S1P has a negative effect on RBC storage quality

Blood storage promotes the rapid depletion of red blood cell (RBC) high-energy adenosine triphosphate and 2,3-diphosphoglycerate, which are critical regulators of erythrocyte physiology and function, as well as oxygen kinetics and post transfusion survival. Sphingosine 1-phosphate (S1P) promotes fluxes through glycolysis. We hypothesized that S1P supplementation to stored RBC units would improve energy metabolism and post-transfusion recovery. We quantified S1P in 1,929 samples (n=643, storage day 10, 23, 42) from the REDS RBC Omics study. We then supplemented S1P (1, 5, 10 uM) to human and murine RBCs from good storer (C57BL6/J) and poor storer strains (FVB), prior to measurements of metabolism and post transfusion recovery. Similar experiments were repeated for mice with genetic ablation of the S1P biosynthetic pathway (Sphk1 KO). Samples were tested for metabolomics at steady state, tracing experiments with 1,2,3-13C3-glucose, proteomics and end of storage post transfusion recovery, under normoxic and hypoxic storage conditions. Storage promoted decreases in S1P levels, which were the highest in units donated by female or older donors. Supplementation of S1P to human and murine RBCs boosted the steady state levels of glycolytic metabolites and glycolytic fluxes, generation of ATP and DPG, at the expense of the pentose phosphate pathway. Lower post-transfusion recovery was observed upon S1P supplementation. All these phenomena were reversed in Sphk1 KO mice or with hypoxic storage. S1P is a positive regulator of energy metabolism and a negative regulator of antioxidant metabolism in stored RBCs, resulting in lower post transfusion recoveries in murine models.