Sanne de Bruin

17 General Introduction and scope of the thesis Storage lesion of platelets Platelet concentrates can be obtained via two different methods: 1) They are obtained from a single donor via apheresis or 2) four to five buffy coats derived from whole blood donations are pooled and processed into one product. The preparation process of platelet concentrates includes several procedural steps such as centrifugation and resuspension of the platelets in an additive solution or plasma unit, depending applied method. These procedural steps are together with the storage of platelets the largest contributor to the platelet storage lesion. Platelets are, in line with their function, easily activated. To minimize platelet activa- tion, platelets are stored at 20-24˚C. The storage temperature of 20-24˚C has several disadvantages, it increases the risk of transfusion-transmitted infection and glucose metabolism is higher at this temperature. Due to the storage at this temperature plate- let concentrates are at a higher risk for bacterial growth. The shelf life is, depending on local regulations, usually limited to 5-7 days. The increased glucose metabolism results in lactate accumulation which negatively effects the function of platelets. Using an additive solution to store buffy coat and apheresis-derived platelet concen- trates reduces the storage lesion, reduces the incidence of transfusion reactions 46 , and possibly extends shelf-life. The composition of the additive solutions is based on main- taining an adequate energy source and minimize platelet activation. Several platelet additive solutions have been developed. Monitoring quality of blood components An important parameter of quality of blood components is the post transfusion recovery (PTR) in vivo . Hb level increment or platelet count increment, after RBC and platelet transfusion respectively is not a precise method as this is largely affected by character- istics of the recipient, especially the circulating volume. It is possible to use human leukocyte antigen (HLA) mismatching to distinguish trans- fused platelets from non-transfused platelets in the circulation. RBCs can be distin- guished by minor antigen mismatched between the donor and the recipient. The main advantage of these methods is that the transfused RBCs and platelets are not manip- ulated before transfusion. However, it has also several downsides, including that this method can only be applied after allogenic transfusion while testing of new products is most often conducted in healthy volunteers using autologous transfusions. Further- more, when a patient receives multiple transfusions, it complicates the HLA or minor antigen mismatch measurement. 1