Advanced platelet-rich fibrin: a new concept for cell-based tissue engineering by means of inflammatory cells

Platelet-rich fibrin: Basics of biological actions and protocol modifications

Platelet-rich fibrin (PRF) represents second generation of platelet concentrates, which has gained increasing awareness in recent years for regenerative procedures. This biologic additive is completely autologous, easy to prepare, has minimal expense, and possesses prolonged growth factor release, together with several other advantages over traditionally prepared platelet concentrates. Since its introduction, various protocols for PRF preparation have been proposed with different amounts of growth factors and other biomolecules necessary for wound healing. However, reference data about potential effect of some PRF components on hard and soft tissue healing are still conflicting. The current article intends to clarify the relevant advances about physiological role of certain PRF components and to provide insight into the new developmental approach. Also, this review summarizes the evolution of platelet concentrates and biologic properties of different modifications of PRF procedure.

Impact of g force and timing on the characteristics of platelet-rich fibrin matrices

Recently, new centrifugation protocols for the preparation of platelet-rich fibrin (PRF) have been introduced in an attempt to further improve the beneficial impact of these 2nd generation platelet concentrate membranes. This in-vitro study aimed to compare the biological and physical characteristics of three types of PRF membranes using two different centrifuges with adapted relative centrifugal forces (RCF): leucocyte- and platelet-rich fibrin, advanced platelet-rich fibrin, and advanced platelet-rich fibrin⁺. Release of growth factors, macroscopic dimensions, cellular content and mechanical properties of the respective membranes, prepared from blood of the same individual were explored. Furthermore, the impact of timing (blood draw-centrifugation and centrifugation-membrane preparation) was assessed morphologically as well as by electron microscopy scanning. No statistically significant differences amongst the three PRF modifications could be observed, neither in their release of growth factors or the cellular content, nor in clot/membrane dimensions. The difference between both centrifuges were negligible when the same g-force was used. A lower g-force, however, reduced membrane tensile strength. Timing in the preparation process had a significant impact. Adaptation of RCF only had a minimal impact on the final characteristics of PRF membranes.

Will stem cells from fat and growth factors from blood bring new hope to female patients with reproductive disorders?

Female reproductive system disorders (FRSD) with or without infertility are prevalent women's health problems with a variety of treatment approaches including surgery and hormone therapy. It currently considering to sub-branch of regenerative medicine including stem cells or growth factors injection-based delivery treatment might be improved female reproductive health life. The most common products used for these patients treatment are autologous cell or platelet-based products from patients, including platelet-rich plasma, plasma rich in growth factor, platelet-rich fibrin, and stromal vascular fraction. In this review, we discuss each of the above products used in treatment of FRSD and critically evaluate the clinical outcome.

Biologization of Pcl-Mesh Using Platelet Rich Fibrin (Prf) Enhances Its Regenerative Potential In Vitro

INTRODUCTION

Resorbable synthetic scaffolds are promising for different indications, especially in the context of bone regeneration. However, they require additional biological components to enhance their osteogenic potential. In addition to different cell types, autologous blood-derived matrices offer many advantages to enhance the regenerative capacity of biomaterials. The present study aimed to analyze whether biologization of a PCL-mesh coated using differently centrifuged Platelet rich fibrin (PRF) matrices will have a positive influence on primary human osteoblasts activity in vitro. A polymeric resorbable scaffold (Osteomesh, OsteoporeTM (OP), Singapore) was combined with differently centrifuged PRF matrices to evaluate the additional influence of this biologization concept on bone regeneration in vitro. Peripheral blood of three healthy donors was used to gain PRF matrices centrifuged either at High (710× g, 8 min) or Low (44× g, 8 min) relative centrifugal force (RCF) according to the low speed centrifugation concept (LSCC). OP-PRF constructs were cultured with pOBs. POBs cultured on the uncoated OP served as a control. After three and seven days of cultivation, cell culture supernatants were collected to analyze the pOBs activity by determining the concentrations of VEGF, TGF-β1, PDGF, OPG, IL-8, and ALP- activity. Immunofluorescence staining was used to evaluate the Osteopontin expression of pOBs. After three days, the group of OP+PRFLow+pOBs showed significantly higher expression of IL-8, TGF-ß1, PDGF, and VEGF compared to the group of OP+PRFHigh+pOBs and OP+pOBs. Similar results were observed on day 7. Moreover, OP+PRFLow+pOBs exhibited significantly higher activity of ALP compared to OP+PRFHigh+pOBs and OP+pOBs. Immunofluorescence staining showed a higher number of pOBs adherent to OP+PRFLow+pOBs compared to the groups OP+PRFHigh+pOBs and OP+pOBs. To the best of our knowledge, this study is the first to investigate the osteoblasts activity when cultured on a PRF-coated PCL-mesh in vitro. The presented results suggest that PRFLow centrifuged according to LSCC exhibits autologous blood cells and growth factors, seem to have a significant effect on osteogenesis. Thereby, the combination of OP with PRFLow showed promising results to support bone regeneration. Further in vivo studies are required to verify the results and carry out potential results for clinical translation.

Activation of Human Osteoblasts via Different Bovine Bone Substitute Materials With and Without Injectable Platelet Rich Fibrin in vitro

INTRODUCTION

The aim of the in vitro study was to compare the effect of four bovine bone substitute materials (XBSM) with and without injectable platelet-reach fibrin for viability and metabolic activity of human osteoblasts (HOB) as well as expression of alkaline phosphatase (ALP), bone morphogenetic protein 2 (BMP-2), and osteonectin (OCN).

MATERIALS AND METHODS

Cerabone® (CB), Bio-Oss® (BO), Creos Xenogain® (CX) and MinerOss® X (MO) ± i-PRF were incubated with HOB. At day 3, 7, and 10, cell viability and metabolic activity as well as expression of ALP, OCN, and BMP-2, was examined.

RESULTS

For non-i-PRF groups, the highest values concerning viability were seen for CB at all time points. Pre-treatment with i-PRF increased viability in all groups with the highest values for CB-i-PRF after 3 and 7 and for CX-i-PRF after 10 days. For metabolic activity, the highest rate among non-i-PRF groups was seen for MO at day 3 and for CB at day 7 and 10. Here, i-PRF groups showed higher values than non-i-PRF groups (highest values: CB + i-PRF) at all time points. There was no difference in ALP-expression between groups. For OCN expression in non-i-PRF groups, CB showed the highest values after day 3, CX after day 7 and 10. Among i-PRF-groups, the highest values were seen for CX + i-PRF. At day 3, the highest BMP-2 expression was observed for CX. Here, for i-PRF groups, the highest increase was seen for CX + i-PRF at day 3. At day 7 and 10, there was no significant difference among groups.

CONCLUSION

XBSM sintered under high temperature showed increased HOB viability and metabolic activity through the whole period when compared to XBSM manufactured at lower temperatures. Overall, the combination of XBSM with i-PRF improved all cellular parameters, ALP and BMP-2 expression at earlier stages as well as OCN expression at later stages.

An Injectable Fibrin Scaffold Rich in Growth Factors for Skin Repair

Platelet aggregates, such as PRP, PRF, and CGF, have been used alone or in combination with other grafting materials to enhance restoration outcomes. The process for preparing these autografting materials requires two-step centrifugation or specific centrifuges. In this study, we obtained an injectable fibrin scaffold (IFS) rich in growth factors by one-step centrifugation of whole blood from rabbits. The purpose of this study is to introduce some characteristics of IFS. This scaffold was characterized using various techniques, including Masson's trichrome staining, scanning electron microscopy, porosity measurements, and cell counting. The sustained release of growth factors, including PDGF, VEGF, TGF-β1, IGF, FGF, and EGF, was quantified using ELISA assay. The obtained IFS was tested for its effects on cell proliferation, extracellular matrix deposition, and full-thickness skin defect repair. The prepared IFS is characterized by a loose fibrin network structure with white blood cells and platelets that slowly release growth factors and can promote the healing of skin defects via the promotion of cell proliferation, collagen deposition, and tissue revascularization. In addition, its liquid properties and porous structure are conducive to its application as a therapeutic component in tissue engineering.

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.

Novel applications of platelet concentrates in tissue regeneration (Review)

Numerous studies have explored the suitability of biocompatible materials in regenerative medicine. Platelet concentrates are derived from centrifuged blood and are named according to their biological characteristics, such as platelet-rich plasma, platelet-rich fibrin and concentrated growth factor. Platelet concentrates have gained considerable attention in soft and hard tissue engineering. Indeed, multiple components of autologous platelet concentrates, such as growth factors, fibrin matrix and platelets, serve essential roles in wound healing. Current studies are focused on cutting-edge strategies to meet the requirements for tissue restoration by improving the properties of autologous platelet concentrates. In the present review, applications of platelet concentrates for tissue engineering are discussed, presenting a selection of recent advances and novel protocols. In addition, several aspects of these strategies, such as the advantages of lyophilized platelet concentrates and the combination of platelet concentrates with biomaterials, stem cells or drugs are discussed. The present review aims to summarize novel strategies using platelet concentrates to improve the outcomes of wound healing.

Tensile strength assay comparing the resistance between two different autologous platelet concentrates (leucocyte-platelet rich fibrin versus advanced-platelet rich fibrin): a pilot study

Background

Since the leucocyte-platelet rich fibrin (L-PRF) was published in 2001, many studies have been developed, analyzing its properties, and also verifying new possibilities to improve it. Thereby, it emerges the advanced-platelet rich fibrin (A-PRF) with a protocol that optimizes the properties obtained by the L-PRF. Nonetheless, there is a gap in the literature to landmark the evolutive process concerning the mechanical properties in specific the resistance to tensile strength which consequently may influence the time for membrane degradation. Thus, this study had the goal to compare the resistance to the traction of membranes produced with the original L-PRF and A-PRF protocols, being the first to this direct comparison.

Findings

The harvest of blood from a healthy single person, with no history of anticoagulant usage. We performed the protocols described in the literature, within a total of 13 membranes produced for each protocol (n = 26). Afterward, the membranes were prepared and submitted to a traction test assessing the maximal and the average traction achieved for each membrane. The data were analyzed statistically using the unpaired t test. Regarding average traction, A-PRF obtained a value of 0.0288 N mm⁻² and L-PRF 0.0192 N mm⁻² (p < 0.05 using unpaired t test). For maximal traction, A-PRF obtained 0.0752 N mm⁻² and L-PRF 0.0425 N mm⁻² (p < 0.05 using unpaired t test).

Conclusion

With this study, it was possible to conclude that indeed A-PRF has a significative higher maximal traction score and higher average traction compared to L-PRF, indicating that it had a higher resistance when two opposing forces are applied.

Platelet-rich fibrin, preparation and use in dermatology

The goal of these recommendations is to provide a framework to practitioners for implementing useful, evidence-based recommendations for the preparation of platelet-rich fibrin (PRF) and its use in various dermatological indications. The Indian Association of Dermatologists, Venereologists and Leprologists (IADVL) assigned the task of preparing these recommendations to its taskforce on platelet-rich plasma. A comprehensive literature search was done in the English language on the PRF across multiple databases. The grade of evidence and strength of recommendation was evaluated on the GRADE framework (Grading of Recommendation, Assessment, Development and Evaluation). A draft of clinical recommendations was developed on the best available evidence which was also scrutinized and critically evaluated by the IADVL Academy of Dermatology. Based on the inputs received, this final consensus statement was prepared. A total of 40 articles (meta-analyses, prospective and retrospective studies, reviews [including chapters in books] and case series) were critically evaluated and the evidence thus gathered was used in the preparation of these recommendations. This expert group recommends use of A-PRF+ protocol, that is (200 g for 8 min) for preparation of solid PRF and C-PRF protocol (700 g for 8 min) for liquid PRF. Swing out bucket model of centrifuge or the horizontal centrifuge is recommended for preparation of both PRF, and liquid PRF. Centrifugation must begin within 90–120 s of drawing of blood. PRF can be used in various indications for skin rejuvenation and nonhealing ulcers as either monotherapy or in combination with other therapies.

Effect of Carbonate Apatite Hydrogel-Advanced Platelet-Rich Fibrin Injection on Osteoblastogenesis during Orthodontic Relapse in Rabbits

Objective  This study aimed to determine the effect of carbonate apatite (CHA) hydrogel-aPRF on osteoblastogenesis during relapse in rabbits.

Materials and Methods  Forty-five rabbits were divided into three groups ( n = 15): the control, CHA, and CHA-autologous platelet-rich fibrin (aPRF) groups. An open-coil spring was compressed between brackets to distalize the lower incisors of the rabbits by delivering a force of 50 cN for 1 week. The new position of the teeth was retained for 14 days, and CHA hydrogel-aPRF was injected every 7 days. The appliances were then debonded to allow relapse. On days 0, 3, 7, 14, and 21 after debonding, transforming growth factor (TGF)-β1 and bone morphogenetic protein (BMP)-2 expression was examined using immunohistochemistry staining and Runx-2 levels were analyzed by enzyme-linked immunosorbent assay. The data collected were analyzed using analysis of variance and a post hoc Tukey’s test ( p < 0.05).

Results  Histomorphometric analysis revealed that TGF-β1 expression in the CHA-aPRF group is statistically higher than that in other groups on days 0, 3, and 7 after debonding ( p < 0.05). BMP-2 expression in the CHA-aPRF group was also statistically higher than that in the other groups on days 3, 14, and 21 after debonding ( p < 0.05). ELISA showed that Runx-2 levels are slightly higher in the CHA-aPRF group than in the other groups ( p > 0.05).

Conclusion  Although injection of CHA-aPRF aids in osteoblastogenesis associated with enhancing TGF-β1 and BMP-2 expressions, it does not significantly upregulate Runx-2 levels.

Histological and Histomorphometric Evaluation of Applying a Bioactive Advanced Platelet-Rich Fibrin to a Perforated Schneiderian Membrane in a Maxillary Sinus Elevation Model

Background

Schneiderian membrane (SM) perforation is a major complication of maxillary sinus elevation with simultaneous bone grafting, yet under this scenario there is no standard biomaterial that maximizes favorable tissue healing and osteogenic effects.

Purpose

To compare the effect of advanced platelet-rich fibrin (A-PRF) and collagen membrane (CM) on a perforated SM with simultaneous bone grafting in a maxillary sinus elevation model.

Materials and Methods

After perforation of the SM was established, 24 animals were randomly divided into two groups: (i) group CM: CM and deproteinized bovine bone mineral (DBBM) (n = 12), (ii) group A-PRF: A-PRF and DBBM (n = 12). Radiographic and histological evaluations were performed at 1 and 4 weeks post-operation.

Results

At 1 week, an intact SM was found in group A-PRF. At each time point, the number of inflammatory cells at the perforated site was higher in group CM, and the area of new osteoid formation was significantly greater in group A-PRF (p < 0.0001). At 4 weeks, the osteogenic pattern was shown as from the periphery to the center of the sinus cavity in group A-PRF.

Conclusion

The higher elasticity, matching degradability, and plentiful growth factors of A-PRF resulted in a fully repaired SM, which later ensured the two osteogenic sources from the SM to generate significant new bone formation. Thus, A-PRF can be considered to be a useful bioactive tissue-healing biomaterial for SM perforation with simultaneous bone grafting.

Implant site preparation application of injectable platelet-rich fibrin for vertical and horizontal bone regeneration: A clinical report

Guided bone regeneration (GBR) using a combined injectable platelet-rich fibrin (i-PRF), leukocyte- and platelet-rich fibrin (L-PRF) and biocompatible bone substitute materials, is a convenient and effective method to augment a combined vertical and horizontal bone defect. This approach can create sufficient bone quality and quantity for implant surgical sites. A 55-year-old Asian woman presented with a severe bone defect in posterior mandible. The edentulous mandibular alveolar ridge was severely resorbed vertically and horizontally.  A GBR procedure using i-PRF and L-PRF combined with particulate bone graft was performed. Postoperative cone beam computed tomography scans, 8 months after the augmentation, revealed a large regeneration of the alveolar bone sufficient for implant placement. A combination i-PRF/L-PRF and particulate bone graft may provide biologically active molecules as well as a scaffold for osteogenesis. This treatment protocol may be a viable option for a large bone defect required augmentation prior to implant placement.

Different Regenerative Responses of Two Platelet Concentrates in the Treatment of Human Periodontal Infrabony Defects: A Clinico-Radiographic Study

Background:

Platelet concentrates usage in the treatment of intrabony defects has been improved due to advancement of research. Many generation of platelet concentrates were used, but research regarding advanced platelet-rich fibrin (A-PRF) regarding periodontal treatment is scanty.

Aim:

The purpose of the study was to evaluate and compare PRF and A-PRF in the treatment of human periodontal infrabony defects (IBDs) both clinically and radiographically.

Materials and Methods:

Twenty-eight patients having IBDs were divided into Group A (PRF) and Group B (A-PRF). Clinical parameters such as plaque index, gingival index, probing pocket depth (PPD), and clinical attachment level (CAL) were recorded at baseline and 3 and 6 months and radiographic examination at baseline and 6 months were also recorded to evaluate defect fill, resolution, and change in the alveolar crest height. Then, all the data were tabulated in a Microsoft Excel sheet and subjected to statistical analysis. Mean and standard deviations of the clinical and radiographic parameters were calculated, and unpaired t-test was performed to assess intergroup comparison at different time intervals.

Results:

Intragroup comparison showed statistically significant improvement in PPD and CAL at 3 and 6 months while statistically significant improvement was observed in mean defect fill and resolution in Group B.

Conclusion:

Individually, both the materials have shown promising results. However, statistically, PRF group (Group A) showed better treatment outcome in terms of bone fill and A-PRF group (Group B) in terms of soft tissue healing.

Evaluation of 24 protocols for the production of platelet-rich fibrin

Background

The aim of this study was to evaluate 24 protocols for the production of platelet rich fibrin (PRF) produced via horizontal centrifugation to better understand cell separation following protocols at various times and speeds.

Methods

All protocols were compared utilizing a recent method to quantify cells in PRF in 1 mL sequential layers pipetted from the upper layer downwards until all 10 mL were harvested. In total, 960 complete blood counts (CBCs) were investigated. Both solid and liquid-based PRF protocols were investigated following 24 protocols involving 6 relative centrifugal force (RCF) values (100, 200, 400, 700, 1000 and 1200g) at 4 centrifugation times (3, 5, 8 and 12 min).

Results

In general, platelets could more easily accumulate in the upper 4 layers when compared to leukocytes owing to their lower cellular density. Protocol time seemed to have a greater impact on the final cell layer separation when compared to the effect of speed. Protocols of greater than 8 min at 400g led to no leukocyte accumulation in the upper PRF layers (found specifically within the buffy coat). Protocols at or below 200g were unable to effectively accumulate platelets/leukocytes. The optimal centrifugation speed and time for solid-PRF ranged between 400 and 700g for 8 min. It was noted that variability in patient baseline platelet/leukocyte/erythrocyte counts (hematocrit) significantly affected cell layer separation. This finding was more pronounced at lower centrifugation speeds.

Conclusions

Within the investigated ranges, a protocol of 700g for 8 min presented the highest yield of platelets/leukocytes evenly distributed throughout the upper PRF layers.

Platelet-rich plasma-Where do we stand today? A critical narrative review and analysis

"Sometimes you have to travel a long way to find what is near." This quote by Paulo Coelho stands true for platelet-rich plasma (PRP) as we know of it today. Large strides have been made to understand this "youth" in blood, but there still seems a long way to go in our understanding of it. Despite advances, clarity in its preparation, biology, and the properties of the final product still remains elusive. The concepts of an ideal number or concentration of platelets in the final enriched plasma, best devices to prepare PRP, an ideal hardware, standard parameters for its preparation, the need for its activation or buffering of the final preparation or whether anticoagulants should be used or not, have evolved, since it was first described. The authors present an analysis of PRP present day status and its usefulness in field of medicine with a review of published literature from "Medline" (via "PubMed"), "Cochrane," the Virtual Health Library, and Google Scholar related to PRP, its biology, types, and classifications, preparation, and use.

Injectable platelet-rich fibrin for facial rejuvenation: A prospective, single-center study

BACKGROUND

Autologous platelet-derived preparations have been used in many surgical fields to improve healing outcomes, with benefits reported in several aesthetic indications.

AIMS

This single-center, prospective, uncontrolled study evaluated the efficacy of injectable platelet-rich fibrin (i-PRF) for facial skin rejuvenation using an objective skin analysis system and validated patient-reported outcome measures.

PATIENTS/METHODS

PRF^® PROCESS system technology was used to prepare i-PRP. Eleven healthy female individuals were included in the study and over 3-months received monthly intradermal injections of i-PRF in 3 facial regions: malar areas (1 mL each side), nasolabial fold (0.5 mL each side), and upper lip skin above the vermilion border (1 mL). The efficacy of the procedures was assessed by objective skin analysis (VISIA^® ) and a subjective patient-reported outcome (FACE-Q) assessment at baseline and after 3 months.

RESULTS

A significant improvement in skin surface spots (P = .01) and pores (P = .03) was seen at 3-months follow-up. Other variables, such as skin texture, wrinkles, ultraviolet spots, and porphyrins, showed a numerical improvement. FACE-Q scales that measure satisfaction with appearance all showed a significant improvement from baseline, including satisfaction with skin (P = .002), satisfaction with facial appearance (P = .025), satisfaction with cheeks (P = .001), satisfaction with lower face and jawline (P = .002), and satisfaction with lips (P = .04). No major adverse effects were reported.

CONCLUSIONS

A series of three i-PRF injections resulted in significant rejuvenation of the face skin at 3-month follow-up, as shown by improved skin analysis parameters and patient self-assessment scores.

A Systematic Critical Appraisal of the Methodological Quality of Systematic Reviews on the Effect of Autologous Platelet Concentrates in the Treatment of Periodontal Intraosseous Defects

The present study aimed to perform a systematic critical appraisal of the methodological quality of systematic reviews (SRs) on the effect of autologous platelet concentrates (APCs) in the treatment of periodontal intraosseous defects and to provide a synthesis of the main clinical findings available. An electronic and hand search was performed up to February 2020; 14 systematic reviews of randomized controlled trials (RCTs), of which 11 were meta-analyses, were included. Only one SR fully satisfied all 11 items of the AMSTAR (“A Measurement Tool to Assess Systematic Reviews”) checklist for methodological quality evaluation, 3 SRs were classified of high quality, 8 of medium quality, and 2 of low quality. There is some evidence on the beneficial additive effect of APCs in the surgical treatment of intraosseous defects when used alone or in combination with bone grafts. APCs did not show any advantage when used together with guided tissue regeneration (GTR) or enamel matrix derivative (EMD). Undertaking SRs which adhere to rigorous standards and protocols is strongly recommended. There are increasing data on the positive adjunctive effect of APCs in the surgical treatment of intraosseous defects but, due to the heterogeneity of the available primary studies, the quality of evidence remains rather low and further long-term well-designed RCTs are encouraged.

Cytokine Expression Pattern and Protein-Protein interaction network analysis of Leucocyte Rich Platelet Rich Fibrin and Injectable Form of Platelet Rich Fibrin

PURPOSE

Platelet-rich fibrin (PRF) such as leucocyte-rich PRF (L-PRF) and injectable form of PRF (i-PRF) are widely used in various surgical applications. L-PRF- and i-PRF-derived cytokine variations and functional pathways are still unexplored. The aim of the study was to evaluate the expression pattern of Th1-, Th2-, and Th17-related cytokines by L-PRF and i-PRF under in vitro.

METHODS

Cytokine levels were evaluated using multi-analyte ELISArray kit. Using elevated level of cytokines, the protein-protein interaction and pathway were predicted by computational method.

RESULTS

The expressed cytokine levels were higher in L-PRF than in i-PRF. Specifically in L-PRF, IL8, IL2, IL6, and IL1A were expressed abundantly, whereas IL4, IL10, and IL6 were significantly high in i-PRF. Furthermore, protein-protein interaction (PPI) networks (cytokine-cytokine interactions) and pathway analyses were predicted using higher-order cytokines. PPI networks and gene ontology enrichment analysis showed functional variations between L-PRF and i-PRF. Kyoto Encyclopedia of Gene and Genome pathway analysis found that L-PRF mediates NF-k B signaling, Toll-like receptor signaling (TLR), and MAPK signaling via T-cell receptor signaling pathway. i-PRF is significantly involved in JAK-STAT signaling pathway through upregulation of STAT1.

CONCLUSION

Our study concludes that L-PRF and i-PRF act via different pathways that confirm functional variations between them. Therefore, we speculate that L-PRF may be effective in acute phase of chronic wounds such as in diabetes mellitus and immunocompromised patients whereas i-PRF may have a better outcome in acute wounds.

Mechanical, chemical, structural analysis and comparative release of PDGF-AA from L-PRF, A-PRF and T-PRF - an in vitro study

BACKGROUND

Platelet concentrates have been popularly used in regenerative periodontal therapy as they are autologous in origin and they provide a supernatural concentration of platelets, growth factors and leukocytes. The release profile of various growth factors is considered important during the various phases of wound healing with the most important being the inflammatory phase where the release of the growth factors help in recruitment of cells and in collagen production. With the more recent modifications of PRF namely A-PRF and T-PRF, the mechanical and chemical degradation properties have also improved. The aim of the present study was to correlate the release profile of PDGF-AA from various forms of platelet concentrates (L-PRF, A-PRF, T-PRF) based on their mechanical and chemical properties.

METHODS

Blood samples were drawn from 2 male and 3 female systemically healthy patients between 20 and 25 years of age who were about to undergo periodontal regeneration for PRF preparation. The blood sample was immediately centrifuged using a table top centrifuge (Remi R4C) at 1060 rpm (208 x g) for 14 min for A-PRF preparation, 1960 rpm (708 x g) for 12 min for L-PRF preparation and 1960 rpm (708 x g) for 12 min in titanium tubes for T-PRF preparation. Tensile test was performed using universal testing machine. The in vitro degradation test of the prepared PRF membranes were conducted by placing the PRF membrane in 10 ml of pH 7.4 PBS on an orbital shaker set at 50 rpm. SEM evaluation of the PRF membrane was done under both low and high magnification. In order to determine the amount of released growth factor PDGF-AA at 15 min, 60 min, 8 h, 1 day, 3 days, and 10 days, samples were placed into a shaking incubator at 37 °C to allow for growth factor release into the culture media.

RESULTS

On comparing the three PRF membranes, it was found that T-PRF contained the maximum tensile strength (404.61 ± 5.92 MPa) and modulus of elasticity (151.9 ± 6.92 MPa). Statistically significant differences between the three groups were found on comparing the groups for their mechanical properties. In the degradation test, it was found that the maximum amount of degradation was found in L-PRF (85.75%), followed by A-PRF (84.18%) and the least was found in T-PRF (82.27%). T-PRF released the highest amount of PDGF-AA (6060.4 pg/ml) at early time points when compared to A-PRF (5935.3 pg/ml). While T-PRF had rapid release of PDGF-AA, A-PRF had a sustained release of growth factors released at later time points.

CONCLUSION

Results from the present study indicate that A-PRF is the most favourable form of platelet concentrate in regenerative periodontal therapy as it has a sustained release of growth factors over time.

Platelet-Derived Products in Veterinary Medicine: A New Trend or an Effective Therapy?

Platelet-derived products (PDPs) have gained popularity, mainly due to their high concentrations of bioactive molecules such as growth factors and cytokines, which play important roles in tissue healing and regeneration. PDPs are obtained through minimally invasive procedures and their therapeutic effect has been widely recognized. In veterinary medicine, however, the lack of standard protocols to generate PDPs is a major hurdle for assessing the clinical relevance of PDP-based therapies and for their widespread usage. The aim of this review is to analyze the technical and scientific specificities of PDPs in terms of preparation methodologies, classification categorization, nomenclature, and biological proprieties to advance their future biotechnological potential in veterinary contexts.

Advanced Platelet-Rich Fibrin in Periosteal Inversion Technique for Root Coverage: A Case Report

INTRODUCTION

The management of gingival recession associated with esthetic concerns and root hypersensitivity is challenging, and its sequelae is based on the assessment of etiological factors and the degree of tissue involvement. Procedures using pedicle flaps, free soft tissue grafts, combination of pedicle flaps with grafts, barrier membranes, and the use of platelet concentrates are all effective for this purpose. The use of the third-generation platelet concentrate, advanced platelet-rich fibrin (A-PRF), has evolved as a promising regenerative material for root coverage procedure wherein it acts as a scaffold and also accelerates wound healing due to its dense fibrin meshwork.

CASE PRESENTATION

This case report, discusses treating an isolated maxillary Miller Class I recession in a 25-year-old male patient by a periosteal inversion method along with the A-PRF membrane. A partial thickness flap was reflected; periosteum was inverted; and an A-PRF membrane was placed over the denuded root surface which aided in enhanced regeneration; 100% root coverage was obtained as seen in follow-up visits.

CONCLUSION

The periosteal inversion technique along with an A-PRF membrane seems to be a novel approach in managing an isolated Miller Class I maxillary gingival recession.

Evaluation of Histological and pH Changes in Platelet-Rich Fibrin and Platelet-Rich Fibrin Matrix: A In vitro Study

Background:

The autologous platelet concentrates (PCs), such as platelet-rich fibrin (PRF) and platelet-rich fibrin matrix (PRFM), are processed through different centrifugation protocols, which can affect their biological properties and in turn influence treatment outcome. The pH value can influence the process of wound healing directly or indirectly. Hence, a study was conducted to evaluate fibrin network pattern, initial pH of obtained matrix, and its changes during degradation matrix and to determine platelet and leukocyte count in PRF and PRFM.

Materials and Methods:

Blood from the volunteers was collected in blood vacutainers for processing PRF and PRFM. It was centrifuged as per the standard protocol. Serum from PRF and PRFM was subjected for analysis of platelet and leucocyte concentration using Hemo-Analyzer. The pH of PRF and PRFM were evaluated over 5 days using a pH meter. PRF and PRFM were subjected to histological and scanning electron microscopic analysis.

Results:

There was no significant variation in the platelet and leukocyte count between PRF and PRFM. A steady rise in the level of pH with respect to PRFM was observed, whereas there was a decrease in the pH levels in PRF. Fibrin network was denser in PRF compared to PRFM.

Conclusion:

The PCs undergo variation in pH upon degradation. Formation of fibrin matrix is influenced by the method of preparation. Fibrin pattern is crucial to facilitate adhesion of cells and transport of nutrients to enable proliferation and differentiation of mesenchymal cells and better wound healing.

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).

The Platelet Concentrates Therapy: From the Biased Past to the Anticipated Future

The ultimate goal of research on platelet concentrates (PCs) is to develop a more predictable PC therapy. Because platelet-rich plasma (PRP), a representative PC, was identified as a possible therapeutic agent for bone augmentation in the field of oral surgery, PRP and its derivative, platelet-rich fibrin (PRF), have been increasingly applied in a regenerative medicine. However, a rise in the rate of recurrence (e.g., in tendon and ligament injuries) and adverse (or nonsignificant) clinical outcomes associated with PC therapy have raised fundamental questions regarding the validity of the therapy. Thus, rigorous evidence obtained from large, high-quality randomized controlled trials must be presented to the concerned regulatory authorities of individual countries or regions. For the approval of the regulatory authorities, clinicians and research investigators should understand the real nature of PCs and PC therapy (i.e., adjuvant therapy), standardize protocols of preparation (e.g., choice of centrifuges and tubes) and clinical application (e.g., evaluation of recipient conditions), design bias-minimized randomized clinical trials, and recognize superfluous brand competitions that delay sound progress. In this review, we retrospect the recent past of PC research, reconfirm our ultimate goals, and discuss what will need to be done in future.

Red and Yellow Injectable Platelet-Rich Fibrin Demonstrated Differential Effects on Periodontal Ligament Stem Cell Proliferation, Migration, and Osteogenic Differentiation

The biological benefits of using two fractions derived from injectable platelet-rich fibrin (i-PRF) in bone regeneration remain unclear. Thus, the current study examined two fractionation protocols producing yellow i-PRF and red i-PRF on periodontal ligament stem cells (PDLSCs). The i-PRF samples from five donors were harvested from two different levels, with and without a buffy coat layer, to obtain red and yellow i-PRF, respectively. The PDLSCs were isolated and characterized before their experimental use. The culture medium in each assay was loaded with 20% of the conditioned medium containing the factors released from the red and yellow i-PRF. Cell proliferation and cell migration were determined with an MTT and trans-well assay, respectively. Osteogenic differentiation was investigated using alkaline phosphatase and Alizarin red staining. The efficiency of both i-PRFs was statistically compared. We found that the factors released from the red i-PRF had a greater effect on cell proliferation and cell migration. Moreover, the factors released from the yellow i-PRF stimulated PDLSC osteogenic differentiation earlier compared with the red i-PRF. These data suggest that the red i-PRF might be suitable for using in bone regeneration because it induced the mobilization and growth of bone regenerative cells without inducing premature mineralization.

3D Printing Approach in Dentistry: The Future for Personalized Oral Soft Tissue Regeneration

Three-dimensional (3D) printing technology allows the production of an individualized 3D object based on a material of choice, a specific computer-aided design and precise manufacturing. Developments in digital technology, smart biomaterials and advanced cell culturing, combined with 3D printing, provide promising grounds for patient-tailored treatments. In dentistry, the "digital workflow" comprising intraoral scanning for data acquisition, object design and 3D printing, is already in use for manufacturing of surgical guides, dental models and reconstructions. 3D printing, however, remains un-investigated for oral mucosa/gingiva. This scoping literature review provides an overview of the 3D printing technology and its applications in regenerative medicine to then describe 3D printing in dentistry for the production of surgical guides, educational models and the biological reconstructions of periodontal tissues from laboratory to a clinical case. The biomaterials suitable for oral soft tissues printing are outlined. The current treatments and their limitations for oral soft tissue regeneration are presented, including "off the shelf" products and the blood concentrate (PRF). Finally, tissue engineered gingival equivalents are described as the basis for future 3D-printed oral soft tissue constructs. The existing knowledge exploring different approaches could be applied to produce patient-tailored 3D-printed oral soft tissue graft with an appropriate inner architecture and outer shape, leading to a functional as well as aesthetically satisfying outcome.

Inflammatory cell profile using different autologous fibrin protocols

Autologous fibrin has been widely used in surgical procedures for both soft and hard tissue repair. There are different protocols and devices to obtain this matrix, with varying centrifugal time, gravity force, speed, angle of the sample tube and spinning radius. The aim of this study was to compare three methods of obtaining autologous fibrin: L-PRF using the Intra-Spin L-PRF centrifuge (Dohan protocol), the advanced PRF (A-PRF) using the Intra-Spin L-PRF centrifuge and autologous leukocyte fibrin (ALF), using the Kasvi centrifuge. Venous blood was collected from 7 healthy volunteers, which were submitted to the 3 different methods of centrifugation. The membranes were tissue-processed and evaluated by immunohistochemistry for CD3, CD20, CD68 and CD138. For CD68+, a lower number of cells was immunolabelled in the L-PRF group when compared to the other groups (A-PRF and ALF). For CD3+, a lower number of immunolabellated cells was observed in the ALF group when compared to the remaining groups (p < 0.05). In the A-PRF group, the CD20+ cell count was lower than in the remaining groups. No difference was observed in CD138+ cell counts between the groups. The 3 protocols tested are suitable for obtaining autologous fibrin membranes.

Allogeneic Fibrin Clot for Odontogenic/Cementogenic Differentiation of Human Dental Mesenchymal Stem Cells

BACKGROUND

Fetal bovine serum is widely used as a growth supplement for cell culture medium; however, animal-borne pathogens increase the risk of transmitting infectious agents. Platelet-rich fibrin is recently considered as a successful alternative but leukocytes present limits to its allogeneic feasibility. The aim of this study was to explore the effects of allogeneic fibrin clot (AFC) without leukocytes on inducing odontogenic/cementogenic differentiation of human dental pulp stem cells (hDPSCs) and human periodontal ligament stem cells (hPDLSCs) in vitro and in vivo.

METHODS

AFC was prepared by high-speed centrifugation and leukocytes were almost removed, and AFC serum was obtained through three freeze-thaw cycles. hDPSCs and hPDLSCs were treated with AFC serum to investigate the odontogenic or cementogenic associated markers by real-time polymerase chain reaction. hDPSCs were treated with AFC serum and placed inside of dentin canal, hPDLSCs were treated with AFC serum to wrap outside of dentin, the mixture was then transplanted into the subcutaneous of nude mice for 12 weeks.

RESULTS

AFC serum exhibited enough growth factors and cytokines to induce odontogenic/cementogenic differentiation of hDPSCs and hPDLSCs in vitro. Furthermore, AFC seurum could induce hDPSCs to differentiate into odontoblasts-like cells and pulp-like tissues, and hPDLSCs to regenerate cementum-like tissues.

CONCLUSION

AFC could be an alternative safe source with growth factors for the expansion of human dental mesenchymal stem cells (hDMSCs).

Liquid platelet-rich fibrin promotes the regenerative potential of human periodontal ligament cells

OBJECTIVE

To compare the biological effect of PRP and liquid-PRF on human periodontal ligament cells (hPDLCs) in vitro.

METHODS

The liquid-PRF was processed with centrifugation at 700 g for 3 min, and PRP was processed according to Curasan's protocol. Migration and proliferation assay were performed by a scratch/Transwell assay and a CCK-8 assay, respectively. To investigate hPDLC differentiation, alkaline phosphatase (ALP) assay, Alizarin Red S staining, and gene expression level detection of Runx2, Col1a1, and OCN were conducted. Furthermore, cells cultured with lipopolysaccharide (LPS) to induce an inflammation condition were utilized to investigate the impact of liquid-PRF on inflammatory resolution.

RESULTS

Either PRP or liquid-PRF can promote proliferation, migration of hPDLCs, and osteogenic differentiation of hPDLCs. It was noteworthy that liquid-PRF demonstrated a significantly higher ability to promote the biological differentiation and mineralization of hPDLCs compared with PRP. Lastly, when hPDLCs were incubated with LPS, cells cultured with liquid-PRF showed significantly lower mRNA expression levels of inflammatory genes.

CONCLUSIONS

Liquid-PRF notably promoted hPDLC activity and attenuated the inflammatory state induced by LPS.

Quantitative Near-Infrared Imaging of Platelets in Platelet-Rich Fibrin (PRF) Matrices: Comparative Analysis of Bio-PRF, Leukocyte-Rich PRF, Advanced-PRF and Concentrated Growth Factors

Platelet-rich fibrin (PRF) is a fibrin matrix enriched with platelets. The PRF matrix is thought to form a steep gradient of platelet density around the region corresponding to the buffy coat in anticoagulated blood samples. However, this phenomenon has not yet been proven. To visualize platelet distribution in PRF in a non-invasive manner, we utilized near-infrared (NIR) imaging technology. In this study, four types of PRF matrices, bio-PRF, advanced-PRF (A-PRF), leukocyte-rich PRF (L-PRF), and concentrated growth factors (CGF) were compared. Blood samples collected from healthy, non-smoking volunteers were immediately centrifuged using four different protocols in glass tubes. The fixed PRF matrices were sagittally divided into two equal parts, and subjected to modified immunohistochemical examination. After probing with NIR dye-conjugated secondary antibody, the CD41⁺ platelets were visualized using an NIR imager. In L-PRF and CGF, platelets were distributed mainly on and below the distal surface, while in bio-PRF and A-PRF, platelet distribution was widespread and homogenous. Among three regions of the PRF matrices (upper, middle, and lower), no significant differences were observed. These findings suggest that platelets aggregate on polymerizing fibrin fibers and float up as a PRF matrix into the plasma fraction, amending the current “gradient” theory of platelet distribution.

Concentrated Growth Factor Matrices Prepared Using Silica-Coated Plastic Tubes Are Distinguishable From Those Prepared Using Glass Tubes in Platelet Distribution: Application of a Novel Near-Infrared Imaging-Based, Quantitative Technique

Platelet-rich fibrin (PRF) matrices were originally prepared using plain glass tubes without the aid of coagulation factors because coagulation factor XII is activated by glass surfaces. Recently, the use of silica-coated plastic tubes as a substitute of glass tubes has been recommended for PRF preparation. This recommendation is owing not only to the shortage of glass tubes for medical use in the market, but also the higher coagulation activity of silica-coated plastic tubes and equal quality of PRF. However, these matrices are not the same. To evaluate the differences, we compared glass- and silica-coated plastic tubes in terms of platelet distribution and quantity in concentrated growth factors (CGF). CGF matrices were immediately prepared from freshly collected blood samples, fixed after red thrombus removal, and divided into two equal pieces sagittally. One piece was used for CD41 detection and the other was applied as an isotype control. Platelet distribution in CGF matrices was examined, without embedding or sectioning, by a novel method using invisible near-infrared imaging. The dehydrated membranous CGF matrix was more transparent. Thus, the fluorescence signal was clearly detectable with less scattering. Platelets were distributed mainly in the distal side of the glass-prepared CGF matrix, but homogeneously in the silica-prepared CGF matrix. Platelet count was positively correlated with fluorescence intensity. Although not yet fully developed, this imaging technique enabled us to recognize the differences in platelet distribution and quantity in CGF matrices by excluding bias caused by the technical limitations of scanning electron microscopy and conventional immunohistochemical methods.

A Comprehensive Review of Concentrated Growth Factors and Their Novel Applications in Facial Reconstructive and Regenerative Medicine

BACKGROUND

Concentrated growth factors (CGFs) are the latest generation of platelet concentrates. The objective of developing CGF is to increase therapeutic efficacy. However, few studies have supported the superiority of CGF in composition and efficacy. The reconstruction and regeneration process is complicated and long term, whereas bioactivity of CGF is not durable. The purpose of this review is threefold. The first is to recommend more comparative studies between CGF and other platelet concentrates. The second is to constitute a continuous drug delivery system by combining CGF with other biomaterials. Finally, the novel use of CGF in facial regenerative and reconstructive medicine will be highlighted.

METHODS

A comprehensive review of literature regarding the use of CGF in facial regenerative and reconstructive medicine was performed. Based on the inclusion and exclusion criteria, a total of 135 articles were included.

RESULTS

The use of CGF involving facial rejuvenation, cartilage grafting, facial bone defects, facial peripheral nerve injury and wounding is reviewed. The reconstructive and regenerative principles lie in firm fibrin scaffolds and continuous in situ delivery of multiple growth factors.

CONCLUSIONS

CGF represents an advance in personalized medicine concept. However, the current scientific evidences about the use of CGF are limited. More basic and clinical studies should be conducted to understand the characteristics and clinical application of CGF.

LEVEL OF EVIDENCE V

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Comparison of the Efficiacy of Intra-Articular Injection of Liquid Platelet-Rich Fibrin and Hyaluronic Acid After in Conjunction With Arthrocentesis for the Treatment of Internal Temporomandibular Joint Derangements

The aim of this study was to evaluate the effectiveness of intra-articular injection of liquid platelet-rich fibrin (I-PRF) versus hyaluronic acid (HA) following arthrocentesis in patients suffering from temporomandibular joint (TMJ) pain and dysfunction. A total of 69 patients with internal TMJ derangement were enrolled in this retrospective, matched cohort study. A total of 47 included patients (67 joints) were divided into 3 groups as follows: 16 participants in the arthrocentesis-only group; 14 patients in the arthrocentesis plus HA injection group (A+HA); and 17 participants in the arthrocentesis plus I-PRF injection group (A+I-PRF). The 2 outcome variables were TMJ pain and maximal mouth opening (MMO) which were evaluated up to 12 months postoperatively. The data were analyzed using the Shapiro-Wilk test, Kruskal-Wallis test, Mann-Whitney U test, Wilcoxon sign test, Fisher exact test, and the χ test. Statistically significant decreases in pain scores and increases in MMO values were observed in all 3 groups during the 12 months of follow-up. The significant decrease in pain values was shown in the A+I-PRF group as compared with the A+HA group at 9 months postoperatively. MMO values in the A+I-PRF group were significantly higher than in the A+HA group at 9 and 12 months postoperatively. All conventional treatment procedures can provide pain reduction and improvement to MMO. However, intraarticular injections of I-PRF in combination with arthrocentesis showed superior performance in terms of the gradual improvement in pain alleviation and range of mouth opening.

Advanced-PRF: Clinical evaluation in impacted mandibular third molar sockets

OBJECTIVE

This prospective study evaluated the efficacy and healing potential of modified formulation of PRF, commonly known as Advanced PRF (A-PRF) in impacted mandibular third molar extraction sockets.

MATERIALS AND METHODS

20 patients with bilateral impacted mandibular third molars were included in this study. Surgical disimpactions were done at 3-4 weeks interval in opposing quadrants of patient. One quadrant received A-PRF while the opposing quadrant in same patient was taken as control. Comparative evaluation was done in terms of pain assessment, analgesics required, swelling, soft tissue healing and trismus on 1st, 3 and 7day follow-up. Comparative assessment of bone healing was also done on 1st, 3and 6month follow-up.

RESULTS

This study involved 12 female and 8 male patients with in age range of 18-35 years. The evaluation of pain, swelling, trismus and soft tissue healing on 3rd postoperative day revealed considerable improvement on A-PRF sites as compared to control sites. The outcomes were found to be statistically significant with p values 0.008, 0.031, 0.0001, 0.05 respectively. Even the analgesic consumption was remarkably less when A-PRF was used (P=0.004). Bone healing evaluation in A-PRF sites on 1st, 3and 6month has shown significantly improved results with P<0.05.

CONCLUSION

Our study infers that A-PRF has enhanced the healing potential of soft tissue as well as bone in extraction socket. Apart from that it has also shown promising results in relief of immediate postoperative symptoms like pain, swelling and trismus which improves the comfort and acceptability of surgical procedures by patients. Enhanced healing and patient comfort in cost effective manner are the highlighting features of A-PRF.

Regenerative Capacity of Leukocyte-rich and Platelet-rich Fibrin in Indirect Sinus Elevation Procedure May be Dependent on Model-Specific Modification of the Centrifugation Cycle

Context:

To compare optical density (OD) and fibrinogen content of leukocyte-rich and platelet-rich fibrin (L-PRF) generated by standard protocol (2700 rotations per minute [RPM] for 12 min) versus relative centrifugal force (RCF)-adjusted protocol across two widely used laboratory centrifuges with swing-out rotors.

Aims:

Centrifuges for PRF production generate forces in excess of 800 g. The study aimed to evaluate OD, fibrinogen content and effectiveness in bone-added osteotome sinus floor elevation (BAOSFE) of leukocyte-rich and platelet-rich fibrin (L-PRF) generated by the standard protocol (2700 RPM for 12 min) versus a RCF-adjusted protocol to generate precisely 400 g of force across two centrifuges with swing-out rotors. The outcomes were compared to a standard centrifuge configured to generate L-PRF as per the original Choukroun guidelines.

Settings and Design:

Sample size for the present study was calculated using proportional power calculation. A minimum sample size of 8 per group was needed to detect a bone height difference of 2 mm when the power of the test is 0.80 at a significance level of 0.05.

Subjects and Methods:

Based on the centrifuge and protocol used to generate L-PRF, 10 participants were assigned to each of the following groups are as follows: D group, fixed angle centrifuge (DUO Quattro^®) at default setting. R-O group: Swing-out centrifuge (Remi 8C^®) + standard protocol. R-A group: Remi 8C^® centrifuge + RCF-adjusted protocol. C-O group: Swing-out centrifuge (Remi C854^®) + standard protocol. and C-A group: Remi C854^® + RCF-adjusted protocol. OD, fibrinogen content, and gain in bone fill and bone height after BAOSFE were the evaluated outcomes.

Statistical Analysis Used:

Data were analyzed using GraphPad Prism^® Software version 6.0 (GraphPad Software Inc., La Jolla, USA) and SAS Software^® version 9.3 versions (SAS, New Delhi, India). Data were summarized by mean ± standard deviation for continuous data and median ± inter-quartile range for the score data. The comparison between different time points was done by analysis of one-way repeated measures test, followed by post hoc test for score data. The comparison between two groups for repeated data was made by analysis of two-way repeated measures test and followed by post hoc test. Spearman's Rho correlation test was used to test the correlation between prognosis and the other variables.

Results:

L-PRF from the Remi C854^® centrifuge with RCF-adjusted protocol showed OD (P = 0.152) and fibrinogen content (P = 0.232) identical to those from the DUO Quattro^® centrifuge. L-PRF from Remi 8C^® centrifuge with the RCF-adjusted protocol resulted in maximum postoperative bone height gain (7.01 ± 1.44 mm) and bone fill (13.50 ± 4.51 mm²) which was higher than that of the outcomes from the DUO Quattro^® centrifuge (6.82 ± 2.92 mm and 12.32 ± 5.31 mm²).

Conclusions:

A reduction in RCF resulted in a less dense clot and had a positive influence on the regenerative potential of L-PRF in BAOSFE procedure.

Tensile strength, growth factor content and proliferation activities for two platelet concentrates of platelet-rich fibrin and concentrated growth factor

Background/purpose

Platelet-rich fibrin (PRF) can be obtained by centrifuging fresh blood in the absence of anticoagulants. Varying the centrifugation speeds may produce tougher and richer concentrated growth factors (CGF). This study examines tensile strength, growth factor content, and the potential of CGF and PRF in promoting periodontal cell proliferation.

Materials and methods

Blood (40 mL/subject) was collected from 44 healthy subjects. PRF and CGF were prepared by centrifuging at 3000 rpm and switching speeds ranging within 3000 rpm, respectively. Fibrin strip was prepared and its tensile strength was measured. Transforming growth factor beta 1 (TGF-β1), platelet-derived growth factor BB (PDGF-BB), and epidermal growth factor (EGF) in the residual serum and fibrin clots were determined by enzyme-linked immunosorbent assay, and their effects on the proliferation of hFOB1.19 osteoblasts and human gingival fibroblasts were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay.

Results

Compared with PRF, tensile strength of CGF was significantly higher. Concentrations and amounts of PDGF-BB and EGF in CGF were significantly higher than those in PRF. Osteoblast number was significantly higher in the cultures with fetal bovine serum (FBS, 10%) and with PRF or CGF fibrin clots (5%, 10%, and 50%) compared to that without FBS. Moreover, osteoblast number in CGF, regardless of the preparation of 10% and 50%, was significantly greater than that in PRF. Similar findings were also observed for gingival fibroblasts among the various subjects.

Conclusion

Varying centrifugation speeds can modify the tensile strength and biological activities of platelet fibrin clots.

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.

Combination of an allogenic and a xenogenic bone substitute material with injectable platelet-rich fibrin - A comparative in vitro study

The aim of the in vitro study was a comparison of an allogenic (ABSM) and a xenogenic bone substitute material (XBSM) with and without injectable platelet-rich fibrin (ABSM-i-PRF & XBSM-i-PRF) on cell characteristics of human osteoblasts (HOB). Here, ABSM and XBSM (+ i-PRF = test; - i-PRF = control) were incubated with HOB for 3, 7 and 10 days. HOB viability, migration, proliferation and differentiation (RT-PCR on alkaline phosphatase (AP), bone morphogenetic protein 2 (BMP-2) and osteonectin (OCN)) were measured and compared between groups. At day 3, an increased viability, migration and proliferation was seen for ABSM-i-PRF. For viability and proliferation (days 7 and 10) and for migration (day 10), ABSM-i-PRF/XBSM-i-PRF showed higher values compared to ABSM/XBSM with maximum values for ABSM-i-PRF and minimum values for XBSM. At days 3 and 7, the highest expression of AP was detected in ABSM-i-PRF/XBSM-i-PRF when compared to ABSM/XBSM, whereas at day 10, AP expression levels were elevated in ABSM-i-PRF/ABSM. The highest BMP-2 expression was seen in ABSM-i-PRF whereas OCN expression showed higher levels in ABSM-i-PRF/XBSM-i-PRF at days 3 and 7 with lowest expression for ABSM. Later on, elevated OC levels were detected for ABSM-i-PRF only. In conclusion, i-PRF in combination with ABSM enhances HOB activity when compared to XBSM-i-PRF or untreated BSM in vitro. Therefore, addition of i-PRF to ABSM and - to a lower extent - to XBSM may influence osteoblast activity in vivo.

Effect of A-PRF Application on Palatal Wound Healing after Free Gingival Graft Harvesting: A Prospective Randomized Study

Objective  The aim of this study was to investigate the healing effect of advanced platelet-rich fibrin (A-PRF) clot membranes in palatal wounds, resulting from free gingival graft (FGG) harvesting, on the reepithelization rate and on the pain experience after surgery.

Materials and Methods  Twenty-five patients requiring FGG have participated in this prospective cohort study. After FGG harvesting, the test group ( n = 14) received A-PRF clot membranes at the palatal wound and the control group ( n = 11) received a gelatin sponge. Epithelialization rate of the palatal wound, wound healing area, correspondent percentage of reduction, and postsurgical pain experience were assessed at 2, 7, 14, 30, and 90 days.

Results  A-PRF group had higher palatal wound reduction than the control group, at 7, 14, and 30 days of follow-up. The highest difference between the groups was attained at 30 days (91.5% for A-PRF vs. 59.0% control group). At 14 days, a significant difference in the proportion of patients showing total epithelization was found: 64.3% for A-PRF versus 9.1% for the control group. At 90 days, both groups showed total recovery. The control group experienced higher pain level and discomfort until the 14th day, being notably higher on the second day.

Conclusion  The results suggest that A-PRF membranes haste the healing process, and promote greater reduction along the recovery period and less painful postoperative period.

Comparison of platelet-rich fibrin (PRF) produced using 3 commercially available centrifuges at both high (~ 700 g) and low (~ 200 g) relative centrifugation forces

OBJECTIVES

Platelet-rich fibrin (PRF) has gained tremendous momentum in recent years as a natural autologous growth factor derived from blood capable of stimulating tissue regeneration. Owing to its widespread use, many companies have commercialized various centrifugation devices with various proposed protocols. The aim of the present study was to compare 3 different commercially available centrifuges at both high and low g-force protocols.

MATERIALS AND METHODS

PRF was produced on three commercially available centrifuges including the IntraSpin Device (IntraLock), the Duo Quattro (Process for PRF), and Salvin (Salvin Dental). Two separate protocols were tested on each machine including the original leukocyte and platelet-rich fibrin (L-PRF) protocol (~ 700 RCF max (~ 400 RCF clot) for 12 min) as well as the advanced platelet-rich fibrin (A-PRF+) protocol (~ 200 g RCF max (~ 130 g RCF clot) for 8 min). Each of the tested groups was compared for cell numbers, growth factor release, scanning electron microscopy (SEM) for morphological differences, and clot size (both weight and length/width).

RESULTS

The present study found that PRF clots produced utilizing the low-speed centrifugation speeds (~ 200 g for 8 min) produce clots that (1) contained a higher concentration of evenly distributed platelets, (2) secreted higher concentrations of growth factors over a 10 day period, and (3) were smaller in size. This was irrespective of the centrifugation device utilized and consistently observed on all 3 devices. The greatest impact was found between the protocols utilized (up to a 200%). Interestingly, it was further revealed that the centrifugation tubes used had a much greater impact on the final size outcome of PRF clots when compared to centrifugation devices. It was found that, in general, the Process for PRF tubes produced significantly greater-sized clots when compared to other commercially available tubes. The Salvin Dental tubes also produced significantly greater PRF clots when compared to the IntraLock tubes on each of the tested centrifugation devices.

CONCLUSIONS

The present study demonstrated the reproducibility of a scientific concept (reduction in RCF produces PRF clots with more evenly distributed cells and growth factors) utilizing different devices. Furthermore, (and until now overlooked), it was revealed for the first time that the centrifugation tubes are central to the quality production of PRF. Future research investigating tube characteristics thus becomes critically important for the future optimization of PRF.

CLINICAL RELEVANCE

This is the first study to reveal the marked impact of centrifugation tubes on the final production of PRF. Future study thus becomes markedly important to further optimize the quality of PRF-based matrices. It was further found that little variability existed between the centrifugation devices if optimized centrifugation protocols (lower centrifugation speeds) were utilized.

A novel approach to regenerate bone loss in an adolescent using concentrated growth factors: One-year follow-up

Destructive periodontal diseases are rare occurrences in the paediatric population. Moreover, the regenerative potential of the periodontal tissues and supporting structures of teeth is even rare, once irreversible damage has occurred. The aim of this paper is to discuss the regeneration of alveolar bone defect in a 14-year-old using concentrated growth factors (CGF). Following crown removal, scaling, debridement and site preparation, CGF was placed and secured in one-walled defect in the mesial side of the lower right permanent molar. The crown was replaced on to the tooth and the patient was followed up at 1, 3, 6, 9 and 12 months for clinical and radiographic evaluation. After 12 months, the radiographic evaluation revealed the defect to be filled with alveolar bone and probing pocket depth had reduced significantly. Thus, CGF can be an effective agent and can act as a potential scaffold for periodontal regeneration in adolescents with bone loss.

Biofunctionalization of porcine-derived collagen matrices with platelet rich fibrin: influence on angiogenesis in vitro and in vivo

Objectives

Porcine-derived collagen matrices (CM) can be used for oral tissue regeneration, but sufficient revascularization is crucial. The aim of this study was to analyze the influence of platelet-rich fibrin (PRF) on angiogenesis of different CM in vitro and in vivo.

Materials and methods

Three different CM (mucoderm, jason, collprotect) were combined with PRF in a plotting process. Growth factor release (VEGF, TGF-β) was measured in vitro via ELISA quantification after 1,4 and 7 days in comparison to PRF alone. In ovo yolk sac (YSM) and chorion allantois membrane (CAM) model, angiogenic potential were analyzed in vivo with light- and intravital fluorescence microscopy after 24 h, then verified with immunohistochemical staining for CD105 and αSMA.

Results

Highest growth factor release was seen after 24 h for all three activated membranes in comparison to the native CM (VEGF 24 h: each p < 0.05; TGF-β: each p < 0.001) and the PRF (no significant difference). All activated membranes revealed a significantly increased angiogenic potential in vivo after 24 h (vessels per mm2: each p < 0.05; branching points per mm2: each p < 0.01; vessel density: each p < 0.05) and with immunohistochemical staining for CD105 (each p < 0.01) and αSMA (each p < 0.05).

Conclusions

PRF improved the angiogenesis of CM in vitro and in vivo.

Clinical relevance

Bio-functionalization of CM with PRF could easily implemented in the clinical pathway and may lead to advanced soft tissue healing.

Autologous platelet-rich fibrin stimulates canine periodontal regeneration

Platelet-rich fibrin (PRF) provides a scaffold for cell migration and growth factors for promoting wound healing and tissue regeneration. Here, we report using PRF in periodontal healing after open flap debridement (OFD) in canine periodontitis. A split-mouth design was performed in twenty dogs. Forty periodontitis surgical sites were randomly categorized into 2 groups; OFD alone and OFD with PRF treatment. Clinical parameters of periodontal pocket depth, gingival index, and the cemento-enamel junction-alveolar bone levels/root length ratio were improved in the OFD + PRF group. The OFD + PRF group also demonstrated a dramatically decreased inflammatory score compared with the OFD group. Collagen accumulation was improved in the OFD + PRF group at later time points compared with baseline. PRF application also significantly reduced inflammatory cytokine expression (TNFA and IL1B), and promoted the expression of collagen production-related genes (COL1A1, COL3A1, and TIMP1) and growth factors (PDGFB, TGFB1, and VEGFA). These findings suggest that PRF combined with OFD provides a new strategy to enhance the overall improvement of canine periodontitis treatment outcomes, especially in terms of inflammation and soft tissue healing. Therefore, PRF use in treating periodontitis could play an important role as a regenerative material to improve canine periodontitis treatment.