Abstract: Objective To study the integration of transplanted cells and host cells by detection of the cellcell junction after transplantation of the myocardiumlike cell derived from the canine umbilical cord blood. Methods The mesenchymal stem cell(MSCs) was transfected by Laz-Z after harvest, culture, induced by 5-azacytidine(5-aza). Thirty-six adult hybrid dogs were randomly divided into cell transplantation group and control group. The canine of myocardium infarction was established. 107 MSCs were transplanted into dogs with acute myocardium infarction by coronary artery infusion and local injection in cell transplantation group and physiologic saline was used in the control group. The specimens were harvested and detected by immunofluorescence for 2, 4 and 8 weeks respectively. Results The umbilical cord blood MSCs were fusiform or spindleshaped. They presented clonal and knittinglike growth.The MSCs could differentiate into myocardium-like cell by the induction of 5-aza and express α-actin, desmin, connexin43.The transplanted cells could survive more than 8 weeks after transplantation. Cadherin and connexin 43 were found in the position of cellcell junction of transplanted cells group and between transplanted cells and host cells. Cadherin and connexin 43 were found in the hose cells of the control group. Conclusion The umbilical cord blood MSCs is able to differentiate into myocardiumlike cell in vitro and form cellcell junction in vivo to communicate with surrounding cells.