Abstract: Objective To investigate the alterations of connexin 43(Cx43) expression and its distribution at different stages of myocardial infarction (MI) in rats after transplantation of allogenic mesenchymal stem cells (MSCs). Methods Wistar rats have been ligated on the left anterior descending coronary artery to make MI models. They were injected with allogenic MSCs, which were induced by 5-aza and labelled by DAPI, under the second operation after 7 days of MI. In subgroups, MSCs were detected by fluorescence microscope. Cx43 expression and GJ distribution were examined by immunohistochemistry after 4, 8 or 12 weeks respectively. Results MSCs differentiated into cardiac muscle cell-like cells which were capable of pulsing spontaneously, expressing cTnT and forming myofilament in vitro. Transplanted MSCs can survive in MI host and upregulate Cx43 expression and normalize Cx43 distribution at ischemic zones after 4, 8 and 12w. No change of Cx43 was seen at infarcted zones. Conclusions MSCs have the plasticity of differentiating into cardiac muscle cell-like cells which can continuously upregulate Cx43 expression and normalize Cx43 distribution at ischemic zones after 4, 8 and 12w.

Key words: Mesenchymal stem cells, Myocardial infarction, Connexin 43