Mechanism of hemoglobin-induced cellular injury in desiccated red blood cells

The current practice of red blood cell banking for transfusion medicine relies primarily on a 6-week liquid storage. A growing demand for red blood cell products has prompted the search for alternative preservation methods, including dry storage. We present a new mechanistic understanding of desiccation-induced cellular injury that is correlated with the oxidative state of the hemoglobin. We demonstrate that water loss induces a drastic increase in the rate of hemoglobin oxidation, formation of intracellular reactive oxygen species, and cellular death. Pharmacological treatment of the hemoglobin oxygen binding site reveals that hemoglobin-induced cellular injury is more prominent in red blood cells that are partially hydrated (about 5.5 to 3.5 g H2O/g dry wt) than in cells that are relatively dry (≤ 2 g H2O/g dry weight). Furthermore, partially hydrated red blood cells contain higher levels of oxidized lipids than more fully desiccated cells. We suggest that hemoglobin-induced oxidative injury is water dependent corresponding to earlier stages of water loss; conversely, biochemical reactions are hindered in the dry state and cellular injury is probably the result of physical and mechanical stress. These differences should be taken into consideration in the design of innovative approaches to red blood cell preservation.