Red cell incubation at 37°C reveals the impact of surface area loss and refrigerated storage on red cell viability

Red blood cells (RBCs) undergo a number of changes during their circulatory odyssey and as well during refrigerated storage. While age-related changes in membrane area and the stabilizing effects of cholesterol on the membrane have been described, the details of cholesterol transfer to plasma lipoproteins and the consequences of cholesterol depletion on erythrocyte properties have not been fully characterized. Likewise, while the 24 hour survival of stored RBCs has been assessed with 41Cr-sodium chromate labeling, this technique does not provide information about the reasons for accelerated post-transfusion RBC sequestration. A 37°C incubation system that simulates an in vivo environment was developed to study decreased erythrocyte resources during their circulatory lifespan and during refrigerated storage.; When RBCs were incubated with plasma at 37°C, we observed a decrease in membrane area with a net transfer of RBC membrane cholesterol to plasma HDL. When membrane area reached a critical value, phosphatidylserine appeared on the membrane outer leaflet. In a second study, RBCs were stored in a variety of storage solutions in the presence or absence of oxygen and with or without metabolic supplement. When these red cells were then incubated at 37°C, significant differences in the percentage of hemolysis were observed. These differences correlated well with 24 hour post-transfusion survival values. In vitro 37°C incubation of RBCs makes it possible to examine the role of membrane area reduction in RBC aging in a system similar to an in vivo environment. In addition, the system provides a convenient, rapid, inexpensive way to compare the efficacy of different blood storage solutions and to identify associated erythrocyte storage lesions.