[Effects of stromal cell-derived factor 1 and platelet factor 4 on the adhesion characteristics and chemotactic function of ex vivo expanded umbilical cord blood CD34+ cells].

ABSTRACT

To investigate the effects of stromal cell-derived factor 1 (SDF-1) and platelet factor 4 (PF4) on the homing-related function of expanded ex vivo umbilical cord blood CD34(+) cells, purified cord blood CD34(+) cells were cultured in serum-free medium containing a HGF combination of FL + SCF + TPO (FST) with either 100 ng/ml SDF-1 alone, 100 ng/ml PF4 alone, or both of these 2 cytokines. The expansion rate of CD34(+) cells, colony formation, homing-related functions including expression of homing-related adhesion molecules of expanded CD34(+) cell, adhesion activity and chemotactic function of the re-selected expanded CD34(+) cells were evaluated at different time points. The results showed that expansion rate of CD34(+) cells and expansion multiple of CFU in SDF-1 groups were higher than those in control. The expression of CD49e on the expanded CD34(+) cells was remarkable up-regulated, in contrast, expression of CXCR-4 on the expanded CD34(+) cells was remarkable down-regulated in SDF-1 groups. The expression of CD49e, CD54 and CXCR-4 on the expanded CD34(+) cells were remarkably up-regulated in the PF4 groups. In all the SDF-1 group, PF4 group and SDF-1 plus PF4 group, the ability of expanded CD34(+) cells adhering to fibronectin layer were higher than those in the control on day 10. Spontaneous migration rate of expanded CD34(+) cells in SDF-1 groups were higher than those in control, while SDF-1-induced migration rate were lower than those in control on day 10. SDF-1-induced migration rate in PF4 groups were higher than those in control on day 10. Spontaneous and SDF-1-induced migration rate of expanded CD34(+) cells in the SDF-1 plus PF4 groups were higher than those in control on day 10. It is concluded that, SDF-1 and PF4 can up-regulate expression of adhesion molecules on expanded CD34(+) cells, and retain the adherent and migration ability of expanded CD34(+) cells, which is helpful for the homing of expanded CD34(+) cells. In short, SDF-1 and PF4 are helpful for the homing-related function of the expanded UCB HSPC.