OBJECTIVETo examine the effects of endothelial progenitor cell (EPC) on hematopoietic reconstitution in allogeneic hematopoietic stem cell transplantation (allo-HSCT) mouse model.

METHODSAllo-HSCT mouse model was established with condition of BU/CY, in which C57BL/6 (H-2b) and BALB/c (H-2d) mice were used as donors and recipients respectively. Recipients were randomly divided into 4 groups: untreated group, BU/CY condition group, bone marrow transplantation (BMT) group and transplantation of BM cells combined with EPCs (combined transplantation) group. The pathological changes of BM cells following transplantation were dynamically observed. Changes of BM sinusoidal endothelium and angiogenesis were observed by MECA-32 antibody immunohistochemical staining. The proportion of intramedullary stem and progenitor cells and serum cytokines were analyzed by flow cytometry. The numbers of peripheral blood cells were also counted.

RESULTS(1) Injuries of BM hematopoietic tissue, sinusoidal endothelium and vascular were less severe in combined transplantation group than of BMT group. (2) EPC infusion significantly increased BM hematopoietic stem cells 21 days after transplantation. The percentage of BM hematopoietic stem cells in combined transplantation group peaked on day +14, which was higher than of BMT group (0.1743 vs 0.0787) (P<0.05). The continuously increased percentage of BM hematopoietic progenitor cells in combined transplantation group was significantly higher than in BMT group on day +21 (0.4550 vs 0.3905) (P<0.05). (3) The number of peripheral white blood cells in combined transplantation group was always higher than of BMT group, which reached the peak on day +14 (0.74×10⁹/L to 0.47×10⁹/L) (P<0.05). The peak number of peripheral blood platelets on day +14 in combined transplantation group was significantly higher than of group BMT (1228.9×10⁹/L to 977.12×10⁹/L) (P<0.05).

CONCLUSIONAllo-HSCT combined with EPC infusion accelerated hematopoietic reconstitution compared with BMT alone in allo-HSCT mouse model.