Abstract 22 CellStor Transfer Freezing Bag: Reliable Closed System for Complex Cord Blood Sample Processing and CD34+ Hematopoietic Stem Cell Cryopreservation

INTRODUCTION: Hematopoietic stem cell (HSC) transplants are effective in the treatment of numerous disorders. Proper processing and storage of umbilical cord blood (UCB) and peripheral blood (PB) HSCs is invaluable for therapeutic applications. Although automated sample processing methods exist, they are unable to accommodate low volume, viscous, fibrin clotted, partially hemolyzed, or otherwise complex samples, resulting in the loss of precious HSCs. The CellBios single-use transfer freezing bag was designed to process peripheral and cord blood samples and freeze HSCs, including from those with the above-mentioned problems. Here we demonstrate the utility of these transfer freezing bags to salvage problematic UCB samples and recover precious HSC material suitable for banking and therapeutics. OBJECTIVE: The objective of this study was to develop a closed UCB sample processing and cryopreservation solution that is amenable to easy manual operation, can deliver excellent HSC viability and recovery, can eliminate contaminating red blood cells (RBCs), and is capable of processing complex/defective starting samples that are incompatible with conventional automated processing systems into therapeutic grade HSC banks. METHODS: We studied 100 randomly selected UCB samples, from various centers throughout India, that were processed and prepared for cryopreservation using our transfer freezing bag. We recorded the pre- and post-sample processing volumes, total nucleated cell counts (TNCC), hematocrit (HCT), CD34+ cell viability, and recovery. RESULTS: Study results showed the following: 94% vs 98% CD34+ cell viability post processing, 77% vs 85% total mononuclear cell viability, 69% vs 85% TNCC recovery in problematic vs normal samples, respectively. It was possible to achieve low RBC carryover –91% HCT reduction post-processing in normal samples; more importantly, problematic samples also had RBC removal evidenced by HCT reduction of 45%. DISCUSSION: We have demonstrated efficient removal of RBCs to alleviate post-transplantation issues and maximized CD34+ HSC recovery in both normal and problematic UCB samples. Crucially, it was possible to salvage precious CB HSCs from defective samples that would be lost had they been processed in conventional automated workflows. The CellBios CellStor Transfer Freezing Bag Set offers best in class performance in preparing umbilical cord blood samples for cryostorage.