Cryopreservation of platelets could drastically simplify storage of platelets, especially for difficult locations such as combat zones, trauma centers, and medical facilities in rural and remote localities. Notably, cryopreserved platelets (CPPs) would also allow facilities to store rare platelet genotypes for at least two years instead of the standard of 5 to 7 days. Despite storage in 6% DMSO, freezing and thawing damage the platelets. Nevertheless, CPPs have been shown to be hemostatically effective and safe in the small trials that have been conducted to-date. In order to obtain more clinical data on the safety and efficacy of CPPs, Slichter and colleagues conducted a randomized, dose-escalation study of CPPs compared to standard platelets in 28 thrombocytopenic patients with WHO Grade 2 bleeding or higher. Four cohorts with 6 patients each were transfused with 0.5, 1, 2, and 3 units of CPPs with an additional patient in each cohort receiving standard platelets. No serious adverse events were reported, and 58% of patients transfused with CPPs had improved bleeding scores including 43% of patients with WHO Grade 4 bleeding. Importantly, no clinical evidence of thrombosis was observed in patients receiving CPPs. Cryopreservation of platelets could simplify platelet storage, but further research is needed.
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