Storage Temperature Affects Platelet Activation and Degranulation in Response to Stimuli

The refrigeration (cold storage) of platelet components provides several benefits over room-temperature (RT) storage, extending the shelf-life up to 21 days. However, the effect of storage conditions on platelet activation in response to stimulation remains unclear. A paired study was conducted where buffy-coat platelet concentrates were pooled, split, and allocated to RT or cold storage (n = 6 in each group). Platelet samples were taken on days 1, 7, 14, and 21, which were tested without stimulation or following activation with TRAP-6, A23187, lipopolysaccharides, or Histone-H4. Imaging flow cytometry was used to assess the surface characteristics of platelets and extracellular vesicles (EVs). The supernatant concentration of EGF, RANTES, PF4, CD62P, IL-27, CD40L, TNF-α, and OX40L was examined using ELISA. Cold-stored platelets generated a greater proportion of procoagulant platelets and EVs than RT-stored platelets in response to stimulation. The supernatant of cold-stored components contained lower concentrations of soluble factors under basal conditions, suggesting that platelet granules were better retained. Cold-stored platelets released higher concentrations of soluble factors following stimulation with TRAP-6, A23187, or Histone-H4. Only cold-stored platelets responded to lipopolysaccharides. These data demonstrate that cold-stored platelets retain the capacity to respond to stimuli after 21 days of storage, which may facilitate improved functional post-transfusion.