Comparison of Cardiac Stem Cells and Mesenchymal Stem Cells Transplantation on the Cardiac Electrophysiology in Rats with Myocardial Infarction

Whether transplanted cardiac stem cells (CSCs) and mesenchymal stem cells (MSCs) improved ventricular fibrillation threshold (VFT) similarly is still unclear. We sought to compare the effects of the CSC and MSC transplantation on the electrophysiological characteristics and VFT in rats with myocardial infarction (MI). MI was induced in 30 male Sprague-Dawley rats. Two weeks later, animals were randomized to receive 5 x 10(6) CSCs labeled with PKH26 in PBS or 5 x 10(6) MSCs labeled with PKH26 in phosphate buffer solution(PBS) or PBS alone injection into the infarcted anterior ventricular free wall. Six weeks after the injection, electrophysiological characteristics and VFT were measured. Labeled CSCs and MSCs were observed in 5 mu m cryostat sections from each heart. Malignant ventricular arrhythmias were significantly (P = 0.0055) less inducible in the CSC group than the MSC group. The VFTs were improved in the CSC group compared with the MSC group. Labeled CSCs and MSCs were identified in the infarct zone and infarct marginal zone. Labeled CSCs expressed Connexin-43, von Willebrand factor, alpha-smooth muscle actin and alpha-sarcomeric actin,while the Labeled MSCs expressed von Willebrand factor, alpha-smooth muscle actin and alpha-sarcomeric actin in vivo. After 6 weeks of cell transplantation, CSCs are superior to MSCs in modulating the electrophysiological abnormality and improving the VFT in rats with MI. CSCs and MSCs express markers that suggest muscle, endothelium and vascular smooth muscle phenotypes in vivo, but MSCs rarely express Connexin-43.