Preparation of cold-stored platelets on-demand: A novel approach to inventory management.

Background: Cold-stored platelets (CSP) are now being used to treat acute bleeding. However, as CSP are less suitable for prophylaxis, both room temperature (RT) platelets and CSP will be required, which complicates inventory management. The production of CSP "on-demand" from RT platelets may be a desirable option. This study investigated whether CSP could be prepared rapidly by cooling RT platelets in a fridge or freezer.

Study design and methods: Double apheresis platelet components (40% plasma/60% PAS-E) were sampled on Day 1 (RT baseline), then split into matched pairs (n = 10). One component was allocated to cold (2-6°C) storage and sampled at 2 h and 14 days. The other component was placed in a freezer (-30°C) and sampled every 5 min for 20 min (on-demand), then transferred to the fridge and sampled at 14 days.

Results: Storage in the fridge for 2 h reduced the temperature to 4.1 ± 0.7°C and induced loss of swirl, shape change, enhanced aggregation, and reduced clotting time. Changes to surface glycoproteins (CD61, CD42b, GPVI) and activation markers (phosphatidylserine, P-selectin, release of alpha-granule proteins, and extracellular vesicles) were not observed after 2 h but became evident after 14 days. Storage in the freezer for at least 15 min induced the expected "cold storage lesion" changes.

Discussion: The morphological and functional characteristics of CSP can be induced within 15 min by exposure to a standard blood-bank freezer, or 2 h in the fridge. This approach to prepare CSP "on-demand" may represent a viable option for balancing patient-tailored transfusion and inventory management.