Effects of recombinant erythropoietin on the concentration and cycling status of human marrow hematopoietic progenitor cells in vivo.

The concentration of human marrow progenitors CFU-E, BFU-E, CFU-GM, and CFU-Mk and the percentage of these progenitor cells in DNA synthesis were studied in nine patients with transfusion-dependent anemia of end-stage renal failure before and 2 weeks after treatment with human recombinant erythropoietin (Epo) at a dose of 150 to 300 U/kg intravenously three times per week. The concentration of CFU-E in the posttreatment marrow increased by a mean of 4.15-fold, BFU-E by 3.37-fold, CFU-GM by 1.86-fold, and CFU-Mk by 1.96-fold as compared with their respective concentrations in the pretreatment marrows. This increase in the concentrations of marrow progenitors was accompanied by almost a doubling of the percentage of these cells in DNA synthesis as assessed by the 3H-thymidine suicide technique. These observations demonstrate that at the progenitor cell level the human marrow responds to therapeutic doses of Epo as an organ rather than by a selective expansion of the erythroid cell line.