Abstract: Objective To study the effect of hepatocyte growth factor (HGF) secrete by mesenchymal stem cell in bone marrow hematopoietic microenvironmen on proliferation and drug sensitivity of leukemia cell line K562 and its drug-resistant variant K562/G01.Methods The MSCs were obtained through culturing in low serum medium.K562 cells and its drug resistant K562/G01 were used. The co-culture of MSCs with leukemia cells are prepared. Leukemia Cells Cultured with MSCs. According to existence of anti-HGF antibody or not, all groups were divided into control group and experiment group.The adhesion of leukemia cells on MSCs cell layer was observed under inverted fluorescence microscope and the adhesion rates were calculated．The pro1iferation of leukemia cells in the co-culture system was observed by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Cell cycle of leukemia cells in the co-culture system was investigated by flow cytometry.The survival rate of K562 cells and K562/G01 cells in the co-culture system was measured by flow cytometry after added imatinib incubation for 48 hours. Results After anti-HGF antibody was added and cultured for 24 hours, adhesion rates in experiment groups were significantly lower than those in control group(P<0.05).The pro1iferation of leukemia cells in experiment groups were all significantly lower than those in control groups in the co-culture system(P<0.05).The percentages of leukemia cells in G0/G1 phase in experiment group were higher than those in control group (P<0.05). 0n the contrary, the proportions of leukemia cells in S phase in experiment group were significantly lower than those in control group (P<0.05). Survival rate that of K562 cells and K562/G01 cells in the co-culture system after added imatinib incubation for 48 hours in experiment groups were respectively significantly lower than those in control groups (P<0.05). Conclusion The HGF promotes the cell survival and proliferation of K562 and K562/G01 cells by affecting cell adhesion and cell cycle, and reduces the killing effect of imatinib on leukemia cells.

Key words: leukemia, hepatocyte growth factor, mesenchymal stem cells, child