Efficacy of doxycycline release collagen membrane on surgically created and contaminated defects in rat tibiae: A histopathological and microbiological study

Emulsion electrospun epigallocatechin gallate-loaded silk fibroin/polycaprolactone nanofibrous membranes for enhancing guided bone regeneration

Guided bone regeneration (GBR) membranes play an important role in oral bone regeneration. However, enhancing their bone regeneration potential and antibacterial properties is crucial. Herein, silk fibroin (SF)/polycaprolactone (PCL) core-shell nanofibers loaded with epigallocatechin gallate (EGCG) were prepared using emulsion electrospinning. The nanofibrous membranes were characterized via scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, water contact angle (CA) measurement, mechanical properties testing, drug release kinetics, and 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH) free radical scavenging assay. Mouse pre-osteoblast MC3T3-E1 cells were used to assess the biological characteristics, cytocompatibility, and osteogenic differentiation potential of the nanofibrous membrane. Additionally, the antibacterial properties againstStaphylococcus aureus (S. aureus)andEscherichia coli (E. coli)were evaluated. The nanofibers prepared by emulsion electrospinning exhibited a stable core-shell structure with a smooth and continuous surface. The tensile strength of the SF/PCL membrane loaded with EGCG was 3.88 ± 0.15 Mpa, the water CA was 50°, and the DPPH clearance rate at 24 h was 81.73% ± 0.07%. The EGCG release rate of membranes prepared by emulsion electrospinning was reduced by 12% within 72 h compared to that of membranes prepared via traditional electrospinning.In vitroexperiments indicate that the core-shell membranes loaded with EGCG demonstrated good cell compatibility and promoted adhesion, proliferation, and osteogenic differentiation of MC3T3-E1 cells. Furthermore, the EGCG-loaded membranes exhibited inhibitory effects onE. coliandS. aureus. These findings indicate that core-shell nanofibrous membranes encapsulated with EGCG prepared using emulsion electrospinning possess good antioxidant, osteogenic, and antibacterial properties, making them potential candidates for research in GBR materials.

Choosing the right animal model for osteomyelitis research: Considerations and challenges

Osteomyelitis is a debilitating bone disorder characterized by an inflammatory process involving the bone marrow, bone cortex, periosteum, and surrounding soft tissue, which can ultimately result in bone destruction. The etiology of osteomyelitis can be infectious, caused by various microorganisms, or noninfectious, such as chronic nonbacterial osteomyelitis (CNO) and chronic recurrent multifocal osteomyelitis (CRMO). Researchers have turned to animal models to study the pathophysiology of osteomyelitis. However, selecting an appropriate animal model that accurately recapitulates the human pathology of osteomyelitis while controlling for multiple variables that influence different clinical presentations remains a significant challenge. In this review, we present an overview of various animal models used in osteomyelitis research, including rodent, rabbit, avian/chicken, porcine, minipig, canine, sheep, and goat models. We discuss the characteristics of each animal model and the corresponding clinical scenarios that can provide a basic rationale for experimental selection. This review highlights the importance of selecting an appropriate animal model for osteomyelitis research to improve the accuracy of the results and facilitate the development of novel treatment and management strategies.

Antibacterial efficacy of epigallocatechin-3-gallate cross-linked small intestinal submucosa guided bone regeneration membrane

The leading cause of guided bone regeneration (GBR) failure is infection. Herein, we developed a new GBR membrane with good mechanical and osteogenic properties by crosslinking the small intestinal submucosa (SIS) with epigallocatechin-3-gallate (EGCG). Meanwhile, EGCG is also a natural antibacterial agent. This study aimed to investigate the antibacterial efficacy of EGCG-crosslinked SIS (E-SIS) against Staphylococcus aureus and Escherichia coli through EGCG release, bacterial count, live/dead staining, scanning electron microscopy, growth curve, and biofilm formation tests. The results showed that E-SIS effectively inhibited bacteria's growth and adhesion, and its antibacterial activity against Staphylococcus aureus was stronger than that against Escherichia coli. 0.5% E-SIS had the most potent antibacterial activity. The antibacterial mechanism of E-SIS might be related to the release of EGCG and the surface properties of E-SIS. In conclusion, 0.5% E-SIS is a promising GBR membrane with good osteogenic and antibacterial properties.

Poly(lactic acid/caprolactone) bilayer membrane blocks bacterial penetration

BACKGROUND AND OBJECTIVE

The clinical outcomes of guided tissue regeneration (GTR) or guided bone regeneration (GBR) procedures can be impaired if a bacterial infection develops at the surgical site. Membrane exposure is one of the causes of the onset of bacterial infection. Previously, we have fabricated a poly(lactic acid/caprolactone) (PLCL) bilayer membrane composed of a porous layer and a compact layer. The compact layer acts as a barrier against connective tissue and epithelial cells, and we hypothesized that it could also be an effective barrier against bacterial cells. The objective of this study was to evaluate the ability of the PLCL bilayer membrane to block bacterial cell penetration, which would be useful for preventing postoperative infections.

METHODS

Porphyromonas gingivalis, Streptococcus mutans, and multispecies bacteria collected from human saliva were used in this study. Bacteria were seeded directly on the compact layer of a PLCL bilayer membrane, and bacterial adhesion to the membrane, as well as penetration into the membrane's structure, were assessed. Bacterial adhesion was evaluated by the number of colonies formed at 6, 24, and 72 h, and penetration was observed using a scanning electron microscope at 24 and 72 h. Commercially available membranes, composed of poly(lactic-co-glycolic acid) or type I collagen, were used as controls.

RESULTS

P. gingivalis, S. mutans, and the multispecies bacteria obtained from human saliva adhered onto all the membranes after only 6 h of incubation. However, fewer adherent cells were observed for the PLCL bilayer membrane compared with the controls for all experimental periods. The PLCL membrane was capable of blocking bacterial penetration, and no bacterial cells were observed in the structure. In contrast, bacteria penetrated both the control membranes and were observed at depths of up to 80 µm after 72 h of incubation.

CONCLUSION

Membrane characteristics may influence how bacterial colonization occurs. The PLCL membrane had reduced bacterial adhesion and blocked bacterial penetration, and these characteristics could contribute to a favorable outcome for regenerative treatments. In the event of membrane exposure at GTR/GBR surgical sites, membranes with an efficient barrier function, such as the PLCL bilayer membrane, could simplify the management of GTR/GBR complications.

Antibiotic-Loaded Polymeric Barrier Membranes for Guided Bone/Tissue Regeneration: A Mini-Review

Polymeric membranes are frequently used for bone regeneration in oral and periodontal surgery. Polymers provide adequate mechanical properties (i.e., Young’s modulus) to support oral function and also pose some porosity with interconnectivity to permit for cell proliferation and migration. Bacterial contamination of the membrane is an event that may lead to infection at the bone site, hindering the clinical outcomes of the regeneration procedure. Therefore, polymeric membranes have been proposed as carriers for local antibiotic therapy. A literature search was performed for papers, including peer-reviewed publications. Among the different membranes, collagen is the most employed biomaterial. Collagen membranes and expanded polytetrafluoroethylene loaded with tetracyclines, and polycaprolactone with metronidazole are the combinations that have been assayed the most. Antibiotic liberation is produced in two phases. A first burst release is sometimes followed by a sustained liberation lasting from 7 to 28 days. All tested combinations of membranes and antibiotics provoke an antibacterial effect, but most of the time, they were measured against single bacteria cultures and usually non-specific pathogenic bacteria were employed, limiting the clinical relevance of the attained results. The majority of the studies on animal models state a beneficial effect of these antibiotic functionalized membranes, but human clinical assays are scarce and controversial.

Finding the Perfect Membrane: Current Knowledge on Barrier Membranes in Regenerative Procedures: A Descriptive Review

Guided tissue regeneration (GTR) and guided bone regeneration (GBR) became common procedures in the corrective phase of periodontal treatment. In order to obtain good quality tissue neo-formation, most techniques require the use of a membrane that will act as a barrier, having as a main purpose the blocking of cell invasion from the gingival epithelium and connective tissue into the newly formed bone structure. Different techniques and materials have been developed, aiming to obtain the perfect barrier membrane. The membranes can be divided according to the biodegradability of the base material into absorbable membranes and non-absorbable membranes. The use of absorbable membranes is extremely widespread due to their advantages, but in clinical situations of significant tissue loss, the use of non-absorbable membranes is often still preferred. This descriptive review presents a synthesis of the types of barrier membranes available and their characteristics, as well as future trends in the development of barrier membranes along with some allergological aspects of membrane use.

Finding the Perfect Membrane: Current Knowledge on Barrier Membranes in Regenerative Procedures: A Descriptive Review

Guided tissue regeneration (GTR) and guided bone regeneration (GBR) became common procedures in the corrective phase of periodontal treatment. In order to obtain good quality tissue neo-formation, most techniques require the use of a membrane that will act as a barrier, having as a main purpose the blocking of cell invasion from the gingival epithelium and connective tissue into the newly formed bone structure. Different techniques and materials have been developed, aiming to obtain the perfect barrier membrane. The membranes can be divided according to the biodegradability of the base material into absorbable membranes and non-absorbable membranes. The use of absorbable membranes is extremely widespread due to their advantages, but in clinical situations of significant tissue loss, the use of non-absorbable membranes is often still preferred. This descriptive review presents a synthesis of the types of barrier membranes available and their characteristics, as well as future trends in the development of barrier membranes along with some allergological aspects of membrane use.

The effect of local application of thymoquinone, Nigella sativa’s bioactive component, on bone healing in experimental bone defects infected with Porphyromonas gingivalis

Purpose

This study was performed to evaluate the influence of local application of thymoquinone (TQ) on bone healing in experimental bone defects infected with Porphyromonas gingivalis (PG).

Methods

Forty-two female rats were randomly divided into 6 groups. A bone defect was created on the right tibia of all animals. The PG, PG/collagen membrane (COL) and PG/TQ/COL groups were infected with PG. In the COL and PG/COL groups, the defects were covered with a COL; in the TQ/COL and PG/TQ/COL groups, the defects were covered with a TQ-containing COL. After 28 days, all animals were sacrificed. Quantitative measurements of new bone formation and osteoblast lining, as well as semiquantitative measurements of capillary density and tissue response, were analyzed. Furthermore, the presence of bacterial infections in defect areas was evaluated.

Results

The new bone formation, osteoblast number, and capillary density were significantly higher in the TQ groups than in the control groups (P<0.001, P<0.001, and P<0.01, respectively). In a comparison between the TQ/COL group, with a TQ-containing COL (TQ/COL), and the PG–infected TQ-containing COL (PG/TQ/COL) group, the newly formed bone and capillary density were higher in the TQ/COL group (P<0.01). When the control group was compared to the PG, PG/COL, and PG/TQ/COL groups in terms of tissue response, the differences were statistically significant (P<0.001, P=0.02, and P=0.041, respectively). The intensity of the inflammatory cell reaction was higher in the PG, PG/COL, and PG/TQ/COL groups (P<0.05).

Conclusions

Within the limitations of this study, the local application of a TQ-containing COL positively affected bone healing even if the bone defects were infected. The results suggest that TQ increased angiogenesis and showed promise for accelerating bone defect healing. Further research is warranted to support these findings and reach more definitive conclusions.

Electrophoretic deposition of silk fibroin coatings with pre-defined architecture to facilitate precise control over drug delivery

The therapeutic precision and clinical applicability of drug-eluting coatings can be substantially improved by facilitating tunable drug delivery. However, the design of coatings which allows for precise control over drug release kinetics is still a major challenge. Here, a double-layered silk fibroin (SF) coating system was constructed by sequential electrophoretic deposition. A mixture of dissolved Bombyx mori SF (bmSF) molecules and pre-made bmSF nanospheres at different ratios was deposited as under-layer. Subsequently, this underlayer was covered by a top-layer comprising Antheraea pernyi SF (apSF) molecules (rich in arginylglycylaspartic acid, RGD) to improve the cellular response of the resulting double-layered coatings. Additionally, model drug doxycycline was either pre-mixed with dissolved bmSF molecules or pre-loaded into pre-made bmSF nanospheres at the same amount before their mixing and deposition. The thickness and nanosphere content of the under-layer architecture were proportional to the deposition time and nanosphere concentration in precursor mixtures, respectively. The surface topography, wettability, degradation rate and adhesion strength were comparable within the double-layered coating system. As expected, RGD-rich apSF top-layer improved cell adhesion, spreading and proliferation compared with bmSF top-layer. Furthermore, the amount and duration of drug release increased linearly with increasing nanosphere concentration at fixed deposition time, whereas drug release amount increased linearly with increasing deposition time. These results indicate that the dosage and kinetics of loaded drugs can be quantitatively tailored by altering nanosphere concentration and deposition time as main processing parameters. Overall, this study illustrates the strong potential of pre-defining coating architecture to facilitate control over drug delivery.

Preventive antibiotic therapy in bone augmentation procedures in oral implantology: A systematic review

INTRODUCTION

Since the beginning of Oral Implantology, preventive antibiotic therapy has been routinely prescribed. However, at present, due to the growing appearance of antimicrobial resistance, its use has been questioned, generating a great debate and an emerging controversy. The present systematic review aims to analyze the scientific literature to determine whether the preventive prescription of antibiotics in augmentation procedures with the insertion of implants in one or two phases decreases the incidence of postoperative infections and/or the survival rate of the implants.

MATERIAL AND METHODS

The MEDLINE database was searched (via PubMed) with the following keywords: (bone grafting OR alveolar ridge augmentation OR bone graft augmentation OR guided bone regeneration OR bone block) AND (dental implants OR dental implant OR oral implantology) AND (antibiotic prophylaxis OR antibiotics). The criteria used were those described by the PRISMA® Statement. The search was limited to randomised clinical trials, systematic reviews and meta-analyses published in the last 15 years (2005-2020).

RESULTS

After reading the titles and abstracts of the resulting articles, only one systematic review meeting the described criteria and 4 randomised clinical trials were included.

CONCLUSIONS

Prescription of 2 or 3 g of amoxicillin one hour before surgery is recommended to reduce the early failure rate of one-stage implants and to decrease the bacterial load of grafted bone particles in bone augmentation procedures with one or two-stage implants.

Antibacterial Collagen Composite Membranes Containing Minocycline

Collagen membranes have been used as bioresorbable barrier membranes in guided tissue/bone regeneration. However, the collagen membranes currently used in clinics lack an active antibacterial function, although infection at surgical sites presents a realistic challenge for guided tissue/bone regeneration. In this study, we successfully prepared novel and advanced collagen composite membranes from collagen and complexes of heparin and chelates of minocycline and Ca²⁺ ions. These membranes were characterized for chemical structures, morphology, elemental compositions and tensile strength. In vitro release studies were conducted to evaluate the release kinetics of minocycline from these membranes. Agar disk diffusion assays were used to assess their sustained antibacterial capability against model pathogenic bacteria Staphylococcus aureus. The chemical and physical characterization confirmed the successful synthesis of minocycline-loaded collagen composite membranes, namely NCCM-1 and NCCM-2. Both membranes had weaker tensile strength as compared with commercial collagen membranes. They achieved sustained release of minocycline for at least 4 weeks in simulated body fluid (pH 7.4) at 37°C. Moreover, both membranes demonstrated potent sustained antibacterial effects against Staphylococcus aureus. These results suggested that the advanced collagen composite membranes containing minocycline can be exploited as novel guided tissue regeneration membranes or wound dressing by providing additional antibacterial functions.

Membranes for Guided Bone Regeneration: A Road from Bench to Bedside

Bone resorption can negatively influence the osseointegration of dental implants. Barrier membranes for guided bone regeneration (GBR) are used to exclude nonosteogenic tissues from influencing the bone healing process. In addition to the existing barrier membranes available on the market, a growing variety of membranes for GBR with tailorable physicochemical properties are under preclinical evaluation. Hence, the aim of this review is to provide a comprehensive description of materials used for GBR and to report the main industrial and regulatory aspects allowing the commercialization of these medical devices (MDs). In particular, a summary of the main attributes defining a GBR membrane is reported along with a description of commercially available and under development membranes. Finally, strategies for the scaling-up of the manufacturing process and the regulatory framework of the main MD producers (USA, EU, Japan, China, and India) are presented. The description of the regulatory approval process of GBR membranes is representative of the typical path that medium- to high-risk MDs have to follow for an effective medical translation, which is of fundamental importance to increase the impact of biomedical research on public health.

Silver Nanoparticles Coated Poly(L-Lactide) Electrospun Membrane for Implant Associated Infections Prevention

Bacterial infection has been a critic problem for implant infections. Poly(L-lactide) (PLLA) membrane has great potential for Guided bone regeneration (GBR), however, PLLA lack antibacterial property and thus may face bacterial infections. In this work, a mussel inspired method was used to treat PLLA membrane with dopamine and formed polydopamine (PDA) coated PLLA (PLLA@PDA), and then silver Nanoparticles (AgNPs) was immobilized on the surface of PLLA via the reduction effect of PDA. The XPS results showed that the silver element contents may be tuned from 1.6% to 15.4%. The AgNPs coated PLLA (PLLA@Ag) showed good antibacterial property (98.3% bactericidal efficiency may be obtained) and good biocompatibility, implying that the PLLA@Ag membrane have potential application as antibacterial GBR membrane, which may enhance the application of PLLA.

The effect of graft application and simvastatin treatment on tibial bone defect in rats. A histological and immunohistochemical study

Purpose:

To evaluate histologically and immunohistochemically the bone regeneration after application of simvastatin on tibial bone defects in rats.

Methods:

Sixty Wistar albino rats were divided into 3 groups as control (6 mm tibial bone defect), defect + graft (allograft treatment), and defect + graft + simvastatin (10 mg/kg/day) for 28 days.

Results:

Histopathological examination revealed inflammation in control group (defect group), congestion in blood vessels, and an increase in osteoclast cells. In defect + graft group, osteoclastic activity was observed and osteocyte cells were continued to develop. In defect + graft + simvastatin group, osteocytes and matrix formation were increased in the new bone trabeculae. Osteopontin and osteonectin expression were positive in the osteclast cells in the control group. Osteoblasts and some osteocytes showed a positive reaction of osteopontin and osteopontin. In defect + graft + simvastatin group, osteonectin and osteopontin expression were positive in osteoblast and osteocyte cells, and a positive expression in osteon formation was also seen in new bone trabeculae.

Conclusion:

The simvastatin application was thought to increase bone turnover by increasing the osteoinductive effect with graft and significantly affect the formation of new bone.

[Research progress on the modification of guided bone regeneration membranes]

Guided bone regeneration (GBR) is an important technique to solve bone defect problems. In this technique, GBR barrier membranes play an irreplaceable role. GBR membranes can act as a barrier protecting fibroblasts from bone defects and promote osteoblast adhesion and proliferation, leading to bone regeneration. GBR barrier membranes should be enhanced because of the disadvantages of collagen membranes, which are extensively applied to the field of GBR. Therefore, various efforts have been devoted to modifying the antibacterial and osteogenic properties of GBR barrier membranes and developing novel materials. This article reviews the research advancements on the modification of GBR barrier membranes and discover future directions for the development of GBR barrier membranes to provide a reference for bone tissue engi-neering and repair.

Barrier membranes: More than the barrier effect?

AIM

To review the knowledge on the mechanisms controlling membrane-host interactions in guided bone regeneration (GBR) and investigate the possible role of GBR membranes as bioactive compartments in addition to their established role as barriers.

MATERIALS AND METHODS

A narrative review was utilized based on in vitro, in vivo and available clinical studies on the cellular and molecular mechanisms underlying GBR and the possible bioactive role of membranes.

RESULTS

Emerging data demonstrate that the membrane contributes bioactively to the regeneration of underlying defects. The cellular and molecular activities in the membrane are intimately linked to the promoted bone regeneration in the underlying defect. Along with the native bioactivity of GBR membranes, incorporating growth factors and cells in membranes or with graft materials may augment the regenerative processes in underlying defects.

CONCLUSION

In parallel with its barrier function, the membrane plays an active role in hosting and modulating the molecular activities of the membrane-associated cells during GBR. The biological events in the membrane are linked to the bone regenerative and remodelling processes in the underlying defect. Furthermore, the bone-promoting environments in the two compartments can likely be boosted by strategies targeting both material aspects of the membrane and host tissue responses.

Modifications of Polymeric Membranes Used in Guided Tissue and Bone Regeneration

Guided tissue/bone regeneration (GTR/GBR) is a widely used procedure in contemporary dentistry. To achieve the required results of tissue regeneration, soft tissues that reproduce quickly are separated from the slow-growing bone tissue by membranes. Many types of membranes are currently in use, but none of them fulfil all of the desired features. To address this issue, further research on developing new membranes with better separation characteristics, such as membrane modification, is needed. Many of the current innovative modified materials are still in the phase of in vitro and experimental studies. A collective review on new trends in membrane modification to GTR/GBR is needed due to the widespread use of polymeric membranes and the constant development in the field of dentistry. Therefore, the aim of this review was to present an overview of polymeric membrane modifications to the GTR/GBR reported in the literature. The authors searched databases, including PubMed, SCOPUS, Web of Science, and OVID, for relevant studies that were published during 1999-2019. The following keywords were used: guided tissue regeneration, membranes, coating, and modification. A total of 17 papers were included in this review. Furthermore, the articles were divided into three groups that were based on the type of membrane modification: antibiotic coating, ion-use modifications, and others modifications, thus providing an overview of current existing knowledge in the field and encouraging further research. The results of included studies on modified barrier membranes seem to be promising, both in terms of safety and benefits for patients. However, modifications result in a large spectrum of effects. Further clinical studies are needed on a large group of patients to clearly confirm the effects that were observed in animal and in vitro studies.

Preclinical therapies to prevent or treat fracture non-union: A systematic review

Background

Non-union affects up to 10% of fractures and is associated with substantial morbidity. There is currently no single effective therapy for the treatment or prevention of non-union. Potential treatments are currently selected for clinical trials based on results from limited animal studies, with no attempt to compare results between therapies to determine which have the greatest potential to treat non-union.

Aim

The aim of this systematic review was to define the range of therapies under investigation at the preclinical stage for the prevention or treatment of fracture non-union. Additionally, through meta-analysis, it aimed to identify the most promising therapies for progression to clinical investigation.

Methods

MEDLINE and Embase were searched from 1^St January 2004 to 10^th April 2017 for controlled trials evaluating an intervention to prevent or treat fracture non-union. Data regarding the model used, study intervention and outcome measures were extracted, and risk of bias assessed.

Results

Of 5,171 records identified, 197 papers describing 204 therapies were included. Of these, the majority were only evaluated once (179/204, 88%), with chitosan tested most commonly (6/204, 3%). Substantial variation existed in model design, length of survival and duration of treatment, with results poorly reported. These factors, as well as a lack of consistently used objective outcome measures, precluded meta-analysis.

Conclusion

This review highlights the variability and poor methodological reporting of current non-union research. The authors call for a consensus on the standardisation of animal models investigating non-union, and suggest journals apply stringent criteria when considering animal work for publication.