Platelet rich fibrin in injectable form (i-PRF): celular, morphological and protein characterization
i-PRF, platelet-rich fibrin, Healing, Growth factors.
One of the great challenges of clinical research is the development of new biomaterials that aid in tissue regeneration and accelerate the healing process. Experimental studies demonstrate the effect of platelet rich fibrin (PRF) on tissue regeneration techniques, optimizing the repair process; and can be used in injectable form (i-PRF). The objective of this research was to determine the cellular, morphology and protein characterizations involved in the repair process and to evaluate its interaction with a bioceramic material from an in vitro model. Blood samples were collected from 15 human volunteers for comparison of the cellular constituents between i-PRF and peripheral blood. Samples of i-PRF and blood clots were cultured in vitro for 10 days. The supernatant of the samples was collected at intervals 1h, 8h, 24h, 3 days and 10 days for quantification of PDGF-AB and VEGF growth factors by ELISA immunoassay. Samples were histologically treated for morphological characterization and submitted to the immunohistochemical methodology for the labeling of IL-10, Osteocalcin and TGF-β proteins. The gene expression of collagen transcription factor type 1 was investigated. Samples of i-PRF mixed with granular bioactive ceramics (HA / β-TCP) were prepared to evaluate the interaction between these compounds through SEM. A higher concentration of leukocytes (8,124 ± 1,419) and platelets (3.96x105 ± 0.72) in i-PRF compared to peripheral blood (p <0.001) was observed, with a higher proportion of lymphocytes (60%) in i- PRF. Higher levels of VEGF were released from the blood clot (1933± 704) compared to i-PRF (852 ± 376; p <0.001); no differences were observed between PDGF-AB levels (p>0.05). Immunohistochemical assay demonstrated staining for TGF-β, IL-10 and Osteocalcin in the i-PRF group. RT-PCR analysis showed increased gene expression of collagen type 1 in the i-PRF group (p>0.05) . Microscopically, the formation of large platelets and fibrin clusters and a fibrin network in a three-dimensional spatial and homogeneous distribution were observed. SEM images showed good integration between the ceramic granules and the fibrin mesh formed by i-PRF. In describing and analyzing the morphological and biological properties of i-PRF in vitro, we can better understand its clinical effects and develop guidelines for future therapeutic applications.