HOW ERYTHROPOIETIN AFFECTS BONE-MARROW OF UREMIC PATIENTS

In a prospective study, 40 maintenance hemodialysis patients, randomiz ed in two equal groups, were treated with recombinant human erythropoi etin (rHuEPO) for their renal anemia, for a period of 2 years. One gro up was treated for 2 years, while the other was untreated control duri ng the first year, but received rHuEPO during the second year of the s tudy. Anemia was corrected in all treated patients and hematocrit main tained between 30 and 35 vol% by low-dose subcutaneous treatment with Recormon(R) (Boehringer Mannheim GmbH, Germany), according to the stud y protocol. Bone marrow biopsy (BMB), from the posterior iliac crest, was taken by the method of Jamshidi from 32 patients. Fourteen patient s from the control group were biopsied twice: once at baseline and the second time at 12 months of treatment, while 15 patients from the oth er group were biopsied only once, at 24 months of rHuEPO treatment. Th e biopsies were embedded in wax and in epoxy resin, and after staining for light and electron microscopy, they were semiquantitatively exami ned for several parameters: cellularity, myeloid:erythroid (M:E) ratio , megakaryocytes, fatty tissue, megaloblasts, and marrow iron. Cellula rity of the bone marrow increased significantly at 12 months of treatm ent and it remained so at 24 months. M:E ratio was significantly reduc ed indicating expansion of the erythroid pool, both at 12 and 24 month s of therapy. The number of megakaryocytes in the bone marrow increase d significantly at 12 months and remained high at 24 months of treatme nt, while fatty tissue was significantly reduced at 12 and 24 months c ompared to the baseline values. There was no significant change in the percentage of megaloblasts in the bone marrow. Hemosiderin was reduce d after treatment indicating mobilization of the bone marrow iron stor es upon treatment with rHuEPO, We concluded that rHuEPO had a benefici al long-term effect on bone marrow.