BACKGROUND: Clinical trials indicate a beneficial effect of intracoronary infusion of progenitor cells on myocardial function in patients with ischemic heart disease. The extent and potential determinants of proangiogenic progenitor cell homing into the damaged myocardium after intracoronary infusion and the underlying mechanisms are still unknown. METHOD AND RESULTS: Circulating proangiogenic progenitor cells isolated from peripheral blood and cultivated for 3 days were labeled with radioactive indium oxine ((111)In-oxine). Radiolabeled proangiogenic progenitor cells (7.6+/-3.0 MBq, mean+/-SD) were administered to patients with previous myocardial infarction and a revascularized infarct vessel at various stages after infarction (5 days to 17 years). Viability of the infarcted myocardium was determined by (18)F-fluorodeoxyglucose-positron emission tomography and microcirculatory function by intracoronary Doppler measurements. One hour after application of progenitor cells, a mean of 6.9+/-4.7% (range, 1% to 19%; n=17) of total radioactivity was detected in the heart, which declined to 2+/-1% after 3 to 4 days. Average activity within the first 24 hours was highest among patients with acute myocardial infarction (14 days to 1 year; 4.5+/-3.2%; n=4) or a chronic stage (infarct age >1 year; 2.5+/-1.6%; n=5). Low viability of the infarcted myocardium and reduced coronary flow reserve were significant (P
BACKGROUND: Clinical trials indicate a beneficial effect of intracoronary infusion of progenitor cells on myocardial function in patients with ischemic heart disease. The extent and potential determinants of proangiogenic progenitor cell homing into the damaged myocardium after intracoronary infusion and the underlying mechanisms are still unknown. METHOD AND RESULTS: Circulating proangiogenic progenitor cells isolated from peripheral blood and cultivated for 3 days were labeled with radioactive indium oxine ((111)In-oxine). Radiolabeled proangiogenic progenitor cells (7.6+/-3.0 MBq, mean+/-SD) were administered to patients with previous myocardial infarction and a revascularized infarct vessel at various stages after infarction (5 days to 17 years). Viability of the infarcted myocardium was determined by (18)F-fluorodeoxyglucose-positron emission tomography and microcirculatory function by intracoronary Doppler measurements. One hour after application of progenitor cells, a mean of 6.9+/-4.7% (range, 1% to 19%; n=17) of total radioactivity was detected in the heart, which declined to 2+/-1% after 3 to 4 days. Average activity within the first 24 hours was highest among patients with acute myocardial infarction (14 days to 1 year; 4.5+/-3.2%; n=4) or a chronic stage (infarct age >1 year; 2.5+/-1.6%; n=5). Low viability of the infarcted myocardium and reduced coronary flow reserve were significant (P