Selecting a relevant animal model for testing the in vivo effects of Choukroun's platelet-rich fibrin (PRF): rabbit tricks and traps

Effect of leukocyte and platelet-rich fibrin on free gingival graft healing: A clinical and histological study in rabbits

Background. Recently, the use of leukocyte- and platelet-rich fibrin (L-PRF) has been recommended due to the presence of various growth factors to increase the success of free gingival grafts (FGG). This study evaluated the effect of using L-PRF in the healing of FGG in rabbits. Methods. Twenty rabbits were randomly divided into two groups. In each group, FGG was performed in two separate sites with or without L-PRF. One of these groups was sacrificed on the 7th day and the other on the 28th day and analyzed in terms of clinical indices, including wound healing, gingi-val thickness (GT), and keratinized tissue width (KTW). Then histologic sections were obtained and stained for type and degree of inflammation and rate of vascular formation analysis. SPSS 22 was used for statistical analysis. Results. The extent of changes in GT, KTW, wound healing index, and vascular formation between the test and control groups was not statistically significant. The difference in the type of inflammation was significant only between the -7day and -28day control groups (P=0.003). The degree of inflammation between the -7day test group and the -28day control group, as well as the -7day and -28day control groups, were statistically significant (P=0.011 and P=0.002, respectively). Conclusion. Using L-PRF with FGG could improve FGG healing compared to using FGG alone, but the results were not statistically significant.

Effects of Platelet-Rich Fibrin on Hard Tissue Healing: A Histomorphometric Crossover Trial in Sheep

Bone defects lead to aesthetic and functional losses, causing dental rehabilitation to be more difficult. The objective of this work is to histologically assess the hard tissue healing of bone defects filled with platelet-rich fibrin (PRF) alone or as an adjuvant for mixing with and covering anorganic bovine bone (ABB), compared to ABB covered with a resorbable collagen membrane (CM). This study was designed as a crossover animal study. Four 5-mm tibia defects, 5 mm apart from each other, were surgically created on the tibias of 6 sheep. The defects were randomly filled with ABB + CM; PRF alone; ABB+PRF; or were left empty. The animals were euthanized on days 10, 20, and 40 post-operatively. No group showed any signs of bone necrosis. Inflammation was observed in 2 control and 3 test defects with no statistically significant difference between groups at each time point. The ABB + CM and ABB + PRF groups experienced the highest bone regeneration ratios. No differences between the empty-defect and PRF groups were observed in regard to bone regeneration. No statistical difference was observed between the ABB+PRF and ABB + CM groups in regard to bone regeneration and the amount of residual graft material at each time point. The use of PRF should be preferred due to its autogenous origin, low cost, and ease of use.

Platelet-Rich Fibrin as a Bone Graft Material in Oral and Maxillofacial Bone Regeneration: Classification and Summary for Better Application

Platelet-rich fibrin (PRF) is an autologous platelet concentrate that consists of cytokines, platelets, leukocytes, and circulating stem cells. It has been considered to be effective in bone regeneration and is mainly used for oral and maxillofacial bone. Although currently the use of PRF is thought to support alveolar ridge preservation, there is a lack of evidence regarding the application of PRF in osteogenesis. In this paper, we will provide examples of PRF application, and we will also summarize different measures to improve the properties of PRF for achieving better osteogenesis. The effect of PRF as a bone graft material on osteogenesis based on laboratory investigations, animal tests, and clinical evaluations is first reviewed here. In vitro, PRF was able to stimulate cell proliferation, differentiation, migration, mineralization, and osteogenesis-related gene expression. Preclinical and clinical trials suggested that PRF alone may have a limited effect. To enlighten researchers, modified PRF graft materials are further reviewed, including PRF combined with other bone graft materials, PRF combined with drugs, and a new-type PRF. Finally, we will summarize the common shortcomings in the application of PRF that probably lead to application failure. Future scientists should avoid or solve these problems to achieve better regeneration.

A Proof of the Low Speed Centrifugation Concept in Rodents: New Perspectives for In Vivo Research

IMPACT STATEMENT

This study evaluated for the first time the composition and bioactivity of platelet-rich fibrin (PRF) produced from small animal blood by reducing the initial blood volume needed for the preparation of PRF from 10 to 3 mL. The results showed that different preparation protocols of PRF produced using 3 mL of animal blood exhibit the same composition, properties, and bioactivity as PRF prepared using 10 mL human blood.

The Role of Oxidative Stress and Hormones in Controlling Obesity

The accumulation of adipose tissue in the body occurs because the energy introduced with food and drink exceeds that expense, but to understand why this imbalance is established and why it is maintained over time, it is important to consider the main causes and risk factors of excess weight. In this review, we will refer to the main factors linked to obesity, starting from oxidative stress to hormonal factors including the role of obesity in breast cancer. Among the many hypotheses formulated on the etiopathology of obesity, a key role can be attributed to the relationship between stress oxidative and intestinal microbiota. Multiple evidences tend to show that genetic, epigenetic, and lifestyle factors contribute to determine in the obese an imbalance of the redox balance correlated with the alteration of the intestinal microbial flora. Obesity acts negatively on the wound healing, in fact several studies indicate morbid obesity significantly increased the risk of a post-operative wound complication and infection. Currently, in the treatment of obesity, medical interventions are aimed not only at modifying caloric intake, but also to modulate and improve the composition of diet with the aim of rebalancing the microbiota-redox state axis.

Can gray values derived from CT and cone beam CT estimate new bone formation? An in vivo study

OBJECTIVES

The main aim of this study was to investigate whether Hounsfield unit derived from computed tomography (HU/CT) and gray value derived from cone beam computed tomography (GV/CBCT) can predict the amount of new bone formation (NBF) in the defects after bone reconstruction surgeries.

MATERIALS AND METHODS

Thirty calvaria defects created in 5 rabbits and grafted with both radiolucent (RL, n = 15) and radiopaque (RO, n = 15) bone substitute materials were evaluated, 8 weeks postoperatively. The defects were scanned by multislice computed tomography (Somatom®, Siemens Healthineers, Erlangen, Germany) and CBCT (NewTom VG®, Qualitative Radiology, Verona, Italy). MSCT and CBCT scans were matched to select the exact region of interest (ROI, diameter = 5 mm and height = 1 mm). HU/CT and GV/CBCT of each ROI were obtained. Mean amount of NBF in whole of the defects was measured using serial histomorphometric assessment. We investigated the correlation between HU/CT and GV/CBCT, HU/CT and NBF, and GV/CBCT and NBF generally, and separately among the RL or RO grafted defects, by linear generalized estimating equation modeling. Receiver operation characteristic analysis was performed to check the accuracy of HU/CT and GV/CBCT in diagnosing more than 10% NBF in the samples.

RESULTS

There were linear correlations between HU/CT and GV/CBCT, HU/CT and NBF, and GV/CBCT and NBF.

CONCLUSION

According to the results, both HU/CT and GV/CBCT can be considered as fairly good predictors for assessment of the amount of NBF following bone reconstruction surgeries.

Hybrid composites of mesenchymal stem cell sheets, hydroxyapatite, and platelet-rich fibrin granules for bone regeneration in a rabbit calvarial critical-size defect model

The reconstruction of large bone defects remains a major clinical challenge, and tissue engineering is a promising technique for resolving this problem. Many attempts have been made to optimize bone tissue engineering protocols. The aim of the present study was to develop a process incorporating mesenchymal stem cell (MSC) sheets with nanoscale hydroxyapatite (nano-HA) and autologous platelet-rich fibrin (PRF) granules for enhanced bone formation within a critical-sized rabbit cranial defect. MSC sheets and PRF were prepared prior to in vivo experiments. The osteogenic differentiation ability of MSCs and the ultrastructure of PRF were also studied. A total of 15 New Zealand white rabbits were used in the current study and critical-size defects (CSDs) were surgically introduced in the cranium (diameter, 15 mm). The surgical defects were treated with MSC/PRF composites, MSC composites or left empty. Animals were euthanized at week 8 post-surgery. Iconography, histological and histomorphometric analysis were performed to assess de novo bone formation. The percentage of new bone in the MSC/PRF group (35.7±5.1%) was significantly higher than that in the MSC (18.3±3.2%; P<0.05) and empty defect groups (4.7±1.5%; P<0.05). The results of the present study suggest that combined application of an MSC sheet with nano-HA and granular PRF enhances bone regeneration in a rabbit calvarial CSD model, and provides a novel insight into bone tissue regeneration for large bone defects.

Canine articular cartilage regeneration using mesenchymal stem cells seeded on platelet rich fibrin: Macroscopic and histological assessments

Objectives

Mesenchymal stem cells have the ability to differentiate into various cell types, and thus have emerged as promising alternatives to chondrocytes in cell-based cartilage repair methods. The aim of this experimental study was to investigate the effect of bone marrow derived mesenchymal stem cells combined with platelet rich fibrin on osteochondral defect repair and articular cartilage regeneration in a canine model.

Methods

Osteochondral defects were created on the medial femoral condyles of 12 adult male mixed breed dogs. They were either treated with stem cells seeded on platelet rich fibrin or left empty. Macroscopic and histological evaluation of the repair tissue was conducted after four, 16 and 24 weeks using the International Cartilage Repair Society macroscopic and the O’Driscoll histological grading systems. Results were reported as mean and standard deviation (sd) and compared at different time points between the two groups using the Mann-Whitney U test, with a value < 0.05 considered statistically significant.

Results

Higher cumulative macroscopic and histological scores were observed in stem cell treated defects throughout the study period with significant differences noted at four and 24 weeks (9.25, sd 0.5 vs 7.25, sd 0.95, and 10, sd 0.81 vs 7.5, sd 0.57; p < 0.05) and 16 weeks (16.5, sd 4.04 vs 11, sd 1.15; p < 0.05), respectively. Superior gross and histological characteristics were also observed in stem cell treated defects.

Conclusion

The use of autologous culture expanded bone marrow derived mesenchymal stem cells on platelet rich fibrin is a novel method for articular cartilage regeneration. It is postulated that platelet rich fibrin creates a suitable environment for proliferation and differentiation of stem cells by releasing endogenous growth factors resulting in creation of a hyaline-like reparative tissue.

Cite this article: D. Kazemi, K. Shams Asenjan, N. Dehdilani, H. Parsa. Canine articular cartilage regeneration using mesenchymal stem cells seeded on platelet rich fibrin: Macroscopic and histological assessments. Bone Joint Res 2017;6:98–107. DOI: 10.1302/2046-3758.62.BJR-2016-0188.R1.

Characterization of Leukocyte-platelet Rich Fibrin, A Novel Biomaterial

Autologous platelet concentrates represent promising innovative tools in the field of regenerative medicine and have been extensively used in oral surgery. Unlike platelet rich plasma (PRP) that is a gel or a suspension, Leukocyte-Platelet Rich Fibrin (L-PRF) is a solid 3D fibrin membrane generated chair-side from whole blood containing no anti-coagulant. The membrane has a dense three dimensional fibrin matrix with enriched platelets and abundant growth factors. L-PRF is a popular adjunct in surgeries because of its superior handling characteristics as well as its suturability to the wound bed. The goal of the study is to demonstrate generation as well as provide detailed characterization of relevant properties of L-PRF that underlie its clinical success.

[Contribution of platelet concentrates to oral and maxillo-facial surgery]

INTRODUCTION

We evaluated the clinical contribution of platelet concentrates to oral and maxillo-facial surgery.

MATERIAL AND METHOD

This bibliographic research was made using the PubMed MeSH database with the following keywords: "platelet rich fibrin" (PRF), "platelet rich plasma" (PRP), "bone", "facial bone", "dental implant", and "blood platelet". The research was made without any date or language limitation since English summaries were available. All summaries were read to evaluate the relevance of the article. Only original articles and case reports were considered. The articles were classified as "in vitro studies", "animal experiments", or "clinical studies". The research was stopped on March 22, 2012.

RESULTS

One hundred and sixty-nine articles were validated after excluding irrelevant articles, reviews, technical notes, and articles without English or French summaries. Seventeen were in vitro studies, 61 animal experiments, and 91 clinical studies. One hundred and ten complete articles were read to complete summary data. The data of in vitro studies univocally supports of using platelet concentrates. The data from animal experiment studies was less consensual and the validity of animal models was contested. The disparity of clinical study designs and the lack of rigorous methodology did not allow clearly determining platelet concentrate benefits for oral and maxillo-facial surgery.

DISCUSSION

PRF or PRP clinical benefit has not been clearly demonstrated yet. French regulations relative to their use should be clarified.

Restoration of a peri-implant defect by platelet-rich fibrin

OBJECTIVE

The objective of this study was to evaluate the application of platelet-rich fibrin (PRF) into a peri-implant defect in vivo.

STUDY DESIGN

Eight New Zealand white rabbits were used for this study. Two peri-implants with defects sized 3.0 × 5.0 mm (width × length) were prepared after drilling to host the dental implant in the tibia. Subsequently, the 2 dental implants were installed (diameter, 3.0 mm and length, 8.0 mm). In the experimental group, PRF was applied into the bony defect. In the control group, the peri-implant defect was left unfilled. The animals were humanely killed 8 weeks after implantation and histomorphometric analysis was done.

RESULTS

In the histomorphometric analysis, mean new bone formation was 29.30% ± 7.50% in the experimental group and 11.06% ± 8.94% in the control group (P = .020). Mean bone-to-implant contact was 39.43% ± 7.39% in the experimental group and 17.11% ± 8.12% in the control group (P = .006).

CONCLUSIONS

In the animal model, peri-implant defect sized 3.0 × 5.0 mm (width × length) was successfully repaired by the application of PRF alone.