BackgroundThe development of platelet-rich fibrin (PRF) drastically simplified the preparation procedure of platelet-concentrated biomaterials, such as platelet-rich plasma (PRP), and facilitated their clinical application. PRF’s clinical effectiveness has often been demonstrated in pre-clinical and clinical studies; however, it is still controversial whether growth factors are significantly concentrated in PRF preparations to facilitate wound healing and tissue regeneration. To address this matter, we performed a comparative study of growth factor contents in PRP and its derivatives, such as advanced PRF (A-PRF) and concentrated growth factors (CGF).MethodsPRP and its derivatives were prepared from the same peripheral blood samples collected from healthy donors. A-PRF and CGF preparations were homogenized and centrifuged to produce extracts. Platelet and white blood cell counts in A-PRF and CGF preparations were determined by subtracting those counts in red blood cell fractions, supernatant acellular serum fractions, and A-PRF/CGF exudate fractions from those counts of whole blood samples. Concentrations of growth factors (TGF-β1, PDGF-BB, VEGF) and pro-inflammatory cytokines (IL-1β, IL-6) were determined using ELISA kits.ResultsCompared to PRP preparations, both A-PRF and CGF extracts contained compatible or higher levels of platelets and platelet-derived growth factors. In a cell proliferation assay, both A-PRF and CGF extracts significantly stimulated the proliferation of human periosteal cells without significant reduction at higher doses.ConclusionsThese data clearly demonstrate that both A-PRF and CGF preparations contain significant amounts of growth factors capable of stimulating periosteal cell proliferation, suggesting that A-PRF and CGF preparations function not only as a scaffolding material but also as a reservoir to deliver certain growth factors at the site of application.

BackgroundFibrin clot membranes prepared from advanced platelet-rich fibrin (A-PRF) or concentrated growth factors (CGF), despite their relatively rapid biodegradability, have been used as bioactive barrier membranes for alveolar bone tissue regeneration. As the membranes degrade, it is thought that the growth factors are gradually released. However, the mechanical and degradable properties of these membranes have not well been characterized. The purpose of this study was to mechanically and chemically characterize these membranes.MethodsA-PRF and CGF clots were prepared from blood samples collected from non-smoking, healthy donors and were compressed to form 1-mm-thick membranes. Platelet-poor plasma-derived fibrin (PPTF) clots were prepared by adding bovine thrombin to platelet-poor plasma. A tensile test was performed at the speed of 1 mm/min. Morphology of the fibrin fibers was examined by SEM. A digestion test was performed in PBS containing trypsin and EDTA.ResultsIn the tensile test, statistical difference was not observed in Young’s modulus, strain at break, or maximum stress between A-PRF and CGF. In strain at break, PPTF was significantly weaker than CGF. Likewise, fibrin fiber thickness and crosslink density of PPTF were less than those of other membranes, and PPTF degraded faster than others.ConclusionsAlthough the centrifugal conditions are different, A-PRF and CGF are prepared by essentially identical mechanisms. Therefore, it is conceivable that both membranes have similar mechanical and chemical properties. Only PPTF, which was prepared by a different mechanism, was characterized as mechanically weaker and enzymatically more degradable.