Effect of advanced platelet-rich fibrin on accelerating alveolar bone formation in dogs: a histological and immunofluorescence evaluation

Regeneration processes of alveolar bone and microvascular changes after the application of platelet-rich fibrin

OBJECTIVES

Platelet-rich fibrin (PRF) is a promising agent for bone regeneration (BR). Platelets contain several growth factors that promote angiogenesis and BR. In this study, we observed the morphology of alveolar BR.

METHODS

PRF (Advanced PRF: A-PRF) was prepared by extracting 10 mL of blood from each dog in a collection tube before tooth extraction. The samples were centrifuged at 200 × g for 8 min and incubated for 10 min to allow clotting. The alveolar socket on the dentition's right side was densely filled with PRF. The opposite side, which did not receive PRF, served as the control group. Different methods were used for specimen preparation and observation. Sections stained with hematoxylin and eosin were observed under a light microscope. Bone specimens were observed using stereoscopic microscopy. The resin cast models were examined using a scanning electron microscope. Moreover, bone formation ratio and height were measured.

RESULTS

Fourteen days postoperatively, angiogenesis and bone deposition were more advanced in the PRF group than in the control group. Thirty days postoperatively, both groups developed porous bone. In the PRF group, new bone trabeculae (BT) and a network of blood vessels were formed in the bone marrow. Ninety days postoperatively, the resin cast showed a normal bone structure with BT and bone marrow. Thick BT were observed in the PRF group.

CONCLUSIONS

Growth factors in PRF stimulate microcirculation and promote angiogenesis and bone deposition. The benefits of PRF include safety and increased bone formation.

Skin and Bone Regeneration of Solid Bone Marrow Aspirate Concentrate Versus Platelet-Rich Fibrin

Solid bone marrow aspirate concentrate (sBMAC) is harvested from bone marrow aspirate without anticoagulants by a centrifugation protocol similar to that for platelet-rich fibrin (PRF) prepared from peripheral blood. It was hypothesized that sBMAC could accelerate not only wound healing but also bone regeneration because of the abundant growth factor (GF) releases from enriched bone marrow cells. The purpose of the present study was to investigate skin wound healing and bone regenerative potential of sBMAC compared with arterial blood-derived PRF (Ar-PRF) and venous blood-derived PRF (Ve-PRF) in a skin defect and calvarial bone defect model in rabbits. GF release assays revealed significantly higher release of transforming growth factor-β (TGF-β), alkaline phosphatase (ALP), and osteocalcin (OCN) from sBMAC compared with PRFs for 24 h. In the skin defect animal model, sBMAC and PRFs promoted wound bed angiogenesis and re-epithelization in skin defect sites with higher collagen 1 synthesis, cytokeratin AE1/AE3, vascular endothelial growth factor (VEGF) expressions on week 1. Furthermore, a calvarial defect assay revealed that sBMAC promoted new bone formation with a sufficient bone marrow structure similar to that of intact bone in the bone defects. Ar-PRF achieved the second highest bone closure and new bone volume but yielded new bone that was thinner than the intact bone. In conclusion, sBMAC treatment might be a good option instead of PRF as an adjuvant therapy for both skin and bone tissue regeneration therapies in certain clinical situations. Impact statement Solid bone marrow aspirate concentrate (sBMAC) is new type of clot material prepared from bone marrow aspirate. The present study for the first time showed that sBMAC significantly accelerated both skin wound healing and bone formation in the defects, compared with conventional platelet-rich fibrin in rabbit experiment models.

Production Protocol Standardisation, Macroscopic and Histological Evaluation, and Growth Factor Quantification of Canine Leukocyte-and Platelet-Rich Fibrin Membranes

Leukocyte-Platelet-Rich Fibrin (L-PRF) is a second generation of platelet concentrates; it was widely used, as an autologous platelet-based wound sealant and hemostatic agent in surgical wound healing. L-PRF clot or membrane is a solid fibrin-based biomaterial, with a specific 3D distribution of the leukocytes and platelet aggregates. This biological scaffold releases growth factors (i.e., TGF- β1, PDGF-AB, VEGF) and matrix proteins (fibronectin, vitronectin and thrombospondin-1) during the healing process after the application. To the Authors' knowledge both in human and veterinary medicine a single standardised protocol was not reported. This prospective study aimed to apply Crisci's L-PRF protocol (which is characterised by 30” of acceleration, 2' at 2,700 rpm, 4' at 2,400 rpm, 3' at 3,000 rpm, and 36” of deceleration and arrest) sin canine species, evaluate macroscopically and histologically the L-PRF membranes obtained by using Wound Box to standardise the L-PRF protocol in dogs and to evaluate the clinical feasibility of using L-PRF membranes by quantitative in vitro analysis of growth factors over 7 days. One hundred twenty-eight dogs in good general condition with no history of recent NSAIDs intake (15 days of washout) and/or any medication or disease related to coagulation process met inclusion criteria and therefore were enrolled. We obtained 172 membrane L-PRF membranes by 86 dogs: half of them underwent macroscopic and histological analysis, the other 86 underwent ELISA analysis. The Wound Box gave a membrane of mean (±SD) length (cm), width (cm) and weight (g) of 1.97 (±0.89), 0.95 (±0.36), 0.46 (±0.20) respectively. Histology analysis confirmed a well-defined histoarchitecture with five layers reproducing density and distribution of blood cells in this biomaterial. Finally, the ELISA assay performed with 22 L-PRF membranes showed a peak in growth factors at 6 h after membrane production, followed by a decrease in release at 24 and 72 h and a second peak in release at 168 h after production. Statistical analysis of demographic variables (age, sex, and body condition score BCS) and the average of growth factors determined by the ELISA assay did not reveal statistical significance, except for the BCS factor compared with the production of VEGF. Our data confirm the effectiveness of this protocol and of Wound Box to produce L-PRF membranes in dogs.

Effect of advanced platelet-rich fibrin and concentrated growth factor on tissues around implants in maxillary anterior region

Aim

To assess the effect of advanced platelet-rich fibrin (APRF) and concentrated growth factor (CGF) on tissues around implants in the maxillary anterior region.

Settings and Design

This was a prospective clinical study.

Materials and Methods

Thirty subjects were divided into three groups with 10 dental implants in each group, i.e., Group 1: Control group, Group 2: Endosseous implant placement with APRF, and Group 3: Endosseous implant placement with CGF. The subjects were assessed at baseline (at the time of prosthesis placement), 2 weeks, 2 months, 6 months, and 1 year for modified sulcular bleeding index, periimplant probing depth, mucosal suppuration, bleeding on probing, crestal bone level as well as implant stability.

Statistical Analysis Used

Oneway Analysis of variance and Post hoc Bonferroni were the statistical tests used.

Results

The difference in implant stability at 2 months was significantly (P < 0.05) more among the control and CGF groups compared to APRF group. However; the crestal bone levels, periimplant probing depth, modified sulcular bleeding index, mucosal suppuration, and bleeding on probing were statistically non-significant (P > 0.05).

Conclusion

CGF and APRF accelerated osseointegration. Furthermore, they had a positive effect on stabilization values. However, CGF showed better results and with further clinical trials may show a positive effect on implant healing period.

Advanced platelet-rich fibrin (A-PRF) has an impact on the initial healing of gingival regeneration after tooth extraction

OBJECTIVES

Platelet-rich fibrin (PRF) is widely used in wound healing because it contains several growth factors, including vascular endothelial growth factor (VEGF). In this study, we investigated the effects of advanced PRF (A-PRF) in early-stage gingival regeneration after tooth extraction.

METHODS

Blood sample was collected from females beagle dogs (age: 12 months) before tooth extraction for A-PRF preparation. All animals were sacrificed by perfusion-fixation on postoperative days 1, 3, and 7. The upper jaws were prepared for hematoxylin and eosin staining and immunostaining (for CD34 and VEGF). The lower jaw samples were prepared for scanning electron microscope observations. Blood flow in the gingiva before and after surgery was measured using laser Doppler flowmetry.

RESULTS

In the A-PRF group, a large number of microvessels were observed in the gingival tissue on postoperative day 1. The microvessels in the control group were fewer and sparse. Regarding the vascular resin cast, a large number of new blood vessels were observed on postoperative day 1 in the A-PRF group. A stronger CD34-positive signal was obtained around the blood vessels in the A-PRF group than in the control group. Further, a strong VEGF-positive signal was observed in the perivascular tissue in the A-PRF group. Gingival blood flow was significantly higher in the A-PRF group after surgery.

CONCLUSION

A-PRF had a positive impact on angiogenesis in the gingiva through the induction of VEGF expression. Thus, A-PRF may be beneficial for gingival tissue regeneration.

Evaluation of the Use of Platelet-Rich Fibrin Xenologous Membranes Derived from Bubaline Blood in Canine Periodontal Defects

Periodontal disease is the most common oral disease in dogs. Platelet-rich fibrin (PRF) is widely utilized to facilitate soft and hard tissue healing and has been proposed in periodontal healing in small animal treatment. However, the quality and amount of autologous PRF is compromised in animals with systemic diseases. The present study aimed to evaluate the efficacy of xenologous bubaline blood-derived PRF (bPRF) on periodontal tissue healing in canine periodontal defects. Split-mouth design was employed in twenty dogs diagnosed with periodontal disease. The defects were divided randomly into two groups: the open-flap debridement (OFD)-treated group and the OFD with bPRF (OFD+bPRF) application group. Results demonstrated that gingival index and periodontal probing depth decreased significantly in the OFD+bPRF group compared with those treated with OFD alone. Application of bPRF in periodontal defects also promoted fibrous tissue formation, as confirmed by the marked increase in fibrosis score. bPRF application significantly increased COL1A1 and PDGFB mRNA levels at day 14 compared with the baseline. Taking this evidence together, bPRF provided a favorable therapeutic modality in canine periodontal defects. bPRF could be an alternative biomaterial for the treatment of periodontal defects in dogs.

Application of deproteinized bovine bone mineral as proangiogenic scaffold for alveolar bone formation in beagle dogs

Alveolar bone repair after tooth extraction is essential after oral surgeries. Various grafting materials are used to promote the regeneration of lost alveolar bone. This study analysed the morphological features of the tissue regeneration process using deproteinized bovine bone mineral (DBBM). DBBM was used to densely fill the extraction sockets in beagle dogs. Following resin casting of the vasculature, stereomicroscopy and scanning electron microscopy were used to observe blood vessels and hard tissues in haematoxylin and eosin-stained sections on postoperative days 14, 30 and 90 in conjunction with vascular endothelial growth factor (VEGF) immunostaining to evaluate alveolar bone vascularization. On day 14 post-operation, the DBBM granules tightly filled the extraction sockets, maintained alveolar margin height and formed a scaffold for aiding angiogenesis and new bone formation. On day 30, new bone formation was observed around the DBBM granules. By day 90, bone tissue regeneration progressed in both groups but was more pronounced in the DBBM group. Alveolar margin height was maintained in the DBBM group throughout the study. Furthermore, VEGF expression in the DBBM group was detected around newly formed bone. We conclude that DBBM acts as a suitable scaffold for new bone generation, as well as angiogenesis around healing alveolar bone, and that it has the potential to play a key role in vascularization and bone formation.

Advanced-platelet-rich fibrin extract promotes adipogenic and osteogenic differentiation of human adipose-derived stem cells in a dose-dependent manner in vitro

Advanced platelet-rich fibrin (A-PRF) is an autogenous biological material obtained from peripheral blood. A-PRF extract (A-PRFe) contains a high concentration of various cytokines that are increasingly appreciated for their roles in improving stem cell repairing function during tissue regeneration. However, the optimal A-PRFe concentration to stimulate stem cells is unknown. This study aimed to identify the optimal concentrations of A-PRFe to promote adipogenic and osteogenic differentiation of human adipose-derived stem cells (ASCs). We produced A-PRFe from A-PRF clots by centrifuging fresh peripheral blood samples and isolated and identified ASCs using surface CD markers and multilineage differentiation potential. Enzyme-linked immunosorbent assay (ELISA) showed the concentrations of several cytokines, including b-FGF, PDGF-BB, and others, increased gradually, peaked on day 7 and then decreased. Cell proliferation assays showed A-PRFe significantly stimulated ASC proliferation, and proliferation significantly increased at higher A-PRFe doses. The degree of adipogenic and osteogenic differentiation increased at higher A-PRFe concentrations in the culture medium, as determined by oil red O and alizarin red staining. Reverse transcription polymerase chain reaction (RT-PCR) showed that expression levels of genes related to adipogenic/osteogenic differentiation (PPARγ2, C/EBPα, FABP4, Adiponectin, and ALP, OPN, OCN, RUNX2), paracrine (HIF-1α, VEGF, IGF-2) and immunoregulation (HSP70, IL-8) function were higher in groups with a higher concentration of A-PRFe than in lower concentration groups. This study demonstrates that A-PRFe is ideal for use in ASC applications in regenerative medicine because it improves biological functions, including proliferation, adipogenic/osteogenic differentiation, and paracrine function in a dose-dependent manner.

Effects of Autologous Platelet-Rich Fibrin in Post-Extraction Alveolar Sockets: A Randomized, Controlled Split-Mouth Trial in Dogs with Spontaneous Periodontal Disease

Simple Summary

The effects of autologous platelet-rich fibrin were evaluated in dogs with spontaneous periodontal disease after tooth extraction. Both radiographic and histological findings attributed to the platelet-rich fibrin a potential ability to stimulate the natural process of tissue healing and regeneration of bone and soft tissues. Platelet-rich fibrin could, therefore, be considered as a simple and effective therapeutic aid in the management of post-extraction socket healing in dogs.

Abstract

Periodontal disease (PD) is a common inflammatory condition in dogs; in severe stages, dental extraction is frequently required. Platelet-rich fibrin (PRF) has been used in human oral surgical procedures and has been experimentally tested on post-extraction sockets in healthy dogs. This is the first split-mouth, randomized, controlled trial designed to compare post-extractive alveolar socket healing with and without topical application of PRF in canine spontaneous PD. Clinical evaluation, radiographic density, and histological scores for inflammation and regeneration were assessed at recruitment (T0) and after a three-week follow up (T1) on 12 dogs, for a total of 31 pairs of sockets. No complications or clinically evident differences between the treated sites and the control sites were observed. Comparing the radiographic densities of the extraction sites measured at T0 and T1, a significant enhancement was observed within the PRF group, but not within control group. The histological score decreased significantly from T0 to T1 within group PRF, but not within the control group; at T1, the PRF group showed a significantly lower histological score than the control group. These findings suggest that PRF could be able to stimulate the natural process of tissue healing and regeneration of post-extraction sites in dogs with spontaneous periodontal disease (PD).

Molecular and Cellular Aspects of Socket Healing in the Absence and Presence of Graft Materials and Autologous Platelet Concentrates: a Focused Review

OBJECTIVES

The present manuscript aims to critically detail the physiologic process of socket healing, in the absence or presence of grafting materials or platelet concentrates, addressing the associated molecular and cellular events that culminate in the restoration of the lost tissue architecture and functionality.

MATERIAL AND METHODS

An electronic search in the National Library of Medicine database MEDLINE through its online site PubMed and Web of Science from inception until May 2019 was conducted to identify articles concerning physiologic process of socket healing, in the absence or presence of grafting materials or platelet concentrates. The search was restricted to English language articles without time restriction. Additionally, a hand search was carried out in oral surgery, periodontology and dental implants related journals.

RESULTS

In total, 122 literature sources were obtained and reviewed. The detailed biological events, at the molecular and cellular level, that occur in the alveolus after tooth extraction and socket healing process modulated by grafting materials or autologous platelet concentrates were presented as two entities.

CONCLUSIONS

Tooth extraction initiates a convoluted set of orderly biological events in the alveolus, aiming wound closure and socket healing. The healing process comprises a wide range of events, regulated by the interplay of cytokines, chemokines and growth factors that determine cellular recruitment, proliferation and differentiation in the healing milieu, in a space- and time-dependent choreographic interplay. Additionally, the healing process may further be modulated by the implantation of grafting materials or autologous platelet concentrates within the tooth socket, aiming to enhance the regenerative outcome.