Stored red-blood-cells inhibit platelet function under physiologic flow

Background and Objectives The DiaMed Impact R tests platelet function under close to physiological flow conditions. The machine is designed to use whole blood but by adding back compatible red cells, it can be used to study stored platelet concentrates. To date, red cells < 14 days old have been used. In this study, the effect on the assay of using red cells stored for up to 60 days was examined. Material and Methods This study looked at buffy coat-derived platelet concentrates on day 2 of storage along with various stored red-blood-cells (RBC). To determine whether the age of the RBC is a factor in supporting adhesion and aggregation, platelets were assayed with either RBC stored between 2 and 60 days or with separated 'young' and 'old' red cell populations obtained using a centrifugation method and confirmed by percoll gradient analysis. Results A statistically significant difference was observed between red-blood-cells stored for < 20 days compared with those which have been stored for 21-60 days in respect of their ability to support platelet adhesion (SC) and aggregation (AS) (P < 0 center dot 01). Separating red cells by centrifugation into top (young population) and bottom (old population) showed that the effect of storage was much greater than was any difference between young and old at the individual time-points e.g. 'young' red cells from stored units were poorer at supporting platelet adhesion and aggregation than 'young' red cells from fresh units. Conclusion Results suggest that the red cells should be stored for less than 21 days when using this assay. This assay may also allow assessment of red cell functionality.