The impact of whole blood processing and freezing conditions on the quality of therapeutic plasma prepared from whole blood

Background The quality of whole blood ( WB )‐derived plasma preparations has been the subject of several studies, but there has been a lack of robust, comparative data for the different methods of processing and freezing. Study Design and Methods Six WB ‐derived plasma units were pooled and split (n = 16) and frozen within either 8 or 24 hours after WB collection, stored at 4° C or at room temperature ( RT ), and then frozen either slowly at −20° C or rapidly to below −30° C . Plasma units were tested for fibrinogen, F actor ( F ) V , FVII , F VIII , FXI , and von Willebrand factor ( VWF ), protein C ( PC ), protein S ( PS ) activity and free PS , prothrombin time, and partial thromboplastin time. Results FVIII was reduced by 9% to 19% after having been stored for 24 hours irrespective of storage temperature. Slow freezing ( SF ) reduced FVIII by 17% to 25% compared to rapid freezing ( RF ) to below −30° C . Storage temperature, but not 24‐hour storage, decreased PS activity by 20% to 28%. PS activity was 8% to 17% lower in plasma units frozen slowly compared to RF . Storage and freezing had no influence on free PS . SF caused small losses of FVII and FXI activity. Conclusion Twenty‐four‐hour hold at RT and SF both reduce FVIII levels below 70  U / dL in many plasma units. PS activity is affected substantially by storage temperature and SF , but free PS is not. With regard to plasma quality, freezing to below −30° C within 1 hour is superior to SF at −20° C .