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

Eleven uraemic patients were treated with recombinant human erythropoietin (rHuEpo). Seven haemodialysis patients and four peritoneal dialysis patients received a starting dose of 80 IU/kg i.v. and 40 IU/kg s.c. respectively, thrice weekly. The number of burst-forming-unit erythroid (BFU-E), colony-forming-unit erythroid (CFU-E), granulocyte-monocyte (CFU-GM) and megakaryocyte (CFU-Mk) were assayed 2 weeks before (DO), and 1 (M1) and 6 months (M6) after the initiation of rHuEpo treatment by means of a commonly applied in-vitro clonal assay. All the patients showed the same haematopoietic response. A significant increase of CFU-E and CFU-Mk could be observed within 1 month of treatment. At this time, no significant modification was observed in BFU-E and CFU-GM number. At the 6th month the increase of CFU-E was maintained, whereas a significant fall of BFU-E, CFU-GM and CFU-Mk was observed. These results suggest that in-vivo effects of rHuEpo are not restricted to the erythroid lineage but that erythropoietin might also act as a co-factor of megakar-yopoiesis. In the long term erythropoietin might induce erythroid differentiation in multipotent progenitor cells at the expense of the non-erythroid progenitors.