In vivo evaluation of the biocompatibility and biodegradation of a new denatured plasma membrane combined with liquid PRF (Alb-PRF)

A Simplified GBR Treatment and Evaluation of Posterior Seibert Class I Ridge Defects via Bio-collagen and Platelet-Rich Fibrin: A Retrospective Study

BACKGROUND

Classical guided bone regeneration (GBR) treatments can achieve favorable clinical results for ridge defects. However, extensive bone augmentation in the non-esthetic area in the posterior region for minor ridge defects is unnecessary. Therefore, this study used a collagen and Platelet-rich fibrin (PRF) mixture for bone augmentation on minor posterior ridge defects and evaluated the effects.

METHODS

22 Seibert Class I ridge defects were treated with BC and covered with a PRF membrane (simplified guided bone regeneration, simplified GBR) and other 22 were treated with Bio-Oss and covered with Bio-Gide (classical GBR). Cone-beam computed tomography imaging was conducted 6 months post-surgery to compare the ridge's horizontal width (HW) and buccal ridge's horizontal width to assess the osteogenic effect. In addition, the buccal ridge contour morphology was studied and classified.

RESULTS

The buccal ridge contour of simplified GBR was Type A in 14 cases, Type B in 7 cases, and Type C in 1 case and it of classical GBR was Type A in 11 cases, Type B in 8 cases, and Type C in 3 cases. The mean HW significantly increased by 1.50 mm of simplified GBR treatment, while it increased by 1.83 mm in classical GBR treatment.

CONCLUSION

The combined use of BC and PRF had a significant effect on bone augmentation and this treatment exhibited promising clinical results for correcting posterior Seibert Class I ridge defects. The morphological classification of the reconstructive effect in this study can be utilized in future clinical work.

Autolougous platelet concentrates in esthetic medicine

This narrative review summarizes current knowledge on the use of autologous platelet concentrates (APCs) in esthetic medicine, with the goal of providing clinicians with reliable information for clinical practice. APCs contain platelets that release various growth factors with potential applications in facial and dermatologic treatments. This review examines several facial esthetic applications of APCs, including acne scarring, skin rejuvenation, melasma, vitiligo, stretchmarks, peri-orbital rejuvenation, peri-oral rejuvenation, hair regeneration and the volumizing effects of APC gels. A systematic review of literature databases (PubMed/MEDLINE) was conducted up to October 2023 to identify randomized controlled trials (RCTs) in the English language on APCs for facial rejuvenation and dermatology. A total of 96 articles were selected including those on platelet rich plasma (PRP), plasma-rich in growth factors (PRGF), and platelet-rich fibrin (PRF). Clinical recommendations gained from the reviews are provided. In summary, the use of APCs in facial esthetics is a promising yet relatively recent treatment approach. Overall, the majority of studies have focused on the use of PRP with positive outcomes. Only few studies have compared PRP versus PRF with all demonstrating superior outcomes using PRF. The existing studies have limitations including small sample sizes and lack of standardized assessment criteria. Future research should utilize well-designed RCTs, incorporating appropriate controls, such as split-face comparisons, and standardized protocols for APC usage, including optimal number of sessions, interval between sessions, and objective improvement scores. Nevertheless, the most recent formulations of platelet concentrates offer clinicians an ability to improve various clinical parameters and esthetic concerns.

Comparison Between Autologous Albumin Gel and Liquid Platelet-Rich Fibrin Mixture Versus Connective Tissue Graft to Modify the Gingival Phenotype: A Randomized Controlled Trial

Objectives To assess changes in gingival thickness (GTH) and the width of keratinized gingival tissue (KTW) following treatment with either connective tissue graft (CTG) or an albumin gel-platelet-rich fibrin mixture (Alb-PRF). Materials and methods Twenty treatment sites were included in a split-mouth design involving 10 patients with a thin gingival phenotype in the mandibular anterior region. The sample was randomly divided into two groups, with the Alb-PRF applied to the experimental group and CTG used for the control group. GTH and KTW were measured at baseline and after one, three, and six months. Results GTH increased in both groups during all follow-up periods. However, no statistically significant differences (p > 0.05) between the groups were observed at baseline and six months. At three months, the experimental group exhibited significantly higher GTH (p < 0.001). Additionally, at three and six months, the CTG group showed a superior increase in KTW (p < 0.05). Conclusion Within the constraints of this study, Alb-PRF application for modifying thin gingival phenotypes proved to be an effective therapeutic option, potentially serving as an alternative to CTGs. Although Alb-PRF resulted in thicker gingiva, CTG demonstrated a greater enhancement in KTW.

Plasma Gel Matrix as a Promising Carrier of Epigallocatechin Gallate for Regenerative Medicine

Plasma gel (PG) is a protein matrix prepared from platelet-poor plasma and can be utilized as a drug carrier for controlled release. We previously demonstrated its applicability as a carrier of polyphosphate. Epigallocatechin-3-gallate (EGCG) is the main flavonoid found in green tea and functions as a strong antioxidant. To explore the applicability of PG as an EGCG carrier, we examined the release of EGCG from the PG matrix using an in vitro system. Pooled platelet-poor plasma (PPP) was prepared from four healthy adult male donors, mixed with EGCG, and heated at 75 °C for 10 or 20 min to prepare the PG matrix. The PG-EGCG matrix was incubated in PBS at 37 °C, and the EGCG released into PBS was determined using spectrophotometry. The antioxidant capacity was determined based on the principle of the iodine decolorization reaction. EGCG precipitated and incorporated into the PG matrix during thermal preparation. Trypsin, used to simulate the in vivo degradation of PG, released EGCG from the PG matrix over time. The released EGCG maintained its antioxidant capacity during incubation. These results indicate that thermally prepared PG matrices can be utilized as a promising EGCG carrier in the fields of tissue engineering and regenerative medicine.

Treatment of a fractured humerus and partially torn supraspinatus tendon in a professional boxer with liquid platelet-rich fibrin and heat-coagulated albumin gel: a case report

INTRODUCTION

Fractures with delayed healing can be a serious complication, especially for athletes depending on quick return to sports. To our knowledge, no cases of increased healing of delayed union fractures with autologous biomedical interventions have been reported.

CASE PRESENTATION

A 33-year-old Swedish professional boxer with a fractured humerus with a delayed union and a partially torn supraspinatus tendon was treated with injections of liquid platelet-rich fibrin and heat-coagulated albumin gel. He recovered almost completely from both injuries in only 1 month and could return to professional boxing in 3 months.

CONCLUSION

This case raises the hypothesis that liquid platelet-rich fibrin and heat-coagulated albumin gel may be an effective, minimally invasive intervention in fractures with a delayed union. Further research is required to test this theory.

Extended platelet-rich fibrin

Platelet-rich fibrin (PRF) has been characterized as a regenerative biomaterial that is fully resorbed within a typical 2-3 week period. Very recently, however, a novel heating process was shown to extend the working properties of PRP/PRF from a standard 2-3 week period toward a duration of 4-6 months. Numerous clinicians have now utilized this extended-PRF (e-PRF) membrane as a substitute for collagen barrier membranes in various clinical applications, such as guided tissue/bone regeneration. This review article summarizes the scientific work to date on this novel technology, including its current and future applications in periodontology, implant dentistry, orthopedics and facial aesthetics. A systematic review was conducted investigating key terms including "Bio-Heat," "albumin gel," "albumin-PRF," "Alb-PRF," "extended-PRF," "e-PRF," "activated plasma albumin gel," and "APAG" by searching databases such as MEDLINE, EMBASE and PubMed. Findings from preclinical studies demonstrate that following a simple 10-min heating process, the transformation of the liquid plasma albumin layer into a gel-like injectable albumin gel extends the resorption properties to at least 4 months according to ISO standard 10 993 (subcutaneous animal model). Several clinical studies have now demonstrated the use of e-PRF membranes as a replacement for collagen membranes in GTR/GBR procedures, closing lateral windows in sinus grafting procedures, for extraction site management, and as a stable biological membrane during recession coverage procedures. Furthermore, Alb-PRF may also be injected as a regenerative biological filler that lasts extended periods with advantages in joint injections, osteoarthritis and in the field of facial aesthetics. This article highlights the marked improvement in the stability and degradation properties of the novel Alb-PRF/e-PRF technology with its widespread future potential use as a potential replacement for collagen membranes with indications including extraction site management, GBR procedures, lateral sinus window closure, recession coverage among others, and further highlights its use as a biological regenerative filler for joint injections and facial aesthetics. It is hoped that this review will pioneer future opportunities and research development in the field, leading to further progression toward more natural and less costly biomaterials for use in medicine and dentistry.

The Association of Nanostructured Carbonated Hydroxyapatite with Denatured Albumin and Platelet-Rich Fibrin: Impacts on Growth Factors Release and Osteoblast Behavior

Platelet-rich Fibrin (PRF), a second-generation blood concentrate, offers a versatile structure for bone regeneration due to its composition of fibrin, growth factors, and cytokines, with adaptations like denatured albumin-enriched with liquid PRF (Alb-PRF), showing potential for enhanced stability and growth factor dynamics. Researchers have also explored the combination of PRF with other biomaterials, aiming to create a three-dimensional framework for enhanced cell recruitment, proliferation, and differentiation in bone repair studies. This study aimed to evaluate a combination of Alb-PRF with nanostructured carbonated hydroxyapatite microspheres (Alb-ncHA-PRF), and how this association affects the release capacity of growth factors and immunomodulatory molecules, and its impact on the behavior of MG63 human osteoblast-like cells. Alb-PRF membranes were prepared and associated with nanocarboapatite (ncHA) microspheres during polymerization. MG63 cells were exposed to eluates of both membranes to assess cell viability, proliferation, mineralization, and alkaline phosphatase (ALP) activity. The ultrastructural analysis has shown that the spheres were shattered, and fragments were incorporated into both the fibrin mesh and the albumin gel of Alb-PRF. Alb-ncHA-PRF presented a reduced release of growth factors and cytokines when compared to Alb-PRF (p < 0.05). Alb-ncHA-PRF was able to stimulate osteoblast proliferation and ALP activity at lower levels than those observed by Alb-PRF and was unable to positively affect in vitro mineralization by MG63 cells. These findings indicate that the addition of ncHA spheres reduces the biological activity of Alb-PRF, impairing its initial effects on osteoblast behavior.

Effect of thermal manipulation on the biological and mechanical characteristics of horizontal platelet rich fibrin membranes

BACKGROUD

Regardless of application scenarios, proper mechanical characteristics and degradation properties are prerequisites for horizontal platelet rich fibrin (H-PRF) to manifest its ability. Among the methods used to modify PRF, thermal manipulation is promising as it is easy to handle without adding extra additives. Yet there is no consensus on optimal temperature treatment. This study aimed to investigate the effects of heating on the biological and mechanical characteristics of H-PRF and explore the optimum heating temperature for H-PRF thermal treatment.

METHODS

We employed a series of temperature gradients, room temperature, 50℃, 75℃, 90℃, 105℃. The microstructure and the mechanical properties were recorded by Scanning Electron Microscope (SEM) and tensile strength tests respectively. The degradation rate of H-PRF membranes was examined by digestion assay with plasmin and trypsin. The viability of cells within H-PRF membranes and the proliferation of osteoblasts cultured with extracts from different H-PRF groups was evaluated using CCK-8 assays.

RESULTS

Compared with the nonheated group, overheated manipulation beyond 90℃ can significantly prolong the degradation properties for up to 3 to 4 weeks and enhance the mass stress of H-PRF membranes. A high-temperature treatment of 105℃ accompanied by the cell activity beneath H-PRF reduced more than half, and thus, the biological effect on human osteoblasts (hFOBs) also reduced dramatically.

CONCLUSIONS

High thermal manipulation can prolong the degradation properties and enhance the mechanical properties of PRF membranes accompanied by the loss of biological effect.

The Use of Nano-Hydroxyapatite (NH) for Socket Preservation: Communication of an Upcoming Multicenter Study with the Presentation of a Pilot Case Report

Background and Objectives: The use of biomaterials in dentistry is extremely common. From a commercial perspective, different types of osteoconductive and osteoinductive biomaterials are available to clinicians. In the field of osteoconductive materials, clinicians have biomaterials made of heterologous bones at their disposal, including biomaterials of bovine, porcine, and equine origins, and biomaterials of natural origin, such as corals and hydroxyapatites. In recent years, it has become possible to synthesize nano-Ha and produce scaffolds using digital information. Although a large variety of biomaterials has been produced, there is no scientific evidence that proves their absolute indispensability in terms of the preservation of postextraction sites or in the execution of guided bone regeneration. While there is no scientific evidence showing that one material is better than another, there is evidence suggesting that several products have better in situ permanence. This article describes a preliminary study to evaluate the histological results, ISQ values, and prevalence of nano-HA. Materials and Methods: In this study, we planned to use a new biomaterial based on nanohydroxyapatite for implantation at one postextraction site; the nano-HA in this study was NuvaBONE (Overmed, Buccinasco, Milano, Italy). This is a synthetic bone graft substitute that is based on nanostructured biomimetic hydroxyapatite for application in oral-maxillofacial surgery, orthopedics, traumatology, spine surgery, and neurosurgery. In our pilot case, a patient with a hopeless tooth underwent extraction, and the large defect remaining after the removal of the tooth was filled with nano-HA to restore the volume. Twelve months later, the patient was booked for implant surgery to replace the missing tooth. At the time of the surgery, a biopsy of the regenerated tissue was taken using a trephine of 4 mm in the inner side and 8 mm deep. Results: The histological results of the biopsy showed abundant bone formation, high values of ISQ increasing from the insertion to the prosthetic phase, and a good reorganization of hydroxyapatite granules during resorption. The implant is in good function, and the replaced tooth shows good esthetics. Conclusions: The good results of this pilot case indicate starting the next Multicentric study to have more and clearer information about this nanohydroxyapatite (NH) compared with control sites.

Plasma Gel Made of Platelet-Poor Plasma: In Vitro Verification as a Carrier of Polyphosphate

Plasma gel (PG) is a blood-derived biomaterial that can be prepared by heating or chemical cross-linking without the aid of intrinsic coagulation activity and has gradually been applied in the field of esthetic surgery. To explore the applicability of PG in regenerative therapy or tissue engineering, in this study, we focused on the advantages of the heating method and verified the retention capacity of the resulting PG for polyphosphate (polyP), a polyanion that contributes to hemostasis and bone regeneration. Pooled platelet-poor plasma (PPP) was prepared from four healthy male adult donors, mixed with synthetic polyP, and heated at 75 °C for 10 or 30 min to prepare PG in microtubes. The PG was incubated in PBS at 37 °C, and polyP levels in the extra-matrix PBS were determined by the fluorometric method every 24 h. The microstructure of PG was examined using scanning electron microscopy. In the small PG matrices, almost all of the added polyP (~100%) was released within the initial 24 h. In contrast, in the large PG matrices, approximately 50% of the polyP was released within the initial 24 h and thereafter gradually released over time. Owing to its simple chemical structure, linear polyP cannot be theoretically retained in the gel matrices used in this study. However, these findings suggest that thermally prepared PG matrices can be applied as carriers of polyP in tissue engineering and regenerative medicine.

Clinical and Biochemical Evaluation of the Use of Alb-PRF versus L-PRF in Mandibular Third Molar Extractions: A Split-Mouth Randomized Clinical Trial

Bone tissue engineering seeks biomaterials that enable cell migration, angiogenesis, matrix deposition, and tissue regeneration. Blood concentrates like platelet-rich fibrin (L-PRF) offer a cost-effective source of cells and growth factors to enhance healing. The present study aimed to evaluate heated serum albumin with liquid PRF (Alb-PRF) and L-PRF clinically and biochemically after placement in dental sockets following mandibular third molar extraction. In a controlled, split-mouth study involving 10 volunteers, 20 extracted molars were treated with either Alb-PRF or L-PRF. Post-extraction, pain, trismus, infection presence, and swelling were measured. The concentrations of different analytes in the surgical sites were also examined. The data were statistically analyzed, with significance defined at p < 0.05 (t-test). No significant difference was noted between the groups for pain and trismus, but Alb-PRF showed a significant reduction in swelling on day seven. The Alb-PRF group showed lower levels of pro-inflammatory cytokines (GM-CSF, IL-1b, IL-6, IFNy, IL-8, IL-15, RANTES, and MIP-1a) after seven days, with only higher expressions of MIP-1b, IL-1b, and MCP-1 found in the L-PRF group. Differences were observed in the release of analytes between L-PRF and Alb-PRF, with Alb-PRF significantly reducing edema after seven days. Alb-PRF reduced edema, while L-PRF increased inflammatory cytokines. When compared to L-PRF, Alb-PRF reduced edema and the release of inflammatory cytokines, suggesting promising effects in socket healing while underscoring the role of growth factors and cytokines in potential applications of blood concentrates.

In vivo evaluation of bone regeneration using ZIF8-modified polypropylene membrane in rat calvarium defects

AIM

The profound potential of zeolitic imidazolate framework 8 (ZIF8) thin film for inducing osteogenesis has been previously established under in vitro conditions. As the next step towards the clinical application of ZIF8-modified substrates in periodontology, this in vivo study aimed to evaluate the ability of the ZIF8 crystalline layer to induce bone regeneration in an animal model defect.

MATERIALS AND METHODS

Following the mechanical characterization of the membranes and analysing the in vitro degradation of the ZIF8 layer, in vivo bone regeneration was evaluated in a critical-sized (5-mm) rat calvarial bone defect model. For each animal, one defect was randomly covered with either a polypropylene (PP) or a ZIF8-modified membrane (n = 7 per group), while the other defect was left untreated as a control. Eight weeks post surgery, bone formation was assessed by microcomputed tomography scanning, haematoxylin and eosin staining and immunohistochemical analysis.

RESULTS

The ZIF8-modified membrane outperformed the PP membrane in terms of mechanical properties and revealed a trace Zn+2 release. Results of in vivo evaluation verified the superior barrier function of the ZIF8-coated membrane compared with pristine PP membrane. Compared with the limited marginal bone formation in the control and PP groups, the defect area was almost filled with mature bone in the ZIF8-coated membrane group.

CONCLUSIONS

Our results support the effectiveness of the ZIF8-coated membrane as a promising material for improving clinical outcomes of guided bone regeneration procedures, without using biological components.

Platelet-rich fibrin combined with a particulate bone substitute versus guided bone regeneration in the damaged extraction socket: An in vivo study

AIM

It has been proposed that platelet-rich fibrin (PRF) can be used to support bone regeneration during alveolar ridge augmentation. The aim of this study was to determine whether an approach utilizing PRF provides similar performance to the established guided bone regeneration (GBR) procedure.

MATERIALS AND METHODS

Two-wall defects were surgically created in beagle dogs and treated in three experimental groups: (i) a sticky bone (SB) substitute prepared using liquid PRF and deproteinized porcine bone mineral (DPBM); (ii) SB covered with solid PRF compressed into a membrane; and (iii) GBR performed using DPBM covered by a collagen membrane. Quantitative reverse-transcription polymerase chain reaction was applied to the specimen after 1 week of healing, and microcomputed tomography (micro-CT) and histological outcomes were analysed after 8 weeks of healing.

RESULTS

Compared with GBR, PRF resulted in a moderate increase in the expression levels of osteoblast and osteoclast markers, osteocalcin, and calcitonin receptor. Moreover, PRF modestly increased angiogenesis and the inflammation markers vascular endothelial growth factor (VEGF) and IL-6. Micro-CT and histological analyses confirmed the expected increased alveolar ridge area, with no significant differences between the three groups. Consistently, graft consolidation, as indicated by new bone formation at the defect site, did not differ significantly between groups.

CONCLUSIONS

The present results demonstrate that PRF-based approaches perform comparably to the established GBR procedure in terms of the consolidation of DPBM in two-wall alveolar defects.

The Use of Alb-PRF as a Drug Delivery System for Malignant Lesion Treatment

Bioengineering is an area of biotechnology that offers tools for different therapeutic strategies, including tissue therapies. For this, cells are associated with growth factors and scaffolds composed of biocompatible biomaterials capable of promoting the regeneration of tissues, such as bones. Autologous biomaterials produced from human peripheral blood have a proven ability to produce/release activating factors for tissue repair, with potential application as a vehicle for carrying substances for local release. The present idea proposes the use of a new blood-derived concentrate, Alb-PRF, an activated plasma albumin gel with the platelet-rich fibrin in the liquid phase (Liquid PRF). Alb-PRF can be able to stabilize the fibrin matrix of the scaffold, acting as a drug delivery system vehicle in malignant lesions.

Evolution and Clinical Advances of Platelet-Rich Fibrin in Musculoskeletal Regeneration

Over the past few decades, various forms of platelet concentrates have evolved with significant clinical utility. The newer generation products, including leukocyte-platelet-rich fibrin (L-PRF) and advanced platelet-rich fibrin (A-PRF), have shown superior biological properties in musculoskeletal regeneration than the first-generation concentrates, such as platelet-rich plasma (PRP) and plasma rich in growth factors. These newer platelet concentrates have a complete matrix of physiological fibrin that acts as a scaffold with a three-dimensional (3D) architecture. Further, it facilitates intercellular signaling and migration, thereby promoting angiogenic, chondrogenic, and osteogenic activities. A-PRF with higher leukocyte inclusion possesses antimicrobial activity than the first generations. Due to the presence of enormous amounts of growth factors and anti-inflammatory cytokines that are released, A-PRF has the potential to replicate the various physiological and immunological factors of wound healing. In addition, there are more neutrophils, monocytes, and macrophages, all of which secrete essential chemotactic molecules. As a result, both L-PRF and A-PRF are used in the management of musculoskeletal conditions, such as chondral injuries, tendinopathies, tissue regeneration, and other sports-related injuries. In addition to this, its applications have been expanded to include the fields of reconstructive cosmetic surgery, wound healing in diabetic patients, and maxillofacial surgeries.

Effect on Cellular Vitality In Vitro of Novel APRF-Chlorhexidine Treated Membranes

INTRODUCTION

Chlorhexidine (CHX) has been used for some time in clinical practice as a local antiseptic agent with excellent efficacy. The combination of CHX with APRF (Advanced-platelet rich fibrin) membrane has the potential to stimulate tissue regeneration and to provide a bactericidal effect. We hypothesize that this may reduce the rate of infections development and protect cell viability.

AIM

The aim of this study was two-fold-to create a stable APRF membrane treated with different concentrations of CHX (0.01% and 0.02%) and to monitor its effect on the viability of PDL cells in vitro. This benefits the introduction of a new protocol for APRF membrane production -CHX-PRF and enriches the available evidence on the effect of this antiseptic agent on PDL (Periodontal ligament) cells.

MATERIALS AND METHODS

APRF membranes were prepared by the addition of two concentrations (0.01% and 0.02%) of CHX. Membranes without the antiseptic were also prepared and used as control samples. PDL cells were cultivated on the membranes for 72 h. Cell number and vitality were examined by fluorescent cell viability assays.

RESULTS

Our results demonstrated that a concentration of 0.01% CHX allowed the production of a stable APRF membrane. This concentration slightly reduced the viability of PDL cells to 96.7%, but significantly decreased the average number of cells attached to the membrane-149 ± 16.5 cells/field compared to controls -336 ± 26.9 cells/field. APRF-CHX 0.02% membranes were unstable, indicating a dose-dependent cytotoxic effect of CHX.

CONCLUSIONS

The introduced novel protocol leads to the production of a new type of APRF membrane-CHX-PRF. The incorporation of an antiseptic into the APRF membrane can improve its bactericidal activity and might serve as an important step for the prevention of postoperative infections.

Exploration of proper heating protocol for injectable horizontal platelet-rich fibrin gel

Purpose

Platelet-rich fibrin (PRF) has been proposed as promising biomaterials with the advantages of host accumulation of platelets and leukocytes with entrapment of growth factors and fibrin scaffold. However, limitations including fast resorption rate (~ 2 weeks) restricts its clinical application. Recent studies have demonstrated heating treatment can prolong PRF degradation. Current published articles used the method of 75 °C for 10 min to obtain longer degradation, while few studies investigated the most suitable temperature for heating horizontal PRF. Our present study was to discover and confirm the optimum temperature for heat treatment before obtaining H-PRF gels by investigating their structure, mechanical properties, and bioactivity of the H-PRF gels after heating treatment.

Methods

In the present study, 2-mL upper layer of horizontal PRF was collected and heated at 45 °C, 60 °C, 75 °C, and 90 °C to heat 2-mL upper layer of horizontal PRF for 10 min before mixing with the 2-mL lower layer horizontal PRF. The weight, solidification time and the degradation properties were subsequently recorded. Scanning electron microscopy (SEM) and rheologic tests were carried out to investigate the microstructure and rheologic properties of each H-PRF gel. The biological activity of each H-PRF gel was also evaluated using live/dead staining.

Results

H-PRF gel prepared at 75 °C for 10 min had the fast solidification period (over a tenfold increase than control) as well as the best resistance to degradation. The number of living cells in H-PRF gel is greater than 90%. SEM showed that H-PRF gel becomes denser as the heating temperature increases, and rheologic tests also revealed that the heat treatment improved the mechanical properties of H-PRF gels when compared to non-heated control group. Future clinical studies are needed to further support the clinical application of H-PRF gels in tissue regeneration procedures.

Conclusions

Our results demonstrated that the H-PRF gel obtained at 75 °C for 10 min could produce a uniform, moldable gel with a short time for solidification time, great rheologic behavior and, high percent of live cells in PRF gel. A promising use of the commonly utilized PRF gel was achieved facilitating tissue regeneration and preventing degradation.

"Sticky Bone" Preparation Device: A Pilot Study on the Release of Cytokines and Growth Factors

Sticky bone, a growth factor-enriched bone graft matrix, is a promising autologous material for bone tissue regeneration. However, its production is strongly dependent on manual handling steps. In this sense, a new device was developed to simplify the confection of the sticky bone, named Sticky Bone Preparation Device (SBPD^®). The purpose of this pilot study was to investigate the suitability of the SBPD^® to prepare biomaterials for bone regeneration with autologous platelet concentrates. The SBPD^® allows the blending of particulate samples from synthetic, xenograft, or autogenous bone with autologous platelet concentrates, making it easy to use and avoiding the need of further manipulations for the combination of the materials. The protocol for the preparation of sticky bone samples using the SBPD^® is described, and the resulting product is compared with hand-mixed SB preparations regarding in vitro parameters such as cell content and the ability to release growth factors and cytokines relevant to tissue regeneration. The entrapped cell content was estimated, and the ability to release biological mediators was assessed after 7 days of incubation in culture medium. Both preparations increased the leukocyte and platelet concentrations compared to whole-blood samples (p < 0.05), without significant differences between SB and SBPD^®. SBPD^® samples released several growth factors, including VEGF, FGFb, and PDGF, at concentrations physiologically equivalent to those released by SB preparations. Therefore, the use of SBPD^® results in a similar product to the standard protocol, but with more straightforward and shorter preparation times and less manipulation. These preliminary results suggest this device as a suitable alternative for combining bone substitute materials with platelet concentrates for bone tissue regeneration.

Polysaccharide-Based Membrane Biocompatibility Study of Anacardium occidentale L. and Polyvinyl Alcohol after Subcutaneous Implant in Rats

Polymeric membranes are a viable and sustainable option for the biotechnology industry from an economic and environmental point of view. In this study, we evaluated tissue response and tolerance to the implantation of a polymeric membrane prepared with cashew gum polysaccharide (CGP) associated with polyvinyl alcohol (PVA). The objective was to characterize the biocompatibility of the CGP/PVA membrane in vivo. Following the evaluation criteria of the ISO 10993-6 standard, we demonstrated that the CGP/PVA membrane showed moderate tissue reaction, with a non-irritating ISO pattern, a thinner fibrous capsule, and a smaller amount of collagen compared to the positive control group. At 30 and 60 days, the membrane presented a similar amount of mast cells to that observed in the negative control group. The data demonstrate that the CGP/PVA membrane presents biocompatibility in accordance with the ISO 10993-6 standard.

Innovative Concepts and Recent Breakthrough for Engineered Graft and Constructs for Bone Regeneration: A Literature Systematic Review

Background: For decades, regenerative medicine and dentistry have been improved with new therapies and innovative clinical protocols. The aim of the present investigation was to evaluate through a critical review the recent innovations in the field of bone regeneration with a focus on the healing potentials and clinical protocols of bone substitutes combined with engineered constructs, growth factors and photobiomodulation applications. Methods: A Boolean systematic search was conducted by PubMed/Medline, PubMed/Central, Web of Science and Google scholar databases according to the PRISMA guidelines. Results: After the initial screening, a total of 304 papers were considered eligible for the qualitative synthesis. The articles included were categorized according to the main topics: alloplastic bone substitutes, autologous teeth derived substitutes, xenografts, platelet-derived concentrates, laser therapy, microbiota and bone metabolism and mesenchymal cells construct. Conclusions: The effectiveness of the present investigation showed that the use of biocompatible and bio-resorbable bone substitutes are related to the high-predictability of the bone regeneration protocols, while the oral microbiota and systemic health of the patient produce a clinical advantage for the long-term success of the regeneration procedures and implant-supported restorations. The use of growth factors is able to reduce the co-morbidity of the regenerative procedure ameliorating the post-operative healing phase. The LLLT is an adjuvant protocol to improve the soft and hard tissues response for bone regeneration treatment protocols.

Structure, Barrier Function, and Bioactivity of Platelet-Rich Fibrin Following Thermal Processing

Platelet-rich fibrin (PRF) has been utilized as a substitute for resorbable membranes during guided bone regeneration therapy as it is a more bioactive biomaterial with living cells and growth factors than resorbable membranes. Nevertheless, PRF poses obvious disadvantages in its mechanical strength since its rapid degradability has been shown to typically resorb within a 2-week time period. In the present study, the barrier function and biological and mechanical properties of PRF were investigated both as standard therapy and after thermal processing. Two heating processes were applied: both single-side heating and double-side heating at 90°C for 10 s using a metal plate heater. The appearance and weight of PRF membranes were documented after heating, along with their morphological and mechanical properties evaluated by scanning electron microscope and tensile strength tests. The viability of cells found within PRF membranes was also evaluated using live/dead cell viability and CCK-8 (cell counting kit-8) assays. To comprehensively evaluate the barrier function of PRF membranes, Hoechst staining of human gingival fibroblasts, which can be distinguished from cells within the PRF membrane by emitting blue light at an excitation wavelength of 488 nm, was seeded onto the surface of PRF membranes. Furthermore, osteoblasts were cultured with extracts from different PRF groups to evaluate the biocompatibility of PRF membranes. The degradation rate of PRF membranes was examined by digestion assay. Compared with the nonheated PRF control, the size and weight of PRF membranes led to a significant decrease with a denser PRF microstructure following heating. In summary, the double-sided heating of PRF membranes not only demonstrated an improvement in mechanical and degradation properties but also led to a decrease in cell viability and proliferation.

Platelet-Rich Fibrin Decreases the Inflammatory Response of Mesenchymal Cells

Chronic inflammation is a pathological process where cells of the mesenchymal lineage become a major source of inflammatory mediators. Platelet-rich fibrin (PRF) has been shown to possess potent anti-inflammatory activity in macrophages, but its impact on mesenchymal cells has not been investigated. The aim of this study was, therefore, to expose mesenchymal cells to inflammatory cytokines together with lysates generated from liquid platelet-poor plasma (PPP), the cell-rich buffy coat layer (BC; concentrated-PRF or C-PRF), and the remaining red clot layer (RC), following centrifugation of blood. Heating PPP generates an albumin gel (Alb-gel) that when mixed back with C-PRF produces Alb-PRF. Membranes prepared from solid PRF were also subjected to lysis. We report here that lysates of PPP, BC, and PRF decreased the cytokine-induced expression of interleukin 6 (IL6) and nitric oxide synthase (iNOS) in the bone marrow-derived ST2 cells. Consistently, PPP, BC, and PRF greatly decreased the phosphorylation and nuclear translocation of p65 in ST2 cells. The inflammatory response caused by Pam3CSK4 was reduced accordingly. Moreover, PPP, BC, and PRF reduced the enhanced expression of inflammatory mediators IL6 and iNOS in 3T3-L1 pre-adipocyte mesenchymal cells, and iNOS and CCL5 in murine calvarial cells. Surprisingly, PRF lysates were not effective in reducing the inflammatory response of human gingival fibroblasts and HSC2 epithelial cells. The data from the present study suggest that both liquid PRF and solid PRF exert potent anti-inflammatory activity in murine mesenchymal cells.

Autologous Biological Vitamin-C-added (ABC) Filler for Facial Volume Restoration

PURPOSE

Face rejuvenation procedures with injectable agents continue to gain popularity. Nowadays, a variety of commercial products are available as filler material. Ideal fillers should be inexpensive, easily obtainable, nontoxic, and biocompatible. The aim of this study is to report a clinical perspective for an appropriate, feasible, and inexpensive protocol of a stable, autologous biological filler for facial volume restoring without any commercial kits.

METHODS

Eight patients were investigated who underwent facial injection with ABC filler. Eleven ml of whole blood was placed in standard tubes containing anticoagulant and for each patient, 8 tubes were prepared. After the centrifugation at 1630 xg for 5 minutes, the upper plasma was taken, calcium was added and cooled. After the addition of vitamin C, the syringes were incubated at 85 °C for 10 minutes. The autologous biological material obtained was used as filling material. For comparison, FACE-Q satisfaction questionnaires were used before and after the procedure.

RESULTS

All patients were followed up for a minimum of 4 months. No major complications were recorded. The patient-reported FACE-Q satisfaction and FACE-Q quality of life pre- and post-procedure results showed statistically significant improvement (p  <  0.05). Overall satisfaction with the outcome was 89.12 ± 16.73 (range 55-100).

CONCLUSIONS

ABC filler can be seen as a reliable, inexpensive, and easily obtainable material to restore facial volume with increased patient satisfaction and quality of life scores. We believe that our study will be encouraging to the application of autologous biological fillers for further clinical and scientific studies.

LEVEL OF EVIDENCE IV

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Second generation liquid platelet concentrates: A literature review

Liquid or injectable platelet rich fibrin (PRF) is a second-generation platelet concentrate which is completely autologous and free of external additives like bovine thrombin and calcium chloride. Additionally, it is the only one to be obtained in a liquid form among the second generation platelet concentrates. This allows for wide applications such as to maximize injections or mixing with biomaterials such as bone grafts or antibiotics. Since it was first introduced in 2015, several modifications of the original protocol have been proposed which aim at maximizing its biological and mechanical properties. This includes changes in centrifugation speed, time, and so on. The aim of this review is to summarize the various modifications of the injectable/liquid formation of PRF as well as to discuss the potential applications and future research direction.

Liquid PRF Reduces the Inflammatory Response and Osteoclastogenesis in Murine Macrophages

Macrophage activation and osteoclastogenesis are hallmarks of inflammatory osteolysis and may be targeted by the local application of liquid platelet-rich fibrin (PRF). Liquid PRF is produced by a hard spin of blood in the absence of clot activators and anticoagulants, thereby generating an upper platelet-poor plasma (PPP) layer, a cell-rich buffy coat layer (BC; termed concentrated-PRF or C-PRF), and the remaining red clot (RC) layer. Heating PPP has been shown to generate an albumin gel (Alb-gel) that when mixed back with C-PRF generates Alb-PRF having extended working properties when implanted in vivo. Evidence has demonstrated that traditional solid PRF holds a potent anti-inflammatory capacity and reduces osteoclastogenesis. Whether liquid PRF is capable of also suppressing an inflammatory response and the formation of osteoclasts remains open. In the present study, RAW 264.7 and primary macrophages were exposed to lipopolysaccharides (LPS), lactoferrin, and agonists of Toll-like receptors (TLR3 and TLR7) in the presence or absence of lysates prepared by freeze-thawing of liquid PPP, BC, Alb-gel, and RC. For osteoclastogenesis, primary macrophages were exposed to receptor activator of nuclear factor kappa B ligand (RANKL), macrophage colony-stimulating factor (M-CSF), and human transforming growth factor-β1 (TGF-β1) in the presence or absence of PPP, BC, Alb-gel, RC lysates and hemoglobin. We show here that it is mainly the lysates prepared from PPP and BC that consistently reduced the agonist-induced expression of interleukin 6 (IL6) and cyclooxygenase-2 (COX2) in macrophages, as determined by RT-PCR and immunoassay. With respect to osteoclastogenesis, lysates from PPP and BC but also from RC, similar to hemoglobin, reduced the expression of osteoclast marker genes tartrate-resistant acid phosphatase (TRAP) and cathepsin K, as well as TRAP histochemical staining. These findings suggest that liquid PRF holds a potent in vitro heat-sensitive anti-inflammatory activity in macrophages that goes along with an inhibition of osteoclastogenesis.

In Vivo Comparative Evaluation of Biocompatibility and Biodegradation of Bovine and Porcine Collagen Membranes

Mechanical barriers prevent the invasion of the surrounding soft tissues within the bone defects. This concept is known as Guided Bone Regeneration (GBR). The knowledge about the local tissue reaction and the time of degradation of absorbable membranes favors the correct clinical indication. This study aimed to evaluate the biocompatibility and biodegradation of a bovine collagen membrane (Lyostypt^®, São Gonçalo, Brazil) and compare it to a porcine collagen membrane (Bio-Gide^®) implanted in the subcutaneous tissue of mice, following ISO 10993-6:2016. Thirty Balb-C mice were randomly divided into three experimental groups, LT (Lyostypt^®), BG (Bio-Gide^®), and Sham (without implantation), and subdivided according to the experimental periods (7, 21, and 63 days). The BG was considered non-irritant at seven days and slight and moderate irritant at 21 and 63 days, respectively. The LT presented a small irritant reaction at seven days, a mild reaction after 21, and a reduction in the inflammatory response at 63 days. The biodegradation of the LT occurred more rapidly compared to the BG after 63 days. This study concluded that both membranes were considered biocompatible since their tissue reactions were compatible with the physiological inflammatory process; however, the Bio-Gide^® was less degraded during the experimental periods, favoring the guided bone regeneration process.

Distribution and quantification of activated platelets in platelet-rich fibrin matrices

Platelet-rich fibrin (PRF) has been widely applied in regenerative therapy owing to its simple preparation protocol. To date, the original protocol for preparing leukocyte-rich (L)-PRF has been modified to produce derivatives such as advanced (A)-PRF, concentrated growth factors (CGF), and horizontal (H)-PRF. However, these derivatives have not been rigorously compared to explore possible differences. We previously developed and validated a nondestructive near-infrared (NIR) imaging method to quantitatively examine the platelet distribution in PRF matrices. To further evaluate the characteristics of platelets in PRF, we herein examined the distribution of activated platelets. Four types of PRF matrices were prepared under different centrifugal conditions from blood samples obtained from the same healthy donors. After fixation and compression, the matrices were stained immunohistochemically without sectioning and visualized using an NIR imager. Qualitative morphological analysis revealed that whole platelets were distributed widely and homogeneously in H-PRF and A-PRF, but localized along the distal tube surface in L-PRF and CGF. Activated platelets were distributed as were whole platelets in A-PRF, L-PRF, and CGF, but localized mainly in the "buffy coat" region in H-PRF. Quantitative analysis revealed that there was no significant difference in the ratio of activated to whole platelets between PRF derivatives. These findings suggest that platelet activation is similarly induced in fibrin matrices regardless of centrifugal speed or rotor angulation. However, only the H-PRF group was distinguishable from the other PRF derivatives in terms of activated platelet distribution.

Liquid Platelet-Rich Fibrin and Heat-Coagulated Albumin Gel: Bioassays for TGF-β Activity

Liquid platelet-rich fibrin (PRF) can be prepared by high centrifugation forces separating the blood into a platelet-poor plasma (PPP) layer and a cell-rich buffy coat layer, termed concentrated PRF (C-PRF). Heating the liquid PPP was recently introduced to prepare an albumin gel (Alb-gel) that is later mixed back with the concentrated liquid C-PRF to generate Alb-PRF. PRF is a rich source of TGF-β activity; however, the overall TGF-β activity in the PPP and the impact of heating the upper plasma layer remains unknown. Here, we investigated for the first time the in vitro TGF-β activity of all fractions of Alb-PRF. We report that exposure of oral fibroblasts with lysates of PPP and the buffy coat layer, but not with heated PPP, provoked a robust increase in the TGF-β target genes interleukin 11 and NADPH oxidase 4 by RT-PCR, and for IL11 by immunoassay. Consistent with the activation of TGF-β signaling, expression changes were blocked in the presence of the TGF-β receptor type I kinase inhibitor SB431542. Immunofluorescence and Western blot further confirmed that lysates of PPP and the buffy coat layer, but not heated PPP, induced the nuclear translocation of Smad2/3 and increased phosphorylation of Smad3. The immunoassay further revealed that PPP and particularly BC are rich in active TGF-β compared to heated PPP. These results strengthen the evidence that not only the cell-rich C-PRF but also PPP comprise a TGF-β activity that is, however, heat sensitive. It thus seems relevant to mix the heated PPP with the buffy coat C-PRF layer to regain TGF-β activity, as proposed during the preparation of Alb-PRF.

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.