S906 PRECLINICAL EVALUATION OF THE PRESERVATION OF RED BLOOD CELL CONCENTRATES IN HYPOXIA BY HYPOXIC STORAGE TECHNOLOGY FOR TRANSFUSION IN SICKLE CELL DISEASE.

Abstract

Background:Sickle cell disease (SCD) is the most common genetic disease, due to a mutation of the sixth amino acid of gene coding for the Hemoglobin (Hb) beta chain. The mutated Hb, called HbS, is able to polymerize which entails red blood cell (RBC) sickling, leading to chronic hemolysis and painful vaso‐occlusive crisis. Transfusion exchange is one of the therapeutic strategies used for this pathology since it allows the replacement of sickle RBCs. The quality of the transfused RBCs is essential, both to improve the transfusion yield but also to limit the pathological interactions between RBCs and endothelial cells, damaged by hemolysis. RBC concentrates can be stored up to 42 days at 4°c, however, during their hypothermic storage, the quality of RBCs decreases, mainly because of oxidative damage. Hypoxic storage technology helps to keep RBC in hypoxia, improving the concentration of ATP, 2‐3DPG, hemolysis and deformability of RBCs.Aims:The purpose of our study was to compare the quality of conventionally conserved RBCs with those conserved with hypoxic storage technology.Methods:We assessed several parameters including sickle RBC flow adhesion to HUVEC (human umbilical vein endothelial cells), previously exposed to hemolysate, to mimic endothelial damage present in patients. We also evaluated hypoxic RBC senescence parameters by flow cytometry. In that purpose, we measured intracellular calcium and reactive oxygen species (ROS) concentration as well as phosphatidylserine exposure by annexin V staining in hypoxic RBCs and control RBCs, after incubation 24 h in plasma from healthy donors and SCD patients. RBC adherence on thrombospondin (TSP) under flow was also quantified, since RBC adhesion to TSP was shown to increase during storage and since TSP concentration is elevated in sickle cell disease patients during acute chest syndrome (ACS) or at risk of ACS. In addition, we assessed hemolysis in the bags by measuring free hemoglobin concentration in the supernatant by spectroscopy.Results:We found a reduction in the concentration of free Hb (produced by RBC lysis) in hypoxic storage bag, a decrease in RBC senescence (ROS and calcium intracellular concentrations) in hypoxic RBCs and a reduced adherence to thrombospondin when hypoxic RBCs are incubated during 24 h in plasma from healthy donors or SCD patients. There was no difference of RBC adhesion to endothelial cells.Summary/Conclusion:These results suggest that hypoxic storage technology meets the safety criteria for transfusion in SCD patients and may provide significant clinical benefits.