ALBERT

Description: Background: Cryopreservation of platelets (PLTs) at -80°C with dimethyl sulfoxide (DMSO) can extend their shelf life up to 2 years. Cryopreserved PLTs (CRY-PLTs) are reported to have a greater in vivo hemostatic effect than liquid-stored PLTs. Aims of this study were: i. to evaluate the thrombin generation potential of buffy coat derived cryopreserved PLTs (CRY- BC PLT) in comparison with fresh buffy coat derived platelets concentrates; ii. to determine the efficacy and safety of CRY-PLTs transfusion in hematological patients with severe thrombocytopenia. Materials and methods: BC PLTs were obtained from 5 buffy coats and pooled. The final PLTs concentrates were leukoreduced by filtration and transferred to a 650 mL patented cryopreservation kit (Promedical ®) which allowed mixing with DMSO 25% in a closed system and following removal of supernatant without further manipulations. BC-PLTs were washed prior freezing, suspended in homologous plasma from 1 of the 5 donors to a final concentration of 200 mL and frozen at - 80°. CRY- BC PLTs were preserved at -80°C with 6% DMSO. A system of 3 accessory bags directly connected to the mother bag was adopted for the in vitro study, to avoid repeated freezing/thawing of samples. In vitro assays were performed before freezing and at 3,6 and 9 months after thawing. Before assay, CRY-BC PLT were thawed at 37°C and diluted in plasma to adjust to 300× 109/L PLTs. Fresh BC PLTs underwent the same dilution to adjust to 300 ×109/L PLTs. Thrombin generation (TGA) was tested in CRY BC-PLTs and compared to TG potential of fresh BC PLTs. TGA was triggered by the addition of 0.5 pmol/L of recombinant human tissue factor. Endogenous thrombin potential (ETP) and peak height (PH) were determined. Flow Cytometry assays for PLTs activation markers and thromboelastography were also determined on each sample. CRY-BC PLTs, separately prepared according to the above described method for in vivo study, were infused in five hematological patients with acute leukemia (AL) and severe thrombocytopenia (PLTs