Abstract: Objective To evaluate the changes of circulating hematopoietic progenitor cells (cHPCs) in patients undergoing
coronary artery bypass graft (CABG) surgery. Methods Fifty-one patients scheduled to undergo elective CABG surgery were
prospectively enrolled in this study. Blood samples were collected at baseline and at 1, 3, and 5 days after the surgery. CD34+
CD45dim，CD133 +CD45dim, and CD34 +CD133 + CD45dim cells were measured by flow cytometry. The functionality of the
circulating progenitor cells were studied in vitro using clonogenic and migration assays. Results All the elective patients
showed a significant postoperative increase of CD34 +CD45dim (1.51 ± 1.26 vs 2.02 ± 1.16, P=0.036) and CD133 +CD45dim cells
(1.16 ± 0.85 vs 1.65 ± 0.99, P=0.008) irrespective of on-pump or off-pump CABG. The perioperative changes of the cHPCs was
more significant in patients undergoing on-pump surgery than those having off-pump surgery. Conclusion In patients
undergoing elective cardiac surgery, cHPC level increased early after the surgery but recovers the normal level over time.