Downscaling to small-volume storage bags supports platelet quality and efficient use of cold-stored platelets for preclinical studies.

BACKGROUND: To maximize the utilization of cold-stored platelets (CSPs) in preclinical research, the use of small-volume storage bags (mini-bags) or tubes would allow multiple treatment groups to be investigated from a single component. It is necessary to determine the effect of using downscaled storage formats on CSP quality and function. METHODS: Mini-bags were prepared by vacuum sealing platelet storage bags to ¼ the standard size. Apheresis platelets (n = 8) in 40% plasma/60% PAS-E (SSP+) were aseptically aliquoted into mini-bags (30 mL) or polypropylene tubes (15 mL; CSP-tubes), and the remaining volume (~190 mL) was retained in the original bag (control). Platelets were refrigerated (2-6°C), and in vitro quality parameters were assessed over 21 days. RESULTS: Metabolic capacity was altered for CSP-tubes, with a significant decline in pH, mitochondrial membrane depolarization, and rapid glycolysis. CSP-tubes had greater storage-related activation, as evidenced by a higher proportion of annexin-V-positive platelets and a greater number of CD61+/annexin-V+ extracellular vesicles (EVs). Similarly, platelet functional capacity in CSP-tubes was compromised, with reduced clot strength compared to controls. CSPs stored in mini-bags remained comparable to controls, with the exception of a greater proportion of annexin-V-positive platelets and EVs at day 21. Importantly, despite these changes, no functional deficits were observed in mini-bag components. CONCLUSIONS: Storage in tubes markedly impairs the metabolic, structural, and functional quality of CSPs, indicating that this approach is unsuitable. In comparison, mini-bag storage preserves key in vitro parameters, supporting a scalable strategy that maximizes the utilization of CSPs for preclinical evaluation.