The effect of hemin in vitro and in vivo on human erythroid progenitor cells.

Hemin stimulates erythropoiesis and hemoglobin synthesis in vitro. We cultured erythroid progenitor cells from normal individuals, patients with sickle cell anemia, and a patient with acute variegate porphyria who received intravenous hemin treatment, with 0-800 microM hemin added in vitro. Fifty to 200 microM hemin consistently stimulated colony growth from normal donors 2- to 8-fold, while concentrations of up to 400 microM were stimulatory in cultures from donors with sickle cell anemia. In vivo hemin decreased the number of blood BFU-e in the patient with porphyria, but did not abrogate the in vitro stimulatory effect of hemin. Hemin concentrations which increased colony numbers increased gamma globin synthesis in some studies and decreased it in others. Hemin thus has clearcut erythroid growth-potentiating activity, although a consistent effect on globin chain regulation is not apparent.