Natural and biosynthetic insulin stimulates the growth of human erythroid progenitors in vitro.

High concentrations of insulin are known to augment the growth of various cell types in vitro. We examined the effect of a purified porcine insulin and biosynthetic human insulin produced in E. coli on the growth of human erythroid progenitors in vitro. Both insulins stimulated peripheral blood erythroid colony formation within the physiological range. An approximately 2-fold augmentation in colony formation was seen at insulin concentrations of 8 ng/ml, and as little as 0.1 ng/ml (0.17 nM) caused detectable stimulation of colony formation. The effect of subnanomolar concentrations of insulin or erythropoiesis in vitro suggests that insulin could modulate erythropoiesis in vitro. Human responsiveness to insulin's growth-promoting activity can be directly assayed in vitro using peripheral blood.