Materials For Bone Regeneration Research Articles

Effect of carbon based fillers on properties of Chitosan/PVA/βTCP based composite scaffold for bone tissue engineering

Abstract Bone tissue engineering has been area of substantial research since few decades but still a gap exists when it comes to strength and healing tendency of biomaterials with respect to age group, accidental complications etc. Many researches are yet in progress to design a perfect material for bone regeneration. Our attempt in the present study is to develop a porous hybrid material based on Chitosan(CS)/Polyvinyl Alcohol(PVA)/ Beta Tricalcium Phosphate (β-TCP) composite matrix incorporated with various carbon based fillers i.e. Graphene Oxide(GO, Reduced Graphene Oxide (RGO), Carbon Nanotube(CNT) . Scanning electron microscopy (SEM) results of fabricated scaffolds revealed nearly threefold increase in pore diameter when the concentration of each carbon filler incorporated in CS/PVA/βTCP increased to 1%. Addition of fillers also demonstrated significant mineral depositions on samples when treated with SBF .The Ca/P ratio of deposited minerals on some scaffolds was found near 1.67, the stoichiometric ratio of natural bone apatite .Increase in carbon filler concentration in CS/PVA/βTCP matrix also increased the compressive modulus of scaffold.

Effects of recombinant human bone morphogenetic protein-2 compared to other biomaterials in the treatment of intrabony defects in periodontitis patients: A systematic review.

Background:Bone morphogenetic proteins have a powerful osteoinductive capacity and have been used as a new adjunct to graft materials for bone regeneration. The objectives of this systematic review are to assess the amount of radiographic bone fill, clinical attachment level (CAL) gain, and reduction in pocket depth (PD) in patients with intrabony defects in periodontitis patients following the use of recombinant human bone morphogenetic protein-2 (rhBMP-2).Materials and Methods:Electronic bibliographic databases search of Medline, Science Direct, and Google Scholar was made from January 1980 to December 2017. Studies using rhBMP-2 to treat periodontal intrabony defects of the maxillary or mandibular region with follow-up period of at least 6 months were searched. Two reviewers performed the systematic review using the PRISMA Statement for reporting and the Cochrane risk-of-bias tool was used for quality assessment.Results:It was found that rhBMP-2 showed statistically significant results with respect to radiographic defect resolution, CAL, and PD reduction at 9 months compared to open-flap debridement but showed statistically significant results only with respect to radiographic bone fill when compared with platelet-rich fibrin at 6 months.Conclusion:The rhBMP-2 may provide a promising alternative to traditional grafting procedures therapy that can enhance periodontal regeneration in patients having intrabony defects. Due to limited human studies, it can be concluded that no definitive evidence exists to ascertain the effectiveness of rhBMP-2 in the treatment of intrabony defects in periodontal diseases.

Mineralized nanofiber segments coupled with calcium-binding BMP-2 peptides for alveolar bone regeneration

Bone loss around tooth extraction sites can occur, thus making future placement of dental implants difficult. Alveolar bone regeneration can be guided by the application of a nanofibrous bone graft coupled with osteoinductive proteins/peptides, following tooth loss or tooth extraction. In the present study, we demonstrate the potential of mineralized nanofiber segments coupled with calcium-binding bone morphogenetic protein 2 (BMP-2) mimicking peptides for periodontal bone regeneration. Thin electrospun nanofiber membranes of PLGA-collagen-gelatin (2:1:1 wt ratios) were mineralized in 10× modified simulated body fluid (10× mSBF) and cryocut to segments of 20 µm. For predetermined weights of the mineralized nanofiber segments, it was possible to load various amounts of heptaglutamate E7-domain-conjugated BMP-2 peptide. Mineralized short fiber grafts (2 mg), with and without E7-BMP-2 peptides, were implanted into 2 mm × 2 mm (diameter × depth) critical-sized socket defects created in rat maxillae, following extraction of the first molar teeth. A sustained release profile of E7-BMP-2 from the mineralized nanofiber segments was recorded over 4 weeks. X-ray microcomputed tomography (µ-CT) analysis of peptide-loaded nanofiber graft filled defects revealed ∼3 times greater new bone volume and bone mineral density over 4 weeks in comparison to unfilled control defects. Further, histopathology data confirmed the formation of greater new osseous tissue in the BMP2 peptide-loaded, mineralized nanofiber segment group than that of fibrous connective tissue in the unfilled defect group. Altogether, the mineralized nanofiber segments coupled with E7-BMP-2 peptides may be an effective treatment option for alveolar bone loss and defects. Statement of SignificanceWith the high incidence of dental implants/fixtures for missing teeth, the success of the surgical procedures in restorative dentistry is dictated by the quality and quantity of the supporting alveolar bone. To address the problem of alveolar bone loss and defects due to tumor, periodontitis, or even postextraction remodeling, the present study is the first report on the application of mineralized nanofiber fragments coupled with calcium-binding osteoinductive BMP-2 peptides as a synthetic graft material for oral bone regeneration. The ease of fabrication and application of cryocut mineralized nanofiber fragments as maxillofacial bone defect fillers present a promising alternative to the current dental bone graft formulations. Furthermore, the nanofiber segments may also be utilized for several biomedical applications including hemostasis, soft tissue engineering, and wound healing.

A standardized rat burr hole defect model to study maxillofacial bone regeneration

With high incidence rate and unique regeneration features, maxillofacial burr hole bone defects require a specially designed bone defect animal model for the evaluation of related bone regenerative approaches. Although some burr hole defect models have been developed in long bones or calvarial bones, the mandible has unique tissue development origins and regenerative environments. This suggests that the defect model should be prepared in the maxillofacial bone area. After dissecting the anatomic structures of rat mandibles, we found that creating defects in the anterior tooth area avoided damaging important organs and improved animal welfare. Furthermore, the available bone volume at the anterior tooth area was superior to that of the posterior tooth and ascending ramus areas. We then managed to standardize the model by controlling the age, weight and gender of the animal, creating standardized measurement instruments and reducing the variations derived from various operators. We also succeeded in deterring the self-rehabilitation of the proposed model by increasing the defect size. The 6 × 2 mm and 8 × 2 mm defects were found to meet the requirements of bone regenerative studies. This study provided a step-by-step standardized burr hole bone defect model with minimal tissue damage in small animals. The evaluations resulting from this model testify to the in vitro outcomes of the proposed regenerative approaches and provide preliminary screening data for further large animal and clinical trials. Therefore, the inclusion of this model may optimize the evaluation systems for maxillofacial burr hole bone defect regenerative approaches. Statement of SignificanceUnremitting effort has been devoted to the development of bone regenerative materials to restore maxillofacial burr hole bone defects because of their high clinical incidence rate. In the development of these biomaterials, in vivo testing in small animals is necessary to evaluate the effects of candidate biomaterials. However, little has been done to develop such defect models in small animals. In this study, we developed a standardized rat mandible burr hole bone defect model with minimal injury to the animals. A detailed description and supplementary video were provided to guide the preparation. The development of this model optimizes the maxillofacial bone regenerative approach evaluation system.

In vitro bioactivity and degradation behaviour of β-wollastonite derived from natural waste

Calcium silicate ceramics, in particular wollastonite (CaSiO3), is the most commonly used bioactive material for bone regeneration and repairing applications. The present study aims to synthesize cost effective wollastonite using natural waste materials such as rice husk ash (RHA) and eggshells, sources of silica and calcium oxide respectively. Wollastonite was prepared by sol-gel method and based on thermogravimetric and differential thermal analysis (TG/DTA) results the samples were sintered at 850 °C. X-ray diffractometer (XRD) revealed that the sintered samples possess single phasic β-wollastonite. The assessment of bioactivity was examined using in vitro studies by immersing the pellets in simulated body fluid (SBF) for different time periods (3, 7, 14, 21 days). The growth of hydroxyapatite layer on the surface of the sample was analysed using XRD, Fourier transform infrared (FTIR) spectroscopy and Scanning electron microscopy-energy dispersive spectrometer (SEM-EDS). The significant change in pH of the SBF solution was observed during the first 11 days of immersion, after which the pH was saturated. Biodegradation test was performed in SBF and Tris buffer solutions according to ISO 10993-14 standard, and the test revealed that the ceramic pellets showed lower degradation rates with slow dissolution of ionic species. MTT assay demonstrated that the prepared wollastonite exhibits cytocompatibility with MG-63 cells at different dosage (1000–50 μg/mL) for 48 h. The results suggested that β-wollastonite can be a low cost bioactive material, which can be useful in biomedical applications.

Doping β-TCP as a Strategy for Enhancing the Regenerative Potential of Composite β-TCP-Alkali-Free Bioactive Glass Bone Grafts. Experimental Study in Rats.

The present work aims at evaluating the potential gains derived from partially replacing calcium in resorbable β-tricalcium phosphate (β-TCP) by two different molar percentages of strontium (5, 10) and zinc (1, 2), concomitantly with a fixed molar percentage (0.5) of manganese. Synthetic granular composite bone filling grafts consisting of doped β-TCP and an alkali-free bioactive glass were prepared and implanted in ~4 mm diameter bone defects drilled in the calvaria of Wistar rats used as animal models. The animals were sacrificed after 9 weeks of implantation and the calvaria was excised. Non-manipulated bone was used as positive control, while empty defects were used as a negative control group. The von Kossa staining revealed an enhanced new bone formation with increasing doping levels, supporting the therapeutic effects exerted by the doping elements. The percentage of newly formed bone was similar when the defects were filled with autologous bone, BG (previous results) or 3TCP2/7BG, which indicates that the latter two are excellent candidates for replacement of autologous bone as bone regeneration material. This finding confirms that doping with suitable doses of therapeutic ions is a good strategy towards transposing the bone graft materials to biomedical applications in humans.

Effect of pre-treatment of crystallized bioactive glass with cell culture media on structure, degradability, and biocompatibility

The silicate glass 45S5 Bioglass® (BG) is a potential scaffold material for bone regeneration because of its excellent bioactivity, biocompatibility and ability to form a strong bond with bone tissues, via the formation of an apatite layer on its surface. The evaluation of in vitro bioactivity in physiological body fluids, whilst challenging, can offer some insights for developing the bone-bonding ability of these glasses in vivo. In this study, we investigated the influence of three different cell culture and tissue fluid-like solutions on the dissolution and calcium-phosphate (CaP) based re-precipitation behaviour at the glass-liquid interface. We also examined pre-treatment of BG with these biological solutions, and how its influence on bone-forming MG-63 osteoblastic cell proliferation, viability and adhesion. The biological solutions used in this comparative study were: commercial cell culture medium (DMEM), a DMEM solution without organic components (DML) and a simulated body fluid (SBF), incorporating TRIS-buffer. Incubation of BG in these solutions over 28 days resulted in differences in weight loss, solution pH and ion release, and the development of CaP-based surface layers. XRD and FT-IR analyses showed clear differences in the characteristics of the CaP-based coating layers formed by the different solutions. The interfacial reactivity between the glass and the solutions depended on the composition and properties of the solutions. The formation of the CaP layer occurred more rapidly in SBF due to the presence of TRIS-buffer, which also significantly accelerated glass dissolution, further reducing the BG mass in SBF. MG-63 osteoblasts proliferated and spread more rapidly across the surfaces of all pre-conditioned BG, compared to fresh BG. The experimental results of this work help clarify differences between in vitro bioactivity of BG observed in cell culture solutions and in vivo BG bioactivity.

Osteoblast responses to injectable bone substitutes of kappa-carrageenan and nano hydroxyapatite

The combination of kappa-carrageenan (κ-CG) and hydroxyapatite (HA) to generate a bone substitute material has been underexplored to date. Carrageenans (CGs) have remarkable characteristics such as biocompatibility, hydrophilicity, and structural similarities with natural glycosaminoglycans (GAGs), and they have demonstrated the ability to stimulate cellular adhesion and proliferation. Hydroxyapatite nanoparticles have been one of the most investigated materials for bone regeneration due to their excellent biocompatibility, bioactivity and osteoconductivity. In particular, this study presents an approach for the preparation of new bioactive composites of κ-CG/nHA for numerous bone regeneration applications. We performed a set of in vitro experiments to evaluate the influence of the bone substitutes on human osteoblasts. Cell culture studies indicated that all samples tested were cytocompatible. Relative to control substrates, cellular attachment and proliferation were better on all the scaffold surfaces that were tested. The S2 and S3 samples, those permeated by 1.5 and 2.5 wt% of CG, respectively, exhibited an enhancement in cell spreading capacity compared to the S1 test materials which were comprised of 1 wt% of CG. Excellent osteoblast viability and adhesion were observed for each of the tested materials. Additionally, the bone substitutes developed for this study presented a distinct osteoconductive environment. Data supporting this claim were derived from alkaline phosphatase (ALP) and calcium deposition analyses, which indicated that, compared to the control species, ALP expression and calcium deposition were both improved on test κ-CG/nHA surfaces. In summary, the injectable bone substitute developed here demonstrated great potential for numerous bone regeneration applications, and thus, should be studied further. Statement of SignificanceThe novelty of this work lies in the determination of the in vitro cytocompatibility behavior of carrageenan and hydroxyapatite composite materials used as injectable bone substitutes. This injectable biomaterial can fill in geometric complex defects, and it displays bioactivity as well as high bone regeneration capacity. In this study, we evaluated the behaviors of osteoblast cells in contact with the scaffolds, including cellular adhesion and proliferation, cellular metabolism, and mineralization on the fabricated injectable bone substitutes. The results show than the carrageenan and hydroxyapatite substitutes provided a biomaterial with a great capacity for promoting cellular growth, adhesion, and proliferation, as well as contributing an osteoinductive environment for osteoblast differentiation and osteogenesis.

3D-printed polycaprolactone scaffold mixed with β-tricalcium phosphate as a bone regenerative material in rabbit calvarial defects.

Defect-specific bone regeneration using 3-dimensional (3D) printing of block bone has been developed. Polycaprolactone (PCL) is biocompatible polymer that can be used as 3D scaffold. The aim of this study is to assess the biocompatibility and osteogenic efficacy of 3D printed PCL scaffold and to evaluate the effectiveness of β-tricalcium phosphate (β-TCP) addition in PCL scaffold. In this work, four circular defects (diameter: 8 mm) in rabbit calvarium were randomly assigned to (1) negative control (control), (2) PCL block (PCL), (3) PCL mixed with 10 wt% β-TCP (PCL/β-TCP), and (4) PCL/β-TCP plus collagen membrane (PCL/β-TCP + M). Animals were euthanized at 2 (n = 5) and 8 weeks (n = 5). Results indicated that in micro-CT, PCL/β-TCP + M showed the highest total augmented volume and new bone volume at 8 weeks, but there was no significant difference among four groups. Histomorphometrically, PCL, PCL/β-TCP, and PCL/β-TCP + M showed the significantly higher total augmented area compared to the control. PCL/β-TCP + M showed the highest new bone area but not statistically higher than the control. New bone formation deep inside the scaffold was observed only in β-TCP added scaffold. PCL showed high biocompatibility with great volume maintenance. Addition of β-TCP to PCL seemed to increase hydrophilicity and osteoconductivity. Developments in 3D-printed PCL material are expected. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1254-1263, 2019.

Functional Graphenic Materials, Graphene Oxide, and Graphene as Scaffolds for Bone Regeneration

Insufficient bone regeneration is a complex problem affecting millions, and treatment would benefit from a complex material that recapitulates the properties of native bone. No current tissue-engineered scaffold can capture all of the properties of healthy bone. Graphene, graphene oxide (GO), and functional graphenic materials (FGMs) have a variety of interesting properties that make them promising foundations on which to craft sophisticated, biomimetic, osteoinductive, synthetic scaffolds for bone regeneration. GO has shown promise in the osteoinduction of stem cells, especially when coupled with growth factors. Additionally, FGMs have tunable surface chemistry and mechanical properties, as well as periodic long-range order, making this class of materials a promising candidate for regeneration of hard tissues. Strategies for controlling and modifying the surface chemistry of graphenic materials have become increasingly sophisticated in recent years, providing access to new FGMs with distinct implications in biomaterials and medicine. In this review, we discuss promising emerging strategies for the use of graphenic materials in bone regeneration, with a focus on biomimetic and bioinstructive FGMs. The regeneration of bone is an interdisciplinary medical, scientific, and engineering challenge. While small fractures heal spontaneously into adulthood, larger injuries and deformities require surgical correction. Currently, grafts or metallic prosthetics are the standard of care, but both suffer limitations. Graphene, graphene oxide, and functional graphenic materials comprise a class of materials that can be derived from graphite (pencil lead) and offer a plethora of promising properties including long-range order, mechanical stability, and autodegradability that make them promising scaffold materials for bone regeneration.

Implant Stability Parameters & Bone Density Values of Different Graft Materials with Immediately Placed Dental Implants

Objectives: This study was conducted to assess and compare the effect of autogenous bonegraft versus mineralized plasmatic matrix (MPM) and versus the Nano hydroxyapatite bone graftas bone regenerative materials during immediate implant placement.Material and Methods: A total of 14 patients with 18 implants have been included in thisstudy, patients were divided into 3 groups. Group I(control group) received autogenous bone graft.Group II (study group A) received Mineralized Plasmatic Matrix (MPM), and group III (studygroup B) received Nano hydroxyapatite as bone regenerative materials for immediate implantplacement. The treatment outcome was evaluated clinically and radiographically at 3 and 6 monthsof implant placement. Implants stability was measured using Osstell radiofrequency device at 3 and6 months postoperatively. Also bone density were measured radiographically at 2 weeks and at 3and 6 months postoperatively and statistically analysed.Results: Statistical analysis of bone density measurements between the three groups showedsignificant difference (P ≤ 0.05) between the control autogenous bone group and the two othergroups (MPM &Nano bone) at all time intervals. Comparison between the test groups revealednon-significant difference (P ≤ 0.05) between (MPM & Nano bone) at two weeks interval. Whileat three & six months postoperatively there was a significant difference (P ≤ 0.05 between the twogroups. Regarding implant stability comparison between the three groups , there was no statisticalsignificant difference between them (P ≤ 0.05) at three and six months post operatively.Conclusion: The autogenous bone graft remains the gold standard for grafting materials but theuse of MPM and Nano hydroxyapatite grafting materials can also give successful results regardingimplant stability and bone density.

Antimicrobial activity of commercial calcium phosphate based materials functionalized with vanillin

Infections represent one of the most frequent causes of arthroplasty revision. Thus, design of new antimicrobial scaffolds to reduce implant rejections, bone infections and associated medical costs is highly desired. In recent years, essential oil components (EOCs) have merged as compounds with significant antimicrobial activity that can be attached to specific surfaces to enhance and prolong their antimicrobial effect. Herein calcium phosphate CaP regenerative materials have been coated with a vanillin derivative to combine its original bone regeneration properties with antimicrobial action of EOCs. Materials in form of microparticles and blocks were prepared and fully characterized. Clonogenic viability tests demonstrated that low concentrations of material (10 mg·mL−1) resulted effective to kill 100% of E. coli DH5α bacteria. Additionally, vanillin containing scaffolds did not display any toxic effect over cells, yet they preserve the ability to express alkaline phosphatase (ALPL), collagen type 1, chain α1 (COL1A1) and bone gamma-carboxyglutamic acid-containing protein or osteocalcin (BGLAP), which are genes typically expressed by osteoblasts. These results demonstrate that commercially available scaffolds can be functionalized with EOCs, achieving antimicrobial activity and open up a new approach for the treatment and prevention of infection. Statement of significanceDuring the last years, the interest in bone regenerative materials with antibiotic properties has increased, since prosthesis infection is one of the most usual complications in implant surgery. In this work, we report a hybrid system composed by a calcium phosphate material (powders and scaffolds) functionalized with the derivative of an essential oil component (EOC). Our purpose was to provide the calcium phosphate material with antimicrobial activity without harming its bone regenerative capability. The obtained results were encouraging, which opens up the possibility of developing new modified materials for the prevention and treatment of bone infection.

Biomineralization‐Inspired Material Design for Bone Regeneration

Synthetic substitutes of bone grafts, such as calcium phosphate-based ceramics, have shown some good clinical successes in the regeneration of large bone defects and are currently extensively used. In the past decade, the field of biomineralization has delivered important new fundamental knowledge and techniques to better understand this fascinating phenomenon. This knowledge is also applied in the field of biomaterials, with the aim of bringing the composition and structure, and hence the performance, of synthetic bone graft substitutes even closer to those of the extracellular matrix of bone. The purpose of this progress report is to critically review advances in mimicking the extracellular matrix of bone as a strategy for development of new materials for bone regeneration. Lab-made biomimicking or bioinspired materials are discussed against the background of the natural extracellular matrix, starting from basic organic and inorganic components, and progressing into the building block of bone, the mineralized collagen fibril, and finally larger, 2D and 3D constructs. Moreover, bioactivity studies on state-of-the-art biomimicking materials are discussed. By addressing these different topics, an overview is given of how far the field has advanced toward a true bone-mimicking material, and some suggestions are offered for bridging current knowledge and technical gaps.

Synthetic and Marine-Derived Porous Scaffolds for Bone Tissue Engineering.

Bone is a vascularized and connective tissue. The cortical bone is the main part responsible for the support and protection of the remaining systems and organs of the body. The trabecular spongy bone serves as the storage of ions and bone marrow. As a dynamic tissue, bone is in a constant remodelling process to adapt to the mechanical demands and to repair small lesions that may occur. Nevertheless, due to the increased incidence of bone disorders, the need for bone grafts has been growing over the past decades and the development of an ideal bone graft with optimal properties remains a clinical challenge. This review addresses the bone properties (morphology, composition, and their repair and regeneration capacity) and puts the focus on the potential strategies for developing bone repair and regeneration materials. It describes the requirements for designing a suitable scaffold material, types of materials (polymers, ceramics, and composites), and techniques to obtain the porous structures (additive manufacturing techniques like robocasting or derived from marine skeletons) for bone tissue engineering applications. Overall, the main objective of this review is to gather the knowledge on the materials and methods used for the production of scaffolds for bone tissue engineering and to highlight the potential of natural porous structures such as marine skeletons as promising alternative bone graft substitute materials without any further mineralogical changes, or after partial or total transformation into calcium phosphate.

Harnessing the Noncovalent Interactions of DNA Backbone with 2D Silicate Nanodisks To Fabricate Injectable Therapeutic Hydrogels.

Injectable hydrogels present several advantages over prefabricated scaffolds including ease of delivery, shear-thinning property, and broad applicability in the fields of drug delivery and tissue engineering. Here, we report an approach to develop injectable hydrogels with sustained drug release properties, exploiting the chemical nature of the DNA backbone and silicate nanodisks. A two-step gelation method is implemented for generating a combination of noncovalent network points, leading to a physically cross-linked hydrogel. The first step initiates the development of an interconnected structure by utilizing DNA denaturation and rehybridization mechanism to form hydrogen bonds between complementary base pairs of neighboring DNA strands. The anisotropic charge distribution of two-dimensional silicate nanodisks (nSi) makes them an active center in the second step of the gelation process. Silicate nanodisks create additional network points via attractive electrostatic interactions with the DNA backbone, thereby enhancing the mechanical resilience of the formulated hydrogel. The thermally stable hydrogels displayed an increase in elasticity and yield stress as a function of nSi concentration. They were able to form self-supporting structures post injection due to their rapid recovery after removal of cyclic stress. Moreover, the presence of nanosilicate was shown to modulate the release of a model osteogenic drug dexamethasone (Dex). The bioactivity of released Dex was confirmed from in vitro osteogenic differentiation of human adipose stem cells and in vivo bone formation in a rat cranial bone defect model. Overall, our DNA-based nanocomposite hydrogel obtained from a combination of noncovalent network points can serve as an injectable material for bone regeneration and carrier for sustained release of therapeutics.

Demineralized Bone Matrix Coating Si-Ca-P Ceramic Does Not Improve the Osseointegration of the Scaffold.

The aim of this study was to manufacture and evaluate the effect of a biphasic calcium silicophosphate (CSP) scaffold ceramic, coated with a natural demineralized bone matrix (DBM), to evaluate the efficiency of this novel ceramic material in bone regeneration. The DBM-coated CSP ceramic was made by coating a CSP scaffold with gel DBM, produced by the partial sintering of different-sized porous granules. These scaffolds were used to reconstruct defects in rabbit tibiae, where CSP scaffolds acted as the control material. Micro-CT and histological analyses were performed to evaluate new bone formation at 1, 3, and 5 months post-surgery. The present research results showed a correlation among the data obtained by micro-CT and the histomorphological results, the gradual disintegration of the biomaterial, and the presence of free scaffold fragments dispersed inside the medullary cavity occupied by hematopoietic bone marrow over the 5-month study period. No difference was found between the DBM-coated and uncoated implants. The new bone tissue inside the implants increased with implantation time. Slightly less new bone formation was observed in the DBM-coated samples, but it was not statistically significant. Both the DBM-coated and the CSP scaffolds gave excellent bone tissue responses and good osteoconductivity.

Fretting corrosion between bone and calcium phosphate-calcium titanate coatings

Biocompatibility is one of the biggest challenges for biomaterials development. This issue arises in the case of coatings. Calcium phosphate (CP) coatings are currently used to cover femoral stem implants, while calcium titanate (CT) has also been proposed as a coating for biomedical applications due to its good biocompatibility and osteoconductivity. However, its behavior under fretting corrosion conditions, one of the degradation mechanisms of hip joint implants, has not been studied. In this work, tribocorrosion behavior of calcium phosphate - calcium titanate coatings obtained by Radio Frequency (RF) magnetron sputtering onto AISI 304 stainless steel was evaluated. The coatings were deposited in 100%CP-0%CT, 75%CP-25%CT, 50%CP-50%CT, 25%CP-75%CT and 0%CP-100%CT volume proportions. An electrochemical cell integrated with a ball-on-flat reciprocating tribometer was used to investigate the performance of the coatings under fretting conditions against bone in Hank´s solution at 37 °C. The suitability of three specific coating compositions for the protection of AISI 304 stainless steel, based on their hardness, non-conductive nature and absence of a passive layer, was demonstrated by open circuit potential measurements. It was concluded that 75CP-25CT and 0CP-100CT coatings are potential materials for bone tissue replacement and regeneration.

Development of a Photo-Crosslinking, Biodegradable GelMA/PEGDA Hydrogel for Guided Bone Regeneration Materials.

Gelatin-based hydrogel, which mimics the natural dermal extracellular matrix, is a promising tissue engineering material. However, insufficient and uncontrollable mechanical and degradation properties remain the major obstacles for its application in medical bone regeneration material. Herein, we develop a facile but efficient strategy for a novel hydrogel as guided bone regeneration (GBR) material. In this study, methacrylic anhydride (MA) has been used to modify gelatin to obtain photo-crosslinkable methacrylated gelatin (GelMA). Moreover, the GelMA/PEGDA hydrogel was prepared by photo-crosslinking GelMA and PEGDA with photoinitiator I2959 under UV treatment. Compared with the GelMA hydrogel, the GelMA/PEGDA hydrogel exhibits several times stronger mechanical properties than pure GelMA hydrogel. The GelMA/PEGDA hydrogel shows a suitable degradation rate of more than 4 weeks, which is beneficial to implant in body. In vitro cell culture showed that osteoblast can adhere and proliferate on the surface of the hydrogel, indicating that the GelMA/PEGDA hydrogel had good cell viability and biocompatibility. Furthermore, by changing the quantities of GelMA, I2959, and PEGDA, the gelation time can be controlled easily to meet the requirement of its applications. In short, this study demonstrated that PEGDA enhanced the performance and extended the applications of GelMA hydrogels, turning the GelMA/PEGDA hydrogel into an excellent GBR material.

Hydroxyapatite from Cuttlefish Bone: Isolation, Characterizations, and Applications

Hydroxyapatite (HA), a bioceramic, is a widely utilized material for bone tissue repair and regeneration because of its excellent properties such as biocompatibility, exceptional mechanical strength, and osteoconductivity. HA can be obtained by both synthetic and natural means. Animal bones are often considered a promising natural resource for the preparation of pure HA for biological and biomedical applications. Cuttlefish bone, also called as cuttlebone, mainly consists of calcium carbonate, and pure HA can be produced by adding phosphoric acid or ammonium hydrogen phosphate to it. Recently, cuttlefish bone-derived HA has shown promising results in terms of bone tissue repair and regeneration. The synthesized cuttlefish bone-derived has shown excellent biocompatibility, cell proliferation, increased alkaline phosphate activity, and efficient biomineralization ability with mesenchymal stem cells and osteoblastic cells. To further improve the biological properties of cuttlefish bone-derived HA, bioglass, polycaprolactone, and polyvinyl alcohol were added to it, which gave better results in terms of cell proliferation and osteogenic differentiation. Cuttlefish bone-derived HA with polymeric substances provides excellent bone formation under in vivo conditions. The studies indicate that cuttlefish bone-derived HA, along with polymeric and, protein materials, will be promising biomaterials in the field of bone tissue regeneration.

Polymeric electrospun scaffolds for bone morphogenetic protein 2 delivery in bone tissue engineering

HypothesisThe development of novel scaffolds based on biocompatible polymers is of great interest in the field of bone repair for fabrication of biodegradable scaffolds that mimic the extracellular matrix and have osteoconductive and osteoinductive properties for enhanced bone regeneration. ExperimentsPolycaprolactone (PCL) and polycaprolactone/polyvinyl acetate (PCL/PVAc) core–shell fibers were synthesised and decorated with poly(lactic-co-glycolic acid) [PLGA] particles loaded with bone morphogenetic protein 2 (BMP2) by simultaneous electrospinning and electrospraying. Hydroxyapatite nanorods (HAn) were loaded into the core of fibers. The obtained scaffolds were characterised by scanning and transmission electron microscopy, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. The in vitro potential of these materials for bone regeneration was assessed in biodegradation assays, osteoblast viability assays, and analyses of expression of specific bone markers, such as alkaline phosphatase (ALP), osteocalcin (OCN), and osteopontin (OPN). FindingsPLGA particles were homogeneously distributed in the entire fibre mat. The growth factor load was 1.2–1.7 μg/g of the scaffold whereas the HAn load was in the 8.8–12.6 wt% range. These scaffolds were able to support and enhance cell growth and proliferation facilitating the expression of osteogenic and osteoconductive markers (OCN and OPN). These observations underline the great importance of the presence of BMP2 in scaffolds for bone remodelling as well as the good potential of the newly developed scaffolds for clinical use in tissue engineering.