Monitoring Cell Activation and Extracellular Vesicle Generation in Platelet Concentrates for Transfusion.

Platelets play a crucial role in blood transfusions, and understanding the changes that occur during their storage is important for maintaining the quality of preparations. In this study, we examined key alternating factors, with a particular focus on platelet activation and the release of extracellular vesicles. Additionally, we compared two detection methods-imaging flow cytometry (IFC) and nanoparticle tracking analysis (NTA)-for their effectiveness in detecting particles. Platelet concentrates were prepared by pooling buffy coats from five blood group-compatible donors in an additive solution. Samples were analysed after one, three, and seven days of storage for residual white blood cells (WBCs), glucose levels, platelet activation, and extracellular vesicle concentrations. Over the storage period, the total platelet concentration decreased slightly, while the residual WBC count remained stable. Glucose levels declined, whereas platelet activation and extracellular vesicle concentration increased, with a positive correlation between the two. The particle size remained relatively unchanged throughout the storage period. Ultimately, despite controlled processing and storage conditions, platelet activation, and the release of extracellular vesicles still occurred, which may have implications for transfusion recipients. Although an optimised method is still needed, IFC has proved to be specific and potentially appropriate for detecting extracellular vesicles in transfusion preparations.