No effect of stem cell mobilization with GM-CSF on infarct size and left ventricular function in experimental acute myocardial infarction

Objectives:. To evaluate the effect of bone marrowpluripotent stem cell mobilization with granulocyte-monocyte colony stimulating factor (GMCSF) on infarct size and left ventricular function, in the setting of acute myocardial infarction, with a protocol easily applicable in clinical practice. Methods:. Ten pigs underwent left thoracotomy and left anterior descending coronary artery occlusion for 1 h, followed by reperfusion. After 50 min of arterial occlusion, the animals were randomly divided between treatment with placebo (Group 1) and subcutaneous GM-CSF (Group 2). The thoracotomy was closed and the animals recovered. In Group 2, GM-CSF, 20 mug/kg, was administered daily, 5 days/week, for 3 weeks. Echocardiograms were obtained at 5 and 28 days after acute myocardial infarction. At 30 days, infarct size, expressed as a percentage of the whole left ventricular mass, was measured. Results:. The white blood cell count increased from 13000 +/- 3338/mul to 28700 +/- 4916/mul (p = 0.001) in the GM-CSF-treated group. Infarct size was 7.8 +/- 6.1% in Group 1 vs 7.5 +/- 7.7% in Group 2 (ns). Similarly, no significant difference was observed between the 2 study groups in any of the echocardiographic measurements made at 28 days. Conclusions:. Subcutaneous GMCSF administered during the early post acute myocardial infarction period neither decreased infarct size nor improved left ventricular function. Other protocols for mobilization of stem cells and their concentration in the injured area should be developed to combine efficacy and clinical applicability.