Cation influences on in vitro growth of erythroid stem cells (CFU-e and BFU-e).

Recent developments have focused on long-term bone marrow cultures and serum-free media to establish clonal hematopoiesis in vitro. Prior investigations have suggested an important role for such ingredients as transferrin, albumin, lipid, selenite, and potassium provided by serum. These factors, when present, can support clonal growth even in the absence of serum. Results reported here further define the importance of the cations K+ and Li+ in the regulation of in vitro erythropoiesis in the presence of both normal and dialyzed fetal calf serum and ouabain. While K+ proved essential for optimal erythroid colony formation, the presence of Li+ in such cultures reduced optimal colony formation of erythroid stem cells. This evidence suggests that in long-term marrow cultures or serum-free media K+ is essential for successful maintenance of self-renewal of erythroid stem cells and their differentiation, and that the monitoring of K+ levels may prove useful in such cultures. Since in vitro erythropoiesis was reduced in the presence of Li+, the mechanisms controlling differentiation of hematopoietic stem cell may be interpreted to be subject to cation influence.