Platelets from platelet-rich-plasma versus buffy-coat-derived platelets: what is the difference?

Platelets can be prepared from whole blood either using the platelet-rich-plasma (PRP) method or the buffy-coat method (BC-PC). Yet a third type of platelet component is collected using the apheresis technique. Only a few countries still produce PRP platelets with the USA remaining among those countries. For this reason, studies on PRP platelets often were published quite a long time ago. Using the PRP method, whole blood units are centrifuged using a soft spin to concentrate the platelets in the supernatant, i.e. the plasma. The PRP is transferred into a satellite bag. After pelleting the platelets by "hard-spin" centrifugation of the PRP with removal of most of the supernatant, platelet poor plasma, platelets are resuspended and stored as a platelet concentrate (PC) in a reduced volume of the remaining plasma. The second centrifugation in the preparation of PC is associated with reversible platelet aggregation, which probably is induced by activation due to the close contact between platelets in the platelet pellet. Several methods for the preparation of buffy-coat derived platelet concentrates (BC-PCs) are used with differences in the time of storing whole blood preceding the preparation of BC, the time before the preparation of platelet units and the platelet storage medium. BC-PCs are generally prepared from a pool of BCs using sterile connections. Pre-storage leukocyte removal by filtration is often preferred. In contrast to the PRP method, BC methods do not involve significant close cell contact between platelets in a pellet. The collection of blood is associated with primary activation of coagulation and the generation of significant levels of thrombin and in the next step, activation of platelets. The activation of platelets may result in the release of cytokines and other factors during preparation and storage of platelets that may cause febrile non-hemolytic transfusion reactions (FNHTR) at transfusion. The activation may also affect platelet metabolism, platelet function and morphology of platelets. In the 1980s, Snyder et al. studied the degree of damage that occurred during the preparation and storage of PC prepared by the PRP method by determining the extracellular percentage of beta-thromboglobulin, a marker for alpha-granule release during the activation of platelets. The results suggested that the degree of in vitro activation, as evidenced by the release of alpha-granule content, was dependent on the different preparative steps. In particular, the concentration of platelets into a pellet by centrifugation was found to result in a large degree of release. However, …