Autologous Platelet-Rich Fibrin Preparation

PRF was prepared according to the L-PRF™ protocol (Intra-Lock, Boca Raton, FL, USA). Briefly, 9 mL autologous venous blood was collected into plastic tubes with a clot activator (Intra-Spin Red Blood Tube, Intra-Lock, Boca Raton, FL, USA). One tube was used as control (without drug), while an increasing amount of different drugs was added to the other tubes (see next section). The tubes were then centrifuged on a fixed-angle centrifuge machine (IntraSpin™, Intra-Lock, Boca Raton, FL, USA) at 2700 rpm (710 g RCF) for 12 min. After centrifugation the red blood cells (RBC) were removed and the PRF membrane was used in the following experiments.