In vitro evaluation of mechanical properties of platelet-rich fibrin membrane and scanning electron microscopic examination of its surface characteristics

Platelet-rich fibrin as an autologous biomaterial for bone regeneration: mechanisms, applications, optimization

Platelet-rich fibrin, a classical autologous-derived bioactive material, consists of a fibrin scaffold and its internal loading of growth factors, platelets, and leukocytes, with the gradual degradation of the fibrin scaffold and the slow release of physiological doses of growth factors. PRF promotes vascular regeneration, promotes the proliferation and migration of osteoblast-related cells such as mesenchymal cells, osteoblasts, and osteoclasts while having certain immunomodulatory and anti-bacterial effects. PRF has excellent osteogenic potential and has been widely used in the field of bone tissue engineering and dentistry. However, there are still some limitations of PRF, and the improvement of its biological properties is one of the most important issues to be solved. Therefore, it is often combined with bone tissue engineering scaffolds to enhance its mechanical properties and delay its degradation. In this paper, we present a systematic review of the development of platelet-rich derivatives, the structure and biological properties of PRF, osteogenic mechanisms, applications, and optimization to broaden their clinical applications and provide guidance for their clinical translation.

Advanced platelet rich fibrin demonstrates improved osteogenic induction potential in human periodontal ligament cells, growth factor production and mechanical properties as compared to leukocyte and platelet fibrin and injectable platelet rich fibrin

OBJECTIVES

This cross-sectional invitro research aimed to compare and contrast the macroscopic and microscopic, mechanical and biochemical features of leukocyte-rich platelet-rich fibrin, advanced platelet-rich fibrin, and injectable platelet-rich fibrin.

MATERIALS AND METHODS

In all, 150 samples were taken from males aged 18 to 25 with good systemic health (n = 50 each for i-PRF, A-PRF, and L-PRF). The samples were assessed for clot length, clot width, membrane length and width. Microscopic parameters assessed were the distribution of cells and fibrin structure. Mechanical tests were performed for tensile strength using a universal testing machine and growth factor analysis was performed for platelet derived growth factor (PDGF), vascular endothelial growth factor (VEGF), and transforming growth factor (TGF)- β on Days 1, 3 and 7 using commercially available ELISA kits. The osteogenic potential was analyzed in a culture of human periodontal ligament cells for 21 days using cell viability assay, alkaline phosphatase formation and alizarin red staining for mineralization.

RESULTS

L-PRF demonstrates statistically superior clot length, width, weight, membrane length, width and weight in comparison to A-PRF (p < 0.05). L-PRF demonstrates a denser fibrin structure in comparison to A-PRF and i-PRF (p < 0.05). The cells in L-PRF are most commonly situated in the proximal of the clot where as they are distributed in the proximal and middle aspect for A-PRF(p < 0.05). A-PRF demonstrates the highest tensile strength followed by L-PRF (p < 0.05). When growth factor release was evaluated, A-PRF showed noticeably increased release of all growth factors, namely PDGF-BB, TGF-ß, and VEGF, in comparison to i-PRF and L-PRF (p < 0.05). On days 7 and 14, the cell viability of human periodontal ligament cells in co-culture with A-PRF was statistically substantially greater than that of L-PRF and i-PRF (p < 0.05). Alkaline phosphatase levels were statistically substantially higher in A-PRF, followed by i-PRF and L-PRF on days 14 and 21 (p < 0.05). After 21 days of culture, A-PRF treated cultures had much more Alizarin Red staining than L-PRF and i-PRF cultures did (p < 0.05).

CONCLUSION

It was determined that although L-PRF exhibits greater size and weight in comparison to A-PRF and i-PRF, A-PRF has superior mechanical properties, increased growth factor releases of TGF-b, PDGF-BB, and VEGF as well as superior cell viability, alkaline phosphatase production, and mineralization on human periodontal ligament cells.

CLINICAL RELEVANCE

Based on these findings, A-PRF can be recommended for improved delivery of growth factors and osteogenesis whereas L-PRF is better-suited for applications relying on the size of membrane.

Antimicrobial effects of clindamycin-loaded platelet-rich fibrin (PRF)

OBJECTIVES

Recent research has demonstrated that platelet-rich fibrin (PRF) is an appropriate carrier for ampicillin/sulbactam. The aim of the study was to investigate whether PRF is also a suitable bio-carrier for clindamycin (CLI).

METHODS

PRF membranes were produced from 36 patients receiving intravenous therapy with CLI (e.g. due to the diagnosis of an osteonecrosis of the jaw or infections). Concentrations of CLI in PRF membranes were measured with liquid chromatography-tandem mass spectrometry, and the antimicrobial effects were investigated in vitro in agar diffusion tests with fresh PRF and PRF stored for 24 h. Storage was performed in an incubator at 36 °C to simulate the in-vivo situation.

RESULTS

The mean concentration of CLI in plasma was 1.0 ± 0.3 μg/100 mg plasma; in resulting PRF membranes 0.7 ± 0.4 μg/100 mg PRF. Agar diffusion tests were performed with Staphylococcus aureus, Streptococcus pneumoniae, Streptococcus mitis, Porphyromonas gingivalis, and Fusobacterium nucleatum. Mean inhibition zones, in mm, for fresh PRF were 17.3, 12.2, 18.8, 17.1, 25.8 and 18.1, 12.7, 19.2, 17.3, and 26.3 for stored PRF, respectively.

CONCLUSION

The results demonstrate that PRF is a suitable bio-carrier for CLI when administered systemically to patients. The concentration in PRF generated from patients after infusion of 600 mg CLI dose suffices to target clinically relevant bacteria.

CLINICAL RELEVANCE

Using PRF as a carrier for local antibiotic application can prevent infections in oral and maxillofacial surgery. Within the study limitations, the findings could expand the scope of PRF application by adding CLI as a new antibiotic to the spectrum of PRF therapy.

Leukocyte- and Platelet-Rich Fibrin (L-PRF) Obtained from Smokers and Nonsmokers Shows a Similar Uniaxial Tensile Response In Vitro

We evaluated and compared the biomechanical properties of Leukocyte-and Platelet Rich Fibrin L-PRF clots and membranes derived from smoker and nonsmoker donors. Twenty venous-blood donors (aged 18 to 50 years) were included after signing informed consent forms. L-PRF clots were analyzed and then compressed to obtain L-PRF membranes. L-PRF clot and membrane samples were tested in quasi-static uniaxial tension and the stress-stretch response was registered and characterized. Furthermore, scanning electron microscope representative images were taken to see the fibrin structure from both groups. The analysis of stress-stretch curves allowed us to evaluate the statistical significance in differences between smoker and nonsmoker groups. L-PRF membranes showed a stiffer response and higher tensile strength when compared to L-PRF clots. However, no statistically significant differences were found between samples from smokers and nonsmokers. With the limitations of our in vitro study, we can suggest that the tensile properties of L-PRF clots and membranes from the blood of smokers and nonsmokers are similar. More studies are necessary to fully characterize the effect of smoking on the biomechanical behavior of this platelet concentrate, to further encourage its use as an alternative to promote wound healing in smokers.

Histological, Immunohistochemical, Biomechanical, and Wettability Evaluations of the Leukocyte- and Platelet-Rich Fibrin Membranes Derived from Canine Blood

This study aimed to perform histological, immunohistochemical, biomechanical, and wettability assessments of leukocyte- and platelet-rich fibrin (L-PRF) membranes obtained from the blood of healthy dogs. Ten client-owned Labrador Retriever dogs were enrolled. Blood samples were obtained from the external jugular vein using a vacuum tube without anticoagulant, which was immediately centrifuged at 400g for 12 min in a dedicated centrifuge. The L-PRF clot was removed from the tube, and the red clot was released from the buffy coat using a spatula. The membrane was produced using a PRF box. Histological examination identified the three portions of the L-PRF membranes. The first portion was composed mainly of red blood cells with the presence of a low number of leukocytes among them. The second portion was composed of white blood cells, mainly neutrophils. The third portion was composed of the fibrin network which was characterized by acidophilic staining. The immunohistochemical analysis showed that vascular endothelial growth factor and platelet-derived growth factor were expressed in all samples at different intensities, both in cellular components and fibrin mesh. The tensile test and wettability assessments were measured in membranes 30 min and 3 h after production. The 30 min L-PRF membranes supported twice the ultimate tensile strength compared to 3 h L-PRF membranes. The wettability of the 30 min sample membranes was statistically higher than the 3 h sample membranes. In conclusion, the centrifugation protocol allowed production of the L-PRF membrane using canine blood and this was confirmed by histological and immunohistochemical analysis. The mechanical resistance and wettability of the L-PRF membrane were significantly reduced over time.

Effects of Platelet Lysate Gels Derived from Different Blood Sources on Oral Mucosal Wound Healing: An In Vitro Study

The rapid healing of oral ulcers is important to prevent secondary infection, especially for chronic oral ulcers. Platelet lysate (PL) is rich in growth factors for cell growth and promotes tissue regeneration. Hence, this study was performed to compare the effects of PL originating from umbilical cord blood (CB) and peripheral blood (PB) on oral mucosal wound healing. The PLs were molded into gel form in the culture insert with the addition of calcium chloride and conditioned medium for sustained release of growth factors. The CB-PL and PB-PL gels were found to degrade slowly in culture and their degradation percentages by weight were 5.28 ± 0.72% and 9.55 ± 1.82% respectively. The results from the scratch assay and Alamar blue assay showed that the CB-PL and PB-PL gels increased the proliferation (148 ± 3% and 149 ± 3%) and wound closure (94.17 ± 1.77% and 92.75 ± 1.80%) of oral mucosal fibroblasts compared to the control with no statistical differences between the two gels, respectively. Quantitative RT-PCR showed that mRNA expressions of collagen-I, collagen-III, fibronectin, and elastin genes in cells treated with CB-PL (11-, 7-, 2-, and 7-fold) and PB-PL (17-, 14-, 3-, and 7-fold) decreased compared with the control, respectively. The concentration of platelet-derived growth factor of PB-PL gel (1303.10 ± 343.96 pg/mL) showed a higher trend than CB-PL gel did (905.48 ± 69.65 pg/mL) from ELISA measurement. In summary, CB-PL gel is as effective as PB-PL gel in supporting oral mucosal wound healing, making it a potential new source of PL for regenerative treatment.

Fabrication and evaluation of Cs/PVP sponge containing platelet-rich fibrin as a wound healing accelerator: An in vitro and in vivo study

Despite significant advances in surgery and postoperative care, there are still challenges in the treatment of wounds. In the current study, a freeze-dried chitosan (Cs)/polyvinylpyrrolidone (PVP) sponges containing platelet-rich fibrin (PRF at 1, 1.5 and 2% w/v) for wound dressing application is fabricated and fully characterized. Addition of 1% w/v of PRF to Cs/PVP (CS/PVP/1PRF) sample significantly increased the tensile strength (from 0.147 ± 0.005 to 0.242 ± 0.001 MPa), elastic modulus (from 0.414 ± 0.014 to 0.611 ± 0.022 MPa) and strain at break (from 53.4 ± 0.9 to 61.83 ± 1.17%) compared to Cs sample, and was hence selected as the optimal sample. The antibacterial activity of Cs/PVP/1PRF sponge wound dressing against E. coli and S. aureus was confirmed to be effective. Enzyme-linked immunosorbent assays revealed that the release of both VEGF and PDGF-AB from PRF powder, as well as PDGF-AB from Cs/PVP/1PRF sample was time-independent, but the release of VEGF from Cs/PVP/1PRF sample increased significantly with time. According to MTT and CAM assays, the Cs/PVP/1PRF sample significantly increased proliferation and angiogenic potential, respectively. Furthermore, in vivo studies demonstrated a 97.16 ± 1.55% wound closure for Cs/PVP/1PRF group after 14 days.

Ultrastructural and Physicochemical Characterization of a Non-Crosslinked Type 1 Bovine Derived Collagen Membrane

In this work, in vitro testing was used to study the properties of non-crosslinked type 1 bovine derived collagen membranes used in bone regeneration surgery. Collagen membranes were prepared, their surface roughness was quantified by interferometry, their morphology was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), their wettability was measured by the contact angle technique, their mechanical properties were investigated by tensile testing, their phase transformation temperatures were measured by Differential Scanning Calorimetry (DSC), and their biocompatibility was evaluated by immunological testing. The calorimetry tests showed that the membrane is formed only by type 1 collagen. The SEM observations showed that the morphology consists of layers of highly organized collagen fibers and patterns of striated fibrils typical of type 1 collagen. The small contact angle showed that the membrane is hydrophilic, with the possibility of rapid absorption of body fluids. The tensile tests showed that the membrane has enough elasticity, ductility, and mechanical strength for use in tissue regeneration. With the immunostaining technique, it was possible to confirm the membrane biocompatibility.

Preparation and characterization of leukocyte- and platelet-rich fibrin membrane derived from cats' blood

Autologous platelet concentrates have been used in regenerative medicine in humans due to the abundance of growth factors, but there are only a few reports in small animals. This study aimed to prepare and characterize a leukocyte and platelet-rich fibrin membrane (L-PRF) produced with blood obtained from cats. Thirteen client-owned healthy adult Maine Coon cats were enrolled. The blood samples were collected and centrifuged at 650g for 12 min using a centrifuge specifically designed for this application. The L-PRF clot was removed from the tube and red blood cell base layer was separated, leaving buffy coat intact. After this, L-PRF clot was compressed by specialized metal plate for 30-60 s, and L-PRF membrane was obtained. Light microscopy examination of the membranes showed three distinct layers: white part, buffy coat, and red part. Immunohistochemical analysis demonstrated expression of vascular endothelial growth factor and platelet derived growth factor. The scanning electron microscopy showed that three-dimensional architecture of fibrin network was more compact in the area near the buffy coat. In conclusion, the method used allowed the characterization of the L-PRF membrane composition, which presented cell types and fibrin network architecture similar to those described in the human species.

Use of Platelet-Rich Fibrin in the Treatment of Periodontal Intrabony Defects: A Systematic Review and Meta-Analysis

Background

Platelet-rich fibrin (PRF) is a kind of autologous platelet concentrate which is easy to obtain and cheap. In recent years, it has been studied to improve the effect of periodontal regeneration. However, few studies have systematically evaluated the complementary effect of PRF in the treatment of intrabony defects. The present review is aimed at systematically assessing the effects of PRF on clinical and radiological outcomes of the surgical treatment of periodontal intrabony defects.

Methods

The protocol was registered at PROSPERO (International Prospective Register of Systematic Reviews) as CRD42020206056. An electronic search was conducted in MEDLINE, Cochrane, and EMBASE databases. Only randomized clinical trials were selected. Systematically healthy patients with two or three walls of intrabony defects were considered. Intrabony defect (IBD) depth reduction and bone fill (BF) % were set as primary outcomes while probing depth (PD) reduction, clinical attachment level (CAL) gain, and gingival margin level (GML) gain were considered as the secondary outcome. When possible, a meta-analysis was performed.

Results

Eighteen articles fulfilled the inclusion criteria, and seventeen studies were quantitatively analyzed. Of 17 studies, four were rated as high risk of bias and thirteen as the moderate risk of bias. Two comparisons were set: (1) open flap debridement (OFD) combined with PRF and OFD alone and (2) bone grafting (BG) combined with PRF and BG alone. Compared to OFD alone, OFD+PRF showed significantly greater in all primary and secondary outcomes. Compared to BG alone, BG+PRF showed significantly greater in IBD depth reduction, PD reduction, CAL gain, and GML gain.

Conclusions

The use of PRF was significantly effective in the treatment of periodontal intrabony defects. The benefit of OFD+PRF may be greater than BG+PRF. PRF can promote early wound healing in periodontal surgery. As all included studies were not at low risk of bias, well-designed RCTs having a high methodological quality are needed to clarify the additional effectiveness of PRF in the treatment of intrabony defects in the future.

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.

The Effects of Photobiomodulation on Leukocyte and Platelet-Rich Fibrin as Barrier Membrane on Bone Regeneration: An Experimental Animal Study

Objective: To compare the effects of leukocyte and platelet-rich fibrin (L-PRF) and photobiomodulation therapy (PBMT)-applied L-PRF (PBMT/L-PRF) as barrier membranes on new bone formation (BV/TV) for the treatment of critical-sized bone defects. Materials and methods: The right iliac crests of five sheep were used in this experimental animal study. Eight critical-sized defects were surgically created in each sheep and a total of 40 defects were obtained. A deproteinized bovine bone graft was placed in all defects, and the defects were divided into four groups to be covered with L-PRF membrane, PBMT/L-PRF membrane, collagen membrane, or left uncovered as controls. Animals were sacrificed at 1 month. The sections obtained were histomorphometrically analyzed. Results: The results showed that the collagen group presented significantly higher values for main bone healing parameters (BV/TV, bone volume, and bone surface; p < 0.05). The PBMT/L-PRF group presented higher values than the L-PRF group and controls for these parameters though not statistically significant (p > 0.05). Conclusions: The findings show that PBMT may provide additional regenerative properties to L-PRF when used as barrier membranes. However, these results did not reach the collagen membranes, which warrants further studies for adapting the laser parameters to increase regenerative capacity of L-PRF.

Wound dressings as growth factor delivery platforms for chronic wound healing

Introduction: Years of tissue engineering research have clearly demonstrated the potential of integrating growth factors (GFs) into scaffolds for tissue regeneration, a concept that has recently been applied to wound dressings. The old concept of wound dressings that only take a passive role in wound healing has now been overtaken, and advanced dressings which can take an active part in wound healing, are of current research interest.Areas covered: In this review we will focus on the recent strategies for the delivery of GFs to wound sites with an emphasis on the different approaches used to achieve fine tuning of spatial and temporal concentrations to achieve therapeutic efficacy.Expert opinion: The use of GFs to accelerate wound healing and reduce scar formation is now considered a feasible therapeutic approach in patients with a high risk of infections and complications. The integration of micro - and nanotechnologies into wound dressings could be the key to overcome the inherent instability of GFs and offer adequate control over the release rate. Many investigations have led to encouraging outcomes in various in vitro and in vivo wound models, and it is expected that some of these technologies will satisfy clinical needs and will enter commercialization.

The distribution pattern and growth factor level in platelet-rich fibrin incorporated skin-derived mesenchymal stem cells: An in vitro study

Background and Aim:

A skin wound in an animal must be cared for to prevent further health issues. Platelet-rich fibrin (PRF) and skin-derived mesenchymal stem cells (SMSCs) have been reported to have potential in increasing the rate of wound healing. This study aimed to analyze the distribution patterns and levels of platelet-derived growth factor (PDGF), insulin-like growth factor (IGF), vascular endothelial growth factor (VEGF), and transforming growth factor-β (TGF-β) in PRF incorporated with SMSCs.

Materials and Methods:

This study employed a true experiment (in vitro) design with post-test only performed in the control group alone. PRF and SMSCs were extracted from the blood and skin of 16 rabbits. SMSCs were characterized using immunocytochemistry to examine clusters of differentiation for 45, 73, 90, and 105. PRF was incorporated into the SMSCs and then divided into four groups (N=32/n=8): Group A (PRF only), Group B (PRF+SMSCs, incubated for 1 day), Group C (PRF+SMSCs, incubated for 3 days), and Group D (PRF+SMSCs, incubated for 5 days). Scanning electron microscopy was used to examine the distribution pattern of SMSCs between groups. The supernatant serum (Group A) and supernatant medium culture (Group D) were collected for the measurement of PDGF, IGF, VEGF, and TGF-β using an enzyme-linked immunosorbent assay sandwich kit. An unpaired t-test was conducted to analyze the differences between Groups A and D (p<0.01).

Results:

Group D had the most morphologically visible SMSCs attached to the PRF, with elongated and pseudopodia cells. There was a significant difference between the levels of growth factor in Groups A and D (p=0.0001; p<0.01).

Conclusion:

SMSCs were able to adhere to and distribute evenly on the surface of PRF after 5 days of incubation. The PRF incorporated SMSCs contained high levels of PDGF, IGF, VEGF, and TGF- β, which may prove to have potential in enhancing wound healing.

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

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

Fabrication, modeling and optimization of lyophilized advanced platelet rich fibrin in combination with collagen-chitosan as a guided bone regeneration membrane

In this study, lyophilized advanced platelet rich fibrin (A-PRF) was used in combination with collagen-chitosan membrane for the first time to combine advantages of both collagen and A-PRF membranes. Response surface methodology (RSM) was used to design the experimental condition and to correlate the effects of parameters, including chitosan/collagen (chit/col) weight ratio and A-PRF concentration on Young's modulus, mesenchymal stem cell (MSCs) viability and degradation rate of the membranes. Results showed that Young's modulus of the membranes was intensified by increasing chit/col weight ratio and decreasing A-PRF concentration from 3 to 8 MPa. Cell viability of MSCs was improved by both increasing chit/col weight ratio and A-PRF concentration. Moreover, as chit/col weight ratio increased from 0 to 4 and A-PRF concentration decreased from 5 to 0, degradation rate of the membranes decreased from 90 to 20% after four weeks incubation. Finally, based on Design Expert Software calculation for minimizing the degradation rate and maximizing both Young's modulus and cell viability, the values of chit/col weight ratio and A-PRF concentration were suggested to be 4 and 0.58 mg/ml, respectively. Alkaline phosphatase (ALP) activity analysis showed that the addition of A-PRF caused higher osteogenic differentiation.

In vitro evaluation of decontamination effects on mechanical properties of fibrin membrane

Background: Tissue engineering has been investigated as a potential method for healing traumatized tissues. Biomaterials are material devices or implants used to repair or replace native body tissues and organs. The present study was conducted to evaluate the effects of decontamination methods on biological/mechanical properties and degradation/adhesion test of the platelet-rich fibrin (PRF) membranes to compare these properties with intact membranes as a biological biomaterial.

Methods: The in vitro degradation tests were conducted by placing the equal sizes of (i) intact PRF membrane, (ii) PRF membrane sterilized by autoclave (iii), ultraviolet (UV), and (iiii) gamma irradiation in phosphate buffer solution on a shaker. The degradation profiles were expressed. Adhesion test was performed by counting adhered mouse fibroblast and sterilized fibrin membrane was compared to normal fibrin membrane by different sterilization methods.

Results: The preliminary findings of sterilized PRF membranes showed that UV exposure (p<0.05) and autoclaved fibrin membranes (p<0.01) have significantly lower degradability compared to normal fibrin membranes. Gamma irradiation is similar to normal membrane in degradability. Cell adherence in all groups of fibrin membrane was significantly lower than the group without membrane, but there was no significant difference between intact and sterilized groups of fibrin membranes.

Conclusion: Sterilization of fibrin membrane with different protocols does not have any adverse effects on cell adhesion; however, cell adherence is naturally very weak even in normal membranes. Also, it seems that ultraviolet ray polymerizes fibrin filaments and merges them to each other and increases the ability of fibrin membrane against degradation. Autoclaved fibrin membrane content proteins are denatured because of pressure and heat and show an increase in hardness and stability against degradation.

The Effects of Autologous Platelet-Rich Fibrin on Flexor Tendon Healing in a Rabbit Model

PURPOSE

Platelet-rich plasma containing large amounts of growth factors is purported to increase repaired flexor tendon strength. However, the use of bovine thrombin has the risk of antibody formation. We evaluated the effects of the newer generation autologous platelet-rich fibrin (PRF) on flexor tendon healing.

METHODS

We performed surgical repair of 32 flexor tendons from the index and ring digits of the hind paws of 8 New Zealand white rabbits. In the PRF group, the PRF membrane was either wrapped around or interposed between the repair sites. At 3 weeks after surgery, the tested tendons were subjected to range of motion analysis, cross-sectional area measurement, biomechanics testing, and histological analysis.

RESULTS

The results showed no significant increase in range of motion in the PRF group compared with the control group, but there was a significant increase in cross-sectional area of the tendons in the PRF group. The biomechanical testing suggested that the control had a higher load to failure and stress to failure but similar stiffness and modulus to the PRF group.

CONCLUSIONS

The PRF did not have a major influence on cellular organization. It also had an undesirable effect on the biomechanical properties of repaired flexor tendons.

CLINICAL RELEVANCE

The findings of this study suggest PRF may, in certain situations, hinder rather than enhance, the healing for repaired flexor tendons.

Adjunctive Effect of Autologus Platelet-Rich Fibrin to Barrier Membrane in the Treatment of Periodontal Intrabony Defects

BACKGROUND AND AIM

Autologous platelet-rich fibrin (PRF) and barrier membranes in the treatment of intrabony defects in chronic periodontitis patients have shown significant clinical benefits. This study evaluates the additive effect of autologous PRF in combination with a barrier membrane versus the use of barrier membrane alone for the treatment of intrabony defects in chronic periodontitis patients.

METHODS

A randomized split-mouth design was used. Sixteen patients with 32 paired intrabony defects were included. In each patient 1 defect was treated using a resorbable collagen membrane along with PRF (test group) and the other defect by guided tissue regeneration alone (control group). The following clinical parameters were measured at baseline and after 9 months: plaque index, modified sulcus bleeding index, probing pocket depth, clinical attachment level, and gingival marginal level. The radiographic defect depth was also assessed at baseline and after 9 months.

RESULTS

Test group showed a statistically significant improvement for probing depth (P = 0.002), clinical attachment level (P = 0.001), and radiographic defect depth (P < 0.001) after 9 months as compared with the control sites. Radiographic defect depth reduction was 58.19 ± 13.24% in the test group as compared with 24.86 ± 9.94% reduction in the control group.

CONCLUSIONS

The adjunctive use of PRF in combination with barrier membrane is more effective in the treatment of intrabony defects in chronic periodontitis as compared with barrier membrane alone.