Optimal temporal delivery of bone marrow mesenchymal stem cells in rats with myocardial infarction.

Abstract

OBJECTIVE: This study was designed to determine the optimal time point for bone marrow mesenchymal stem cell (MSC) transplantation after myocardial infarction (MI). METHODS: MSCs from donor rats were labeled with DAPI before transplantation. The animals underwent MI by ligation of left anterior descending coronary artery, and received intramyocardial injection of MSCs at 1h, 1 week and 2 weeks after MI, respectively. Sham-operated and MI control groups received equal volume phosphate buffered saline. Cardiac function, histological analysis and immunoblot for troponin T were performed 4 weeks after cell transplantation. RESULTS: MSC transplantation attenuated left ventricular chamber dilation, reduced infarct size, and improved cardiac function in rats after MI. The greatest benefit was achieved in rats that received cells 1 week after MI, engrafted MSC survival, angiogenesis and functional cardiomyocytes in the injured hearts were more abundant in these rats than that in other transplantation groups. CONCLUSIONS: The optimal functional benefit of MSC transplantation was observed in 1-week transplantation group. At this time point scar formation has not occurred and the inflammation is reduced, which should facilitate integration of transplanted cells and functional recovery.