Platelet-rich fibrin (PRF) by Choukroun's technique is produced in a totally natural manner, without using anticoagulant during blood harvest nor bovine thrombin and calcium chloride for platelet activation and fibrin polymerization. When delicately pressed between two gauzes, the PRF clot becomes a strong membrane with high potential in clinical application and tissue engineering. In this study, blood collection was carried out from healthy volunteers. Osteoblast cell line U2OS was used to evaluate the cell proliferation resulting from PRF by using colorimetric assay. Western blot was employed to evaluate the expression of phosphorylated extracellular signal-regulated protein kinase (p-ERK), receptor activator of nuclear factor-kappa B ligand (RANKL), and osteoprotegerin (OPG) in U2OS cells. PRF was found to increase osteoblast proliferation during 5 day incubation period (p < 0.05). PRF was found to increase ERK phosphorylation in U2OS cells (p < 0.05). OPG was significantly elevated by the stimulation with PRF (p < 0.05). However, there was no significant change in RANKL expression (p > 0.05). Taken together, PRF can stimulate osteoblasts proliferation. The activation of p-ERK and OPG expression by PRF suggests a potential role for new bone formation. The application of PRF may provide the benefit for the bone regeneration
