Enhancing effects of co-transduction of both human erythropoietin receptorand c-kit cDNAs into hematopoietic stem/progenitor cells from cord blood on proliferation and differentiation of erythroid progenitors

Steel factor (SLF) and erythropoietin (Epo) play critical roles in erythrop oiesis. To evaluate Interactive effects of Epo and SLF receptors (R) in ery thropoiesis, CD34(+) and CD34(+++) cord blood cells were transduced with hu man EpoR and c-kit cDNAs by retroviral mediated gene transfer. Erythroid (B FU-E) colonies derived from CD34(+) or CD34(+++) cells transduced with eith er the EpoR or c-kit gene were significantly increased in the presence of i nterleukin (IL)-3, granulocyte-macrophage colony-stimulating factor (GM-CSF ), Epo, and different concentrations of SLF compared with that from mock tr ansduced cells. This number was further enhanced by co-transduction of both genes. Enhancement was move apparent in the absence of SLF. Cell numbers i n individual erythroid colonies were also significantly increased in cells transduced with both genes compared with cells transduced with a single gen e. Short-term liquid culture showed that ex vivo expansion for five days an d numbers of CD34(+)CD71(+) cells in expanded cells from single CD34(+++) c ells co-transduced with both EpoR and c-kit genes were increased compared w ith those of EpoR or c-kit-transduced cells. These results demonstrate that co-transduction of both c-kit and EpoR enhances the proliferative capacity of erythroid progenitors under cytokine stimulation above that of single-g ene transduced cells.