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Escafoldes para implantes ósseos em alumina/hidroxiapatita/biovidro: análises mecânica e in vitro ; Scaffolds in alumina, hydroxyapatite and bio-glass for bone implants: mechanical tests and in vitro analysis

Camilo, Claudia Cristiane
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 16/08/2006 PT
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37.09%
Escafoldes em alumina foram fabricados e em suas superfícies impregnou-se biovidro e hidroxiapatita; realizou-se análise das propriedades mecânica e de interação célula-escafolde in vitro. Estruturas porosas denominadas escafoldes são utilizadas como suportes para crescimento de tecidos, devem apresentar poros abertos interconectados, com morfologia, distribuição e quantidade de poros que confiram resistência mecânica e induzam o crescimento ósseo. Os escafoldes simulam a matriz extracelular e são a chave para a engenharia de tecidos que está conceituada na cultura prévia de células com proteínas morfogenéticas, oferecendo suporte para o crescimento celular na formação do tecido maduro. Neste trabalho desenvolveu-se técnica de manufatura onde foram conformados escafoldes como corpos-de-prova em alumina, em hidroxiapatita e em alumina infiltrada com biovidro e hidroxiapatita. Os escafoldes foram submetidos a ensaios mecânicos de compressão e sofreram análise de interação com células in vitro. A morfologia e a concentração da porosidade dos escafoldes foram analisadas por microscopia de varredura eletrônica e apresentaram porosidade volumétrica de aproximadamente 70% e diâmetro médio de poros em torno de 190 µm. Observou-se interação das células mais vigorosas e com pronunciada mitose nos escafoldes infiltrados relativamente aos escafoldes de alumina e hidroxiapatita. Os resultados indicaram resistência mecânica para os corpos infiltrados de 43...

Obtenção e utilização de microesferas de parafina para confecção de arcabouços teciduais baseados em cimento de α-fosfato tricálcico; Production and use of paraffin microspheres for tissue scaffolds based on α-tricalcium phosphate cement

Machado, Jeferson Luis de Moraes; Santos, Luis Alberto dos
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
POR
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36.94%
Um dos fatores mais importantes na técnica conhecida por engenharia de tecidos é o crescimento de células em suporte porosos tridimensionais conhecidos por arcabouços. Os arcabouços guiam o crescimento celular e facilitam a formação de tecidos e órgãos funcionais. Cimentos ósseos são materiais desenvolvidos há aproximadamente uma década para aplicações biomédicas. Um cimento deste tipo pode ser preparado misturando um sal de fosfato de cálcio com uma solução aquosa para que se forme uma pasta que possa reagir à temperatura corporal dando lugar a um precipitado que contenha hidroxiapatita. O desenvolvimento de estruturas porosas de cimento de fosfato de cálcio é de grande utilização em engenharia de tecidos, além de outras áreas da traumatologia. O objetivo deste trabalho foi o uso de cimento de α-TCP (α-fosfato tricálcico) para obtenção desses arcabouços, através da obtenção e utilização de esferas de parafina como corpos geradores de poros. O α-TCP foi sintetizado por resfriamento brusco de seus precursores e, as esferas foram produzidas por suspensão em uma solução aquosa de poli (álcool vinílico) e sulfato de sódio. As quantidades de cada um destes reagentes foram estudadas com relação ao tamanho das esferas formadas. Pela análise de difração de raios X foi detectada a presença de β-TCP como fase indesejada no processo de síntese do α-TCP e de hidroxiapatita deficiente em cálcio após a reação de pega do cimento. Foi analisada a extração da parafina dos arcabouços por utilização de um método térmico. A porosidade dos arcabouços confeccionados com esferas de parafina foi observada por microscopia eletrônica de varredura...

Porous titanium scaffolds produced by powder metallurgy for biomedical applications

Vasconcellos, Luana Marotta Reis de; Oliveira, Marize Varella de; Alencastro Graça, Mário Lima de; Vasconcellos, Luis Gustavo Oliveira de; Carvalho, Yasmin Rodarte; Cairo, Carlos Alberto Alves
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 275-280
ENG
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37%
Porous titanium scaffolds are promising materials for biomedical applications such as prosthetic anchors, fillers and bone reconstruction. This study evaluated the bone/titanium interface of scaffolds with interconnected pores prepared by powder metallurgy, using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Porous scaffolds and dense samples were implanted in the tibia of rabbits, which were subsequently killed 1, 4, and 8 weeks after surgery. Initial bone neoformation was observed one week after implantation. Bone ingrowth in pores and the Ca/P ratio at the interface were remarkably enhanced at 4 and 8 weeks. The results showed that the interconnected pores of the titanium scaffolds promoted bone ingrowth, which increased over time. The powder metallurgy technique thus proved effective in producing porous scaffolds and dense titanium for biomedical applications, allowing for adequate control of pore size and porosity and promoting bone ingrowth.

Effect of flow perfusion on the osteogenic differentiation of bone marrow stromal cells cultured on starch-based three dimensional scaffolds

Gomes, Manuela E.; Sikavitsas, V. I.; Behravesh, E.; Reis, R. L.; Mikos, Antonios G.
Fonte: Wiley Interscience Publicador: Wiley Interscience
Tipo: Artigo de Revista Científica
Publicado em //2003 ENG
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This study aims to investigate the effect of culturing conditions (static and flow perfusion) on the proliferation and osteogenic differentiation of rat bone marrow stromal cells seeded on two novel scaffolds exhibiting distinct porous structures. Specifically, scaffolds based on SEVA-C (a blend of starch with ethylene vinyl alcohol) and SPCL (a blend of starch with polycaprolactone) were examined in static and flow perfusion culture. SEVA-C scaffolds were formed using an extrusion process, whereas SPCL scaffolds were obtained by a fiber bonding process. For this purpose, these scaffolds were seeded with marrow stromal cells harvested from femoras and tibias of Wistar rats and cultured in a flow perfusion bioreactor and in 6-well plates for 3, 7, and 15 days. The proliferation and alkaline phosphatase activity patterns were similar for both types of scaffolds and for both culture conditions. However, calcium content analysis revealed a significant enhancement of calcium deposition on both scaffold types cultured under flow perfusion. This observation was confirmed by Von Kossa-stained sections and tetracycline fluorescence. Histological analysis and confocal images of the cultured scaffolds showed a much better distribution of cells within the SPCL scaffolds than the SEVA-C scaffolds...

Morphology, mechanical characterization and in vivo neo-vascularization of chitosan particle aggregated scaffolds architectures

Malafaya, P. B.; Santos, T. C.; Griensven, Martijn van; Reis, R. L.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2008 ENG
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37.03%
The present study intended to evaluate the performance of chitosan-based scaffolds produced by a particle aggregation method aimed to be used in tissue engineering applications addressing key issues such as morphological characteristics, mechanical performance and in vivo behaviour. It is claimed that the particle aggregation methodology may present several advantages, such as combine simultaneously a high interconnectivity with high mechanical properties that are both critical for an in vivo successful application. In order to evaluate these properties, micro-Computed Tomography (micro-CT) and Dynamical Mechanical Analysis (DMA) were applied. The herein proposed scaffolds present an interesting morphology as assessed by micro-CT that generally seems to be adequate for the proposed applications. At a mechanical level, DMA has shown that chitosan scaffolds have an elastic behaviour under dynamic compression solicitation, being simultaneously mechanically stable in the wet state and exhibiting a storage modulus of 4.21 ! 1.04 MPa at 1 Hz frequency. Furthermore, chitosan scaffolds were evaluated in vivo using a rat muscle-pockets model for different implantation periods (1, 2 and 12 weeks). The histological and immunohistochemistry results have demonstrated that chitosan scaffolds can provide the required in vivo functionality. In addition...

Novel hydroxyapatite/carboxymethylchitosan composite scaffolds prepared through an innovative ‘‘autocatalytic’’ electroless coprecipitation route

Oliveira, Joaquim M.; Costa, S. A.; Leonor, I. B.; Malafaya, P. B.; Mano, J. F.; Reis, R. L.
Fonte: Wiley Publicador: Wiley
Tipo: Artigo de Revista Científica
Publicado em //2009 ENG
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36.98%
A developmental composite scaffold for bone tissue engineering applications composed of hydroxyapatite (HA) and carboxymethylchitosan (CMC) was obtained using a coprecipitation method, which is based on the ‘‘autocatalytic’’ electroless deposition route. The results revealed that the pores of the scaffold were regular, interconnected, and possess a size in the range of 20–500 lm. Furthermore, the Fourier transform infra-red spectrum of the composite scaffolds exhibited all the characteristic peaks of apatite, and the appearance of typical bands from CMC, thus showing that coprecipitation of both organic and inorganic phases was effective. The X-ray diffraction pattern of composite scaffolds demonstrated that calciumphosphates consisted of crystalline HA. From microcomputed tomography analysis, it was possible to determine that composite scaffolds possess a 58.9% 6 6% of porosity. The 2D morphometric analysis demonstrated that on average the scaffolds consisted of 24% HA and 76% CMC. The mechanical properties were assessed using compressive tests, both in dry and wet states. Additionally, in vitro tests were carried out to evaluate the wateruptake capability, weight loss, and bioactive behavior of the composite scaffolds. The novel hydroxyapatite/ carboxymethylchitosan composite scaffolds showed promise whenever degradability and bioactivity are simultaneously desired...

Novel 3D scaffolds of chitosan-PLLA blends for tissue engineering applications : preparation and characterization

Duarte, Ana Rita C.; Mano, J. F.; Reis, R. L.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em //2010 ENG
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This work addresses the preparation of 3D porous scaffolds of blends of chitosan and poly(l-lactic acid), CHT and PLLA, using supercritical fluid technology. Supercritical assisted phase-inversion was used to prepare scaffolds for tissue engineering purposes. The physicochemical and biological properties of chitosan make it an excellent material for the preparation of drug delivery systems and for the development of new biomedical applications in many fields from skin to bone or cartilage regeneration. On the other hand, PLLA is a synthetic biodegradable polymer widely used for biomedical applications. Supercritical assisted phase-inversion experiments were carried out in samples with different polymer ratios and different polymer solution concentrations. The effect of CHT:PLLA ratio and polymer concentration and on the morphology and topography of the scaffolds was assessed by SEM and Micro-CT. Infra-red spectroscopic imaging analysis of the scaffolds allowed a better understanding on the distribution of the two polymers within the matrix. This work demonstrates that supercritical fluid technology constitutes a new processing technology, clean and environmentally friendly for the preparation of scaffolds for tissue engineering using these materials.

Cartilage regeneration approach based on squid chitosan scaffolds : in-vitro assessment

Reys, L. L.; Silva, S. S.; Pirraco, Rogério; Marques, A. P.; Mano, J. F.; Silva, Tiago H.; Reis, R. L.
Fonte: Wiley Publicador: Wiley
Tipo: Conferência ou Objeto de Conferência
Publicado em /10/2012 ENG
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37.03%
During the past decades, marine organisms have been the focus of considerable attention as potential source of valuable materials. For instance, chitosan is a biopolymer with high potential in the biomedical field and can be produced from crustacean shells and squid pens [1]. In this sense, we propose the use of chitosan to produce scaffolds for regenerative medicine purposes. An alkaline solution was used to deproteinize squid pens and isolate β- chitin (Chaussard 2004), which was further converted into chitosan through a deacetylation reaction. Chitosan was then processed into porous structures by freeze-drying [3], where chitosan solutions (4%) were submitted to different freezing temperature of -80ºC and - 196ºC. The produced structures were further submitted to neutralization methods with 4% NaHO, including in some cases a pre-washing step using ethanol/water solutions (100:0; 90:10, 80:20; 70:30 and 50:50) [4]. The morphology of scaffolds produced using either squid or commercial chitosan revealed a lamellar structure, independent of the source and/or freezing temperature. All chitosan scaffolds produced exhibited no-cytotoxic behaviour over L929 cells. To test the in vitro functionality of the scaffolds, cells from the mouse chondrogenic cell line ATDC-5 were seeded in the scaffolds and cultured for different time periods. Scaffolds made from squid chitosan were shown to promote better cell adhesion than commercial chitosan scaffolds and comparable or better cell proliferation. This demonstrates that squid chitosan is a valuable alternative to produce scaffolds for different applications in regenerative medicine...

Novel approach to create hybrid and hierarchical scaffolds aimed for tissue regeneration

Oliveira, S. M.; Silva, Tiago H.; Reis, R. L.; Mano, J. F.
Fonte: Wiley Publicador: Wiley
Tipo: Artigo de Revista Científica
Publicado em /10/2012 ENG
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37.1%
Tissue Engineering scaffolds with a wide range of properties and using several types of materials have been produced using different processing techniques. Among those, hybrid scaffolds, made of synthetic biodegradable and natural-origin polysaccharides, have been arising as the most adequate 3D structures to support the mechanical solicitations once implanted as well as cell adhesion, proliferation and differentiation. A well-known methodology to combine micro/nanofibers with/ within scaffolds is the combination of electrospinning and bare scaffold. However, in the common approach, fibers are not homogeneously distributed along the 3D scaffold, being limited to its surface; to achieve deposition on the interior of the scaffold, the electrospinning has to be used during bare scaffolds preparation in a complex process that may lead to structure delamination. Herein, we present a novel approach to hybridize and introduce fibrillar structures and coatings inside 3D scaffolds, rendering truly hierarchical systems. The structures were created combining an unconventional layer-by-layer (LbL) electrostatic selfassembly technology with physical crosslinking by freeze-drying. LbL is based on a simple alternated deposition of polyanions and polycations...

Gellan gum-based hydrogel bilayered scaffolds for osteochondral tissue engineering

Pereira, D. R.; Canadas, Raphael F.; Correia, Joana Silva; Marques, A. P.; Reis, R. L.; Oliveira, Joaquim M.
Fonte: Trans Tech Publications Publicador: Trans Tech Publications
Tipo: Artigo de Revista Científica
Publicado em /01/2014 ENG
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36.94%
It has been shown that hydrogel bilayered scaffolds combining cartilage- and bone-like layers are most advantageous for treating osteochondral defects. In this study, it is proposed the use of low acyl gellan gum (LAGG) for developing bilayered hydrogel scaffolds for osteochondral tissue engineering. The cartilage-like layer of the GG-based bilayered hydrogel scaffolds is composed of LAGG (2 wt%). By adding a 2 wt% LAGG aqueous solution to different amounts of HAp (5-20 wt%) it was possible to produce the bone-like layer. In vitro bioactivity tests were performed by means of soaking the LAGG/LAGG-HAp hydrogel scaffolds in a simulated body fluid solution up to 14 days. Scanning electron microscopy, Fourier transform infra-red spectroscopy and X-ray diffraction analyses demonstrated that apatite formation is limited to the bone-like layer of the LAGG/LAGG-HAp bilayered hydrogel scaffolds.

Avaliação de "engineering scaffolds" de hidroxiapatite e fosfato tricálcico para crescimento ósseo.

Reis, J; Potes, J; Capela e Silva, F; Relvas, C; Simões, J
Fonte: Universidade de Évora Publicador: Universidade de Évora
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
37%
A Engenharia de Tecidos envolve a utilização de células com matrizes biológicas ou artificiais, ou scaffolds, que direccionam as células durante o processo de reparação ou regeneração dos tecidos. Os scaffolds têm sido usados na reconstrução de segmentos ósseos, já que existem limitações importantes na utilização de enxertos autólogos, homólogos ou heterólogos. A composição dos scaffolds e as suas características estruturais desempenham um papel fundamental nas respostas biológicas do tecido ósseo. O presente estudo teve como objectivo a avaliação da utilização in vivo de scaffolds de hidroxiapatite (HA) e de hidroxiapatite/fosfato tricálcico (HA/TCP) no recrutamento e diferenciação de células osteogénicas, para aplicação em ortopedia como superfície osteocondutora/osteoindutora, quer enquanto material de revestimento quer como material para preenchimento de defeitos ósseos. Para o efeito, foram concebidos e fabricados protótipos de scaffolds, com 75% de porosidade, os quais se implantaram nas tíbias de duas ovelhas. Três meses após a cirurgia os animais foram sacrificados e foi feita a avaliação histológica de osso não descalcificado em secções incluídas em resina e coradas com Giemsa Eosina. A avaliação histológica efectuada sugere que os scaffolds de HA parecem ter uma maior capacidade de recrutamento e de diferenciação de células osteogénicas e de formação de osso compacto...

Fiber Scaffolds of Poly (glycerol-dodecanedioate) and its Derivative via Electrospinning for Neural Tissue Engineering

Dai, Xizi
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
Relevância na Pesquisa
37.03%
Peripheral nerves have demonstrated the ability to bridge gaps of up to 6 mm. Peripheral Nerve System injury sites beyond this range need autograft or allograft surgery. Central Nerve System cells do not allow spontaneous regeneration due to the intrinsic environmental inhibition. Although stem cell therapy seems to be a promising approach towards nerve repair, it is essential to use the distinct three-dimensional architecture of a cell scaffold with proper biomolecule embedding in order to ensure that the local environment can be controlled well enough for growth and survival. Many approaches have been developed for the fabrication of 3D scaffolds, and more recently, fiber-based scaffolds produced via the electrospinning have been garnering increasing interest, as it offers the opportunity for control over fiber composition, as well as fiber mesh porosity using a relatively simple experimental setup. All these attributes make electrospun fibers a new class of promising scaffolds for neural tissue engineering. Therefore, the purpose of this doctoral study is to investigate the use of the novel material PGD and its derivative PGDF for obtaining fiber scaffolds using the electrospinning. The performance of these scaffolds, combined with neural lineage cells derived from ESCs...

Synthesis of spirocyclic scaffolds by aminoallylation/RCM sequence and approach toward the total synthesis of the Macrolide Dictyostatin; Synthese spiroverknüpfter Scaffolds durch eine Aminoallylierung/Ringschluss Metathese Sequenz und ein Zugang zur Totalsynthese des Macrolids Dictyostatin

Prusov, Evgeny
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
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37.07%
Die Dissertation besteht aus zwei Teilen. Der erste Teil beschäftigt sich mit der Synthese von spiroverknüpften Scaffolds. Heterozyklische Spiroverbindungen sind für Medizinische Chemie wegen ihrer potentiellen Mehrzahl durch Derivatisierung und wegen ihrer besonderen Orientierung der Ringe im Raum interessant. Vor kurzem wurde die Ringschluss Metathese Reaktion als direkter Zugang zu den spirozyklischen Systemen anerkannt. Wir fanden heraus, dass die Sequenz der Aminoallylierung von zyklischen Keton mit Carbaminsäureester und Allyltrimethylsilan mit Zugabe von Bortrifluorid-diethylether Komplex und darauf folgender Alkylierung mit -Brommethylacrylsäure Methylester und anschließendem Ringschluss Metathese bietet einen effizienten und innovativen Weg zum stickstoffhaltigen spirozyklischen Scaffolds. Im Gegenzug zu den früher mit ähnlichen Methoden synthetisierten Verbindungen, besitzen unsere Scaffolds eine funktionalisierte Doppelbindung, welche für weitere Derivatisierungen geeignet ist. Mehrere Substanzen, die geschützte Stickstoffatome in verschiedenen Ringpositionen enthalten, wurden in Grammmenge synthetisiert. Um das synthetische Potential von hergestellten ,-ungesättigte Ester darzustellen...

Development of biocomposite scaffolds and injectable biocement for bone regeneration.

Wu, Fan
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2013
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37.12%
To repair massive bone defects caused by disease and trauma, a bone grafting procedure is required. The limitations associated with the use of autografts (tissue grafts from one point to another of the same individual's body) and allografts (tissue grafts between genetically nonidentical individuals) have boosted the research and development of bone graft substitutes. Calcium phosphate cement (CPC) is a promising bone graft substitute because of its bioactivity, osteoconductivity and bone replacement capability. However, difficulties with injectability and slow resorption rate have limited the wider applications of CPC. To overcome these limitations, premixed and injectable calcium deficient apatite biocement (cd-AB) were prepared in the initial phase of this study. Using a non-aqueous solution as the liquid phase, the resulting premixed cd-AB had the advantage of remaining stable in the syringe and only hardened following delivery to the defect site. As well, when injected into an aqueous environment, this premixed cd-AB exhibited improved washout resistance when compared to the conventional cd-AB using water as the liquid phase. However, the premixed cd-AB required a longer setting time and developed a reduced compressive strength compared to the conventional cd-AB. The hydration products of premixed cd-AB were a mixture of calcium deficient hydroxyapatite (cd-HA) and PLA. In vitro Tris-HCl immersion tests demonstrated that the premixed cd-AB was degradable. The results revealed that the premixed cd-AB was cytocompatible and no adverse effects were observed after attachment and proliferation of MG-63 osteoblast-like cells in vitro. The most distinct advantages of premixed and injectable PLA-modified cd-AB were its excellent washout resistance and in vitro degradability...

Direct-write assembly of 3D scaffolds using colloidal calcium phosphates inks

Richard,Raquel C.; Oliveira,Renata N.; Soares,Gloria D.A.; Thiré,Rossana M.S.M.
Fonte: Rede Latino-Americana de Materiais Publicador: Rede Latino-Americana de Materiais
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 EN
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37.05%
Additive manufacture techniques using concentrated colloidal inks are a promising approach for creating three-dimensional (3D) calcium phosphates scaffolds for bone repair and regeneration. Among those, the direct-write assembly allows building scaffolds with precise size and geometry. In the present work, commercial β-TCP and HA were used to produce two types of colloidal ink. According to the ink composition used to build the scaffolds, two different groups were obtained. Group I: scaffolds produced with β-TCP-based ink; and Group II: scaffolds produced with biphasic CaP-based ink (BCP). The 3D scaffolds were assembled in a cylindrical shape (Φ = 8mm x H= 16 mm) with interconnected pore channels of approximately 500μm by robotic deposition of 64 layers using a robocasting machine. The mechanical compression property of the scaffolds was determined using universal testing machine. To assure the controlled geometry of the scaffolds, digital images were obtained by reconstructing each individual scan obtained with a micro-computed tomography. An optical contact angle measurement system was used to evaluate the wettability of the materials. After analyzing the results it was concluded that: the robocasting system is suitable for building 3D periodic calcium phosphates scaffolds; the direct-write assembly didn't change the hydrophilic characteristic of CaPs; and presented mean compressive strength around 11 MPa (β-TCP group) and 15 MPa (BCP group)...

Composite polymer-bioceramic scaffolds with drug delivery capability for bone tissue engineering

Mouriño, Viviana Silvia Lourdes; Cattalini, Juan Pablo; Roether, J.; Dubey, P.; Roy, I.; Boccaccini, A. R.
Fonte: Informa Healthcare Publicador: Informa Healthcare
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
ENG
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37.05%
Next-generation scaffolds for bone tissue engineering (BTE) should exhibit the appropriate combination of mechanical support and morphological guidance for cell proliferation and attachment while at the same time serving as matrices for sustained delivery of therapeutic drugs and/or biomolecular signals, such as growth factors. Drug delivery from BTE scaffolds to induce the formation of functional tissues, which may need to vary temporally and spatially, represents a versatile approach to manipulating the local environment for directing cell function and/or to treat common bone diseases or local infection. In addition, drug delivery from BTE is proposed to either increase the expression of tissue inductive factors or to block the expression of others factors that could inhibit bone tissue formation. Composite scaffolds which combine biopolymers and bioactive ceramics in mechanically competent 3D structures, including also organic--inorganic hybrids, are being widely developed for BTE, where the affinity and interaction between biomaterials and therapeutic drugs or biomolecular signals play a decisive role in controlling the release rate.This review covers current developments and applications of 3D composite scaffolds for BTE which exhibit the added capability of controlled delivery of therapeutic drugs or growth factors. A summary of drugs and biomolecules incorporated in composite scaffolds and approaches developed to combine biopolymers and bioceramics in composites for drug delivery systems for BTE is presented. Special attention is given to identify the main challenges and unmet needs of current designs and technologies for developing such multifunctional 3D composite scaffolds for BTE. One of the major challenges for developing composite scaffolds for BTE is the incorporation of a drug delivery function of sufficient complexity to be able to induce the release patterns that may be necessary for effective osseointegration...

Control of Crosslinking for Tailoring Collagen-based Scaffolds Stability and Mechanics

Davidenko, N.; Schuster, C. F.; Bax, D. V.; Raynal, N.; Farndale, R. W.; Best, S. M.; Cameron, R. E.
Fonte: Elsevier Publicador: Elsevier
Tipo: Article; published version
EN
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This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.actbio.2015.07.034; We provide evidence to show that the standard reactant concentrations used in tissue engineering to cross-link collagen-based scaffolds are up to 100 times higher than required for mechanical integrity in service, and stability against degradation in an aqueous environment. We demonstrate this with a detailed and systematic study by comparing scaffolds made from (a) collagen from two different suppliers, (b) gelatin (a partially denatured collagen) and (c) 50% collagen-50% gelatin mixtures. The materials were processed, using lyophilisation, to produce homogeneous, highly porous scaffolds with isotropic architectures and pore diameters ranging from 130-260m. Scaffolds were cross-linked using a carbodiimide treatment, to establish the effect of the variations in crosslinking conditions (down to very low concentrations) on the morphology, swelling, degradation and mechanical properties of the scaffolds. Carbodiimide concentration of 11.5mg/ml was defined as the standard (100%) and was progressively diluted down to 0.1%. It was found that 10fold reduction in the carbodiimide content led to the significant increase (almost 4fold) in the amount of free amine groups (primarily on collagen lysine residues) without compromising mechanics and stability in water of all resultant scaffolds. The importance of this finding is that...

Optimisation of UV Irradiation as a Binding Site Conserving Method for Crosslinking Collagen-based Scaffolds

Davidenko, Natalia; Bax, Daniel B.; Schuster, Carlos F.; Farndale, Richard W.; Hamaia, Samir W.; Best, Serena M.; Cameron, Ruth E.
Fonte: Springer Publicador: Springer
Tipo: Article; accepted version
EN
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This is the author accepted manuscript. It is currently embargoed pending publication.; Short wavelength (?=254nm) UV irradiation was evaluated over a range of intensities (0.06 to 0.96 J/cm2) as a means of cross-linking collagen- and gelatin-based scaffolds, to tailor their material characteristics whilst retaining biological functionality. Zero-link carbodiimide treatments are commonly applied to collagen-based materials, forming cross-links from carboxylate anions (for example the acidic E of GFOGER) that are an essential part of integrin binding sites on collagen. Cross-linking these amino acids therefore disrupts the bioactivity of collagen. In contrast, UV irradiation forms bonds from less important aromatic tyrosine and phenylalanine residues. We therefore hypothesised that UV cross-linking would not compromise collagen cell reactivity. Here, highly porous (~99%) isotropic, collagen-based scaffolds were produced via ice-templating. A series of scaffolds (pore diameters ranging from 130-260?m) with ascending stability in water was made from gelatin, two different sources of collagen I, or blends of these materials. Glucose, known to aid UV crosslinking of collagen, was added to some lower-stability formulations. These scaffolds were exposed to different doses of UV irradiation...

Biomimetic Composite Scaffolds for the Functional Tissue Engineering of Articular Cartilage

Moutos, Franklin Thomas
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação Formato: 18431936 bytes; application/pdf
Publicado em //2009 EN_US
Relevância na Pesquisa
36.98%

Articular cartilage is the connective tissue that lines the ends of long bones in diarthrodial joints, providing a low-friction load-bearing surface that can withstand a lifetime of loading cycles under normal conditions. Despite these unique and advantageous properties, the tissue possesses a limited capacity for self-repair due to its lack of vasculature and innervation. Total joint replacement is a well-established treatment for degenerative joint disease; however, the materials used in these procedures have a limited lifespan in vivo and will likely fail over time, requiring additional - and increasingly complicated - revision surgeries. For younger or more active patients, this risk is unacceptable. Unfortunately, alternative surgical options are not currently available, leaving pain management as the only viable treatment. In seeking to discover a new therapeutic strategy, the goal of this dissertation was to develop a functional tissue-engineered cartilage construct that may be used to resurface an entire diseased or damaged joint.

A three-dimensional (3-D) woven textile structure, produced on a custom-built miniature weaving loom, was utilized as the basis for producing novel composite scaffolds and cartilage tissue constructs that exhibited initial properties similar to those of native articular cartilage. Using polyglycolic acid (PGA) fibers combined with chondrocyte-loaded agarose or fibrin hydrogels...

Development of Cartilage-Derived Matrix Scaffolds via Crosslinking, Decellularization, and Ice-Templating

Rowland, Christopher
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação
Publicado em //2015
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Articular cartilage is a connective tissue that lines the surfaces of diarthrodial joints; and functions to support and distribute loads as wells as facilitate smooth joint articulation. Unfortunately, cartilage possesses a limited capacity to self-repair. Once damaged, cartilage continues to degenerate until widespread cartilage loss results in the debilitating and painful disease of osteoarthritis. Current treatment options are limited to palliative interventions that seek to mitigate pain, and fail to recapitulate the native function. Cartilage tissue engineering offers a novel treatment option for the repair of focal defects as well as the complete resurfacing of osteoarthritic joints. Tissue engineering combines cells, growth factors, and biomaterials in order to synthesize new cartilage tissue that recapitulates the native structure, mechanical properties, and function of the native tissue. In this endeavor, there has been a growing interest in the use of scaffolds derived from the native extracellular matrix of cartilage. These cartilage-derived matrix (CDM) scaffolds have been show to recapitulate the native epitopes for cell-matrix interactions as well as provide entrapped growth factors; and have been shown to stimulate chondrogenic differentiation of a variety of cell types. Despite the potent chondroinductive properties of CDM scaffolds...