In vitro properties of platelet concentrates

Background: The influence of different preparation techniques and storage time on in vitro function of platelet concentrates (PC) was studied. Material and Methods: PC were separated (n = 10 each) by single-donor apheresis with two different cell separators (AS-104 for AS-PC and CS 3000 for CS-PC) and from CPD-anticoagulated blood either by the buffy coat (BC) method (BC-PC) or by the platelet-rich plasma method (PRP-PC). The BC was stored for either 3 h (BC-3-PC) or 20 h (BC-20-PC) before further preparation. PC were stored for 5 days. Expression of activation antigens (GMP-140, GP-53), release of beta -thromboglobulin (beta -TG) and LDH, morphology score, metabolic status (pH, lactate), and cell counts were measured on days 0, 3, and 5. Results: BC-3-PC were less activated than platelets prepared by the PRP method (GMP-140, beta -TG release) and maintained better morphology scores during storage. However, extending the storage time of BC from 3 to 20 h resulted in increased initial activation (GP-53, GMP-140), release of beta -TG and lactate production (BC-20-PC). Platelets collected by cell separation without pelletation (AS-PC) were significantly less activated than platelets from BC (GMP-140, beta -TG release) and maintained better morphology scores and better metabolic status (LDH, lactate). AS-PC even showed less LDH release, lactate production, and activation (GMP-140, GP-53, beta -TG release) during storage than PC prepared by apheresis with the CS 3000 cell separator (CS-PC). Conclusions: There are some significant differences of in vitro function and morphology between PC prepared by different separation methods. Apheresis and centrifugation procedures using pelletation and resuspension of the platelets impede platelet function. The best platelet function was found in PC separated by apheresis without pelletation. The clinical relevance of the in vitro differences of the various products still has to be proven.