Automated processing of Meryman-frozen red blood cells: A novel protocol for deglycerolization.

Background: Many blood services maintain large inventories of red blood cell (RBC) units cryopreserved in glycerol using the Meryman method. With the discontinuation of the COBE® 2991 cell processor, an alternative thawing method is needed. We aimed to develop a deglycerolization protocol for Meryman-frozen units using the ACP® 215 cell washer.

Methods: In the optimization phase, Meryman-frozen RBC units stored for 10 years were thawed, paired, and divided into two groups: one with a centrifugation step to remove glycerol before deglycerolization ("volume reduction") and one without. Biochemical and hematological parameters assessed included hemolysis, hematocrit, hemoglobin, ATP, pH, and osmolality. The protocol was then validated.

Results: Hemolysis rates were lower with than without volume reduction (0.4% vs. 0.6%). Centrifuged RBCs also showed higher recovery (72% vs. 63%), increased hematocrit (0.51 L/L vs. 0.40 L/L), and improved pH stability (6.17 vs. 6.11). In the validation phase, six RBC units deglycerolized using the volume reduction step met Canadian Standards Association requirements for hematocrit, hemoglobin, hemolysis, and sterility.

Discussion: We optimized and validated a new protocol leveraging the ACP® 215 cell washer to deglycerolize Meryman-frozen RBCs. This method yielded low hemolysis, acceptable pH, and satisfactory recovery, especially with prior glycerol removal by centrifugation. The protocol has been successfully implemented, and Meryman-frozen RBC units have since been reliably thawed, meeting regulatory standards and supporting hospital needs.