Fibrina rica em plaquetas injetável (I-PRF): caracterização celular, morfológica e proteica

Abstract

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 thereby optimizing the repair process, and can also be used in liquid form (i-PRF). The objective of this research was to determine the cellular composition of i-PRF, to characterize its morphology at a microscopic level, to investigate the expression of proteins involved in the repair process and to evaluate its interaction with a bioceramic material from an in vitro model. Materials and methods: Blood samples were collected from 15 human volunteers to compare the cellular constituents between i-PRF and peripheral blood. I-PRF and blood clot samples were cultured in vitro for 10 days. The supernatant of the samples was collected at intervals of 1h, 8h, 24h, 3 days and 10 days for quantification of PDGF-AB and VEGF growth factors by ELISA. Samples were histologically treated for morphological characterization and submitted to the immunohistochemical methodology for the labeling of IL-10, OC and TGF-β proteins. The gene expression of collagen transcription factor type 1 was investigated. I-PRF samples mixed with granular bioactive ceramics (HA/β-TCP) were prepared to evaluate the interaction between these compounds through SEM. Results: 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. Immunohistochemical assay demonstrated expression for TGF-β, IL-10 and Osteocalcin in the i-PRF group. RT-PCR analysis showed increased expression of collagen type 1 in the i-PRF group. The formation of large platelets, fibrin clusters and a fibrin network in a three-dimensional spatial and homogeneous distribution were observed microscopically. SEM images showed good integration between the ceramic granules and the fibrin mesh formed by i-PRF. Conclusions: Morphological analyses revealed that the slow polymerization of i-PRF results in a three-dimensional fibrin network embedding platelets, leukocytes, type I collagen, osteocalcin, and growth factors. Thus, i-PRF becomes a good approach as an injectable material to be associated with other biomaterials.