(P-BC-73) Safeguarding Rare Blood Resources: Validation of a Closed System Cell Processor to Deglycerolize Red Blood Cell Units Previously Frozen with a Manual Method

Background/Case Studies: Frozen RBC repositories of rare units up to 30 years old are critical resources, and availability of cell processors for glycerolization (glyc) and deglycerolization (deglyc) is essential for treating patients requiring compatible antigen-negative blood. Of the two FDA approved devices, however, the predicate, open system (Device 1) is being discontinued, and the alternate, closed system (Device 2) is not approved for units glyc with the Meryman 40% glycerol method. Since most rare RBC were cryopreserved with the Meryman method, thousands of these units are potentially unusable. This study evaluated Device 2 for the deglyc of RBC manually glyc with Meryman method and compared the QC results with retrospective data using Device 1.

Study

Design/Methods: Following successful validation of Device 2 for glyc and deglyc RBC, the closed system processor was used to deglyc a group of cryopreserved RBC that had been manually glyc using the Meryman method. These RBC, stored at -65C, ranged in age from 1.7 – 9.7 years. Thawed RBC were transferred from the original bag to a Device 2 compatible kit and deglyc followed manufacturer instructions. Deglyc products were evaluated for % recovery and hemolysis using free Hgb% estimate and visualization vs. a color comparator. An acceptable hemolysis level was grade ≤4 on the color comparison chart. QC parameters for Device 2 deglyc RBC were compared to retrospective data from units deglyc on Device 1 from 2022-2024.

Results/Findings: Fourteen frozen RBC units averaging 5.2 years (range 1.7 - 9.7) were deglyc on Device 2 (see Table). The deglyc units had an average % recovery of 80.9% (range 68-97%). All but one unit were confirmed to have an acceptable hemolysis (free Hgb% < 150 and/or color chart ≤ 4. Donor factors were ruled out, since another frozen unit from the same donor yielded acceptable results. A possible cause could be an inadequate amount of glycerol added during freezing. A retrospective cohort of 14 units deglyc on Device 1, averaging 1.4 years (range 13 days – 3.5 years) had an average % recovery of 79.7% (range 53-99%).

Conclusions: This study demonstrated that manually glycerolized (Meryman) and cryopreserved RBC up to 9 years old could successfully be deglycerolized using a closed system cell processor. Quality parameters of the resulting RBC were comparable to historical data for RBCs deglycerolized using the predicate open system processor. The results support using current technology to access frozen rare RBC repositories for patient transfusion.