Objective - To assess platelet count, mean platelet volume (MPV), metabolic characteristics, and platelet function in a dimethyl sulfoxide (DMSO)-stabilized canine frozen platelet concentrate (PC). Sample Population - 11 units of a commercial frozen PC in 6% DMSO and fresh platelet-rich plasma from 6 healthy control dogs. Procedures - PCs were thawed, and the following data were collected: thaw time, platelet count, MPV, pH, Pco2, and Po2 and HCO3-, glucose, and lactate content. Phosphatidylserine translocation was determined by use of flow cytometry. Fresh platelet-rich plasma from healthy dogs served as a source of control platelets for flow cytometric analysis. Results - At thaw, the platelet count in the frozen PC ranged from 243,000 to 742,000 platelets/μL. Median platelet count of paired samples was 680,000 platelets/μL and decreased significantly to 509,000 platelets/μL at 2 hours after thaw. Median MPV at thaw was 11.15 femtoliters and was stable after 2 hours. Compared with fresh platelets, frozen PC had increased amounts of phosphatidylserine in the outer leaflet of the platelet membrane in the resting (ie, not treated with thrombin) state (19% vs 99%, respectively) and alterations in cellular morphology, all of which were consistent with platelet activation. Conclusions and Clinical Relevance - Results of this in vitro study indicated that there was a decrease in platelet quantity and function as well as an increase in platelet activation during the freeze-and- thaw process in DMSO-stabilized canine frozen PC. In vivo effects on PC remain to be determined.
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