In vitro erythropoietin assay based on erythroid colony formation in fetal mouse liver cell culture.

Critical studies were made on erythroid colony formation from cultured fetal mouse liver cells in an attempt to develop a simple and sensitive erythropoietin (Epo) assay procedure. The maximum colony formation was observed 24 h after plating of the cells when an evident dose-response relation was found for Epo added. The colony forming ability decreased steadily as the gestational age of the fetus advanced and was gradually lost by postnatal days 10-11. By morphological and cytochemical criteria almost all the colonies were found to be erythroid. 59Fe-labelling experiments revealed a fairly good correlation between the colony number and 59Fe incorporation into both cells and haem. Dose-response curves for plasma were parallel to the Epo standard curve. Based on these findings we developed a procedure which could measure as little as 0.4 mU of Epo without requiring 59Fe. Using this method, plasma Epo titres were determined in 16 normal and 69 anaemic subjects.