(P-BC-21) Cryopreservation of Platelets: Characterisation of a New Technology to Preserve Platelets

Sunday, October 20, 2024

12:00 PM - 1:00 PM

Presenting Author(s)

Denese C. Marks, PhD

Research and Development, Australian Red Cross Lifeblood
Sydney, New South Wales, Australia

Background/Case Studies: Cryopreserved platelets have reduced platelet recovery and function following thawing and efforts to improve their quality are warranted. Vitrafy™ is a vertically integrated cryopreservation platform used to control heat transfer rates for the specific needs of a range of biological materials. The aims of this study were to compare platelets cryopreserved with the Vitrafy system to standard methods and to determine whether the Vitrafy platform is suitable for cryopreserving platelets in order to retain high post thaw recovery rates.

Study

Design/Methods:

Apheresis platelets (n=8) were prepared for cryopreservation with either 0% cryoprotective agent (CPA), or with 6% DMSO, and were either left neat or concentrated by centrifugation and removal of supernatant. Platelets were then frozen in a low volume in 2mL tubes using either a liquid nitrogen free controlled rate freezing system (Vitrafy) or by placing directly into a -80°C freezer (control). Vitrafy platelets were thawed using the Vitrafy controlled rate thawing system and control platelets were thawed in a standard laboratory water bath. Concentrated platelets were resuspended in freshly thawed plasma while neat platelets were not modified further. Platelets were then assessed by flow cytometry and thromboelastography (TEG). Statistical analysis was performed using a one-way ANOVA.

Results/Findings: The recovery of 0% CPA and 6% DMSO neat Vitrafy platelets was higher than matched controls, while no difference was observed in the 6% DMSO concentrated group. Surface expression of GPIIb (CD41a), GPIIIa (CD61), and GPIbα (CD42b) was high in all treatment groups. The proportion of platelets expressing GPVI was low in the 0% CPA group, but higher when DMSO was used. A lower proportion of 6% DMSO neat and concentrated Vitrafy platelets expressed CD62P, while a higher proportion externalised phosphatidylserine compared to matched control platelets. The release of microparticles and platelet function (TEG) were comparable between Vitrafy and matched control platelets. Generally, most differences in platelet quality parameters were observed between preparation methods, rather than between Vitrafy and matched control platelets.

Conclusions: Overall, these data confirm the capability of the Vitrafy controlled rate freezing system to cryopreserve platelets under operating conditions that can be replicated in full volume platelet units. The Vitrafy controlled rate freezing and thawing devices had similar effects on the in vitro quality parameters compared to control platelets. Further investigations and scale-up will determine if similar results or any enhancements are possible using the Vitrafy solution to cryopreserve platelets suitable for transfusion.