Enhancement Of All-trans Retinoic Acid-induced HL-60 Leukemia Cell Differentiation By Human Umbilical Cord Mesenchymal Stem Cells

This study was aimed to investigate the enhancement of all-trans retinoic acid-induced HL-60 leukemia cell differentiation by umbilical cord mesenchymal stem cell. The HL-60 cells were divided into four groups:control group without ATRA treatment, hUCMSC group co-cultured with hUCMSCs, ATRA group with ATRA treatment as well as ATRA+hUCMSC group with ATRA treatment and co-cultivation with hUCMSCs. The proliferation of control group and hUCMSC group was compared by Cell Counting Kit-8 (CCK8). The morphology of HL-60 cells and NBT positive rate in four groups were observed and compared by microscopy, the c-myc expression of HL-60 cells in different groups was evaluated by real-time PCR, and the CDllb expression on HL-60 cells in different groups were detected by flow cytometry. The results showed that, in the co-culturing system, hUCMSCs can inhibit the proliferation of HL-60 (hUCMSC:HL-60 is 1:1,48h P<0.05,72h P<0.01; hUCMSC:HL-60 is 1:5, 72h P<0.05). With ATRA treatment, compared ATRA+hUCMSC group with ATRA group, there are more neutrophil like HL-60 cells and higher NBT positive rate (P<0.05) in ATRA+hUCMSC group. The c-myc expression of HL-60 cells in ATRA+hUCMSC group was lower than ATRA group (P<0.05). Furthermore, HL-60 cells in ATRA+hUCMSC group had stronger CD11b expression than ATRA group (48h P<0.05, 72h P<0.01). It is concluded that hUCMSC not only can inhibition the proliferation of HL-60 cells, but also can enhance the differentiation potential of ATRA on HL-60 cells.In addition, we also investigate the effects of hUCMSCs on the HL-60 differetiation induced by 1,25(OH)2D3. When treated by 1,25(OH)2D3, we use flow cytometry to test the expression of CD11b and CD 14 on the HL-60 cells. After co-culturing on the hUCMSC, there is an enhancement of CDllb on the HL-60 cells, but there is no significant change of the expression of CD 14. In some degree, hUCMSCs also can enhance the differentiation effects of 1,25(OH)2D3, while 1,25(OH)2D3 can induce HL-60 cells to neutrophil like cells rather than macrophage cells on hUCMSCs.