Methods and Results-We randomly allocated 20 patients with reperfused acute myocardial infarction (AMI) to receive intracoronary infusion of either bone marrow-derived (n=9) or circulating blood-derived progenitor cells (n=11) into the infarct artery 4.3+/-1.5 days after AMI. Transplantation of progenitor cells was associated with a significant increase in global left ventricular ejection fraction from 51.6+/-9.6% to 60.1+/-8.6% (P=0.003), improved regional wall motion in the infarct zone (-1.5+/-0.2 to -0.5+/-0.7 SD/chord; P<0.001), and profoundly reduced end-systolic left ventricular volumes (56.1+/-20 mL to 42.2+/-15.1 mL; P=0.01) at 4-month follow-up. In contrast, in a nonrandomized matched reference group, left ventricular ejection fraction only slightly increased from 51+/-10% to 53.5+/-7.9%, and end-systolic volumes remained unchanged. Echocardiography revealed a profound enhancement of regional contractile function (wall motion score index 1.4+/-0.2 at baseline versus 1.19+/-0.2 at follow-up; P<0.001). At 4 months, coronary blood flow reserve was significantly (P<0.001) increased in the infarct artery. Quantitative F-18-fluorodeoxyglucose-positron emission, tomography analysis revealed a significant (P<0.01) increase in myocardial viability in the infarct zone. There were no differences for any measured parameter between blood-derived or bone marrow-derived progenitor cells. No signs of an inflammatory response or malignant arrhythmias were observed.

Conclusions-In patients with AMI, intracoronary infusion of autologous progenitor cells appears to be feasible and safe and may beneficially affect postinfarction remodeling processes.