In vitro measures of membrane changes reveal differences between red blood cells stored in saline‐adenine‐glucose‐mannitol and AS ‐1 additive solutions: a paired study

Background S aline‐adenine‐glucose‐mannitol ( SAGM ) and a variant solution, AS ‐1, have been used for more than 30 years to preserve red blood cells ( RBC s). Reputedly these RBC components have similar quality, although no paired study has been reported. To determine whether differences exist, a paired study of SAGM RBC s and AS ‐1 RBC s was conducted to identify membrane changes, including microparticle ( MP ) quantitation and in vitro RBC –endothelial cell ( EC ) interaction. Study Design and Methods Two whole blood packs were pooled and split and RBCs were prepared (n = 6 pairs). One pack was suspended in SAGM and one in AS ‐1. Samples were collected during 42 days of refrigerated storage. RBC shape and size and glycophorin A ( GPA ) + and phosphatidylserine ( PS ) + MP s were measured by flow cytometry. RBC adhesion to EC s was determined by an in vitro flow perfusion assay. Routine variables ( pH , hemolysis) were also measured. Results Compared to SAGM RBC s, AS ‐1 RBC s had lower hemolysis (p < 0.04), lower GPA + MP s (p < 0.03), and lower PS + MP s (p < 0.03) from D ay 14 onward. AS ‐1 RBC s had higher (p < 0.02) side scatter from D ay 28 onward compared to SAGM RBCs . SAGM RBCs were more adherent to ECs on D ay 28 of storage compared to AS ‐1 RBC s (p = 0.04), but reversed on D ay 42 (p = 0.02).Conclusion SAGM RBC s lose more membrane during storage. SAGM RBC s had increased adherence to EC s on D ay 28 of storage, while AS ‐1 RBC s were more adherent on D ay 42. The effect of these differences on the function and survival of SAGM RBC s and AS ‐1 RBC s after transfusion remains to be determined.