Cryopreservation of apheresis platelets treated with riboflavin and UV light

Background: Pathogen reduction technology (PRT) is increasingly used in the preparation of platelets for therapeutic transfusion. As the Czech Republic considers PRT, we asked what effects PRT may have on the recovery and function of platelets after cryopreservation (CP), which we use in both military and civilian blood settings. Study design and methods: 16 Group O apheresis platelets units were treated with PRT (Mirasol, Terumo BCT, USA) before freezing; 15 similarly collected units were frozen without PRT as controls. All units were processed with 5-6% DMSO, frozen at - 80 degrees C, stored > 14 days, and reconstituted in thawed AB plasma. After reconstitution, all units were assessed for: platelet count, mean platelet volume (MPV), platelet recovery, thromboelastography, thrombin generation time, endogenous thrombin potential (ETP), glucose, lactate, pH, pO2, pCO2, HCO3, CD41, CD42b, CD62, Annexin V, CCL5, CD62P, and aggregates > 2 mm and selected units for Kunicki score. Results: PRT treated platelet units had lower platelet number (247 vs 278 x109/U), reduced thromboelastographic MA (38 vs 62 mm) and demonstrated aggregates compared to untreated platelets. Plasma coagulation functions were largely unchanged. Conclusions: Samples from PRT units showed reduced platelet number, reduced function greater than the reduced number would cause, and aggregates. While the platelet numbers are sufficient to meet the European standard, marked platelets activation with weak clot strength suggest reduced effectiveness.