Experimental study on ex vivo expanded hematopoietic stem/progenitor in the two step culture from human umbilical cord blood transplanted into NOD/SCID mice

The effects of hematopoietic stem/progenitor cells(HSPCs)expanded in the two step coculture with human bone marrow mesenchymal stem cells(hMSCs)on the hematopoietic reconstruction of irradiated NOD/SCID mice were studied.Mononuclear cells(MNCs)were isolated from human umbilical cord blood(UCB)and cultured in the non-coculture scheme of rhSCF+rhG-CSF +rhMDGF combination and the coculture scheme of rhSCF+rhG-CSF+rhMDGF+hMSCS.Sublethally-irradiated NOD/SCID mice were transplanted with ex vivo expanded HSPCS with the dose of 8.5×106 cells per mouse.After transplantation.the dynamics of WBC in the transplanted mice was measured periodically,and the Alu sequence fragment special for human in the transplanted mice was inspected by PCR.Results showed that the coculture scheme increased proliferation of UCB-derived HSPCs.After transplantation with expanded HSPCS,the population of WBC in the transplanted mice increased in 12 d and reached the first peak in 25 d,then showed the second increasing of WBC in 45～55 d.Expanded cells from the coculture scheme appeared to be favorable for the second increasing of WBC in the transplanted mice.After 85 d,the Alu sequence fragment was detected in the probability of 87.5%(7/8)for the non-coculture scheme and 88.9%(8/9)for the coculture scheme.