ABSTRACT
[Objective]To investigate the effects of mesenchymal stem cells (MSC) feeder layer, culture sere and freeze-thaw lysates on expansion and differentiation of cord blood CD34~+ cells in vitro. [Methods] MSC were isolated from human bone marrow and cultured until the third passage. Sera were obtained from the cultured MSC, and freeze-thaw lysates were obtained by repeated freeze-thaw procedures. Cord blood CD34~+ cells were isolated by magnetic cell separation system, and were co-cultured with the MSC feeder layer, culture sera, freeze-thaw lysates and hematopeietic growth factors (HGFs), respectively. The nucleated cells, CD34~+ cells, CD34~+CD38~- cells, CD41~+ cells and CD3~+ cells in the above culture system were detected by flow cytometry on day 6 and day 12. [Results] ①MSC feeder layer had a strong effect on nucleated cells, CD34~+,CD34~+CD38~- cells expansion. The MSC sera and freeze-thaw lysates had similar effect on cell expansion, but the effect was weaker than that of feeder layer (P<0.05). ② Both MSC sera and feeder layer inhibited cord blood CD34~+ cells differentiation toward CD3~+ cells or CD19~+ cells, and no significant differences were found between these two groups (P>0.05). ③ Both MSC sera and feeder layer promoted cord blood CD34~+ cells differentiation toward CD41~+ cells, and the effect was stronger in the feeder layer than that of the sera (P<0.05). ④ Freeze-thaw lysates had no effect on cell expansion and differentiation, and were similar with that of HGFs (P>0.05). [Conclusions] The MSC sera have positive effects on expansion of cord blood CD34~+ and CD34~+CD38~- cells, moreover they have the ability of promoting cord blood CD34~+ cells differentiation toward CD41~+ cells.