Factors affecting the viability of erythrocytes stored in the frozen state

Abstract

The post-transfusion survival of human red cells stored in a glycerol-citrate-phosphate medium at -20 degrees C diminishes as the period of storage increases. After 6 months' storage the survival of the cells, 24 h after transfusion, is about 75%; after 2 years' storage it is about 45%. In suspensions of red cells stored at -20 degrees C metabolism is almost arrested, as judged by the very slow rate of disappearance of glucose. It has now been observed that the red cell content of adenosine triphosphate (ATP) diminishes progressively during storage at -20 degrees C. Although the loss of viability of red cells stored at -20 degrees C runs parallel to the fall in ATP, restoration of ATP, by incubation of the stored red cells with adenosine before transfusion, results in only a partial restoration of viability. When red cells are stored at -45 degrees C, and subsequently thawed, the final concentration of glycerol in the suspension must be increased to about 4.5 M if haemolysis is to be completely prevented. The trial of glycerol concentrations as high as 7.0 M led to the chance observation that exposure to such concentrations for relatively brief periods interferes with red cell metabolism and diminishes post-transfusion survival. Some of the metabolic effects can be reversed by incubation with adenosine and subsequent washing. Red cells stored at -45 degrees C in 4.5M-glycerol deteriorate only very slowly, so that after 1 year their content of organic phosphates and their post-transfusion survival are not significantly lower than that of cells stored for a few weeks at this temperature.