Effects of platelet-rich fibrin on osteogenic genes and bone microstructure in rats with peri-implant bone defect

Abstract

BACKGROUND: Peri-implant bone defects may affect implant stability. Platelet-rich fibrin, a second-generation autologous platelet concentrate, contains abundant growth factors and fibrin scaffolds and can facilitate bone regeneration. Nevertheless, its mechanism of action in the context of peri-implant bone defects remains to be fully investigated. OBJECTIVE: To investigate the effects of platelet-rich fibrin on osteogenic genes, bone microstructure, and IκB kinase/inhibitor of nuclear factor-κB/nuclear factor-κB signaling pathway in rats with peri-implant bone defect using a rat tibia model to simulate peri-implant bone defects, combined with ligature-induced inflammation. METHODS: Thirty male Sprague-Dawley rats were selected, and 20 of them were selected to establish peri-implant bone defect model. After modeling, they were randomly divided into model group and platelet-rich fibrin group, with an average of 10 rats per group, and the remaining 10 rats were assigned to the control group. The control group and the model group were not treated with any intervention, and the platelet-rich fibrin group was treated with platelet-rich fibrin implantation at the bone defect site. After 8 weeks, Image-Pro-Plus software was used to detect implant-bone contact rate and new bone formation rate; Micro-CT was used to detect bone microstructure changes; hematoxylin-eosin staining was used to observe histopathological changes; western blot was used to detect the protein expression of nuclear factor-κB, inhibitor of nuclear factor-κB, and IκB kinase in tibial tissue; RT-PCR was used to detect the expression of osteogenic-related genes osteopontin, osteocalcin, and Runt-related transcription factor 2. RESULTS AND CONCLUSION: (1) At 4 and 8 weeks after surgery, the new bone formation rate and implant-bone contact rate in the model group and platelet-rich fibrin group were increased (P < 0.05); the new bone formation rate and implant-bone contact rate in the platelet-rich fibrin group were significantly higher than those in the model group (P < 0.05). (2) Compared with the control group, the model group showed decreased trabecular bone number, bone volume fraction, Lane-Sandhu histological score, and mRNA expression of Runt-related transcription factor 2, osteocalcin, and osteopontin (P < 0.05), while trabecular separation, and protein expression of IκB kinase, inhibitor of nuclear factor-κB, and nuclear factor-κB were increased (P < 0.05). Compared with the model group, the platelet-rich fibrin group showed increased trabecular bone number, bone volume fraction, Lane-Sandhu histological score, and mRNA expression of Runt-related transcription factor 2, osteocalcin, and osteopontin (P < 0.05), while trabecular separation, and protein expression of IκB kinase, inhibitor of nuclear factor-κB, and nuclear factor-κB were decreased (P < 0.05). (3) Micro-CT showed no new bone tissue formation in the model group, while a large amount of new bone formation and connection with bone ends were observed in the platelet-rich fibrin group. (4) Hematoxylin-eosin staining showed that the platelet-rich fibrin group had good bone repair status and a large number of new bone cells around the defect. These results suggest that platelet-rich fibrin can accelerate the process of bone cell repair, has a significant promoting effect on bone healing in rats with peri-implant bone defects, can increase the expression level of osteogenic-related genes, improve bone microstructure, and enhance the activity of the IκB kinase/inhibitor of nuclear factor-κB/nuclear factor-κB signaling pathway.

1. Introduction

Peri-implant bone defects are common complications of dental implants, often arising from surgical trauma, infection, inflammation, and circulatory disturbances [1-3]. With the widespread use of implant technology, the issue of peri-implant bone defects has gained increasing attention. Reports indicate that the incidence of peri-implant inflammation ranges from 10% to 50% [4-5], and peri-implant inflammation is a major contributor to bone defects, necessitating timely and effective treatment to promote bone healing and repair. Surgical management typically involves grafting artificial or natural bone substitutes to fill the defect and facilitate bone regeneration. In recent years, advances in medical technology have improved treatment outcomes for peri-implant bone defects.

Platelet-rich fibrin (PRF) is a biological material prepared from the patient's own blood, characterized by the separation of high concentrations of platelets and fibrin during centrifugation [6-7]. PRF is rich in various growth factors and cytokines, exhibits excellent biocompatibility, and possesses the ability to induce tissue regeneration [8-9]. Consequently, PRF has been widely applied in orthopedics, plastic surgery, and dentistry. Nuclear factor-κB (NF-κB) is a crucial intracellular signal transduction factor that plays a key role in inflammatory responses and cellular immunity [10-11]. In the pathological process of peri-implant bone defects, NF-κB is significantly upregulated, and its activation promotes the release of inflammatory mediators, exacerbating inflammation at the defect site. Inhibitor of NF-κB (IκB) typically binds to NF-κB to regulate its activity [12-13]. IκB kinase (IKK) is a key enzyme that regulates IκB phosphorylation, directly influencing the activation and inhibition of NF-κB [14]. Based on this, the present study aims to investigate the effects of PRF on osteogenic genes, bone microstructure, and the IKK/IκB/NF-κB signaling pathway in rats with peri-implant bone defects, providing a theoretical basis for the clinical application of PRF in bone defects.