Clot formation and resolution properties of platelets during cold storage for 21 days.

Abstract

Background: Cold storage (2-6°C) preserves the aggregatory and clot formation properties of platelets beyond the standard 7-day shelf life. Comparatively little is known about the effect of cold storage on clot resolution functions, which are necessary to ensure normal hemostatic balance is maintained.

Study design and methods: Double-dose apheresis platelets (n = 8) were collected using the Trima apheresis platform (40% plasma/60% PAS-E). Platelets were sampled on Day 1 post-collection and allocated to room temperature (RT; 20-24°C) or cold storage (2-6°C). In vitro testing was performed over a 21-day period.

Results: The coagulation profile of cold-stored platelets was better maintained throughout storage compared to RT platelets. Cold-stored platelets showed increased thrombin generation potential (faster lag time, higher peak, and increased ETP) compared to RT platelets throughout storage. By viscoelastic testing, the IN-test and EX-test clotting times (CT) were maintained over cold storage for 21 days, while the clot strength (MCF) decreased by approximately 15%. The lysis time (LT) was unchanged during cold storage. Macroscopically, less clot retraction and a higher percentage of internal lysis were observed in cold-stored platelets; however, susceptibility to external lysis was not affected.

Conclusion: Hemostasis requires a delicate balance between clot formation and resolution, and we have shown that the key functional properties of cold platelets stored in PAS-E are well-regulated during extended storage for 21 days.