Resorbable Membranes for Guided Bone Regeneration: Critical Features, Potentials, and Limitations

Immobilization of Antibacterial Chlorhexidine on Biodegradable Polycaprolactone/Estradiol Electrospun Nanofibrous Membrane for Bone Regeneration

Membrane-based scaffold for bone regeneration is vastly being explored to address issues that persist in defective bone regeneration, associated with infection and inflammation. This study focused on incorporating estradiol (E2) into biodegradable polycaprolactone (PCL) electrospun nanofibrous membrane, followed by the immobilization with antibacterial chlorhexidine (CHX) through the aid of a polydopamine (PDA) grafting layer. Several analyses including field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), wettability, biodegradation, drug release, antibacterial, and cytotoxicity analyses were conducted to study the physicochemical and biological properties of the membranes. The nanofibers were constructed with an average diameter of 1.32-1.33 μm and a porosity of 51%-53%, which is accommodating bone regeneration. The grafting of PDA was not only able to improve the surface wettability, which in turn allowed controllable degradability and sustained the release of E2 and CHX from the nanofibrous membranes. The immobilization of CHX on the PCL/E2 nanofibers has greatly retarded Gram-negative Escherichia coli compared to Gram-positive Staphylococcus aureus. The in vitro cytotoxicity assay statistically depicted the ability of the fabricated nanofibrous membranes to support cell proliferation without cytotoxic effects at the cell viability above 70%. These cumulative results indicate the potential development of CHX-immobilized PCL/E2 membrane as an alternative strategy to resolve bone regeneration issues.

Bone Regeneration: A Review of Current Treatment Strategies

Bone regeneration has emerged as a critical research and clinical advancement field, fueled by the growing demand for effective treatments in orthopedics and oncology. Over the past two decades, significant progress in biomaterials and surgical techniques has led to the development of novel solutions for treating bone defects, surpassing the use of traditional autologous grafts. This review aims to assess the latest approaches in bone regeneration, including autologous, allogenic, and xenogenic grafts, naturally derived biomaterials, and innovative synthetic substitutes such as bioceramics, bioactive glasses, metals, polymers, composite materials, and other specialized applications. A comprehensive literature search was conducted on PubMed, focusing on studies published between 2019 and 2024, including meta-analyses, reviews, and systematic reviews. The review evaluated a range of bone regeneration strategies, examining the clinical outcomes, materials used, surgical techniques, and the effectiveness of various approaches in treating bone defects. The search identified numerous studies, with the inclusion criteria focused on those exploring innovative bone regeneration strategies. These studies provided valuable insights into the clinical and biological outcomes of different biomaterials and graft types. Results indicated that while advancements in synthetic and naturally derived biomaterials show promising potential, challenges remain in optimizing therapeutic strategies across diverse patient populations and clinical settings. The findings emphasize the need for an integrated approach that combines scientific research, clinical practice, and technological innovation to improve bone regeneration therapies. Further research is required to establish standardized protocols and determine the optimal application of various materials and techniques to enhance patient outcomes and the quality of care.

Magnesium Nanocomposite Hydrogel Reverses the Pathologies to Enhance Mandible Regeneration

The healing of bone defects after debridement in medication-related osteonecrosis of the jaw (MRONJ) is a challenging medical condition with impaired angiogenesis, susceptible infection, and pro-inflammatory responses. Magnesium (Mg) nanocomposite hydrogel is developed to specifically tackle multiple factors involved in MRONJ. Mg-oxide nanoparticles tune the gelation kinetics in the reaction between N-hydroxysuccinimide-functionalized hyperbranched poly (ethylene glycol) and proteins. This reaction allows an enhanced mechanical property after instant solidification and, more importantly, also stable gelation in challenging environments such as wet and hemorrhagic conditions. The synthesized hydrogel guides mandible regeneration in MRONJ rats by triggering the formation of type H vessels, activating Osterix+ osteoprogenitor cells, and generating anti-inflammatory microenvironments. Additionally, this approach demonstrates its ability to suppress infection by inhibiting specific pathogens while strengthening stress tolerance in the affected alveolar bone. Furthermore, the enhanced osteogenic properties and feasibility of implantation of the hydrogel are validated in mandible defect and iliac crest defect created in minipigs, respectively. Collectively, this study offers an injectable and innovative bone substitute to enhance mandible defect healing by tackling multiple detrimental pathologies.

Development and characterization of nitazoxanide-loaded poly(ε-caprolactone) membrane for GTR/GBR applications

OBJECTIVE

Guided tissue/guided bone regeneration (GTR/GBR) membranes are widely used for periodontal bone regeneration, but their success depends on a bacteria-free environment. Systemic antibiotic treatment often proves inadequate, moreover, the increasing prevalence of antibiotic resistance in oral infections exacerbates this challenge. This study aimed to fabricate antibacterial membranes using a new class of antibiotics for local drug delivery, to eradicate infections and promote tissue regeneration.

METHODS

Membranes loaded with nitazoxanide (NTZ) were fabricated via electrospinning using poly(ε-caprolactone) (PCL) with varying concentrations of NTZ (0 %, 2.5 %, and 5 % w/w) relative to the polymer weight. Morphochemical of NTZ-loaded membranes were assessed using scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) and Fourier Transform Infrared spectroscopy (FTIR). Mechanical properties were evaluated using universal testing machine and NTZ release profile from membranes was determined by spectrophotometer (λmax = 444) for 14 days. Antimicrobial efficacy against periodontal pathogens, cell compatibility and mineralization were evaluated using periodontal ligament stem cells (PDLSCs).

RESULTS

Optimized spinning parameter maintained a uniform fiber diameter and successful loading of NTZ was confirmed by SEM-EDS and FTIR. NTZ incorporation did not significantly affect mechanical properties, whereas the drug release kinetics showed an initial burst, followed by sustained release over 14 days. NTZ-loaded membranes demonstrated antibacterial activity against Aggregatibacter actinomycetemcomitans (Aa) and Fusobacterium nucleatum (Fn). Importantly, the presence of NTZ showed minimal cell toxicity; however, it reduced the mineralization potential compared with that of the pure PCL membrane, which increased over time.

SIGNIFICANCE

Taken together, these findings established that NTZ-loaded membranes could be promising barrier membrane to counteract microbial environment and aid periodontal bone regeneration.

Evaluating Osteogenic Cell Differentiation Efficacy in the Presence of Polylactide Samples With Varied Compositions for Bone Grafting: In Vitro Study

In oral implantology, surgeons often confront the need to improve alveolar bone quality and volume before implantation in patients with bone defects. Whereas guided bone regeneration with titanium meshes is a clinical gold standard for bone augmentation, mesh removal pre-implantation presents a drawback. This study explores biodegradable scaffolds as an alternative. The research investigates the impact of various compositions of customized bone-grafting scaffolds on proliferation and osteogenic differentiation processes in vitro. Plates (10 × 10 × 0.5 mm) were fabricated from polylactide (PLA), PLA with 15% hydroxyapatite nanoparticles (PLA/HA), and polylactide with glycolic acid copolymers (PLGA 60:40 and 85:15). Gingival fibroblasts assessed the influence of experimental samples on proliferation and osteogenic differentiation in a low-glucose medium. Osteogenic differentiation was induced, and alizarin red staining measured extracellular matrix calcification via spectrophotometry. Active proliferation of gingival fibroblasts occurred along scaffold edges during cultivation. Although cells proliferated with experimental samples, rates were lower than control cells. PLA/HA showed higher alizarin red staining intensity, indicating enhanced matrix calcification. Experimental samples (PLA, PLA/HA, PLGA 85:15, PLGA 60:40) supported cell proliferation at lower rates than control. PLA/HA demonstrated increased matrix calcification. Biodegradable membranes were nontoxic, suggesting potential for bone augmentation.

Enhanced bone formation of rat mandibular bone defects with collagen membranes loaded on bone morphogenetic protein-9

Background/purpose

Bone morphogenetic protein-9 (BMP-9) has demonstrated multiple advantages in promoting osteogenesis. Our previous findings have indicated that the use of an absorbable collagen membrane (ACM) as a carrier for growth factors is effective in stimulating bone regeneration. The objective of this study was to assess the synergistic impact of BMP-9 incorporated into ACM (ACM/BMP-9) on bone formation within rat mandibular bone defects.

Materials and methods

Circular bone defects of critical size were surgically induced on both sides of the rat mandibular bone, with subsequent random allocation into distinct groups: control, ACM alone, and ACM loaded with low (0.5 μg) or high (2.0 μg) concentrations of BMP-9. We conducted real-time in vivo micro-computerized tomography scans at the baseline and at 2, 4, and 6 weeks, and measured the volume of newly formed bone (NFB), bone mineral density (BMD) of NFB, and the closure percentage of the NFB area. Histological and histomorphometric analyses were performed at 6 weeks.

Results

Real-time assessment revealed notably higher levels of bone volume, BMD, and closure percentage in the NFB area for the groups treated with ACM/BMP-9 compared to the control and ACM groups. Within the high concentration of BMP-9 group, the volume and BMD of NFB exhibited a significant increase at 6 weeks compared to baseline. Histological examination confirmed the existence of osteoblasts, osteocytes, and blood vessels within the NFB.

Conclusion

Considering the limitations of this research, the real-time evaluation finding indicates that ACM/BMP-9 effectively promotes bone formation in critical-size mandibular defects in rats.

Fabrication of Bioresorbable Barrier Membranes from Gelatin/Poly(4-Hydroxybutyrate) (P4HB)

Dental implant surgery is a procedure that replaces damaged or missing teeth with an artificial implant. During this procedure, guided bone regeneration (GBR) membranes are commonly used to inhibit the migration of epithelium and GBR at the surgical sites. Due to its biodegradability, good biocompatibility, and unique biological properties, gelatin (GT) is considered a suitable candidate for guiding periodontal tissue regeneration. However, GT-based membranes come with limitations, such as poor mechanical strength and mismatched degradation rates. To confront this challenge, a series of GT/poly(4-hydroxybutyrate) (P4HB) composite membranes are fabricated through electrospinning technology. The morphology, composition, wetting properties, mechanical properties, biocompatibility, and in vivo biodegradability of the as-prepared composite membranes are carefully characterized. The results demonstrate that all the membranes present excellent biocompatibility. Moreover, the in vivo degradation rate of the membranes can be manipulated by changing the ratio of GT and P4HB. The results indicate that the optimized GT/P4HB membranes with a high P4HB content (75%) may be suitable for periodontal tissue engineering because of their good mechanical properties and biodegradation rate compatible with tissue growth.

Fabrication of Electrospun Double Layered Biomimetic Collagen-Chitosan Polymeric Membranes with Zinc-Doped Mesoporous Bioactive Glass Additives

Several therapeutic approaches have been developed to promote bone regeneration, including guided bone regeneration (GBR), where barrier membranes play a crucial role in segregating soft tissue and facilitating bone growth. This study emphasizes the importance of considering specific tissue requirements in the design of materials for tissue regeneration, with a focus on the development of a double-layered membrane to mimic both soft and hard tissues within the context of GBR. The hard tissue-facing layer comprises collagen and zinc-doped bioactive glass to support bone tissue regeneration, while the soft tissue-facing layer combines collagen and chitosan. The electrospinning technique was employed to achieve the production of nanofibers resembling extracellular matrix fibers. The production of nano-sized (~116 nm) bioactive glasses was achieved by microemulsion assisted sol-gel method. The bioactive glass-containing layers developed hydroxyapatite on their surfaces starting from the first week of simulated body fluid (SBF) immersion, demonstrating that the membranes possessed favorable bioactivity properties. Moreover, all membranes exhibited distinct degradation behaviors in various mediums. However, weight loss exceeding 50% was observed in all tested samples after four weeks in both SBF and phosphate-buffered saline (PBS). The double-layered membranes were also subjected to mechanical testing, revealing a tensile strength of approximately 4 MPa. The double-layered membranes containing zinc-doped bioactive glass demonstrated cell viability of over 70% across all tested concentrations (0.2, 0.1, and 0.02 g/mL), confirming the excellent biocompatibility of the membranes. The fabricated polymer bioactive glass composite double-layered membranes are strong candidates with the potential to be utilized in tissue engineering applications.

Inflammatory Profile of Different Absorbable Membranes Used for Bone Regeneration: An In Vivo Study

BACKGROUND

Guided bone regeneration (GBR) has become a necessary practice in implantology. Absorbable membranes have shown advantages over non-absorbable membranes, such as blood support of bone tissue. This study aimed to evaluate five collagen membranes in rat calvaria critical-size defects through a histomorphometric analysis of the inflammatory profile during the initial phase of bone repair.

MATERIALS AND METHODS

A total of 72 Albinus Wistar rats were used for the study, divided into six groups, with 12 animals per group, and two experimental periods, 7 and 15 days. The groups were as follows: the CG (clot), BG (Bio-Gide®), JS (Jason®), CS (Collprotect®), GD (GemDerm®), and GDF (GemDerm Flex®).

RESULTS

Data showed that the BG group demonstrated an inflammatory profile with an ideal number of inflammatory cells and blood vessels, indicating a statistically significant difference between the JS and CS groups and the BG group in terms of the number of inflammatory cells and a statistically significant difference between the JS and CS groups and the GD group in terms of angiogenesis (p < 0.05).

CONCLUSIONS

We conclude that different origins and ways of obtaining them, as well as the thickness of the membrane, can interfere with the biological response of the material.

A Biomimetic Multifunctional Scaffold for Infectious Vertical Bone Augmentation

The regenerative treatment of infectious vertical bone defects remains difficult and challenging today. Current clinical treatments are limited in their ability to control bacteria and infection, which is unfavorable for new bone formation and calls for a new type of material with excellent osteogenic and antibacterial properties. Here a multifunctional scaffold is synthesized that mimics natural bone nanostructures by incorporating silver nanowires into a hierarchical, intrafibrillar mineralized collagen matrix (IMC/AgNWs), to achieve the therapeutic goals of inhibiting bacterial activity and promoting infectious alveolar bone augmentation in rats and beagle dogs. An appropriate concentration of 0.5 mg mL-1 AgNWs is selected to balance biocompatibility and antibacterial properties. The achieved IMC/AgNWs exhibit a broad spectrum of antimicrobial properties against Gram-negative Porphyromonas gingivalis and Gram-positive Streptococcus mutans. When the IMC/AgNWs are cocultured with periodontal ligament stem cells, it possesses excellent osteoinductive activities under both non-inflammatory and inflammatory conditions. By constructing a rat mandibular infected periodontal defect model, the IMC/AgNWs achieve a near-complete healing through the canonical BMP/Smad signaling. Moreover, the IMC/AgNWs enhance vertical bone height and osseointegration in peri-implantitis in beagle dogs, indicating the clinical translational potential of IMC/AgNWs for infectious vertical bone augmentation.

A chitosan-coated PCL/nano-hydroxyapatite aerogel integrated with a nanofiber membrane for providing antibacterial activity and guiding bone regeneration

A guided bone regeneration (GBR) membrane can act as a barrier to prevent the invasion and interference from foreign soft tissues, promoting infiltration and proliferation of osteoblasts in the bone defect area. Herein, a composite scaffold with dual functions of osteogenesis and antibacterial effects was prepared for GBR. A polycaprolactone (PCL)/nano-hydroxyapatite (n-HA) aerogel produced by electrospinning and freeze-drying techniques was fabricated as the loose layer of the scaffold, while a PCL nanofiber membrane was used as the dense layer. Chitosan (CS) solution served as a middle layer to provide mechanical support and antibacterial effects between the two layers. Morphological results showed that the loose layer had a porous structure with n-HA successfully dispersed in the aerogels, while the dense layer possessed a sufficiently dense structure. In vitro antibacterial experiments illustrated that the CS solution in the middle layer stabilized the scaffold structure and endowed the scaffold with good antibacterial properties. The cytocompatibility results indicated that both fibroblasts and osteoblasts exhibited superior cell activity on the dense and loose layers, respectively. In particular, the dense layer made of nanofibers could work as a barrier layer to inhibit the infiltration of fibroblasts into the loose layer. In vitro osteogenesis analysis suggested that the PCL/n-HA aerogel could enhance the bone induction ability of bone mesenchymal stem cells, which was confirmed by the increased expression of the alkaline phosphatase activity. The loose structure facilitated the infiltration and migration of bone mesenchymal stem cells for better osteogenesis. In summary, such a composite scaffold exhibited excellent osteogenic and antibacterial properties as well as the barrier effect, thus holding promising potential for use as GBR materials.

The potential bone regeneration effects of leptin- and osteolectin-coated 3D-printed PCL scaffolds: anin vivostudy

This study investigated the effectiveness of bone regeneration upon the application of leptin and osteolectin to a three-dimensional (3D) printed poly(ϵ-caprolactone) (PCL) scaffold. A fused deposition modeling 3D bioprinter was used to fabricate scaffolds with a diameter of 4.5 mm, a height of 0.5 mm, and a pore size of 420-520 nm using PCL (molecular weight: 43 000). After amination of the scaffold surface for leptin and osteolectin adhesion, the experimental groups were divided into the PCL scaffold (control), the aminated PCL (PCL/Amine) scaffold, the leptin-coated PCL (PCL/Leptin) scaffold, and the osteolectin-coated PCL (PCL/Osteo) scaffold. Next, the water-soluble tetrazolium salt-1 (WST-1) assay was used to assess cell viability. All groups exhibited cell viability rates of >100%. Female 7-week-old Sprague-Dawley rats were used forin vivoexperiments. Calvarial defects were introduced on the rats' skulls using a 5.5 mm trephine bur. The rats were divided into the PCL (control), PCL/Leptin, and PCL/Osteo scaffold groups. The scaffolds were then inserted into the calvarial defect areas, and the rats were sacrificed after 8-weeks to analyze the defect area. Micro-CT analysis indicated that the leptin- and osteolectin-coated scaffolds exhibited significantly higher bone regeneration. Histological analysis revealed new bone and blood vessels in the calvarial defect area. These findings indicate that the 3D-printed PCL scaffold allows for patient-customized fabrication as well as the easy application of proteins like leptin and osteolectin. Moreover, leptin and osteolectin did not show cytotoxicity and exhibited higher bone regeneration potential than the existing scaffold.

Review of Spider Silk Applications in Biomedical and Tissue Engineering

This review will present the latest research related to the production and application of spider silk and silk-based materials in reconstructive and regenerative medicine and tissue engineering, with a focus on musculoskeletal tissues, and including skin regeneration and tissue repair of bone and cartilage, ligaments, muscle tissue, peripheral nerves, and artificial blood vessels. Natural spider silk synthesis is reviewed, and the further recombinant production of spider silk proteins. Research insights into possible spider silk structures, like fibers (1D), coatings (2D), and 3D constructs, including porous structures, hydrogels, and organ-on-chip designs, have been reviewed considering a design of bioactive materials for smart medical implants and drug delivery systems. Silk is one of the toughest natural materials, with high strain at failure and mechanical strength. Novel biomaterials with silk fibroin can mimic the tissue structure and promote regeneration and new tissue growth. Silk proteins are important in designing tissue-on-chip or organ-on-chip technologies and micro devices for the precise engineering of artificial tissues and organs, disease modeling, and the further selection of adequate medical treatments. Recent research indicates that silk (films, hydrogels, capsules, or liposomes coated with silk proteins) has the potential to provide controlled drug release at the target destination. However, even with clear advantages, there are still challenges that need further research, including clinical trials.

Regeneration of Rabbit Calvarial Defects with Combination of Stem Cells and Enamel Matrix Derivative: A Microcomputed Tomography and Histological Evaluation Comparing Two- and Three-Dimensional Cell Constructs

Background and Objectives: This study addresses the challenge of bone regeneration in calvarial defects, exploring the efficacy of stem cell-based therapies and enamel matrix derivative (EMD) in tissue engineering. It assesses the regenerative potential of two- and three-dimensional cell constructs combined with mesenchymal stem cells (MSCs) and EMD in rabbit calvarial defects. Materials and Methods: This research involved the use of bone-marrow-derived MSCs cultured in silicon elastomer-based concave microwells to form spheroids. White rabbits were grouped for different treatments, with Group 1 as control, Group 2 receiving only EMD, Group 3 getting EMD plus stem cells, and Group 4 being treated with EMD plus stem cell spheroids. Computed tomography (CT) and microcomputed tomography (micro-CT) imaging were used for structural assessment, while histological evaluations were conducted using hematoxylin and eosin, Masson's trichrome, and Picro-sirius red staining. Results: CT and micro-CT analyses revealed varying degrees of bone regeneration among the groups. Group 4, treated with three-dimensional MSC spheroids and EMD, showed the most significant improvement in bone regeneration. Histological analyses corroborated these findings, with Group 4 displaying enhanced bone formation and better collagen fiber organization. Conclusions: The study supported the biocompatibility and potential efficacy of three-dimensional MSC constructs combined with EMD in bone regeneration. Further investigations are needed to confirm these findings and optimize treatment protocols.

Development of a rapid-shaping and user-friendly membrane with long-lasting space maintenance for guided bone regeneration

The success of guided bone regeneration (GBR) surgery depends largely on the use of GBR membranes to maintain space for bone regeneration and prevent soft tissue ingrowth. However, currently available commercial degradable GBR membranes are often limited by poor space maintenance ability and require additional suture or nail for fixation. To overcome these limitations, we developed a rapid-shaping, adhesive, and user-friendly GBR membrane (PLGA film-PGN) with long-lasting space maintenance by immersing an electrospun poly(lactide-co-glycolic acid) film in a photo-crosslinkable hydrogel composed of polyethylene glycol diacrylate, gelatin methacryloyl, and nanosilicate (PGN). The PGN hydrogel significantly improved the mechanical strength of the PLGA film-PGN and endowed it with plasticity and adhesive properties, making it more maneuverable. The maximum bending force that the PLGA film-PGN could withstand was over 55 times higher than that of the HEAL ALL film (a commonly used commercial GBR membrane). PLGA film-PGN also promoted the proliferation and osteogenic differentiation of rBMSCs. According to a critical-size rat calvarial defect model, PLGA film-PGN maintained the space within the defect area and significantly enhanced bone formation 4 weeks after the surgery. To conclude, the study provided a novel perspective on GBR membrane design and the multifunctional PLGA film-PGN membrane demonstrated great potential for bone defect reconstruction.