(428) In Vitro Apheresis Platelet Function Under Additive Solution and Pathogen Reduction Strategies

Introduction: As one of the fundamental components of clot formation, platelets are a scarce resource but in high demand. Select platelet additives are being explored to extend their shelf life, reduce risk of adverse reaction (platelet additive solution, PAS) and reduce risk of infection (pathogen reduction, PR). This study sought to evaluate apheresed platelets stored under PAS and PR conditions by evaluating aggregation capability in response to agonists over time. We additionally evaluated the effect of cytochrome c (cyt c) supplementation, which has previously been shown to extend platelet storage time in vitro. We hypothesized that PR would lead to decline of platelet function as compared to PAS.

Methods: Platelet apheresis units were collected, (N=5) and divided into PR or no PR (PAS) and supplemented with vehicle or cyt c (100µM). Units were stored at 4°C for 15-days and sequential aliquots were removed. Platelet/mitochondrial respiratory function, aggregation capability, and biochemical parameters were measured.

Results: Maximum clot strength showed no difference in clot strength between PAS and PR from Day 0 to Day 5 but declined in PR platelets on days 10 and 15. Platelet aggregation in response to ADP was low across both groups, however aggregation was higher in the PAS group at day five. Aggregation function in response to arachidonic acid (AA) was higher in PR versus PAS platelets across all time points. The pH level in PR was higher than in PAS on day 1 but subsequently declined in both groups. Oxygen consumption declined at the same rate in PAS and PR platelets and rate of lactate and TCO2 decrease in PR platelets was greater than in PAS platelets.

Conclusions: Platelet storage leads to decline in function independent of whether platelets are stored under PAS and PR conditions. Supplementation of PAS or PR stored platelets with cyt c does not impact platelet function. We demonstrate that both pathogen reduction and platelet additive solution strategies are viable strategies for resource conservation. Elucidating the mechanisms by which each group responds to receptor mediated aggregation may provide novel targets for further improvements in platelet storage.