Effects of thrombopoietin on the in vitro expansion of c-Kit~+Lin~-cells from bone marrow

Objective To elucidate the effect of thrombopoietin(TPO) in vitro expansion of c-Kit+Lin-cells from bone marrow.Methods c-Kit+Lin-cells were isolated by high-gradient magnetic cell sorting system(MACS) and then expanded with combinations of stem cell factor(SCF),FLt-3 ligand(FL),leukemia inhibitor factor(LIF)and different concentration of thrombopoietin(TPO) for 7days.Totall cells and Annexin-V positive cells were examined by fluorescence-activated cell sorter(FACS).Results Each group expanded c-Kit+Lin-cells effectively and rapidly,and the number of cells expanded were 4～7 times as compared with initiative one.Adding 50 μg/L TPO into SCF+FL+LIF increased expasions of c-Kit+Lin-and total cells by 7.07 and 40.19 times.When the concentration of TPO increased,the c-Kit+Lin-cells decreased,and the apoptosis rate rised.Conclusion The results showed TPO synergistic actions with SCF+FL+LIF to expand c-Kit+Lin-cells but too much TPO may induce its differentiation and apoptosis.The best concentration to expand c-Kit+Lin-cells is 50 μg/L TOP.