Studies of red blood cell biochemistry and erythropoiesis intensity in humans during a 520-day isolation study

Abstract

Erythrocyte metabolism and erythropoiesis intensity were studied in human subjects (six males, 25 to 37 years old) volunteered for experimental simulation of various factors in a mission to Mars, such as a very long duration (520 days) of isolation and confinement, autonomy, delayed communication with Earth, emergencies, and limited consumable resources. Venous blood and isolated erythrocytes were analyzed in the baseline data collection period (2 weeks before the experiment), on days 60, 120, 170, 240, 300, 360, 417 and 510 of the experiment and on days 7–8 after its completion. Erythrocyte metabolic and plasma membrane parameters were measured. Blood serum was analyzed for iron metabolism; erythropoiesis intensity was evaluated by the erythropoietin level. The results of the study showed phase-type shifts in the parameters throughout the experiment, which were particularly significant on days 60 and 120. Inhibition of energy production in erythrocytes and enhancement of reparative processes in the cell could be regarded as compensatory responses aimed at decreasing oxidative processes and increasing the antioxidative status of the cell. The phase-type changes in the lipid and phospholipid composition of membranes indicate an increased microviscosity of the plasma membrane at the beginning and end of the experiment. Hemoglobin content in blood and erythrocytes significantly increased on day 510 of isolation and during the recovery period. Data on iron metabolism and erythropoietin level are evidence of an adequate bone marrow response to the changed hemoglobin content in blood.