Platelet‐Rich Plasma‐Derived Fibrin Clot Formation Stimulates Collagen Synthesis in Periodontal Ligament and Osteoblastic Cells In Vitro

Background: Platelet‐rich plasma (PRP) contains several growth factors, including platelet‐derived growth factor (PDGF) and transforming growth factor‐β (TGF‐β), at high levels. We have demonstrated the PRP functions like TGF‐β to modulate cell proliferation in a cell‐type specific manner. In addition, PRP forms gel‐like materials in several, but not all, cell cultures tested. This study was designed to investigate PRP's action on extracellular matrix production in periodontal ligament (PDL) and osteoblastic MG63 cell cultures. Methods: PRP was prepared from the plasma obtained from autologous blood of healthy volunteers and stored at −20°C until used. Cells treated with PRP (0.5% to 2%) were immunocytochemically stained for type I collagen and fibrin and the viscosity of the culture media was visually evaluated. Fibrinogen in PRP was detected by immunodot‐blotting while endogenous thrombin expression in cells was detected by a modified enzymelinked immunosorbent assay. Results: Gel‐like material rapidly (