Development of a simplified platelet cryopreservation method: An in vitro investigation of reducing the DMSO concentration to allow administration without its pre-transfusion removal.

Background and objectives: The most widely used method of platelet cryopreservation requires the addition of 5%-6% dimethylsulphoxide (DMSO), followed by its pre-freeze removal via centrifugation, to minimize toxicity. However, this adds complexity to the pre-freeze and post-thaw processing. Accordingly, the aim of this study was to simplify platelet cryopreservation by reducing the DMSO concentration and omitting the requirement for pre-transfusion removal.

Materials and methods: Apheresis platelets were cryopreserved at -80°C according to standard blood-banking methods using 5.5% DMSO, with centrifugation, pre-freeze removal of DMSO and reconstitution in plasma following thawing (standard). In parallel, doses of DMSO (0%, 1.5%, 3%, 5.5%) were tested without centrifugation and reconstitution (no-wash). In vitro platelet quality was assessed by flow cytometry, aggregation, viscoelastic testing (thromboelastography [TEG]) and clot retraction.

Results: Many in vitro platelet quality parameters showed DMSO dose dependency using the no-wash protocol (recovery, annexin-V, TEG maximum amplitude [MA]). Platelets frozen using the no-wash method with 3% DMSO showed a higher abundance of GPIbα (3% DMSO no-wash median fluorescence intensity [MFI]: 228 ± 16; standard MFI: 184 ± 16; p = 0.0016) and less degranulation (reduced P-selectin-positive platelets and concentration of supernatant P-selectin) than platelets frozen using the standard method. All functional properties measured were comparable to those of platelets frozen using the standard method.

Conclusion: This study shows that improvements in cryopreserved platelet quality parameters can be obtained by removing the centrifugation processes (standard vs. 5.5% DMSO no-wash). A reduction in DMSO to 3% supports quality parameters, and if shown to be clinically acceptable, this cryopreservation method could improve platelet accessibility, as it is simpler and cheaper than the standard method.