The purpose of this study is to investigate the safety and efficacy of intracoronary human umbilical Wharton's jelly-derived mesenchymal stem cell (WJ-MSC) transfer in patients with ST-segment elevation acute myocardial infarction.

It has been demonstrated that MSCs have the potential to differentiate into cardiomyocytes both in vitro and in vivo. Several clinical trials have been performed using autologous bone marrow-derived MSCs, but the results of these trials have been unsatisfactory because of a low number of MSCs in older patients and in those with coronary heart disease. WJ-MSCs from the human umbilical cord matrix which are of epiblastic origin and contain both human embryonic stem cell (hESC) and human mesenchymal stem cell markers appear to have a number of important advantages: they do not raise ethical issues, are widely multipotent, are not tumorigenic, and are not immunogenetic. Because of a short population doubling time they can be rapidly scaled up in large numbers. We performed a double-blind, placebo-controlled, multicenter trial, randomly assigning 160 patients with acute ST-segment elevation myocardial infarction to receive an intracoronary infusion of WJ-MSCs or placebo medium into the infarct artery 4-7 days after successful reperfusion therapy.

Inclusion Criteria:

1. Patients at least 18 years of age；
2. Patients with 1st acute ST-elevation myocardial infarction (AMI) who undergo successful primary percutaneous coronary intervention (PCI) thrombolysis in myocardial infarction (TIMI) flow grade 3, but have a substantial residual left ventricular regional wall-motion abnormality measured by 2-D echocardiography.
3. No contraindications to undergoing cell-therapy procedure within 1 weeks after AMI and PCI.
4. Hemodynamic stability-defined as no requirement for intra-aortic balloon pump or for inotropic or blood-pressure supporting medications.
5. Consent to protocol and agree to comply with all follow-up visits and studies.

Exclusion Criteria:

1. Presence of cardiogenic shock ( defined as systolic blood pressure < 80 mmHg requiring intravenous pressors or intra-aortic balloon counterpulsation);
2. Major bleeding requiring blood transfusion after acute reperfusion treatment;
3. A history of leucopenia;
4. Thrombocytopenia;
5. Hepatic or renal dysfunction;
6. Evidence for malignant diseases;
7. Unwillingness to participate;