| The experimental study of engraftment in BALB/C mice With hematopoietic cells of human umbilical cord blood after ex vitro expansionUmbilical cord blood(UCB) contains more abundant hematopoietic stem/progenitor cells(HSC/HPC) compared to bone marrow(BM)and peripheral blood(PB),such as CD34+CD38' cells and CD344Thy-l"Lin-cells, and becomes an important source of HSC/HPC. Another characteristic of UCB transplantation(UCBT) is the lower severity and accident of acute graft-versus-host (GVHD) than bone marrow transplantation(BMT) and peripheral blood stem cell transplantation(PBSCT). However, the relative small volumes and the limited number of progenitor cells of placental blood is presently a potential restriction for the widespread use of UCBT in adults. Expanded UCB hematopoietic cells were tried to transplant in vitro on adults. But the HSC are usually exhausted by differention in culture when the progenitor cells are induced to expand to the maximum. So we explore a probable way for UCBT to be used on adults.Rational cytokines combination is important in UCB HPC/HSC expansion in vivo. We based on the previous experimental results and then studied the expansion effects of the cytokines combination(SCF+FL+GM-CSF+IL-3+IL-6) on UCB Mononuclear cells in strome-free liquid culture system for 21 days. Immunologic markers , cell cycle and CFU-GM, BFU-E colonies were analyzed dynamically every week. We found that both CD34+ cells proportion and CFU-GM, BFU-E colonies reached the highest level at day7.In order to study the engraftment capability and hematopoieticpotential of the expanded cells, We established the BALB/C mice model of UCBT which were sensitive to the Y radiation. Three groups of UCB hematopoietic cells were transplanted to the lethally irradiated BALB/C mice by tail vein: fresh cellss a half part of fresh cells and a half part of cells expanded for a week, cells expanded for a week. Human CD45+ cells can be detected in the BM cells of the three groups of live mice by FACS after inocuration for 30 days, Which shows that all the three groups of cells can reconstitute hematopoiesis. And the later two groups of cells can more rapidly accelerate the recovery of early-period hematopoiesis. So We conclude the way transplanted with UCB hematopoietic cells ex vivo expanded for a week or transplanted with a half part of fresh UCB hematopoietic cells and a half part of UCB hematopoietic cells ex vivo expanded for a week is the probable way for adults' UCBT. |
