Effect of cold-storage in the accumulation of bioreactive substances in platelet concentrates treated with second messenger effects.

BACKGROUND AND OBJECTIVES The mandatory 5-day of shelf-life platelet concentrates (PCs) creates outdating and inventory control problems in blood banking. Moreover, storage of PCs at 22-24 degrees C has been associated with a time-dependent accumulation of pyrogenic cytokines, potentially harmful for recipients. Previous studies have shown that supplementation of PCs with ThromboSol, a mixture of second-messengers effectors, might allow storage of functionally active platelets at refrigerated temperature to be extended. This study further investigates this storage approach by comparing the accumulation of bioactive compounds in standard and refrigerated PCs. DESIGN AND METHODS The PCs were supplemented with ThromboSol or a control solution and stored in parallel at 24 degrees C with continuous agitation or undisturbed at 4 degrees C. Samples were removed on days 1, 5, 9 of storage, and assayed for their content of interleukin (IL)-6, IL-8, tumour necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta1, and anaphylatoxins C3a and C4a. RESULTS Throughout storage, refrigerated PCs, both ThromboSol-treated and untreated units, displayed a slightly lower level of IL-6 and significantly lower concentration of IL-8 than conventionally stored PCs. ThromboSol slightly reduced the level of these cytokines in PCs. Throughout storage at 22 degrees C, an accumulation of anaphylatoxins C3a and C4a was seen both in both control and ThromboSol-treated PCs. This accumulation was significantly reduced in control PCs stored at 4 degrees C, but not in refrigerated PCs supplemented with ThromboSol. Cold-storage, with or without ThromboSol, had a minor effect on the accumulation of TGF-beta1 in PCs. INTERPRETATION AND CONCLUSIONS Our data confirm that release of bioactive compounds during in vitro storage of PCs is a temperature-sensitive process. The ThromboSol-refrigeration system could be a useful alternative for extending storage of PCs, without increasing the accumulation of cytokines (IL-6, IL-8), known to be involved in febrile reactions in recipients. Nevertheless, this storage system has no benefit on the level of other bioactive compounds (TGF-beta1, anaphylatoxins C3a and C4a) in PCs.