Background-Phase 1 clinical trials of granulocyte-colony stimulating factor (G-CSF) treatment after myocardial infarction have indicated that G-CSF treatment is safe and may improve left ventricular function. This randomized, double-blind, placebo-controlled trial aimed to assess the efficacy of subcutaneous G-CSF injections on left ventricular function in patients with ST-elevation myocardial infarction. Methods and Results-Seventy-eight patients (62 men; average age, 56 years) with ST-elevation myocardial infarction were included after successful primary percutaneous coronary stent intervention Ͻ12 hours after symptom onset. Patients were randomized to double-blind treatment with G-CSF (10 g/kg of body weight) or placebo for 6 days. The primary end point was change in systolic wall thickening from baseline to 6 months determined by cardiac magnetic resonance imaging (MRI). An independent core laboratory analyzed all MRI examinations. Systolic wall thickening improved 17% in the infarct area in the G-CSF group and 17% in the placebo group (Pϭ1.0). Comparable results were found in infarct border and noninfarcted myocardium. Left ventricular ejection fraction improved similarly in the 2 groups measured by both MRI (8.5 versus 8.0; Pϭ0.9) and echocardiography (5.7 versus 3.7; Pϭ0.7). The risk of severe clinical adverse events was not increased by G-CSF.In addition, in-stent late lumen loss and target vessel revascularization rate in the follow-up period were similar in the 2 groups. Conclusions-Bone marrow stem cell mobilization with subcutaneous G-CSF is safe but did not lead to further improvement in ventricular function after acute myocardial infarction compared with the recovery observed in the placebo group.

Cumulatively, available evidence does not support a beneficial effect of G-CSF in patients with AMI after reperfusion.

Spontaneous sequential fluctuations in MSC and the increase in vascular growth factor concentrations after STEMI suggest that the optimal time for additional stem cell therapy is three weeks after a myocardial infarction to obtain the maximum effects by stimulating endogenous growth factors on the delivered stem cells.