(P-BT-23) The impact of cryopreservation media on the function and immunology of platelets

Background/Case Studies: Cryopreserved platelets has gained interest due to the limited shelf-life of conventional room temperature platelets. The short shelf life of platelets poses additional challenges in pre-hospital and emergency situations, where time is critical. Cryopreservation of platelets can help overcome this logistical supply challenge and provide a readily available source of platelets for remote locations or in emergency scenarios.
Although the safety of cryopreserved platelets has been demonstrated, there is currently no consensus of the cryopreservation media and the impact on platelet hemostatic function and immunology.
The preliminary data from this study aims to identify the best cry preservative reagents for platelets and assess the expression of surface markers that potentially modulate immune function.

Study

Design/Methods: Whole blood units were obtained from healthy donors after signing the informed consent form. Platelet rich plasma (PRP) and platelet poor plasma (PPP) were separated by centrifugation after resting two hours at room temperature. PRP and PPP were incubated at 21°C overnight then cryopreserved at -80°C using 2 commercially available cryopreservation medias as well as autologous PPP supplemented with 6% DMSO. Platelet viability: aggregation and immune biomarkers including CD61, PAC1, CD47, CD107a, CD154 and CD284 were tested prior to cryopreservation and on days 7 and 13 post cryopreservation.

Results/Findings: The expression of CD61, PAC1 and CD47 showed significant decrease during the cryopreservation period, while CD154 increased significantly (Table 1). The other markers did not show any notable changes in their expression. In addition, Annexin staining at day 7 showed a loss of membrane asymmetry of 30.4%, 27.5% and 27.8% for CS5, CS10 and PPP + 6% DMSO cryopreservation media, respectively. At day 13, these values did not change significantly. Together, all cryopreservation media had a direct impact on platelet function compared to baseline values, with a 30 to 40% decrease in aggregation capacity.

Conclusions: The decrease in the expression of CD61, PAC1, and CD47, and the concomitant increase in CD154 expression in cryopreserved platelets suggest possible alterations in the immune function of these cells. Our study indicates that various cryopreservation media can lead to a loss of membrane integrity, as well as immune function. These results also suggest that the use of lower concentrations of DMSO in the cryopreservation media could be important for preserving the post-cryopreservation function of platelets. Further research is necessary to fully comprehend the effects of cryopreservation on shelf-life and the immunological function of platelets to optimize cryopreservation protocols for clinical application.

Importance of research: Short shelf-life of platelets poses a significant challenge in the field of transfusion. Thus, identifying the optimal cryopreservation conditions is crucial for increasing product's shelf-life and standardization of the process. Furthermore, understanding the immune function of platelets after cryopreservation is vital, as it can enhance transfusion outcomes leading to improved transfusion practices that utilize the immune function of platelets, ultimately improve patients outcomes.