The impact of refrigerated storage of UVC pathogen inactivated platelet concentrates on in vitro platelet quality parameters

Background and Objectives Refrigeration (cold-storage) of pathogen inactivated (PI) platelet components may increase the shelf-life and safety profile of platelet components, compared to conventional room-temperature (RT) storage. Whilst there is substantial knowledge regarding the impact of these individual treatments on platelets, the combined effect has not been assessed. Materials and methods Using a pool-and-split study design, paired buffy-coat derived platelets in 70% platelet additive solution (SSP+; MacoPharma) were left untreated or PI-treated using the THERAFLEX UV-Platelets System (UVC; MacoPharma). Units from each pair were split and stored at room temperature (20-24 degrees C) or cold-stored (2-6 degrees C) to yield RT, cold, RT-UVC and cold-UVC study groups (n = 8 in each group). In vitro quality and function was tested over 9 days. Results Cold-storage of UVC-treated platelets reduced glycolytic metabolism (glucose consumption and lactate production) compared to RT-UVC units. Cold-UVC platelets demonstrated complete abrogation of HSR by day 5, increased externalisation of phosphatidylserine (annexin-V binding) and activation of the GPIIb/IIIa receptor (PAC-1 binding) above the levels observed with the individual treatments. Aggregation responses (ADP and collagen) were enhanced in the cold-UVC platelets compared to both RT groups, but this was primarily mediated by cold-storage. Haemostatic function, as measured using TEG, was similar between the groups. Conclusion Cold-storage of UVC-treated platelets reduced PI-induced acceleration of glycolytic metabolism. However, combining cold-storage and UVC-treatment resulted in additional phenotypic changes compared to each treatment individually. Further work is required to understand the impact of these changes in clinical efficacy.