New Technology for Red Blood Cell Preservation.

A method for freeze-drying red blood cells (RBCs) while maintaining a high degree of viability, has important implications in blood transfusion and clinical medicine. The disaccharide trehalose, found in animals capable of surviving dehydration can aid in this process. We are reporting a method for loading RBCs with trehalose followed by subsequent freeze-drying and rehydration. The loading of erythrocytes is based on the thermal properties of the RBC plasma membranes and provides efficient uptake of the sugar at 37°C in a time span of 7 hours. The data show that RBCs can be loaded with trehalose from the extracellular medium through a combination of osmotic imbalance and the phospholipid phase transition, producing an intracellular trehalose concentration of about 40 mM. Freeze-drying of trehalose loaded RBCs results in water contents in the range between 2 and 4 % and a level of survival of around 37 %, as measured by the extent of hemolysis. Surprisingly, freeze-dried and rehydrated RBCs showed high levels of ATP and 2,3-DPG and low methemoglobin. Biochemical analysis demonstrated that the activities of superoxide dismutase, catalase and acetylcholine esterase in freeze-dried RBCs are similar to those in fresh RBCs. These data provide an important step toward a stable erythrocyte product, which will be invaluable for transfusion and clinical applications. Supported by DARPA grant N66001-03-1-9827