Long-term effects of recombinant human erythropoietin on bone marrow progenitor cells

Eleven uraemic patients were treated with recombinant humanerythropoietin (rHuEpo). Seven haemodialysis patients and fourperitoneal dialysis patients received a starting dose of 80IU/kg i.v. and 40 IU/kg s.c. respectively, thrice weekly. Thenumber of burst-forming-unit erythroid (BFU-E), colony-forming-uniterythroid (CFU-E), granulocyte-monocyte (CFU-GM) and megakaryocyte(CFU-Mk) were assayed 2 weeks before (DO), and 1 (M1) and 6months (M6) after the initiation of rHuEpo treatment by meansof a commonly applied in-vitro clonal assay. All the patientsshowed the same haematopoietic response. A significant increaseof CFU-E and CFU-Mk could be observed within 1 month of treatment.At this time, no significant modification was observed in BFU-Eand CFU-GM number. At the 6th month the increase of CFU-E wasmaintained, whereas a significant fall of BFU-E, CFU-GM andCFU-Mk was observed. These results suggest that in-vivo effects of rHuEpo are notrestricted to the erythroid lineage but that erythropoietinmight also act as a co-factor of megakar-yopoiesis. In the longterm erythropoietin might induce erythroid differentiation inmultipotent progenitor cells at the expense of the non-erythroidprogenitors.