HEMIN ENHANCES THE INVITRO GROWTH OF PRIMITIVE ERYTHROID PROGENITOR CELLS

Abstract

Since exogenous hemin exerts a variety of stimulatory effects on erythroid cells, including the augmentation of Hb synthesis, its effects on early stages of erythroid development were determined by employing clonal cell assays. The addition of hemin at a concentration of 2 .times. 10-4 M to cultures of normal murine marrow substantially increased the observed number of primitive BFU-E [erythroid burst-forming unit], which was in contrast to its lack of an effect on more mature erythroid colony-forming cells. This cell-specific enhancement of primitive BFU-E resulted in marrow frequencies equivalent to or exceeding those reported in the presence of burst-promoting activity. In the presence of hemin, the number of BFU-E was linearly related to the number of cells plated at very low plating densities and the cell titration curve was observed to extrapolate to the origin. Hemin may be a primary growth regulator of early developmental stages of erythroid progenitor cells.