Electrospinning is a process by which micro and nanofibrous scaffolds can be easily fabricated to mimic structures such as the extracellular matrix of bone. A number of materials have been used to fabricate such scaffolds making the process an extremely versatile tool in the field of bone tissue engineering. Many scaffolds however are hydrophobic, leading to poor cellular attachment and proliferation, whilst the actual process of electrospinning is highly variable, producing irregular scaffolds that can ultimately influence cell invasion and differentiation. The focus of this thesis was to address the issues of poor biocompatibility and irregular scaffold production in three commonly used polymers each with different mechanical properties and degradation profiles. Poly (ε-caprolactone) (PCL), polyethylene terephthalate (PET) and poly lactic-co-glycolic acid (PLGA) were functionalised with surfactants in order to improve the biocompatibility and osteoinductive properties of electrospun scaffolds, whilst electrospinning equipment was modified to improve uniformity of scaffold production. Reducing variables known to affect scaffold formation such as temperature and humidity through the use of an environmental stability cabinet improved the reproducibility of scaffolds. The introduction of a Faraday cage, a larger electrode and a negative mandrel potential also improved the quality and quantity of electrospun fibres collected. Lecithin was selected as an appropriate additive for both improving biocompatibility and uniformity of electrospun fibres as it is naturally occurring and induced dose dependent reductions in water contact angle, allowing tailored hydrophobicity. Through gravimetric determination of pore sizes coupled with mathematical modelling, the addition of lecithin was found to reduce both mean fibre diameter and pore size in all scaffolds, improving scaffold homogeneity. At low concentrations (i.e. 2 %) lecithin generally did not affect the mechanical properties of scaffolds, however significant improvements in tensile strength for PCL and nanoindentation for PET were evident, indicating these scaffolds remained suitably strong for bone regeneration purposes. Reduced hydrophobicity acted to improve cellular attachment of Saos-2 osteoblasts to polymers, whilst proliferation on all scaffolds was similar to TCP controls. Furthermore, lecithin incorporation induced osteoinduction, as bone marrow mesenchymal stem cells seeded on these hybrid scaffolds expressed upregulated gene expression for alkaline phosphatase, collagen 1, osteocalcin and osteopontin. In conclusion, these scaffolds, functionalised with lecithin, improve the homogeneity of fibrous mats allowing increased reproducibility and efficiency of the electrospinning process. Furthermore, the improved biocompatibility and osteoinductivity that lecithin presents, allows for the production of more suitable electrospun scaffolds in the field of bone tissue engineering.

Yes / The clinical application of composites seeks to exploit the mechanical and chemical properties of materials which make up the composite, and in researching polymer composites for biomedical applications the aim is usually to enhance the bioactivity of the polymer, while maintaining the mechanical properties. To that end, in this study medical grade Poly(L-lactic) acid (PLLA) has been reinforced with short phosphate-based glass fibers (PGF). The materials were initially mixed by melting PLLA granules with the short fibers, before being extruded to form a homogenous filament, which was pelletized and used as feedstock for compression moulding. As made the composite materials had a bending strength of 51 MPa ± 5, and over the course of eight weeks in PBS the average strength of the composite material was in the range 20–50 MPa. Human mesenchymal stromal cells were cultured on the surfaces of scaffolds, and the metabolic activity, alkaline phosphatase production and mineralization monitored over a three week period. The short fiber filler made no significant difference to cell proliferation or differentiation, but had a clear and immediate osteoinductive effect, promoting mineralization by cells at the material surface. It is concluded that the PLLA/PGF composite material offers a material with both the mechanical and biological properties for potential application to bone implants and fixation, particularly where an osteoinductive effect would be valuable. / funded in part by the EPSRC Centre for Doctoral Training in Additive Manufacturing and 3D Printing (EP/L01534X/1), the EPSRC Centre for Innovative Manufacture in Medical Devices (EP/K029592/1), and Glass Technology Services Ltd., Sheffield, UK.

Made available in DSpace on 2014-06-11T19:30:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-12-06Bitstream added on 2014-06-13T19:00:25Z : No. of bitstreams: 1 nunes_el_dr_botfm_prot.pdf: 2705473 bytes, checksum: cb2a12239895cd0f0391a25351fea181 (MD5) / Nas últimas décadas, os materiais utilizados para reparações ósseas de estruturas faciais tiveram um aprimoramento que muito facilitou a fixação interna rígida. Entretanto, este campo permanece aberto para as pesquisas até os dias atuais, uma vez que não se tem ainda o material ideal para este fim. Objetivo: avaliar a reparação de fraturas da parede orbitária usando a fixação interna rígida com miniplacas de titânio e de polímero vegetal comparando-as. Material e método: foi realizado um estudo experimental, prospectivo, na Faculdade de Medicina de Botucatu, no qual foram utilizados 45 coelhos albinos, submetidos a fratura do assoalho da órbita e divididos em três grupos especiais... / In the last few decades, the advances in material used for repairing facil bone fractures have greatly improved internal rigid fixing. However research in this area remains open as there still no ideal material. Objective: to evaluate the repair of orbital wall fractures with internal rigid fixings comparing mini titanium and reabsorbable vegetal polymer plates... (Complete abstract, click eletronic address below)

Osteoporosis is a systemic skeletal disease that affects millions of people worldwide. There are many possible etiologies for osteoporosis, including inherent variables like genetics and sex, and lifestyle variables like diet and exercise. Characterized by low bone mass and increased fracture risk, the disease places a burden on both the patients and the healthcare industry. Therefore, it is vital that research determine the mechanisms by which the risk factors affect BMD so that better diagnosis and treatment options may be developed. The purpose of this study was to examine the relationship between various osteoporosis risk factors and biochemical markers of osteogenic cell activity derived from bone-marrow MSCs. It was hypothesized postmenopausal white women, having the greatest risk for osteoporosis, would have elevated hydroxyproline and decreased ALP, indicative of greater bone resorption. Acetabular reamings were collected from 26 patients (15 males and 11 females) undergoing total hip arthroplasty at Boston Medical Center. MSCs from the reamings were plated and underwent osteoinduction into osteoblasts. The cells were then harvested and assayed for various indicators of cell growth and bone cell activity, such as DNA, ALP, and hydroxyproline. Our hypothesis was generally supported in that postmenopausal white women did have less ALP, an indicator of bone deposition, than premenopausal women and postmenopausal African American women. Additional findings and directions for future studies are further discussed in this paper.

No description available.

The replacement of missing teeth by osseointegrated dental implants is a commonly utilised treatment option in dentistry. However, successful treatment outcomes are dependent on sufficient bone quantity in the proposed surgical site for implant placement (Buser et al., 2004). Surgical augmentation of bone defects is commonly performed prior to or during implant placement. Bone augmentation procedures of the maxillary sinus or guided bone regeneration (GBR) procedures of alveolar ridge defects have utilised a variety of bone graft materials in block or particulate form, either alone or in combination with resorbable or non-resorbable barrier membranes. Objective: The aim of this study was to determine whether Hydroxyapatite β-Tricalcium Phosphate (HA-TCP) either alone or combined with Enamel Matrix Derivative (EMD) or recombinant human Platelet Derived Growth Factor-BB (rhPDGF-BB) is osteoinductive when implanted into a nonosseous site. Methods: Twenty CD-1 adult male mice underwent intramuscular implantation into both hindlimbs of an empty gelatine capsule or a gelatine capsule containing one of the following: 10 mg of uncoated particulate HA-TCP, (Straumann Bone Ceramic®, HA-TCP), EMD coated HA-TCP, (Emdogain®, HATCP + EMD) or rhPDGF-BB coated HA-TCP (HA-TCP + PDGF). Ten animals were sacrificed at four and eight weeks with five specimens from each group retrieved at each time point. The area of graft placement was radiographed and after graft retrieval, a semi-quantitative histological examination was performed with the aim of assessing the inflammatory changes, reparative processes and osteoinduction within the graft site. Results: At both 4 and 8 weeks, histological analysis failed to demonstrate any osteoinductive activity in any of the specimens from the three experimental groups. A minimal chronic inflammatory response and foreign body reaction was seen in the experimental groups which reduced over time. The particles were embedded within fibrous connective tissue and were encapsulated by a dense cellular layer consisting of active fibroblasts and occasional macrophages with the thickness of this layer decreasing over time. At 4 weeks, a greater density of the fibrous connective tissue was demonstrated in the HA-TCP + EMD group (P<0.001) while a greater thickness in the capsule thickness was seen in the HA-TCP group (P=0.022) although no differences were seen after 8 weeks. Greater neovascularisation was seen in the HA-TCP + PDGF group after 8 weeks (P=0.043) while greater amounts of adipose tissue surrounding the particles were detected in the HA-TCP + PDGF group at 4 weeks (P=0.002) and in the HA-TCP + EMD group at eight weeks (P=0.002). Conclusions: The results of this study suggest that the use of commercially available HA-TCP alone or in combination with EMD or rhPDGF-BB is biocompatible but not osteoinductive in the murine model. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1522641 / Thesis (D.Clin.Dent.) -- University of Adelaide, School of Dentistry, 2010

Made available in DSpace on 2014-06-11T19:31:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-06-25Bitstream added on 2014-06-13T20:41:25Z : No. of bitstreams: 1 lacretajunior_acc_dr_jabo.pdf: 805914 bytes, checksum: 44e9be8105f00a126bb8355d24887832 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O retardamento ou a ausência do processo de consolidação óssea nas correções cirúrgicas das fraturas são situações indesejadas por cirurgiões, haja vista que às vezes se torna um problema de difícil resolução na cirúrgia ortopédica. A união óssea inicia-se imediatamente após a fratura por meio de mecanismos fisiológicos com fases bem definidas. Cada uma dessas fases é mediada por substâncias biológicas distintas específicas e indispensáveis no processo completo da neofomação óssea. Essas substâncias biológicas podem ativar ou impedir a osteogênese dependendo da sua presença, quantidade ou qualidade em cada fase da consolidação óssea. Dentre os inúmeros oteoindutores biológicos e sintéticos existentes, a próstata do cão, recentemente testada mostrou-se efetiva na estimulação da osteogênese. O presente estudo consistiu em avaliar a capacidade osteindutora da próstata do cão em ossos longos, utilizando-a na ostectomia parcial do rádio em coelhos. Os coelhos foram distribuidos em dois grupos (controle e tratado), cada qual com dois subgrupos de 30 e 60 dias, que foram submetidos a ostectomia parcial do rádio, e cujos animais do grupo tratado recebem o implante do fragmento da próstata do cão. Segundo os aspectos clínicos, radiológicos e histológicos, ao longo do tempo, após o procedimento cirúrgico, os resultados sugerem que a próstata induz a osteogênese, e que seu uso nas cirurgias ortopédicas poderá ser uma ferramenta importante no auxílio à consolidação óssea. / The retardation or absence of the process of bone healing in the surgical corrections of the fractures are situations not desired for surgeons, has seen that the times if it becomes a problem of dificult in the orthopaedic surgery. The bone healing immediately initiates after the fracture by means of physiological mechanisms with well defined phases. Each one of these phases is mediated by specific and indispensable distinst substances biological in the complete process of the new bone formation. These biological substances can activate or hinder the osteogenesis depending on its presence, amount or quality in each phase the bone helding. Amongst the innumerale existing biological and syntheticosteoinductors, the prostate of the dog, recently tested reveled effective in the simulation of osteogenesis. The present study in consisted of evaluating the osteinduction capacity of the prostate of the dog in long bones, using it in the partial radius ostectomy in rabbits. The rabbits had been divided in two groups (control and treated) and four sub-groups, had been submitted the partial radius ostectomy, whwere they had received the implantation of the dog prostate pieces. After the surgery had been evaluated by clinical, radiography and histological examination. The results had demosntred that prostate induces osteogenesis, and thatits use in the orthopaedics surgeries could bean important tool in the aid of the bone healing.

La surface naturelle des prothèses, tels que des implants métalliques, n'est pas idéale pour l'obtention d'une bonne ostéo-intégration. Par conséquent, l'amélioration des propriétés de surface pour les rendre ostéo-condutrices ou ostéo-inductrices est souhaitable. La délivrance contrôlée de protéines ostéo-inductrices de la famille des bone morphogenetic proteins (BMPs) par la surface des matériaux implantables permettrait une formation osseuse optimisée et plus rapide autour de l'implant. En particulier, la BMP-2 est importante dans la phase initiale de la différenciation vers l'os. En raison de leur similarité avec les tissus naturels, l'utilisation des revêtements de biopolymères qui ont une bonne affinité avec les molécules bioactives, semble prometteuse pour le chargement et la délivrance de BMP-2. L'équipe a déjà mis au point un film à base des biopolymères hyaluronane et de poly(L-lysine), en utilisant la technique d'assemblage couche par couche. Ce film constitue un réservoir qui permet de présenter la BMP-2 "liée à la matrice". La bioactivité in vitro et les propriétés ostéo-inductrices in vivo de ces films ont déjà prouvées. Dans ce travail, nous avons cherché à mieux comprendre l'interaction de la BMP-2 avec le film et l'interaction des cellules avec la BMP-2. Tout d'abord, nous avons étudié la structure de la BMP-2 piégée dans les films et l'avons comparé à celle en solution; puis nous avons évalué l'impact du séchage, du stockage à long terme et de la stérilisation sur la structure du film et sa bioactivité. Enfin, nous avons étudié l'internalisation de la BMP-2 par les cellules en fonction de la réticulation du film et avons étudié la relation entre internalisation et voies de signalisation. / The natural surface of bulk prostheses materials, such as metallic implants, is not suitable for successful osteointegration of implants. Therefore, improving the surface to render it osteoconductive and osteoinductive is needed. The controlled delivery of osteoinductive bone morphogenetic proteins (BMPs) from the surface of implantable materials would enable faster and better bone formation around the implant. In particular, BMP-2 plays an important role in the early phase of differentiation of stems cells in bone cells. The coating of natural polymers that have a high affinity for BMP-2 would enable BMP retention and localized delivery at the implant surface. Using the layer-by-layer technique, we have developed a coating made of the biopolymers hyaluronan and poly(L-Lysine), which acts as a reservoir to trap BMP-2 and to present them to cells in a "matrix-bound" manner. The in vitro bioactivity and in vivo osteoinductive properties of BMP-2-loaded films have previously been proved. In this work, the aim is to further understand the interaction of the BMP-2 with the film and the uptake of BMP-2 by the cells. First, the secondary structure of matrix-bound BMP-2 was studied and compared to its structure in solution. Second, the impact of drying, long term storage and sterilization on film structure and bioactivity were assessed. Finally, we investigated if and how matrix-bound BMP-2 is internalized by the cells from the different cross-linked films, the internalization route and its relation to BMP-2 signaling.

Orientador: Silvana Artioli Schellini / Banca: Claudia Helena Pellizon / Banca: Jair Cortez Montovani / Banca: Antonio Carlos Neder / Banca: Suzana Matayoshi / Resumo: Nas últimas décadas, os materiais utilizados para reparações ósseas de estruturas faciais tiveram um aprimoramento que muito facilitou a fixação interna rígida. Entretanto, este campo permanece aberto para as pesquisas até os dias atuais, uma vez que não se tem ainda o material ideal para este fim. Objetivo: avaliar a reparação de fraturas da parede orbitária usando a fixação interna rígida com miniplacas de titânio e de polímero vegetal comparando-as. Material e método: foi realizado um estudo experimental, prospectivo, na Faculdade de Medicina de Botucatu, no qual foram utilizados 45 coelhos albinos, submetidos a fratura do assoalho da órbita e divididos em três grupos especiais... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In the last few decades, the advances in material used for repairing facil bone fractures have greatly improved internal rigid fixing. However research in this area remains open as there still no ideal material. Objective: to evaluate the repair of orbital wall fractures with internal rigid fixings comparing mini titanium and reabsorbable vegetal polymer plates... (Complete abstract, click eletronic address below) / Doutor

Orientador: Júlio Carlos Canola / Banca: Paola Castro Moraes / Banca: Naida Cristina Borges / Banca: José Wanderley Cattelan / Banca: Aureo Evangelista Santana / Resumo: O retardamento ou a ausência do processo de consolidação óssea nas correções cirúrgicas das fraturas são situações indesejadas por cirurgiões, haja vista que às vezes se torna um problema de difícil resolução na cirúrgia ortopédica. A união óssea inicia-se imediatamente após a fratura por meio de mecanismos fisiológicos com fases bem definidas. Cada uma dessas fases é mediada por substâncias biológicas distintas específicas e indispensáveis no processo completo da neofomação óssea. Essas substâncias biológicas podem ativar ou impedir a osteogênese dependendo da sua presença, quantidade ou qualidade em cada fase da consolidação óssea. Dentre os inúmeros oteoindutores biológicos e sintéticos existentes, a próstata do cão, recentemente testada mostrou-se efetiva na estimulação da osteogênese. O presente estudo consistiu em avaliar a capacidade osteindutora da próstata do cão em ossos longos, utilizando-a na ostectomia parcial do rádio em coelhos. Os coelhos foram distribuidos em dois grupos (controle e tratado), cada qual com dois subgrupos de 30 e 60 dias, que foram submetidos a ostectomia parcial do rádio, e cujos animais do grupo tratado recebem o implante do fragmento da próstata do cão. Segundo os aspectos clínicos, radiológicos e histológicos, ao longo do tempo, após o procedimento cirúrgico, os resultados sugerem que a próstata induz a osteogênese, e que seu uso nas cirurgias ortopédicas poderá ser uma ferramenta importante no auxílio à consolidação óssea. / Abstract: The retardation or absence of the process of bone healing in the surgical corrections of the fractures are situations not desired for surgeons, has seen that the times if it becomes a problem of dificult in the orthopaedic surgery. The bone healing immediately initiates after the fracture by means of physiological mechanisms with well defined phases. Each one of these phases is mediated by specific and indispensable distinst substances biological in the complete process of the new bone formation. These biological substances can activate or hinder the osteogenesis depending on its presence, amount or quality in each phase the bone helding. Amongst the innumerale existing biological and syntheticosteoinductors, the prostate of the dog, recently tested reveled effective in the simulation of osteogenesis. The present study in consisted of evaluating the osteinduction capacity of the prostate of the dog in long bones, using it in the partial radius ostectomy in rabbits. The rabbits had been divided in two groups (control and treated) and four sub-groups, had been submitted the partial radius ostectomy, whwere they had received the implantation of the dog prostate pieces. After the surgery had been evaluated by clinical, radiography and histological examination. The results had demosntred that prostate induces osteogenesis, and thatits use in the orthopaedics surgeries could bean important tool in the aid of the bone healing. / Doutor