Guided Bone Tissue Regeneration Research Articles

Guided bone regeneration activity of different calcium phosphate/chitosan hybrid membranes

To fulfill the properties of membrane for guided bone tissue regeneration, chitosan (CS) and calcium phosphates were blended to produce porous hybrid membranes by lyophilization. We synthesized three different calcium phosphates: calcium deficient hydroxyapatite (CDHA), biphasic calcium phosphate (BCP) and β‑tricalcium phosphate (TCP) by a reverse emulsion method followed by calcination, and compared their efficacy on bone regeneration. The CDHA/CS, BCP/CS, and TCP/CS membranes had an interconnected pore structure with porosity of 91–95% and pore size of 102–147 μm. These hybrid membranes could promote the permeability and adhesiveness to bone cells as demonstrated by in-vitro cell culture of primary osteoblast. Particularly, the CDHA/CS and BCP/CS could further increase the cell attachment and differentiation, whereas the BCP/CS and TCP/CS could enhance cell proliferation. Finally, these hybrid membranes were assessed for guided bone regeneration in the critical-size calvarial bone defects created in SD rats. Histological and histomorphometric analyses revealed that the BCP/CS membrane had the most effective bone regeneration compared to the other two hybrid membranes. At three-week post-surgery, the BCP/CS membrane could enhance new bone generation up to 57% of the original bone defect area. The BCP/CS membrane thus has the potential to be applied for guided bone regeneration.

Scaffold Structural Microenvironmental Cues to Guide Tissue Regeneration in Bone Tissue Applications.

In the process of bone regeneration, new bone formation is largely affected by physico-chemical cues in the surrounding microenvironment. Tissue cells reside in a complex scaffold physiological microenvironment. The scaffold should provide certain circumstance full of structural cues to enhance multipotent mesenchymal stem cell (MSC) differentiation, osteoblast growth, extracellular matrix (ECM) deposition, and subsequent new bone formation. This article reviewed advances in fabrication technology that enable the creation of biomaterials with well-defined pore structure and surface topography, which can be sensed by host tissue cells (esp., stem cells) and subsequently determine cell fates during differentiation. Three important cues, including scaffold pore structure (i.e., porosity and pore size), grain size, and surface topography were studied. These findings improve our understanding of how the mechanism scaffold microenvironmental cues guide bone tissue regeneration.

Development of a PCL/gelatin/chitosan/\u03b2-TCP electrospun composite for guided bone regeneration

Many approaches have been developed to regenerate biological substitutes for repairing damaged tissues. Guided bone/tissue regeneration (GBR/GTR) that employs a barrier membrane has received much attention in recent years. Regardless of substantial efforts for treatment of damaged tissue in recent years, an effective therapeutic strategy is still a challenge for tissue engineering researchers. The aim of the current study is to fabricate a GBR membrane consisting of polycaprolactone (PCL)/gelatin/chitosan which is modified with different percentages of β-tricalcium phosphate (β-TCP) for improved biocompatibility, mechanical properties, and antibacterial activity. The membranes are examined for their mechanical properties, surface roughness, hydrophilicity, biodegradability and biological response. The mechanical properties, wettability and roughness of the membranes are improved with increases in β-TCP content. An increase in the elastic modulus of the substrates is obtained as the amount of β-TCP increases to 5% (145–200 MPa). After 5 h, the number of attached cells is enhanced by 30%, 40% and 50% on membranes having 1%, 3% and 5% β-TCP, respectively. The cell growth on a membrane with 3% of β-TCP is also 50% and 20% higher than those without β-TCP and 5% β-TCP, respectively. Expression of type I collagen is increased with addition of β-TCP by 3%, while there is no difference in ALP activity. The results indicated that a composite having (3%) β-TCP has a potential application for guided bone tissue regeneration.

Clinical Safety of a New Synthetic Resorbable Dental Membrane: A Case Series Study.

Dental membranes are commonly used in oral and maxillofacial surgery for the regeneration of small osseous defects. A new synthetic resorbable membrane has recently demonstrated its biocompatibility and bone regeneration capacity in preclinical studies. This membrane is made of poly(D,L-lactic/glycolic acid 85/15), has a bi-layered structure with a dense film to prevent gingival epithelial cell invasion, and a microfibrous layer to support osteogenic cells and bone healing. This membrane completely degrades by hydrolysis in 4 to 6 months without signs of inflammation. Based on this research, a clinical study was conducted to evaluate the safety of the new membrane in guided tissue regeneration (GTR). In total, 26 patients (age: 50.5 ± 12.4, min-max 31-72 years; male/female 42/58%) were operated on at 7 independent private dental practices. Dental surgeons used the membrane together with various bone fillers in GTR for immediate and delayed implant placement (23 cases, 88%) and, to a lesser extent, socket preservation (2 cases, 8%) and alveolar crest augmentation (1 case, 4%). Surgeons reported an easy placement of the membrane (satisfaction index: 3.8/5). Fourteen days postsurgery, 15 patients had no pain while the others declared minimal pain (verbal rating scale: 2.2/10), and none had minor or serious complications related to the membrane. Exposure of the membrane without loosening the biomaterial granules was observed in 3 cases while mucosa healed normally over time. At 4 months postimplantation, no infection or mucosal inflammation was reported, and the overall dentist satisfaction with the clinical performance of the membrane was 4.5/5 on average. This clinical study demonstrated that the new synthetic resorbable membrane is safe for guided bone tissue regeneration in various dental surgery indications.

Novel poss reinforced chitosan composite membranes for guided bone tissue regeneration.

In this study, novel composites membranes composed of chitosan matrix and polyhedral oligomeric silsesquioxanes (POSS) were fabricated by solvent casting method. The effect of POSS loading on the mechanical, morphological, chemical, thermal and surface properties, and cytocompatibility of composite membranes were investigated and observed by tensile test, atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), protein adsorption assay, air/water contact angle analysis and WST-1 respectively. Swelling studies were also performed by water absorption capacity determination. Results showed that incorporation of Octa-TMA POSS® nanofiller to the chitosan matrix increased the surface roughness, protein adsorption and swelling capacity of membranes. The addition of POSS enhanced significantly the ultimate tensile strength and strain at break of the composite membranes up to 3 wt% POSS loaded samples. An increase of about 76% in tensile strength and of strain at break 1.28% was achieved for 3 wt% POSS loaded nanocomposite membranes compared with chitosan membranes. The presence of POSS filler into polymer matrix increased the plasma protein adsorption on the surface. Maximum protein capacity and swelling was obtained for 10 wt% loaded samples. High cell viability results were obtained with indirect extraction of chitosan/POSS composites. Besides, cell proliferation and ALP activity results showed that POSS incorporation significantly increased the ALP activity of Saos-2 cells cultured on chitosan membranes. This novel composite membranes with tunable properties could be considered as a potential candidate for guided bone regeneration applications.

Development and characterization of clay-polymer nanocomposite membranes containing sodium alendronate with osteogenic activity

The preparation of new biocompatible polymer systems could accelerate processes underlying guided bone tissue regeneration (GBR) by acting as adjuvants. Here, different reaction conditions were investigated to engineer nanocomposites based on chitosan and sodium montimorilonite (Na-Mt) that can be used to generate biocompatible membranes. The goal was a balanced combination of flexibility and tensile strength for use in orthopedic and periodontal surgical procedures for improved GBR. The execution of different experimental protocols aimed to control the polymer intercalation process inside the Na-Mt lamellae, and to avoid their exfoliation, by varying its concentration while applying, at same time, ultrasonic energy as a pretreatment. To increase the therapeutic efficacy of the membranes formed, sodium alendronate was included in the compositions as well as plasticizers to optimize their mechanical and physical-chemical properties. All membranes were analyzed by powder x-ray diffraction, nuclear magnetic resonance, differential scanning calorimetry and thermogravimetric analysis, as well as high performance chromatography to characterize the sodium alendronate content. Surface roughness, water absorption (swelling) and tensile strength were evaluated by scanning electron microscope and profilometry. As a model for human osteoblasts, the proliferation of Saos-2 cells was measured by colorimetric assays and microscopy to assess the potential performance of the membranes in GBR. Membranes with improved mechanical and physical-chemical properties along with excellent biocompatibility could be generated from 33% sodium montmorillonite (w/w) intercalated with chitosan and containing sodium alendronate, glycerol (20% [w/w]) and Labrasol® (3% [w/w]) that also supported the induction of Saos-2 cell proliferation and differentiation, exhibiting potential to develop a novel biomaterial device for GBR

Ionic Colloidal Molding as a Biomimetic Scaffolding Strategy for Uniform Bone Tissue Regeneration.

Inspired by the highly ordered nanostructure of bone, nanodopant composite biomaterials are gaining special attention for their ability to guide bone tissue regeneration through structural and biological cues. However, bone malformation in orthopedic surgery is a lingering issue, partly due to the high surface energy of traditional nanoparticles contributing to aggregation and inhomogeneity. Recently, carboxyl-functionalized synthetic polymers have been shown to mimic the carboxyl-rich surface motifs of non-collagenous proteins in stabilizing hydroxyapatite and directing intrafibrillar mineralization in-vitro. Based on this biomimetic approach, it is herein demonstrated that carboxyl functionalization of poly(lactic-co-glycolic acid) can achieve great material homogeneity in nanocomposites. This ionic colloidal molding method stabilizes hydroxyapatite precursors to confer even nanodopant packing, improving therapeutic outcomes in bone repair by remarkably improving mechanical properties of nanocomposites and optimizing controlled drug release, resulting in better cell in-growth and osteogenic differentiation. Lastly, better controlled biomaterial degradation significantly improved osteointegration, translating to highly regular bone formation with minimal fibrous tissue and increased bone density in rabbit radial defect models. Ionic colloidal molding is a simple yet effective approach of achieving materials homogeneity and modulating crystal nucleation, serving as an excellent biomimetic scaffolding strategy to rebuild natural bone integrity.

Silk fibroin membrane used for guided bone tissue regeneration

With the aim to develop a novel membrane with an appropriate mechanical property and degradation rate for guided bone tissue regeneration, lyophilized and densified silk fibroin membrane was fabricated and its mechanical behavior as well as biodegradation property were investigated. The osteoconductive potency of the silk fibroin membranes were evaluated in a defect rabbit calvarial model. Silk fibroin membrane showed the modulated biodegradable and mechanical properties via ethanol treatment with different concentration. The membrane could prevent soft tissue invasion from normal tissue healing, and the amounts of new bone and defect closure with silk fibroin membrane were similar to those of commercially available collagen membrane.

Important topics in the future of biomaterials and stem cells for bone tissue engineering: Comments from the participants of the International Symposium on Recent Trend of Biomaterials and Stem Cells for Bone Tissue Engineering at Changchun, China.

Fundamental and clinical experts from Japan, Korea and China, warmly gathered on the beautiful ice and snow city—Changchun, the capital of Jilin Province, China—during 23-26 January 2015, to present their research findings and participated in discussion relating to progress in biomaterials, stem cells and bone tissue engineering. The International Symposium on Recent Trend of Biomaterials and Stem Cells for Bone Tissue Engineering (BTE 2015) was hosted by the Key Laboratory of Polymer Ecomaterials, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, and co-organized by the Department of Orthopaedics, China-Japan Union Hospital, Jilin University. It provided a new platform of academic and technological communication for fundamental researchers and orthopedic surgeons to express their diverse ideas and inspiring new cooperation. The field of tissue engineering has emerged as an important approach to the clinical therapy of damaged bone due to trauma, tumor resections or congenital anomalies [1–3]. Besides bone forming cells and growth factors, we have profoundly recognized that the development of bone tissue engineering is directly related to changes in materials technology [4, 5]. However, after experiencing the rapid development of bone tissue engineering over the past several decades, we still currently face a tremendous challenge to design a new platform that can integrate bioscaffolds and growth factors or stem cells into biomimetic bone substitutes with new technologies for reconstruction of large-size orthopedic defects [6, 7]. The participants focused on discussing the recent development of synthetic or natural bioscaffolds that can provide 3D architecture [8, 9], appropriate topography and suitable surface chemistry [7, 10, 11], as well as enough mechanical strength [12, 13], which can encourage desired cellular activities and guide bone tissue regeneration. The introduction of bioactive molecules into 3D porous scaffolds physically or chemically to mimic the in vivo microenvironment is a promising strategy for tissue engineering and stem cell research [14]. A series of engineered binding growth factors [14–16] or peptides [17] have been designed and employed to study the biomaterial-stem cell interactions and to direct stem cell behaviors. Genetic tissue engineering was developed by bone marrow-derived mesenchymal stem cells (MSCs) reinforced with gene-transfecting for local delivery of bone morphogenetic proteins (BMPs) [18, 19]. The post-materials technology, or named offline materials technology, is also proposed in the symposium for researchers and surgeons to focus on the research of combination of current material products and clinical available resources, which will broaden and accelerate the clinical application of current material products. We made a concise report on this symposium, and some comments of the key speakers in the symposium were presented. We hope that their comments can arouse further interests of readers in discussing future strategies of bone tissue engineering and regenerative medicine. Moreover, we believed that the frequent appointment of researchers and orthopedic surgeons may inspire more and more ideas in the development of future clinical products of tissue engineering for orthopedic application.

A biocomposite of collagen nanofibers and nanohydroxyapatite for bone regeneration

This work aims to design a synthetic construct that mimics the natural bone extracellular matrix through innovative approaches based on simultaneous type I collagen electrospinning and nanophased hydroxyapatite (nanoHA) electrospraying using non-denaturating conditions and non-toxic reagents. The morphological results, assessed using scanning electron microscopy and atomic force microscopy (AFM), showed a mesh of collagen nanofibers embedded with crystals of HA with fiber diameters within the nanometer range (30 nm), thus significantly lower than those reported in the literature, over 200 nm. The mechanical properties, assessed by nanoindentation using AFM, exhibited elastic moduli between 0.3 and 2 GPa. Fourier transformed infrared spectrometry confirmed the collagenous integrity as well as the presence of nanoHA in the composite. The network architecture allows cell access to both collagen nanofibers and HA crystals as in the natural bone environment. The inclusion of nanoHA agglomerates by electrospraying in type I collagen nanofibers improved the adhesion and metabolic activity of MC3T3-E1 osteoblasts. This new nanostructured collagen–nanoHA composite holds great potential for healing bone defects or as a functional membrane for guided bone tissue regeneration and in treating bone diseases.

Morphological Effects of HA on the Cell Compatibility of Electrospun HA/PLGA Composite Nanofiber Scaffolds

Tissue engineering is faced with an uphill challenge to design a platform with appropriate topography and suitable surface chemistry, which could encourage desired cellular activities and guide bone tissue regeneration. To develop such scaffolds, composite nanofiber scaffolds of nHA and sHA with PLGA were fabricated using electrospinning technique. nHA was synthesized using precipitation method, whereas sHA was purchased. The nHA and sHA were suspended in PLGA solution separately and electrospun at optimized electrospinning parameters. The composite nanofiber scaffolds were characterized by FE-SEM, EDX analysis, TEM, XRD analysis, FTIR, and X-ray photoelectron. The potential of the HA/PLGA composite nanofiber as bone scaffolds in terms of their bioactivity and biocompatibility was assessed by culturing the osteoblastic cells onto the composite nanofiber scaffolds. The results from in vitro studies revealed that the nHA/PLGA composite nanofiber scaffolds showed higher cellular adhesion, proliferation, and enhanced osteogenesis performance, along with increased Ca+2 ions release compared to the sHA/PLGA composite nanofiber scaffolds and pristine PLGA nanofiber scaffold. The results show that the structural dependent property of HA might affect its potential as bone scaffold and implantable materials in regenerative medicine and clinical tissue engineering.

Effects of density of anisotropic microstamped silica thin films on guided bone tissue regeneration—In vitrostudy

The growing demand for better implant aesthetics has led to increased research on the development of all-ceramic dental implants. The use of microtextured coatings with enhanced properties has been presented as a viable way to improve tissue integrability of all-ceramic implants. The aim of this study was to evaluate the effects of different densities of anisotropic microtextured silica thin films, which served as a model coating, on the behavior of human osteoblast-like cells. The differential responses of human osteoblast-like cells to anisotropic silica microtextures with varying densities, produced via a combination of sol-gel and soft lithography processing, were evaluated in terms of alignment, elongation (using fluorescence microscopy), overall cellular activity, and the expression/activity levels of alkaline phosphatase (ALP). Statistical analysis was conducted using one-way ANOVA/Tukey HSD post hoc test. The thin films were thoroughly characterized via scanning electron microscopy/energy dispersive spectroscopy, Fourier transform infrared, and contact angle measurements. Thin film characterization revealed increased nanoscale roughness and reduced wettability on the micropatterned surfaces. Cell culture experiments indicated that the microtextures induced cell alignment, elongation, and guided colonization on the surface. Cells cultured on denser micropatterns exhibited increased metabolic activity (t = 14-21 days). The early expression/activity levels of ALP released into the medium were found to be significantly higher only on the least dense micropattern. These results suggest the possibility that microstructured silica thin films could be used to guide and enhance peri-implant cell/tissue responses, potentially improving tissue integration for metallic and all-ceramic dental implants.

Asymmetric Composite Membranes from Chitosan and Tricalcium Phosphate Useful for Guided Bone Regeneration

To fulfill the properties of barrier membranes useful for guided bone tissue regeneration in the treatment of periodontitis, in this study a simple process combining lyophilization with preheating treatment to produce asymmetric barrier membranes from biodegradable chitosan (CS) and functional β-tricalcium phosphate (TCP) was proposed. By preheating TCP/CS (3:10, w/w) in an acetic acid solution at 40°C, a skin layer that could greatly increase the mechanical properties of the membrane was formed. The asymmetric membrane with a skin layer had a modulus value almost 4-times that of the symmetric porous membrane produced only by lyophilization. This is beneficial for maintaining a secluded space for the bone regeneration, as well as to prevent the invasion of other tissues. The subsequent lyophilization at −20°C then gave the rest of material an interconnected pore structure with high porosity (83.9–90.6%) and suitable pore size (50–150 μm) which could promote the permeability and adhesiveness to bone cells, as demonstrated by the in vitro cell-culture of hFOB1.19 osteoblasts. Furthermore, the TCP particles added to CS could further increase the rigidity and the cell attachment and proliferation of hFOB1.19. The TCP/CS asymmetric composite membrane thus has the potential to be used as the barrier membrane for guided bone regeneration.

Electrospun poly (lactic-co-glycolic acid)/ multiwalled carbon nanotubes composite scaffolds for guided bone tissue regeneration

A series of poly (lactic-co-glycolic acid) (PLGA)/multiwalled carbon nanotubes (MWNTs) composite scaffolds was prepared by electrospinning for tissue engineering applications. The effect of MWNTs content on the structure and properties of composite scaffolds was characterized by scanning electron microscopy (SEM), X-ray diffractrometry (XRD), thermogravimetric analysis (TGA), and universal testing machine (UTM). The attachment ability and viability of rat bone marrow-derived mesenchymal stem cells (BMSCs) in the presence of the scaffolds were also investigated. Morphological characterization showed that the addition of different amounts of MWNTs increased the average fiber diameter; for instance, from 717 nm (neat PLGA) to 2193 nm at 1.0% MWNTs. Thermal characterization showed that the incorporation of MWNTs into the PLGA matrix increased the thermal stability of the composite scaffolds. The analysis of mechanical properties of the PLGA/MWNTs composites revealed great improvement over pure PLGA scaffold. The attachment and proliferation of BMSCs were significantly increased in the PLGA/MWNTs scaffolds compared with the PLGA control. Therefore, the PLGA/MWNTs composite scaffolds fabricated by electrospinning may be potentially useful in tissue engineering applications, particularly as scaffolds for bone tissue regeneration.

Polymeric composites containing carbon nanotubes for bone tissue engineering

Several natural and synthetic polymers are now available for bone tissue engineering applications but they may lack mechanical integrity. In recent years, there are reports emphasizing the importance of carbon nanotubes (CNTs) in supporting bone growth. CNTs possess exceptional mechanical, thermal, and electrical properties, facilitating their use as reinforcements or additives in various materials to improve the properties of the materials. Biomaterials containing polymers often are placed adjacent to bone. The use of CNTs is anticipated in these biomaterials applied to bone mainly to improve their overall mechanical properties and expected to act as scaffolds to promote and guide bone tissue regeneration. This review paper provides a current state of knowledge available examining the use of the polymeric composites containing CNTs for promoting bone growth.

A novel composite membrane of chitosan-carboxymethyl cellulose polyelectrolyte complex membrane filled with nano-hydroxyapatite I. Preparation and properties

A novel tri-component composite membranes of chitosan/carboxymethyl cellulose (CS/CMC) polyelectrolyte complex membranes filled with different weight ratios of nano-hydroxyapatite (n-HA)(0, 20, 40 and 60 wt%), namely, n-HA/CS/CMC composite membrane, were prepared by self-assembly of static electricity. The structure and the properties of the composite membranes were investigated by Fourier transformed infrared spectroscopy(IR), X-ray diffraction(XRD), Scanning electron microscopy(SEM), mechanical performance measurement, swelling behavior test, and soaking behavior study in phosphate buffered saline (PBS) and simulate body fluid (SBF). The results showed that the n-HA/CS/CMC composite membrane was formed though superficial static electricity interaction among n-HA, CS and CMC. For the n-HA/CS/CMC composite membrane, the microstructure compatibility, mechanical property, swelling behavior, the degradation and bioactivity in vitro of the composite membrane were improved by the addition of n-HA, compared with CS/CMC polyelectrolyte complex membrane. Moreover, the n-HA/CS/CMC composite membrane with 40 wt% n-HA had the most highest mechanical property, which suggested that the novel n-HA/CS/CMC composite membrane with 40 wt% n-HA was more suitable to be used as guided bone tissue regeneration membrane than CS/CMC polyelectrolyte complex membrane.

Carbon Nanotubes for Biomaterials in Contact with Bone

Carbon nanotubes (CNTs) possess exceptional mechanical, thermal, and electrical properties, facilitating their use as reinforcements or additives in various materials to improve the properties of the materials. Furthermore, chemically modified CNTs can introduce novel functionalities. In the medical field, biomaterials are expected to be developed using CNTs for clinical use. Biomaterials often are placed adjacent to bone. The use of CNTs is anticipated in these biomaterials applied to bone mainly to improve their overall mechanical properties, for applications such as high-strength arthroplasty prostheses or fixation plates and screws that will not fail. In addition, CNTs are expected to be used as local drug delivery systems (DDS) and/or scaffolds to promote and guide bone tissue regeneration. However, studies examining the use of CNTs as biomaterials still are in the preliminary stages. In particular, the influence of CNTs on osteoblastic cells or bone tissue is extremely important for the use of CNTs in biomaterials placed in contact with bone, and some studies have explored this. This review paper clarifies the current state of knowledge in the context of the relationship between CNTs and bone to determine whether CNTs might perform in biomaterials in contact with bone, or as a DDS and/or scaffolding for bone regeneration.

Evaluation of two membranes in guided bone tissue regeneration: histological study in rabbits

The purpose of this study was to evaluate bone regeneration in rabbits, comparing two types of physical barriers used to treat bone defects in guided tissue regeneration (GTR). Two osseous defects (8 mm in diameter) were performed in each hind-foot of four adult rabbits, using surgical burs with constant sterile saline solution irrigation. Defects obtained on the right hind-foots were protected with polytetrafluoroethylene (PTFE) barriers while Gengiflex membranes were used over wounds created in the left hind-foots. Rabbits were sacrificed after three months for histological evaluation of treatments performed. Defects covered with PTFE barriers were completely re- paired with bone tissue. Incomplete lamellar bone formation was detected in defects treated with Gengiflex membrane, resulting in voids and lack of continuity of bone deposition. Results withdrawn from this study demonstrated that the non-porous PTFE barrier fulfilled all requirements to induce natural bone tissue regeneration, thus becoming a more effective alternative to treat osseous defects than Gengiflex membrane.