Bioceramics 20

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Authors: David J. Wood, J. Dyson, K. Xiao, Kenny W. Dalgarno, P. Genever
Abstract: There is a clinical and socio-economic need to produce synthetic alternatives to autologous or allogenic bone grafts. Bioactive glasses and glass-ceramics offer great potential in this area. The aims of this study were to optimise production of apatite-wollastonite (A-W) glassceramic scaffolds produced by selective laser sintering, in terms of their physical and biological properties and to look at how human Mesenchymal Stem Cells (MSCs) responded to these 3-D scaffolds in vitro. An indirect selective laser sintering process successfully produced strong, porous scaffolds. Depending upon particle size(s) and infiltration of the porous structure, flexural strengths between 35 MPa and 100 MPa were obtained. Following static seeding of A-W scaffolds with MSCs, fluoresecent actin and nuclei staining, as observed by confocal microscopy, showed that these scaffolds supported the adherence of human MSC’s at time periods of up to 21 days. As such these seeded scaffolds show great potential for use in bone regenerative medicine.
Authors: Anna Tampieri, Monica Sandri, Elena Landi, Daniele Pressato
Abstract: The present work describes the development of biomimetic materials for osteochondral tissue substitution and repair, which can be the start for a revolution in the classical procedures of orthopedic surgery. Performing biomineralization process, we succeeded to prove that biological system store and process information at the molecular level. The substitute consist in three layers: the lower layer, mimicking bone tissue, is formed by HA/Collagen (70/30)wt; the intermediate layer, mimicking the tade-mark, is formed by HA/Collagen (40/60)wt; and the upper layer, mimicking the cartilagineous layer, is formed by Collagen containing Hyaluronic Acid. In vivo tests performed on small and large size animals should that: the bony portion well integrate and gradually are reabsorbed in contact with femoral bone in rabbit. The osteochondral substitute showed the ability to repair defect in osteochondral lesion opened in horses knee and differently stimulate cells thanks to the different chemico-morphological-microstructural features of the scaffold layer.
Authors: Conor T. Buckley, K.U. O’Kelly
Abstract: Tissue-engineering scaffold-based strategies have suffered from limited cell depth viability when cultured in vitro, with viable cells existing within the outer 250-500μm from the fluid-scaffold interface. This is primarily believed to be due to the lack of nutrient delivery into and waste removal from the inner regions of the scaffold construct. Other issues associated with porous scaffolds involve poor seeding efficiencies and limited cell penetration resulting in heterogeneous cellular distributions. This work focuses on the development a novel hydroxyapatite multi-domain porous scaffold architecture (i.e. a scaffold providing a discrete domain for cell occupancy and a separate domain for nutrient delivery) with the specific objectives of embodying in one scaffold the structures required to optimise cell seeding, cell proliferation and migration and potentially to facilitate vascularisation once implanted in vivo. This paper presents the development of the multidomain architecture and preliminary results on cell viability which show a significant improvement in cell viability in the scaffold interiors.
Authors: D.H. Yoon, Eui Kyun Park, Suk Young Kim, J.M. Lee, H.W. Shin, Hong In Shin
Abstract: To develop a suitable scaffold for tissue-engineered bone regeneration, we compared the efficiency of tissue-engineered bone regeneration according to the porous structure of calcium metaphosphate (CMP) ceramic scaffolds. Each scaffold was prepared with a sponge method and a foam-gel method, respectively. Both scaffolds, having either interconnected trabecular pores formed by the sponge method or fully interconnected globular pores formed by the foam-based technology, were not cytotoxic and elicited neither an immune nor an inflammatory response regardless of geometry and fabrication method. The fully interconnected globular porous scaffold showed more favorable compression strength and facilitated osteogenic repair by favoring cellular attachment and osteogenic differentiation with good osteoconductivity compared to the interconnected trabecular pore structured scaffold. These results suggest that the fully interconnected globular porous structure would be more suitable for both a bone substitute and scaffold for bioactive material-based or cell-based tissue bone regeneration.
Authors: Juliane Isaac, S. Loty, A. Hamdan, Tadashi Kokubo, Hyun Min Kim, A. Berdal, J.M. Sautier
Abstract: Titanium has limitations in its clinical performance in dental and orthopaedic applications. Over the last decade, numerous implant surface modifications have been developed and are currently used with the aim of enhancing bone integration. In the present study, we have experimented a bioactive titanium prepared by a simple chemical and moderate heat treatment that leads to the formation of a bone-like apatite layer on its surface in simulated body fluids. We haved used foetal rat calvaria cell cultures to investigate bone nodule formation on bioactive titanium. Scanning electron microscopy (SEM) showed that cells attached and spread on the bioactive surfaces. After 22 days of culture, bone nodules were detected on the material surface. Furthermore, the mineralized bone nodules remained attached to the bioactive titanium surface but not to untreated titanium. SEM observations and EDX microanalysis of sectioned squares showed that bone-like tissue directly bonded to bioactive titanium, but not pure titanium. These results indicated the importance of the implant surface composition in supporting differentiation of osteogenic cells and the subsequent apposition of bone matrix allowing a strong bond to bone. Furthermore, these findings may provide promising strategies for the development of biologically active implants.
Authors: S. Motojima, N. Igeta, Michiyo Honda, Nobuyuki Kanzawa, Mamoru Aizawa
Abstract: We have successfully fabricated apatite-fiber scaffolds (AFSs) that enable three-dimensional cell culture. The AFSs possessing large pores of 100~250 μm and micro pores of about 5 μm were fabricated by firing the green compacts consisting of the single-crystal apatite fibers and the carbon beads with a size of 150 μm. In order to enhance the mechanical properties of the AFSs, we have improved the process of AFS fabrication: Collagen gel (type I) solutions were introduced into the pores in the scaffolds; in addition, the resulting apatite/collagen scaffolds were chemically modified by thermally dehydrated cross-linking. Actually, the results of compressive strength tests show that the value of the AFS with chemically cross-linked I-collagen was about twice as high as that of the conventional AFS without I-collagen. We conclude that combination of I-collagen and thermal dehydrated cross-linking is effective for enhancement of the mechanical properties of AFSs.
Authors: S. Teixeira, S.M. Oliveira, M.P. Ferraz, F.J. Monteiro
Abstract: Calcium phosphate ceramics are widely used as bone substitutes since they are biocompatible and bioactive. Having a chemical composition close to natural bone, calcium phosphate ceramics are promising bone substitute materials in orthopaedics, maxillofacial surgery and dentistry. Hydroxyapatite (HA) and tricalcium phosphate (TCP) are the most commonly used calcium phosphates, because their calcium/phosphorus (Ca/P) ratios are close to that of natural bone and they are relatively stable in physiological environment. HA is a major constituent of bone materials and is resorbed after a long time of residence in the body. In this work, highly porous hydroxyapatite scaffolds were produced by polymer replication method and their properties evaluated by Scanning Electron Microscopy (SEM) and micro computerized tomography ()-CT).
Authors: Y.F. Li, Qian Peng, C.Y. Bao, Y.L. Qiu, X. Wei, Jie Weng
Abstract: This study was aimed to estimate the cell-activity after culture of the cell-material composite and to evaluate the feasibility of constructing tissue-engineered bone using this novel material. Hollow HA mcirospheres (H-HAMs), porous PLA\HA tube,polyurethane plunger were prepared respectively. Mesenchymal stem cells (MSCs), which were derived from rat bone marrow were utilized as seed cells.Two different methods were used to integrate the seed cells and scaffold materials. Group A: H-HAMs were filled into porous HA tube, and porous polyurethane plungers were used to cover onto the ends of HA/PLA tubes as a whole, Then MSCs were cultured on the composite scaffolds; Group B: MSCs were compounded with H-HAMs completely first, then the pre-seeded composite of H-HAMs and cells was put into the porous PLA\HA tube which was then sealed with the polyurethane plunger. 1,3,5,7 and 9 days after cell-material composites were cultured, the growing status and adhesions of seed cells were observed. The viability of cells was quantified and increased over time in different methods, but was significantly higher in Group B after 9 days of culture. SEM detection revealed that more cells were detected on the PLA\HA tube and the outer layer of H-HAMs; growth of cells was more widespread and more cells were detected on H-HAMs in Group B. However, cells on H-HAMs seem to diminish over time in both groups. As a novel 3-D Hydroxyapatite scaffold, its H-HAMs are more easy to be integrated with seed cells, to be shaped according to clinical needs because of its semi-liquidity. However, the growth of cells especially in the inner core of the integrated material needs further research.
Authors: Heike Brandt, Peter Greil, Frank A. Müller
Abstract: Knits made of cellulose are promising scaffolds for bone tissue engineering applications due to their multi-scale interconnected porosity, biocompatibility and adjustable biodegradability. The approach of this study combines the modification of cellulose with strontium to generate scaffolds capable of forming bone like apatite during exposure to physiological solutions and the release of strontium as an active agent, that might encourage the development of new bone tissue. The Sr-release kinetics during static exposure to simulated body fluid is dominated by an accelerated Sr-release in the initial state followed by a reduced release corresponding to a diffusion controlled rate. Microstructural analyses indicate that initially precipitated SrCO3 transforms to SrxCa1-xCO3 solid solutions that subsequently serve as a template for the precipitation of bone like carbonated hydroxyapatite.
Authors: Andrea Ruffini, Simone Sprio, Anna Tampieri
Abstract: The development of innovative ceramic scaffolds for bone substitution with superior biomechanical features and smart anisotropic performances was performed through chemical and physical transformations of natural hierarchic structures, as trees, shrubs, palms, etc. These final structures will be highly organized from the molecular to nano, micro and macro-scales, with extremely functional architectures able to constantly adapt to ever changing mechanical and biofunctional needs. This study reports the preliminary results of the ceramisation process: starting from suitable vegetal raw materials pyrolysed to produce carbon templates characterized by complex pore structure, then infiltrated by vapour phase calcium to produce calcium carbide and finally transformed into porous ceramic of calcium carbonate by multi-step thermic and hydrothermal treatment in controlled environment.

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