Abstract:Objective To investigate the pattern and affecting factors of hematopoietic stem cell mobilization after off-pump coronary artery bypass grafting（OPCAB）. Methods Fifty-five patients of coronary artery disease without acute myocardial infarction （AMI） who underwent selective OPCAB were chosen for this study. Four ml blood sample was taken at 30 min before operation, and 6, 12, 24, 48, 72 and 120 h after operation. The hematopoietic stem cell count was made by flow cytometer with CD34 and CD45 double antibody. The serum myoeardium enzyme and troponin T （cTnT） were measured at the same time. Results The hematopoietic stem cell count was 0. 13%±0. 12% of all nucleated cells in the peripheral blood circulation before operation. It increased significantly witha peak value at 24 halter OPCAB（0.34%±0.20%）. It turned back to pre-operativelevelat 120h after operation. Smoking, hyperlipemia and diabetes mellitus had no effect on hematopoietic stem cell mobilization. But hypertension could reduce its mobilization significantly. The hematopoietic stem cell count was positively correlated with creatine kinase （CK）, creatine kinase-MB isoenzyme （CK-MB）, lactate de hydrogenase （LDH） and cTnT （r=0. 692,P=0. 000; r=0. 558, P=0. 000; r=0. 447, P=0. 000 and r=0. 401, P=0. 004, respectively） 24h after OPCAB. Conclusion Hematopoietic stem cells mobilize rapidly and temporarily after OPCAB. Myocardial injury and CABG risk factors take part in hematopoietic stem cell mobilization.