Stimulation of alpha and beta polypeptide chain synthesis in cultured human marrow by erythropoietin.

Abstract

Erythropoietin (ESF) acts on erythroid progenitor cells inducing their differentiation into definitive erythroblasts (1, 2). Associated with this ESF effect there is, in many species, an increase in the rate of heme synthesis (2–5). In addition, in lower mammals, both in vivo and in vitro, the hormone has been shown to increase the rate of globin synthesis (6). There is also evidence that ESF stimulates globin formation in cultured human marrow cells (7,8). Further studies on the mechanism of action of ESF have shown that in cultured rodent marrow cells the increase of hemoglobin synthesis by ESF is preceded by an increase in the formation of 9S RNA which may represent globin polypeptide messenger (9). Indirect support for these results has been the increase in production of alpha, beta and gamma globin polypeptide chains by ESF in cultured neonatal calf marrow cells (10). The present studies were undertaken to define further the mechanism of action of ESF on human marrow cells growing in primary culture. The data obtained indicate that associated with the increase in the rate of heme and globin synthesis (8) ESF causes a comparable increase in the rate of synthesis of both the alpha and beta polypeptide chains of globin in these cultured marrow cells. Materials and Method. Culture of bone marrow cells. Human bone marrow cells were obtained by sternal aspiration in patients undergoing this procedure as part of an evaluation for possible metastatic pulmonary carcinoma. Only morphologically normal aspirates were used. The aspirated marrow cells were immediately placed in cold NCTC 109 solution and cultured by the method of Krantz (4). In brief, bone marrow cells were washed twice with cold NCTC 109 solution and then suspended in an incubation medium consisting of 60% NCTC 109 solution, 40% heat-inactivated human plasma of AB type and 50 units/ml of penicillin so as to obtain a cell concentration of 2000 nucleated cells (approx 25% erythroid)/mm of medium.