ABSTRACT
<p><b>OBJECTIVE</b>To investigate the anatomical bases for electrical coupling of mesenchymal stem cells (MSCs)-derived myocardial cells with host cardiac myocytes.</p><p><b>METHODS</b>MSCs isolated from adult inbred Wistar rats were cultured and expanded in vitro and labeled with gree fluorescence protein (GFP). The model of acute myocardial infarction (AMI) was established in rats of the same species by occlusion of the left anterior descending arteries (LAD). One week after operation, 1.0x10(7) MSCs were injected into the infarcted area and 4 week after transplantation, the cardiac function of the recipient rats was evaluated. The heart tissues were taken after hemodynamic measurement for histological examination and morphometric measurement using image analysis system, and the expression of connexin-43 in the MSCs was detected by immunofluorescent cytochemistry.</p><p><b>RESULTS</b>Four weeks after transplantation, the transplanted MSCs in the infarcted area showed significantly higher expression rate of connexin-43, and the cell transplantation resulted in decreased infarct size and thickening of the left ventricle wall.</p><p><b>CONCLUSION</b>In a rat AMI model, MSCs differentiate into myocardial cells which can be integrated into host myocardial cells through formation of gap junction, resulting in effective improvement of the cardiac function.</p>