Restoration of in vitro responses in platelets stored in plasma

Conventional platelet storage in a blood bank is up to 5 days at room temperature in plasma. We investigated the optimal medium for assessing the quality of stored platelets by comparing in vitro test responses after resuspension in autologous plasma prepared from platelet-rich plasma after 5 days of storage at room temperature, autologous plasma stored cell-free for 5 days at room temperature, or autologous plasma stored cell-free for 5 days at -20 degrees C. Five-day-old platelets were prepared from aliquots of the same unit and resuspended in I of the 3 plasma preparations. The platelet-plasma mixtures were monitored for changes in pH, mean platelet volume, hypotonic shock response, P-selection expression, and aggregation. There were statistically significant differences between platelets resuspended in original plasma and platelets resuspended in either plasma stored cell-free at room temperature or frozen, with regard to hypotonic shock response, agonist-induced aggregation, and P-selectin expression. Plasma stored with platelets for 5 days yielded inferior platelet function test responses when compared with plasma stored cell-free at room temperature or frozen. Therefore, for direct comparison of platelet responses following novel storage methods, the resuspending plasma should be stored under the same conditions as the control platelet unit.