Impact of cold storage on platelets treated with Intercept pathogen inactivation

BACKGROUND: Pathogen inactivation and cold or cryopreservation of platelets (PLTs) both significantly affect PLT function. It is not known how PLTs function when both are combined. STUDY DESIGN AND METHODS: Standard PLT concentrates (PCs) were compared to pathogen-inactivated PCs treated with amotosalen photochemical treatment (AS-PCT) when stored at room (RT, 22 degrees C), cold (4 degrees C, n = 6), or cryopreservation (-80 degrees C, n = 8) temperatures. The impact of alternative storage methods on both arms was studied in flow cytometry, light transmittance aggregometry, and hemostasis in collagen-coated microfluidic flow chambers. RESULTS Platelet aggregation of cold-stored AS-PCT PLTs was 44% +/- 11% compared to 57% +/- 14% for cold-stored standard PLTs and 58% +/- 21% for RT-stored AS-PCT PLTs. Integrin activation of cold-stored AS-PCT PLTs was 53% +/- 9% compared to 77% +/- 6% for cold-stored standard PLTs and 69% +/- 13% for RT-stored AS-PCT PLTs. Coagulation of cold-stored AS-PCT PLTs started faster under flow (836 +/- 140 sec) compared to cold-stored standard PLTs (960 +/- 192 sec) and RT-stored AS-PCT PLTs (1134 +/- 220 sec). Fibrin formation rate under flow was also highest for cold-stored AS-PCT PLTs. This was in line with thrombin generation in static conditions because cold-stored AS-PCT PLTs generated 297 +/- 47 nmol/L thrombin compared to 159 +/- 33 nmol/L for cold-stored standard PLTs and 83 +/- 25 nmol/L for RT-stored AS-PCT PLTs. So despite decreased PLT activation and aggregation, cold storage of AS-PCT PLTs promoted coagulation. PLT aggregation of cryopreserved AS-PCT PLTs (23% +/- 10%) was not significantly different from cryopreserved standard PLTs (25% +/- 8%). CONCLUSION: This study shows that cold storage of AS-PCT PLTs further affects PLT activation and aggregation but promotes (pro)coagulation. Increased procoagulation was not observed after cryopreservation