cells located at the infarcted area and the border zone. Conclusion: The majority of BMMSCs delivered by transcoronary infusion retained in the heart. BMMSCs could cross the vessel wall and home to the interstitial compartment and the injured area in a few hours.

Key words: myocardial infarction, cell transplantation, bone marrow mesenchymal stem cell (BMMSC)