Background & Aim
Leukapheresis products are commonly used as source material for cell and gene therapy products. To avoid risks associated with shipping/storing fresh products and to optimize manufacturing logistics, this starting material may be cryopreserved soon after collection. Cryopreparation, the process of preparing cells for cryopreservation, typically involves several manual steps including concentration/plasma depletion, optional washing/plasma removal, and formulation with cryoprotectant. In this study, an automated system was compared to manual processing for cryoprep of leukapheresis material using either autologous plasma (AP) or synthetic solution (SYN), then frozen in either vials or bags.
Methods, Results & Conclusion
Peripheral blood mononuclear cells (n=4) were collected from healthy donors, shipped at 4°C to the processing facility, and processed within 24 hours. Products were split, then processed manually via centrifugation in a test tube (MAN) or with a fully-automated prototype small-volume processing system (AUTO, Fresenius Kabi). Cells were concentrated and washed to <2e8 TNC/mL with either AP or SYN solution (2-8CELLsius, Protide Pharmaceuticals). Suspensions were then diluted 1:1 with a fully-defined synthetic cryomedia (2-8CELLsius + 10% DMSO, Protide Pharmaceuticals) to achieve a final concentration of 5% DMSO and <1e8 TNC/mL. The formulated cells were aliquoted into bags (20mL fill, AUTO samples) or vials (1mL fill, all samples) and frozen at ∼-1°C/min in a controlled rate freezer. Once frozen <-110°C, cells were immediately thawed in a 37°C bath. Samples were evaluated for pre-freeze and post-thaw cell enumeration and viability (CD45+/7AAD−).
Hematology analyzer results showed no significant differences in TNC recovery between cryopreparation method used (101.2% [±8.5%] MAN vs 102.2% [±4.4%] AUTO), wash solution (101.2% [±5.6%] AP vs 102.4% [±6.4%] SYN), nor freezing format (104.2% [±3.3%] BAG vs 100.6% [±6.6%] VIAL). Similarly, post-thaw viability showed no significant difference between variables tested (84.4% [±7.1%] MAN vs 82.9% [±5.3%] AUTO vs 85.6% [±3.8%] AP vs 81.1% [±6.8%] SYN vs 80.2% [±5.3%] BAG vs 84.9% [±5.6%] VIAL).
Leukapheresis cryoprep using a fully-automated system and synthetic wash solution results in comparable post-thaw cell recovery and viability to manual processing with autologous plasma.
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© 2020 Published by Elsevier Inc.