Abstract
BACKGROUND: Stored red blood cells (RBCs) progressively lose metabolic and structural features that are critical for efficient oxygen release, potentially reducing transfusion efficacy. Compared to the standard storage additive saline-adenine-glucose-mannitol (SAGM), successive refinements such as phosphate-adenine-glucose-guanosine-saline-mannitol (PAGGSM) and SOLX (AS-7) have demonstrated better preservation of metabolic and structural properties. Measuring RBC oxygen release permits further evaluation of such refinements within, and beyond, current storage durations. STUDY DESIGN AND METHODS: Leukoreduced whole blood (WB) units from six pools of three ABO/Rh-matched donors were processed into red cell concentrates and stored in SAGM, PAGGSM, or SOLX under standard blood bank conditions for 56 days. Periodic sampling during storage assessed hemolysis, adenosine 5'-triphosphate (ATP) content, and oxygen-unloading kinetics measured by single-cell oxygen saturation imaging or estimated by FlowScore recorded on a hematology analyzer. RESULTS: Hemolysis remained below the European regulatory threshold of 0.8% to day 49 in all units, with SOLX-stored units showing less variation and more consistent late-stage compliance. SOLX-stored units preserved ATP for longer than SAGM and PAGGSM. Oxygen unloading from SOLX- and PAGGSM-stored RBCs was faster than with SAGM; a similar effect was reported for FlowScore, indicating the utility of this surrogate to benchmark additive solutions. Overall, storage in SOLX halved the rate of attrition in oxygen release kinetics, with a statistically significant benefit emerging by week 3 of storage. CONCLUSION: Over 56 days, SOLX- and PAGGSM-stored RBCs demonstrated faster oxygen release kinetics than SAGM, as measured directly and by the flow-cytometric surrogate. Additionally, SOLX-stored RBCs maintained better ATP levels and hemolysis compliance.