The storage lesion of single donor platelets:: Insights from flow cytometric analysis and transmission electron microscopy

Background: During storage, platelets undergo morphological and immunological alterations. This study was performed to investigate the influence of storage on platelet antigens by flow cytometry and on morphology by electron microscopy. Materials and Methods: Platelet concentrates (n=24 were prepared by continuous-flow centrifugation plateletpheresis. Afterwards, they were stored in polyvinylchloride (PVC) containers for 7 days. Aliquots were taken daily to examine platelet glycoproteins CD41a, CD42b, CD62p, and CD63 by flow cytometry. Every second day, aliquots were drawn for electron microscopic analyses. Results: During storage, the expression of CD62p (P-selectin) and CD63 (gp53) progressively increased. Mean channel fluorescence intensity (MCFI) for CD62p increased from day 1 to day 7 from 21.3 to 43.4 (p < 0.05), MCFI of CD63 from 19.5 to 29.5 MCFI (p < 0.05). MCFI of CD41a decreased from 1,165.2 to 1,119.0 and subsequently returned to baseline levels (p < 0.05). MCFI of CD42b continuously decreased from 301.6 to 279.7 from day 0 to 7 (p < 0.05). Transmission electron microscopy (TEM) revealed progressive platelet activation and destruction. Over the storage period external and internal reorganization became clearly apparent. Conclusion: During storage of platelet concentrates, antigens and morphology of platelets are altered. Flow cytometry and TEM provide insights into the storage lesion and are suitable techniques for quality control of platelet concentrates and evaluation of biocompatibility. However, due to the more objective, faster and more sensitive analysis, only now cytometry may also be suitable for routine applications in quality control.