Enhancement of erythroid colony growth in culture by hemin

Hemin was found to enhance the growth of murine erythroid colonies in culture. In the presence of 100 mU/ml erythropoietin (EPO), the addition of hemin (0.05-0.2 mM) resulted in the growth of twice as many colonies as were obtained with EPO alone. Hemin also significantly increased erythroid colony formation in culture in the absence of added EPO. Hemoglobin synthesis as measured by the incorporation of 59Fe into cyclohexanone extractable heme was augmented in culture by hemin. Neither delta-aminolevulinic acid, a hemin precursor, nor FeCl3 increased colony number.