Aggregate formation in cold-stored platelet products is associated with donor source, not with storage shelf style nor label orientation.

Background and objectives: Cold-stored platelets (CSPs) stored out to 14 days are approved in the United States for use in actively bleeding patients when conventional room temperature-stored platelets are unavailable. Cold storage promotes aggregate formation, yet how specific storage conditions impact aggregate formation remains poorly defined. As CSPs are stored in gas-permeable bags, we investigated how the shelving style (perforated, solid) or label orientation (up, down) affects CSP aggregate formation.

Materials and methods: Single-donor apheresis platelets (N = 17, Trima 100% plasma) were split equally into small-volume platelet storage bags to create four mini-units/donor. These were stored for 14 days (1-6°C) under the following conditions: (i) perforated shelving, label down; (ii) perforated shelving, label up; (iii) solid shelving, label down; and (iv) solid shelving, label up. Units were visually scored for aggregates and assayed for platelet count, mean platelet volume, immature platelet fraction and metabolic parameters. In a subset of units (N = 11 donors), we evaluated surface receptor expression, thrombin generation, aggregation and occlusion under physiologically relevant flow.

Results: Aggregate occurrence was similar across all four storage conditions, and varied more with respect to donor (coefficient of variation [CV] = 116%) than storage condition (CV = 14%). While units stored on solid shelves had statistically significant different metabolic parameters compared to units stored on perforated shelves, phenotypical and functional differences between shelving styles were unremarkable. There were no differences in intrinsic haemostatic function of units under all four conditions.

Conclusion: Aggregate formation in CSPs appears to be donor-dependent, and not impacted by shelf style or label placement.