Scheduled transplantation of human umbilical cord blood to severe combined immunodeficient mice

Objective: To explore a new method for developing the efficiency of human umbilical cord blood (UCB) cells engraftment, and further understand the growth characteristic of hematopoietic stem cells (HSC) in vivo. Methods: Sublethally irradiated severe combined immunodeficient (SCID) mice were transplanted i.v. with UCB cells which had been cryo-preserved at -80 degree C. The human cells in recipient mice were detected by flow cytometry and CFU-GM assay. Results: In contrast to the single transplantation, scheduled engraftment of similar numbers of UCB cells resulted in a proportionally obvious increase in the percentages of CD45+, CD34+ cells produced in SCID mouse bone marrow (BM). When the donor cells were reduced to 20 percent, an identical reconstitution of both hematopoietic and part of immunologic functions was achieved. Conclusion: Scheduled engraftment improves the repopulating ability of HSC, which would provide a novel way for clinical cord blood engraftment in adult objects