Peripheral blood mononuclear cells (PBMCs), derived from whole blood or leukapheresis, encompass several major immune cell populations including lymphocytes, monocytes, NK cells and dendritic cells. Apheresis material is a PBMC-enriched blood product widely used in cell therapy, the maximum shelf life of which is 48h when supplied fresh. The collection, processing, and shipment of fresh apheresis material must therefore by rigorously controlled to ensure optimal cell quality and performance for the patient or downstream application. Timely shipment and delays encountered during global transfer between clinical and manufacturing sites adds to further decline in sample viability and quality. A solution to avoid this demanding process is cryopreservation, which permits the long-term storage of frozen PBMCs. Many companies now supply frozen leukopaks to gain this additional flexibility, however cold-chain supply is notably more expensive and impractical for transportation at the global scale. Equally, cryopreservation is a relatively violent process in which freezing and thawing methods can cause physical and chemical stress on cells, resulting in changes in the cell surface markers and function. Among PBMCs, monocytes are particularly sensitive to these freeze-thaw insults, and have been reported to show unfavourable alterations in yield, function, and gene expression following cryopreservation (1), (2) . Solutions such as cryopreservatives including DMSO can increase viability upon thawing, however, are toxic when exposure is prolonged. A modern solution is therefore required to enable the transport and temporary storage of high-quality, fresh monocytes with a longer shelf life.
Atelerix’s technology known as LeukoStor, provides a cryo-free storage and shipment solution for apheresis material at 2-8°C. Our evaluation of the monocyte population within LeukoStor-preserved apheresis material shows that encapsulation at 2-8°C maintains 80-85% monocyte viability after 5 days’ storage (Figure 1A) and offers a considerable improvement in monocyte yield compared to competitor solution and NGC (Figure 1B). This technology offers a novel solution to avoid the logistics and costs associated with cryopreservation, while maintaining high monocyte quality and yield. This has important implications for both clinical trials and research that relies on the use of fresh, non-cryopreserved monocytes and PBMCs.
Figure 1. LeukoStor preserves monocyte viability and yield after 5 days of storage at 5°C. Apheresis material was stored with or without LeukoStor before assessing quality by flow cytometry. A. Live monocytes corresponded 80-85% of total monocytes following 5 days’ storage in LeukoStor. Monocytes were defined as single, CD45+ CD11b+ CD14+ cells, and as live (unstained), apoptotic (AnV+) or dead (7AAD+). B. Total Monocyte yield (CD11b+ CD14+ cells as a % of Day 0 non-stored) at day 5 following storage was improved by LeukoStor compared to the no-gel control (NGC) which represented non-manipulated apheresis material, and HT-FRS. (n=5).
References
1. Anderson J. Effect of peripheral blood mononuclear cell cryopreservation on innate and adaptive immune responses. J Immunol Methods. 2019;465:61–6.
- Li B. Comprehensive evaluation of the effects of long-term cryopreservation on peripheral blood mononuclear cells using flow cytometry. BMC Immunol. 2022;23(30).
