Modulation of human erythropoiesis by hydrocortisone in vitro

The effect of hydrocortisone on the formation of erythroid colonies was studied in vitro in cultures of normal human bone marrow in an agar system. A range of concentrations of hydrocortisone (10(-10) to 10(-3) mol/l) showed significant effects on erythroid burst formation, in terms of the number of colonies, on d 10 and 14 of culture. At subphysiological concentrations (10(-10) to 10(-8) mol/l), no effect was seen, but at both physiological (10(-7) mol/l) and pharmacological (10(-6) and 10(-5) mol/l) concentrations stimulation of erythroid burst formation was noted. At 10(-4) mol/l hydrocortisone inhibited erythroid colony formation and 10(-3) mol/l was uniformly lethal. In the concentration range of 10(-7) to 10(-5) mol/l hydrocortisone also appeared to increase erythroid colony size. Thus hydrocortisone (10(-7) to 10(-5) mol/l) stimulates erythroid colony growth and it is suggested that the hormone may play a role in the physiological regulation of human erythropoiesis.