Bioactivity and stability of endogenous fibrogenic factors in platelet-rich fibrin.

Platelet-rich fibrin (PRF) is an autologous fibrin sealant (FS) enriched with a platelet concentrate (> 1,000,000 platelets/microL) produced by the automated Vivostat system and used to enhance wound healing. The effects of PRF were compared with supernatant from thrombin-activated platelet concentrate, recombinant human platelet-derived growth factor (rhPDGF) isoforms, and a homologous FS in cultured normal human dermal fibroblasts. Also, the release of selected endogenous growth factors from PRF and their stability against proteolytic degradation were studied. The proliferative effect of PRF exceeded that of FS and rhPDGF-BB, although it was lower than thrombin-activated platelet concentrate possibly due to sustained growth factor release from platelets in PRF. Anti-PDGF antibody blocked the mitogenic effect of rhPDGF-BB but not that of PRF in growth-arrested fibroblasts. PRF promoted secretion of carboxyterminal propeptide of type I collagen into conditioned medium while rhPDGF-AB had no significant effect on collagen biosynthesis. Limited proteolysis of PDGF-AB and no proteolysis of transforming growth factor-beta1 (TGF-beta1) in PRF were observed with trypsin treatment, whereas rhPDGF-AB and rhTGF-beta1 in bovine serum albumin, matching the total protein concentration of PRF, were almost completely degraded after 24 hours at 37 degrees C. To conclude, PRF provides sustained release and protection against proteolytic degradation of endogenous fibrogenic factors important for wound healing.