Orientador: Bruno Watanabe Minto / Banca: Luis Gustavo Gosuen Gonçalves Dias / Banca: Paulo César Jark / Resumo: A cartilagem articular possui capacidade de reparação limitada, aumentado a predisposição ao desenvolvimento de alterações degenerativas, muitas vezes irreversíveis. Diversas formas de tratamento, cirúrgicas ou conservativas, são descritas, entretanto a terapêutica da osteoartrite continua sendo grande desafio ao médico veterinário. Neste contexto, a pesquisa envolvendo células-tronco mesenquimais destaca-se na busca de melhorias e avanços na reparação da cartilagem articular. Objetivou-se, no presente projeto, comparar a regeneração cartilaginosa da articulação coxofemoral de coelhos, com e sem o transplante de células-tronco mesenquimais autólogas, por meio de exames radiográficos e histopatológicos. Dois grupos, com 15 animais da espécie leporina cada, foram submetidos à indução química de osteoartrite com solução de colagenase 2% na articulação coxofemoral direita. No Grupo 1 (Células-tronco) realizou-se a aplicação intra-articular de células-tronco mesenquimais autólogas, enquanto que, o Grupo 2 (Controle) foi constituído por animais submetidos à aplicação intra-articular de solução salina estéril. Foram realizadas avaliações radiográficas e histopatológicas aos 30, 60 e 90 dias após a aplicação. Os resultados histológicos deste ensaio indicam que células-tronco mesenquimais (Grupo 1) melhoraram discretamente a qualidade do tecido de reparo, de acordo com os critérios da escala semi-quantitativa ICRS 1 ("International Cartilage Repair Society"). O Grupo 1 (Células-Tronco... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The articular cartilage has limited repair capacity, leading to an increased risk for degenerative changes, potentially irreversible. Several treatments, surgical or not, are described, however osteoarthritis remains a major challenge for the veterinarian. In this context, research involving mesenchymal stem cells stands out. The aim of this study was to compare cartilage regeneration of the hip in rabbits, with and without the transplantation of autologous mesenchymal stem cells. Radiographic and histopathological evaluation were used. Thirty rabbits were submitted to chemical induction of osteoarthritis with a 2% colagenase in the right hip. They were divided into 2 groups of 15 animals each: Group 1 (intra-articular application of autologous mesenchymal stem cells) and Group 2 (control - intra-articular application of sterile saline solution). Radiographic and histopathological evaluations were performed at 30, 60 and 90 days after application. The mesenchymal stem cells group (Group 1) showed slight improvement of the quality of the repair tissue, according to the semi-quantitative scale criteria ICRS 1 (International Cartilage Repair Society). The Group 1 (Stem Cells) showed superiority in relation to Group 2, specially in the parameters joint surface, extracellular matrix and cellular distribution. / Mestre

Orientador: Ibsen Bellini Coimbra / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-07T22:55:15Z (GMT). No. of bitstreams: 1 Andrade_AndreLuisLugnanide_M.pdf: 2450375 bytes, checksum: f33edb219ba25e56f663f1256a99bbeb (MD5) Previous issue date: 2006 / Resumo: Introdução: Os condrócitos da cartilagem articular vivem em um ambiente com baixa concentração de oxigênio. Nestas condições, a proteína do fator induzido por hipóxia (HIF-1a) mantém-se estável e ativa genes que são fundamentais na homeostase do oxigênio. A expressão do HIF-1a aumenta, em joelhos com osteoartrite (OA), principalmente nas áreas mais afetadas pela degeneração. Os condrócitos são capazes de produzir mediadores inflamatórios, como a interleucina-1 (IL-1) e o fator de necrose tumoral a (TNF-a), que estimulam a produção de prostaglandinas, metaloproteinases e óxido nítrico e relacionam-se com o início e com a progressão da osteoartrite. Os antiinflamatórios são drogas freqüentemente utilizadas no tratamento sintomático da OA. Material e Método: condrócitos humanos de joelhos osteoartríticos cultivados em suspensão e em condições normais de oxigênio foram divididos em quatro grupos: 1) controle, 2) estimulados com IL-1 ou TNF-a, 3) estimulados com meloxicam ou parecoxibe e 4) estimulados com meloxicam ou parecoxibe associados a IL-1 ou TNF-a. Os grupos foram submetidos à extração de RNA (ácido ribonucléico) e de proteína nuclear. O RNA foi convertido em cDNA, sendo então realizada a reação de PCR em tempo real para verificar a expressão do HIF-1a. As proteínas nucleares foram extraídas, quantificadas e analisadas pela técnica de Western Blotting. Resultados: Foi detectada a expressão de HIF-1a e cDNA de HIF-1a em todos os grupos de condrócitos cultivados em suspensão em tensões normais de oxigênio, não havendo diferenças significativas entre os grupos. Discussão: a meia-vida do HIF-1a é extremamente curta em normóxia e marcadamente prolongada em hipóxia, por isso muitos pesquisadores acreditam não ser possível a detecção da proteína do HIF-1a em condrócitos cultivados em condições normais de oxigênio. Neste estudo foi possível constatar a expressão do HIF-1a em normóxia, possivelmente devido ao modelo de cultura utilizado. O estímulo com IL-1, TNF-a e inibidores da COX-2 não alterou a expressão de HIF-1a. Condrócitos oriundos de articulações osteoartríticas avançadas poderiam apresentar resistência à ação das citocinas / Abstract: Introduction: The chondrocytes of joint surface live in low concentration of oxygen environment. In this condition, the hypoxia inducible factor 1 a (HIF-1a) becomes stable and regulates the expression of genes that are important for oxygen homeostasis. The expression of HIF-1a mRNA is augmented in chondrocytes from osteoarthritic knees, especially in more degenerated areas. Chondrocytes are capable of producing inflammatory mediators, such as interleukin 1 (IL-1) and tumoral necrosis factor a (TNF-a), that stimulate the production of prostaglandin, metalloproteinases and nitric oxide, correlated with the onset and progression of osteoarthritis. Antiinflammatory drugs are frequently used in the treatment of symptoms of osteoarthritis. Material e Methods: human chondrocytes from osteoarthritic knees were cultivated in suspension and in normal tension of oxygen. The cells were divided in 4 groups: control, stimulated with IL-1 or TNF-a, stimulated with meloxicam or parecoxib and the last one stimulated with meloxicam or parecoxib and IL-1 or TNF-a. Nuclear protein and RNA were extracted from these cells. cDNA was synthesized from RNA and real time PCR was performed with this product in order to determine HIF-1a expression. Nuclear protein was analyzed using the Western-Blotting method. Results: HIF-1a and HIF-1a mRNA was detectable in all cell groups, and there was not a statistic significant difference between them. Discussion: As half live of HIF-1a is extremely short when in normoxic and greater in hypoxic conditions, many researchers believe it is not possible to detect this protein in chondrocytes cultivated in normoxic environment. Our results presented expression of HIF-1a in normal oxygen tensions, probably due to the fact that chondrocytes were cultivated in suspension. As chondrocytes were obtained from advanced osteoarthritic knees and in such conditions the cells can be more resistant to the action of cytokines, this could explain why IL-1, TNF-a and antiinflamatory did not result in modification of HIF-1a / Mestrado / Clinica Medica / Mestre em Clinica Medica

Orientador: Célia Marisa Rizzatti Barbosa / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-18T16:04:07Z (GMT). No. of bitstreams: 1 FariasNeto_Arcelino_D.pdf: 1895628 bytes, checksum: 3d9e789620307fdbeaffe939bf75437e (MD5) Previous issue date: 2011 / Resumo: A cartilagem articular do côndilo mandibular é responsável pelo crescimento ósseo endocondral durante o desenvolvimento mandibular. Ela depende do funcionamento adequado da articulação temporomandibular (ATM) para sua diferenciação e maturação. Trabalhos demonstram que a manipulação funcional da mandíbula foi capaz de alterar a dinâmica fisiológica dessa cartilagem. Nesse sentido, a protrusão diminuiria a ação de cargas sobre o côndilo mandibular, estimulando o crescimento endocondral, e de forma inversa, a retrusão aumentaria a pressão sobre a cartilagem, inibindo o crescimento. Essas técnicas têm sido utilizadas com relativo sucesso na ortopedia facial com o intuito de corrigir discrepâncias maxilo-mandibulares. Entretanto, alguns quadros patológicos presentes nas ATMs podem alterar o seu desenvolvimento normal. Um dos fatores etiológicos que pode ser associado à presença de alterações no côndilo mandibular é a oclusão dental. A hipótese formulada é de que a presença de instabilidade ortopédica causada por um fator oclusal durante a fase de desenvolvimento pode levar à deficiência do crescimento mandibular e alterações intra-articulares. Assim, este trabalho teve por objetivo avaliar, em modelo animal, alterações da oclusão dental sobre o crescimento mandibular e tecidos intra-articulares. O estudo foi randomizado e cego. Foram utilizadas 40 ratas Wistar com 5 semanas de idade divididas aleatoriamente em 4 grupos com o mesmo número de animais: controle, com interferência oclusal, com ausência dos molares inferiores unilateral e com ausência dos molares inferiores bilateral. Os animais foram acompanhados por 8 semanas, período que correspondeu a sua fase de maturação óssea. Após esse período, os animais foram sacrificados e realizou-se tomografia computadorizada de feixe cônico (Cone beam) de suas cabeças para construção de protótipos de biomodelos, sobre os quais foram mensurados o comprimento da mandíbula, a altura do ramo mandibular e distância intercondilar. Em seguida, as articulações temporomandibulares foram cuidadosamente preparadas para análise imunohistoquímica dos níveis de colágeno tipo II, Fator de Crescimento Endotelial Vascular, e Interleucina 1? na cartilagem condilar. Os dados foram submetidos a análise estatística através do Software SPSS versão 17.0. As médias entre os grupos foram comparadas através do One-way Anova, enquanto as diferenças entre os lados da mandíbula foram avaliadas através do teste t de Student (?=0.05). A partir da análise dos resultados, observou-se que alterações oclusais podem afetar o desenvolvimento do osso mandibular, bem como alterar a expressão de Colágeno tipo II, Fator de Crescimento Endotelial Vascular e Interleucina 1? na cartilagem condilar. Diante do exposto, conclui-se que a oclusão dentária é capaz de interferir na dinâmica dos tecidos intra-articulares, sendo um fator importante durante o desenvolvimento craniofacial / Abstract: The condylar cartilage regulates the endochondral ossification during mandibular development. Mechanical stimulus in the temporomandibular joint (TMJ) plays an important role in cell proliferation and differentiation of mandibular condyle. Studies have shown that functional mandibular displacement can affect TMJ cartilage dynamics. Mandibular advancement induces profound metabolic changes in the condyle and enhances growth. In contrast, mandibular retraction reduces growth. The overall picture emerging from the data is that unloading of the condyle increases growth, while loading reduces it. Therefore, dental occlusion could be one of the factors associated with the alteration of the TMJ growth. The hypothesis is that orthopedic instability caused by occlusal factors present during TMJ development can affect mandibular growth and intra-articular tissue. Thus, the purpose of this study was to evaluate the influence of dental occlusion on mandibular growth and intra-articular tissue in Wistar rats. The study was randomized and blinded. Forty 5 weeks old female Wistar rats composed the sample. The animals were randomly allocated to four groups with the same number of rats: (1) control, (2) occlusal appliance for functional posterior displacement of the mandible, (3) unilateral mandibular tooth extraction, (4) bilateral mandibular tooth extraction. The rats were sacrificed after 8 weeks, when they had achieved skeletal maturity. Immediately after death, the heads were fixed in 10% paraformaldehyde, and cone beam CT scan images were taken using the Classic I-CAT (Imaging Sciences International, Hatfield, PA, USA). The 3-dimensional images of rats' skulls were exported in multifile Digital Imaging and Communications in Medicine (DICOM) format, and acrylic rapid-prototyped templates of the mandibles were constructed for measurement of mandibular growth. Immunostaining was used for the detection of type II collagen, vascular endothelial growth factor (VEGF) and interleukin-1?. The data were processed with SPSS software (V 17.0 for Windows, SPSS Inc, Chicago, IL, USA). Differences among the groups were analyzed by one-way ANOVA (Tukey test as post-hoc test), while differences between sides were analyzed by non-paired Student's t test. Shapiro-Wilk and Levene tests were used to observe normality and variance homogeneity, respectively. Confidence level was set at 5%. The results of this study showed that dental occlusion is an important factor for the integrity of intra-articular tissues and to the healthy craniofacial development, emphasizing the importance of early treatment to normalize occlusion and create appropriate conditions for normal craniofacial development / Doutorado / Protese Dental / Doutor em Clínica Odontológica

A articulação do cotovelo é complexa e tem grande relevância clínica nos atendimentos aos pequenos animais. Esta região já foi bem explorada em pesquisas anteriores pelos métodos radiográficos e tomográficos, porém, ainda há poucos estudos relacionados à ultrassonografia. O objetivo deste estudo foi descrever a anatomia ultrassonográfica da articulação do cotovelo de cães e comparar com os achados das demais modalidades de diagnóstico por imagem. Dessa forma, demonstrar a capacidade da técnica de identificar as principais estruturas desta articulação e seu potencial uso em regiões onde a tomografia computadorizada e ressonância magnética não estiverem disponíveis. Dez animais com peso entre 5 kg e 15 kg foram radiografados e selecionados para o estudo ultrassonográfico. O protocolo para a descrição ultrassonográfica foi estabelecido dividindo-se as áreas da articulação em porções proximal, média e distal; e faces lateral, cranial, medial e caudal. A avaliação foi realizada nos planos longitudinais, transversais e oblíquos e as estruturas musculoesqueléticas foram descritas conforme sua arquitetura, ecogenicidade e ecotextura. Como parte complementar deste estudo um dos animais foi submetido aos exames de tomografia computadorizada e ressonância magnética. Em relação às estruturas visibilizadas, o exame ultrassonográfico foi eficiente para as análises muscular, tendínea e ligamentar. Os contornos ósseos e regiões sede de alterações de importância clínica, como processo coronóide medial da ulna e processo ancôneo também foram visibilizados, porém de forma limitada. O conhecimento prévio da anatomia ultrassonográfica normal da articulação do cotovelo, assim como das vantagens e limitações da técnica, permitem a realização de estudos subsequentes, relacionados às possíveis identificações de alterações musculoesqueléticas. / The elbow is a complex joint and has a great clinical relevance at the small animal medicine care. Previous research of this region has been explored using radiographic and tomographic methods, however, there are few studies related to ultrasonography. The aim of this study was to describe the ultrasonographic anatomy of the elbow joint of dogs and compare it with the findings of other types of diagnostic imaging. Thus, demonstrate the ability of this technique to identify the main structures of this joint and its potential use in regions where computed tomography and magnetic resonance imaging are not available. Ten animals weighing between 5 kg and 15 kg were radiographed and selected to the ultrasonographic study. The protocol was established for the ultrasonographic description dividing the articular areas in proximal, middle and distal; and lateral cranial, medial, and caudal faces. The approach was made in longitudinal, transverse and oblique planes and the musculoskeletal structures were described according to the architecture, echogenicity and echotexture. Computed tomography and magnetic resonance scans were made in one animal as an additional part of this study. Regarding visualized structures, the ultrasonography was efficient for muscle, tendon and ligament analysis. Bone contours and regions that have clinical significance such as medial coronoid process and anconeus process were identified, but with limited access. Prior knowledge of the normal sonographic anatomy of the elbow joint as well as the technical advantages and limitations allow pursuing further studies related to the possible identification of musculoskeletal disorders.

In vitro grown cartilage is functionally inferior to native tissue, and improvements in its quality should be attempted so it can be used therapeutically. In these studies we investigated the effects of cell shape on tissue quality through alteration of substrate geometry and application of mechanical stimuli. Articular chondrocytes were isolated and cultured on the surface Ti-6Al-4V substrates with various geometries. When cultured on fully porous titanium alloy substrates, chondrocyte spreading was enhanced over those grown on substrates with solid bases. Chondrocytes which remained round did not synthesize significant amounts of matrix and were thus unable to form cartilaginous tissue. In contrast, chondrocytes which were directed to spread to a limited amount, resulting in a polygonal morphology, accumulated significantly more matrix molecules and in time formed cartilage-like tissue. Computational fluid dynamics analyses demonstrated that cells on fully porous substrates experience time-dependent shear stresses that differ from those experienced by cells on substrates with solid bases where media flow-through is restricted. Integrin-blocking experiments revealed that integrins are important regulators of cell shape, and appeared to influence the accumulation of collagen and proteoglycans by chondrocytes. Furthermore, compressive mechanical stimulation induced a rapid, transient increase in chondrocyte spreading by 10 minutes, followed by a retraction to pre-stimulated size within 6 hours. This has been shown to be associated with increased accumulation of newly synthesized proteoglycans. Blocking the α5β1 integrin, or its β1 subunit, inhibited cell spreading and resulted in a partial inhibition of compression-induced increases in matrix accumulation, thereby substantiating the role of β1 integrins in this process. These results suggest that both fluid induced shear forces and compressive forces regulate chondrocyte matrix accumulation by altering cell morphology, which is mediated by integrins. Identifying the molecular mechanisms that influence chondrocyte shape and thus tissue formation may ultimately lead to the development of a tissue that more closely resembles native articular cartilage.

Alterações na articulação emporomandibular (ATM) comumente geram desequilíbrios musculares que estão associados à alterações no tecido ósseo. Esta articulação pode sofrer a influência de traumas, fatores congênitos ou desordens de crescimento. Estudos sobre alterações de crescimento do complexo maxilomandibular decorrentes de problemas da ATM são escassos. O objetivo deste trabalho foi avaliar por meio da microtomografia os efeitos da remoção do disco articular e a remoção conjugada do disco e cartilagem articular no crescimento e na microarquitetura óssea da mandíbula de ratos. Trinta ratos da raça Wistar com um mês de idade foram divididos em três grupos: CTR (controle operado); RD (remoção de disco articular) e RDC (remoção conjugada do disco e cartilagem articular). Apenas o lado direito foi operado; o lado esquerdo permaneceu intacto. Após dois meses de acompanhamento, os ratos foram sacrificados e as hemimandíbulas escaneadas em microtomógrafo A remoção do disco articular e a remoção conjugada do disco e cartilagem articular alteram o volume e microestrutura do osso trabecular da mandíbula de ratos jovens. Estas duas intervenções provocaram uma queda na qualidade de parâmetros da microestrutura do trabeculado do processo angular e diminuição do crescimento da hemimandíbula do lado operado. / Changes in the temporomandibular joint (TMJ) lead to muscle dysfunctions that are associated with bone changes. This joint region can be influenced by trauma, congenital factors or growth disorders. Studies linking TMJ problems and growth alterations are scarce. The aim of this study was to evaluate the effects of the articular disc removal or articular disc and cartilage removal on the bone microarchitecture and mandibular growth of young rats. Thirty Wistar rats (one month old) were divided into three groups: CTR (sham operated); RD (disc removal) and RDC (disc and cartilage removal). Only the right side was operated, keeping the left side intact. After two months, the rats were sacrificed and the mandibles scanned on micro-CT for quantitative analysis. Some microstructural parameters were altered by the disc removal or disc and cartilage removal. The right side presented lower growth than the left side.

Alterações na articulação emporomandibular (ATM) comumente geram desequilíbrios musculares que estão associados à alterações no tecido ósseo. Esta articulação pode sofrer a influência de traumas, fatores congênitos ou desordens de crescimento. Estudos sobre alterações de crescimento do complexo maxilomandibular decorrentes de problemas da ATM são escassos. O objetivo deste trabalho foi avaliar por meio da microtomografia os efeitos da remoção do disco articular e a remoção conjugada do disco e cartilagem articular no crescimento e na microarquitetura óssea da mandíbula de ratos. Trinta ratos da raça Wistar com um mês de idade foram divididos em três grupos: CTR (controle operado); RD (remoção de disco articular) e RDC (remoção conjugada do disco e cartilagem articular). Apenas o lado direito foi operado; o lado esquerdo permaneceu intacto. Após dois meses de acompanhamento, os ratos foram sacrificados e as hemimandíbulas escaneadas em microtomógrafo A remoção do disco articular e a remoção conjugada do disco e cartilagem articular alteram o volume e microestrutura do osso trabecular da mandíbula de ratos jovens. Estas duas intervenções provocaram uma queda na qualidade de parâmetros da microestrutura do trabeculado do processo angular e diminuição do crescimento da hemimandíbula do lado operado. / Changes in the temporomandibular joint (TMJ) lead to muscle dysfunctions that are associated with bone changes. This joint region can be influenced by trauma, congenital factors or growth disorders. Studies linking TMJ problems and growth alterations are scarce. The aim of this study was to evaluate the effects of the articular disc removal or articular disc and cartilage removal on the bone microarchitecture and mandibular growth of young rats. Thirty Wistar rats (one month old) were divided into three groups: CTR (sham operated); RD (disc removal) and RDC (disc and cartilage removal). Only the right side was operated, keeping the left side intact. After two months, the rats were sacrificed and the mandibles scanned on micro-CT for quantitative analysis. Some microstructural parameters were altered by the disc removal or disc and cartilage removal. The right side presented lower growth than the left side.

This study aimed to characterize the in-situ mechanical property and morphology of individual collagen fibril in osteoarthritic (OA) cartilage using indentation-type atomic force microscopy (IT-AFM). The specimens with intact articular cartilage (AC), mild to severe degenerated OA cartilage were collected with informed consent from the postmenopausal women who underwent hip or knee arthroplasty. The fresh specimens were cryo-sectioned by layers with 50m thick for each from the articular surface to calcified cartilage, and then processed for AFM imaging and nanoindentation test. For each layer, a total of twenty collagen fibrils were randomly selected for testing. AFM tips with the nominal radius less than 10 nm were employed for probing the individual collagen fibril, and the obtained cantilever deflection signal and displacement were recorded for calculating its elastic modulus. Besides AFM nanoindentation, AFM and scanning electron microscopy (SEM) images, haematoxylin & eosin (H&E) staining and micro-indentation were performed on AC to study the changes of ultrastructure and composition between intact AC and OA cartilage. Results showed that an intact AC exhibited a gradation in elastic modulus of collagen fibrils from surface region (2.65±0.31GPa) to bottom region (3.70±0.44GPa). It was noted in the initial stage of OA cartilage that the coefficient of variation for mechanical properties of collagen fibers, ranging from 25~48%, significantly increased as compared with intact one (12%). The thickened and stiffened collagen fibrils initially occurred at either surface region (3.11±0.91GPa) or bottom region (5.64±1.10GPa) with OA progression. Besides thickens, alteration of D-periodic banding patterns of collagen fibrils was observed. It was echoed by fibrotic changes of surface region and tidemark irregularities. On the contrast, the micromechanical properties of cartilage decreased while AC suffered from OA. This result revealed the different approachs of nano and micro-mechanical properties changes in AC. In summary, the alteration of mechanical properties of collagen fibrils started from calcified cartilage as well as articular surface during OA onset, and the low compliance of thickened collagen fibrils deteriorated along disease progression. This study also reveals that the outstanding ability by AFM, in investigating the structure and mechanical properties of collagen fibrils and AC in nanometer scale, is impressive and this nanotechnological instrument is worth to be expected in further development for clinical use. / published_or_final_version / Mechanical Engineering / Master / Master of Philosophy

Tissue engineering holds great promise for developing functional tissue to repair damaged articular cartilage. However, cartilaginous tissues formed in vitro typically possess poor mechanical properties in comparison to native tissue due to the inability of chondrocytes to accumulate adequate amounts of extracellular matrix (ECM). While mechanical stimuli can enhance the properties of engineered cartilage, it may be more efficient to harness the underlying mechanotransduction pathways responsible. Substantial evidence suggests that the mechanotransduction signaling cascade is initiated by rapid adenosine 5’-triphosphate (ATP) release from chondrocytes (purinergic receptor pathway). Thus, the purpose of this study was to investigate the effects of exogenous ATP supplementation on the biochemical and mechanical properties of tissue engineered cartilage. Primary bovine articular chondrocytes, seeded on MilliporeTM filters, were grown in the presence of 0, 62.5 or 250 µM ATP for a period of four weeks. Both anabolic and catabolic effects were examined and a therapeutic dose range of ATP was determined. ATP stimulation (62.5 - 250 µM) enhanced ECM synthesis by 23 - 43% and long-term collagen accumulation by 16 - 26%, in a dose-dependent manner; however, long-term proteoglycan accumulation decreased as a result of 250 µM ATP. In addition, ATP supplementation significantly improved the mechanical properties of the developed tissues (5- to 6.5-fold increase in tissue stiffness). Interestingly, high doses of ATP (250 µM) also elicited a 2-fold increase in MMP-13 gene expression, 39% increase in MMP-13 activity, and 54% more extracellular inorganic pyrophosphate (ePPi) – an ATP degradation product. Dose-dependent increases in MMP-13 activity suggested that catabolic effects were occurring alongside anabolic effects, which initiated the investigation of a therapeutic dose of ATP. Doses of 31.25 µM and 125 µM ATP were added to cartilaginous tissues and investigated in terms of MMP-13 activity and ECM synthesis. Tissues supplemented with 62.5 – 125 µM ATP exhibited a balance between anabolic and catabolic effects. By harnessing the purinergic receptor pathway, anabolic effects of mechanical stimuli were achieved in the absence of externally applied forces. Understanding how the catabolic effects of ATP are manifested would be valuable in order to further maximize the therapeutic potential of ATP stimulation. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2010-09-22 14:08:28.114

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