Preservation of trehalose-loaded red blood cells by lyophilization

A method for freeze-drying red blood cells (RBCs) while maintaining high viability has important implications in blood transfusion and clinical medicine. RBCs loaded with the disaccharide trehalose can be freeze-dried in a formulation of hydroxyethyl starch, human serum albumin, and trehalose to residual water contents between 2% and 4%. Rehydration of the freeze-dried erythrocytes resulted in about 55% survival, based on the percent hemolysis. The surviving cells can synthesize ATP and 2,3-DPG, have preserved morphology, and have low levels of methemoglobin. Biochemical analyses showed that the activities of superoxide dismutase and catalase in freeze-dried RBCs are very similar to those of fresh RBCs. Secondary structure of hemoglobin was similar to that of fresh hemoglobin. Trehalose loading is required to achieve the stabilization of hemoglobin. These data provide an important step towards a stable erythrocyte product, which can prove invaluable for transfusion and clinical applications.