Evaluation of the hemostatic capacity of methylene blue-treated liquid (not frozen) plasma stored up 14 days at 2° to 6°C

Background: Early plasma transfusion for management of bleeding, particularly trauma, is associated with better outcomes. Improving the availability/safety of plasma transfusion for patients is essential for transfusion services. The aim of this study is to evaluate the hemostatic capacity of methylene-blue (MB) liquid (not frozen) plasma over time. Materials and methods: Twenty whole blood-derived plasma units collected from male donors were separated and processed within 18 h of collection. Individual plasmas were treated with MB and stored in liquid status at 2-6 degrees C for 14 days. A range of coagulation assays, including thrombin generation, rotational thromboelastometry (ROTEM), and Thrombodynamics were tested at different time-points, together with bacterial growth. Results: Apart from Factor (F)XII, other coagulation factors (fibrinogen, FV, FVIII, FXI) reduced significantly after MB treatment, with levels remaining stable except for FVIII afterward. By day 14, most clotting factors were >0.7 IU/ml, apart from FVIII. There was a disproportionate decrease in Protein S (PS) activity compared to free PS antigen and by day 14 its value was similar to 50%. There was no significant difference in maximum clot formation (ROTEM) and clot-density (Thrombodynamics) over time. Endogenous thrombin potential (Thrombin-Generation), clot-size, and velocity index (Thrombodynamics) decreased significantly over time consistent with clotting factor reduction. There was no bacterial growth. Conclusions: MB-treated liquid plasma stored at 2-6 degrees C can be used for up to 14 days: the long shelf-life, the liquid status, and the MB treatment will improve its availability for management of bleeding as well as providing a safe component from pathogens.