Studies on Platelet Storage Biomarkers: Effect of Different Protein Extraction Buffers on Platelet Gelsolin and B-Actin Profiling

Platelet concentrates (PCs) are one of the blood cell components that play a major role in transfusion medicine. The shelf-life of PC is 5–7 days at 22°C. During storage PCs undergo certain morphological changes as well as physiological changes such as loosing of its surface glycoproteins, and reduced aggregation response to its agonists, which are collectively referred to as “storage lesions”. To date there is no in vitro “gold standard” that unequivocally serves as a surrogate marker to predict PC quality in vivo following transfusion. A comprehensive survey of reports in this field clearly indicate that there is some confusion with regards to the determination of which platelet protein or a panel of proteins could serve as potential markers associated with PC storage. Following a careful review of all available information, we recognized that perhaps one core issue to the observed discrepancies could be the buffer system that is being utilized by individual laboratories in extracting proteins in profiling protein alterations in PCs during storage. To address this, in the present study we analyzed two platelet proteins, b-actin and gelsolin-related 40 kDa protein. Profiles of these two proteins were previously reported by others to be altered during PC storage and hence implicated to be useful as biomarkers of platelet storage. By employing 3 different protein extraction buffer systems to isolate proteins from platelets at three storage intervals (Table 1), our results indicate that

• b-actin and gelsolin 40 kDa protein levels do not appear to change with time in platelet storage and therefore may not be useful as platelet storage markers and

• Buffer systems do make a difference in extracting different platelet proteins for analysis, for example 40 kDa gelsolin was not extractable in buffer 3 (Table 1), suggesting that one should be careful in selecting a buffer system for platelet proteomics to have meaningful results.

The findings and conclusions in this abstract have not been formally disseminated by the Food and Drug Administration and should not be construed to represent any Agency determination or policy.