The effects of additive solution pH and metabolic rejuvenation on anaerobic storage of red cells.

Background: Red cell (RBC) storage can be extended to 9 weeks under anaerobic or alkaline conditions. Simultaneous use of these approaches has not provided additive benefit. Our objective was to determine whether anaerobic storage with acidified additive solution (AS) coupled with metabolic rejuvenation might further improve the benefits of anaerobic storage.

Study Design And Methods: RBC storage in AS with a pH value of 6.5, 7.4, or 8.3 in aerobic or anaerobic conditions was examined using a panel of in vitro biochemical and RBC markers. RBC rejuvenation during cold storage was also evaluated. A randomized crossover radiolabeled recovery study (eight subjects) evaluated anaerobic RBC storage using AS65 with cold rejuvenation for up to 16 weeks of storage.

Results: Adenosine triphosphate (ATP) and diphosphoglycerate acid (DPG) were better maintained in anaerobic storage than in aerobic storage. Acidic or neutral AS preserved ATP concentration better, while a neutral or basic pH AS favored maintenance of DPG levels at higher levels for a longer period. AS pH had less of an effect on exposure of phosphatidylserine (PS), vesicle protein release, and hemolysis. Rejuvenation of RBCs during cold, anaerobic storage resulted in increases in ATP and DPG levels and a reversal of PS exposure. Anaerobic storage of RBCs in pH 6.5 AS rejuvenated at 7 weeks of storage yielded RBC 24-hour recoveries of 77.3 +/- 12.5 percent after 10 weeks' storage time. After a second rejuvenation at Week 11, six subjects' units demonstrated a recovery of 75.9 +/- 7.3 percent at 12 weeks of storage.

Conclusion: Extended RBC storage may be achieved using anaerobic conditions combined with low-pH AS and rejuvenation during storage.