Erythroid cell growth and differentiation in vitro in the simulated microgravity environment of the NASA rotating wall vessel bioreactor

Prolonged exposure of humans and experimental animals to the altered gravit ational conditions of space flight has adverse effects on the lymphoid and erythroid hematopoietic systems. Although some information is available reg arding the cellular and molecular changes in lymphocytes exposed to microgr avity, little is known about the erythroid cellular changes that may underl ie the reduction in erythropoiesis and resultant anemia. We now report a re duction in erythroid growth and a profound inhibition of erythropoietin (Ep o)-induced differentiation in a ground-based simulated microgravity model s ystem. Rauscher murine erythroleukemia cells were grown either in tissue cu lture vessels at 1 x g or in the simulated microgravity environment of the NASA-designed rotating wall vessel (RWV) bioreactor. Logarithmic growth was observed under both conditions; however, the doubling time in simulated mi crogravity was only one-half of that seen at 1 x g. No difference in apopto sis was detected. Induction with Epo at the initiation of the culture resul ted in differentiation of approximately 25% of the cells at 1 x g, consiste nt with our previous observations. In contrast, induction with Epo at the i nitiation of simulated microgravity resulted in only one-half of this degre e of differentiation. Significantly, the growth of cells in simulated micro gravity for 24 h prior to Epo induction inhibited the differentiation almos t completely. The results suggest that the NASA RWV bioreactor may serve as a suitable ground-based microgravity simulator to model the cellular and m olecular changes in erythroid cells observed in true microgravity.