Blood sampling and preparation of platelet-poor plasma

PB was drawn from patients directly into commercially available buffered sodium citrate tubes (citrate 0.129 mol/l; pH 5.5; Sarstedt, Germany) and was processed within 4 hours. For preparation of platelet-rich plasma (PRP), samples were centrifuged at 200 g for 8 min. Then, 1 ml of supernatant was additionally centrifuged at 1500 g for 20 min for preparation of for platelet-poor plasma (PPP), both at room temperature. Finally, 500 μl supernatant was frozen as PPP at −80°C until further processing. Thawing for further processing was done at room temperature.