Platelet apoptosis and activation in platelet concentrates stored for up to 12 days in plasma or additive solution

Study design and methods: Pooled buffy coat PC (n = 7) were prepared in either 100% plasma or 70% Composol and stored at 22 degrees C for 12 days. A third arm of the study stored PC in 100% plasma at 37 degrees C, which is thought to induce apoptosis. PC were tested for mitochrondrial membrane potential, annexin V binding, microparticles, caspase-3/7 activity and decoy cell death receptor 2, as well as standard platelet quality tests. Results: Composol units remained >= pH 6 center dot 88, with 36% lower lactate and higher pH vs plasma by day 12 (P < 0 center dot 001). Platelet function was better maintained, and activation and apoptotic markers tended to be lower in Composol units towards the end of storage. However, levels of all apoptosis markers assessed were not significantly different in units stored in Composol. Storage at 37 degrees C saw stronger correlation of apoptotic markers with standard quality tests compared to 22 degrees C, but loss of correlation of caspase-3/7 activity with other apoptosis markers. Conclusion: We conclude that storage of platelets in 70% Composol vs 100% plasma does not increase the rate of platelet apoptosis. Our data agree with other studies suggesting that platelet apoptosis is sequential to high levels of activation, but share a significant degree of overlap.