[Hematopoietic repopulating ability of human CD34+ cells and CD34- cells in NOD/SCID mice]

The hematopoietic repopulating ability of fresh and cultured CD34+ cells and CD34- cells derived from cord blood were compared by nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mouse model. Fresh CD34+ cells and CD34- cells were isolated from fresh cord blood. Cultured CD34+ cells and CD34- cells were separated from cultured mononuclear cells (MNC). We transplanted these cells into sublethally irradiated NOD/SCID mice via the tail vein and sacrificed surviving mice after 6 weeks. The peripheral blood, spleen and bone marrow from each mouse were harvested for flow cytometry, colony-forming cells and human Alu sequences analyses. The proportions of CD45+ cells and human multilineage hematopoietic cells in NOD/SCID mice received CD34+ cells were close to that in the mice received both CD34+ cells and CD34- cells, while it was significantly higher than that in the mice received CD34- cells. Six weeks after transplantation, all the mice injected with cultured CD34- cells dead. The survival rate of mice injected with cultured CD34+ cells was 66.7%. All of the mice injected with both cultured CD34- and CD34+ cells survived. Moreover, CD45+ cells could be detected in all surviving mice, and human CD34, CD3, CD19, CD33 and CD71 antigen also could be detected on these CD45+ cells. The results showed that both fresh and cultured CD34+ cells had the capability of engraftment and hematopoiesis reconstitution, but CD34- cells hadn't the ability. However, CD34- cells had assistant effect on the hematopoietic repopulating ability of CD34+ cells.