This study aimed to investigate the safety and feasibility of intracoronary injection of human umbilical cord-derived mesenchymal stem cells in very elderly patients with chronic total coronary occlusion into the coronary artery that provides collateral circulation to the heart. Patients were randomly assigned to the low-dose 3×106, medium-dose 4×106, and high-dose 5×106 groups. Single photon emission computed tomography (99m) Tc images were obtained at 12 and 24 months after infusion.

During the 24-month study period, no major cardiac adverse events were reported. None of the patients had coronary care unit admissions further coronary revascularizations acute myocardial infarction and death.

Patients had a significant reduction in infarct size and a significant increase in left ventricular ejection fraction compared with secondary outcomes. This study suggested that stem cell transplantation was safe and feasible. The cells could be used to improve the degree of ischemic myocardium, decrease the size of the infarct necrosis zone, and increase left ventricular ejection fraction