Abstract: Objective To investigate the changes in plasma levels of vascular endothelial growth factor(VEGF) and stromal cell-derived factor-1(SDF-1) and in peripheral CD34+ cells in patients with acute myocardial infarction(AMI),and explore their role in AMI.Methods Enzyme-linked immunoassay(ELISA) was employed for measuring the levels of VEGF and SDF-1 in AMI patients on days 1,3,7,10,and 14 of onset and in normal control subjects.The absolute counts of CD34+ in the peripheral blood were measured on days 1,7,and 14 by flow cytometry in AMI patients,with their myocardial enzyme and troponin I detected and electrocardiography(ECG) and echocardiography(UCG) recorded.Results Peripheral CD34+ cells obviously increased on day 7 after AMI onset(2.35±0.72/μl vs 1.48±0.49/μl,P<0.05).VEGF levels were significantly higher in AMI patients than in the control subjects,reaching the peak level and on day 14(197.56±39.87 vs 53.79±18.12 pg/ml,P<0.01).SDF-1 level obviously decreased on day 1 after AMI onset(1683.12±224.79 vs 2178.67±265.34 pg/ml,P<0.01),followed by gradually increased to the control level.Obvious correlation was noted between the level of VEGF on day 7 and the peak level of peripheral CD34+ cells,and the peak plasma VEGF level was obviously associated with the peak serum CK-MB and troponin I levels.Conclusion The stem cells are mobilized into the peripheral blood in the event of AMI.Obviously increased VEGF level following AMI may persist for at least 2 weeks,whereas SDF-1 level undergoes temporary decrement after AMI.The dynamic changes of VEGF and SDF-1 can be related to the mobilization and homing of the stem cells to the injured myocardium.