Articular cartilage is the connective tissue lining the ends of long bones, providing a dynamic surface that bears load while providing a smooth surface for articulation. When damaged, however, this tissue exhibits a poor capacity for repair, lacking the lymphatics and vasculature necessary for remodeling. Osteoarthritis (OA), a growing health and economic burden, is the most common disease afflicting the knee joint. Impacting nearly thirty million Americans and responsible for approximately $90 billion in total annual costs, this disease is characterized by a progressive loss of cartilage accompanied by joint pain and dysfunction. Moreover, while generally considered to be a disease of the elderly (65 years and up), evidence suggests the disease may be traced to joint injuries in young, active individuals, of whom nearly 50% will develop signs of OA within 20 years of the injury. For these reasons, significant research efforts are directed at developing tissue-engineered cartilage as a cell-based approach to articular cartilage repair. Clinical success, however, will depend on the ability of tissue-engineered cartilage to survive and thrive in a milieu of harsh mechanical and chemical agents. To this end, previous work in our laboratory has focused on growing tissues appropriate for repair of focal defects and entire articular surfaces, thereby investigating the role of mechanical and chemical stimuli in tissue development. While we have had success at producing replacement tissues with certain qualities appropriate for clinical function, engineered cartilage capable of withstanding the full range of insults in vivo has yet to be developed. For this reason, and in an effort to address this shortcoming, the work described in this dissertation aims to (1) further characterize and (2) optimize the response of tissue-engineered cartilage to physical loading and the concomitant chemical insult found in the injured or diseased diarthrodial joint, as well as (3) provide a clinically relevant strategy for joint resurfacing. Together, this holistic approach maximizes the chances for in vivo success of tissue-engineered cartilage. Regular joint movement and dynamic loads are important for the maintenance of healthy articular cartilage. Extensive work has been done demonstrating the impact of mechanical load on the composition of the extracellular matrix and the biosynthetic activity of resident chondrocytes in explant cultures as well as in tissue-engineered cartilage. In further characterizing the response of tissue-engineered cartilage to mechanical load, the work in this dissertation demonstrated the impact of displacement-controlled and load-controlled stimulation on the mechanical and biochemical properties of engineered cartilage. Additionally, these studies captured tension-compression nonlinearity in tissue-engineered cartilage, highlighting the role of the proteoglycan-collagen network in the ability to withstand dynamic loads in vivo, and optimized a commercial bioreactor for use with engineered cartilage. The deleterious chemical environment of the diseased joint is also well investigated. It is therefore essential to consider the impact of pro-inflammatory cytokines on the mechanical and biochemical development of tissue-engineered cartilage, as chemical injury is known to promote degradation of extracellular matrix constituents and ultimately failure of the tissue. Combining expertise in interleukin-1\alpha, dexamethasone, and drug delivery systems, a dexamethasone drug delivery system was developed and demonstrated to provide chondroprotection for tissue-engineered cartilage in the presence of supraphysiologic doses of pro-inflammatory cytokines. These results highlight the clinical relevance of this approach and indicate potential success as a therapeutic strategy. Clinical success, however, will not only be determined by the mechanical and biochemical properties of tissue-engineered cartilage. For engineered cartilage to bear loads in vivo, it is necessary to match the natural topology of the articular surface, recapitulating normal contact geometries and load distribution across the joint. To ensure success, a method for fabricating a bilayered engineered construct with biofidelic cartilage and subchondral bone curvatures was developed. This approach aims to create a cell-based cartilage replacement that restores joint congruencies, normalizes load distributions across the joint, and serves as a potential platform for the repair of both focal defects and full joint surfaces. The research described in this dissertation more fully characterizes the benefits of mechanical stimulation, prescribes a method for chondroprotection in vivo, and provides a strategy for creating a cartilage replacement that perfectly matches the native architecture of the knee, thus laying the groundwork for clinical success of tissue-engineered cartilage.

Made available in DSpace on 2014-06-11T19:30:52Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-11-24Bitstream added on 2014-06-13T20:40:39Z : No. of bitstreams: 1 arruda_mf_dr_arafcf.pdf: 1544944 bytes, checksum: 75a1678618fc45bbed80bdb04d417b13 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A osteoartrose se caracteriza pela degeneração articular, perda de cartilagem e alterações no osso subcondral. Pouco se sabe sobre a patogênese e mudanças que ocorrem na osteoartrose como também em seu reparo. As técnicas terapêuticas disponíveis podem resultar em alívio dos sintomas, mas não na regeneração do tecido lesado. Um dos métodos usuais para pesquisa em osteoartrose com o preceito de mimetizar esta situação e também realizada neste trabalho, é o modelo experimental utilizando a inoculação intra-articular de zymosan (Saccharamyces cerevisiae), gerando artrite em grau progressivo. A eletroterapia potencializa a reparação de tecidos conjuntivos representando uma alternativa na reparação de lesões da cartilagem hialina. O acido ascórbico é um dos precurssores do colágeno que junto com outras estruturas complexas como a trama de glicosaminoglicanas e proteoglicanas constitui a cartilagem. A utilização dessa técnica para administração do acido ascórbico em tecido biológico é fator substancial do presente trabalho. Objetivo: O objetivo do presente estudo foi verificar a resposta imuno-bioquímica e avaliar microscopicamente a cartilagem articular de ratos artrose induzidos, frente ao tratamento com iontoforese na presença e ausência de acido L - ascórbico. Materiais e Métodos: Ratos wistar machos divididos em 6 grupos de 6 animais cada um, diferenciados em grupos: controle positivo C+, controle negativo C-,gavagem com solução fisiológica GSF, gavagem com ácido ascórbico GAA, iontoforese solução fisiológica IFSF iontoforese com ácido ascórbico IFAA.Resultados: Histológicos demonstraram em coloração Hematoxilina e Eosina que com o grupo IFAA obteve normalidade da variável celularidade (40.1 mm2), e manutenção da cartilagem não calcificada (75.5mm) (p<0.05), sugerindo espessuras normais. Quanto ao grupo não tratado C+ apresentou-se menor... / Osteoarthritis is characterized by joint degeneration, loss of cartilage and subchondral bone changes. Little is known about the pathogenesis and changes that occur in osteoarthritis as well as in its repair. Available therapeutic techniques can result in relief of symptoms but not in the regeneration of injured tissue. One of the usual methods for research used in this study is the experimental model which uses intra-articular inoculation of zymosan (Saccharamyces cerevisiae), causing arthritis in progressive degree. Electrotherapy enhances the healing of tissues representing an alternative in the repair of hyaline cartilage injuries. Ascorbic acid is one of the forerunners of collagen which along with other complex structures like the chains of glycosaminoglycans and proteoglycans form the cartilage. The use of this technique for administration of ascorbic acid in biological tissue is a substantial factor in this study. Objective: The objective of this study was to investigate the immune-biochemical reply and evaluate microscopically the histology of articular cartilage in rats arthritis induced, compared to treatment with iontophoresis in the presence and absence of L - ascorbic acid. Methods: Male wistar rats were divided into 6 groups of 6 animals each, in different groups: positive control C+, negative control C-, gavage with saline solution GSS, gavage with ascorbic acid GAA, saline iontophoresis IPSS, iontophoresis with ascorbic acid IPAA. Results: Histological it was demonstrated that in hematoxylin and eosin staining the group that received IPAA obtained normality of variable (40.1 mm2), and maintenance of non calcified cartilage (75.5mm) (p<0.05), suggesting normal thickness. Regarding the untreated group C+, it presented lower average in the number of chondrocytes (13.0mm2), and with regard to the thickness of cartilage it had a higher average of calcified cartilage with... (Complete abstract click electronic access below)

INTRODUÇÃO e OBJETIVO: A osteoartrite (OA) embora frequente tem patogênese incerta em humanos. Descrevemos modelo experimental original de OA em cães, analisando em dois tempos diferentes as consequências da Ruptura Espontânea do Ligamento Cruzado Cranial (RLCCr). MÉTODOS: Vinte animais machos com menos de 5 anos ( 20 a 45 Kg) com RLCCr submetidos à artrotomia para estabilização articular tiveram fragmentos articulares removidos para análise. O grupo RLCCr < 20 (10 animais) foi operado antes dos vinte dias e o grupo > 20 (10 animais) após 20 dias do início da lesão. Sete animais com OA pré-existente (OA) que morreram por quaisquer motivos e 7 animais normais (NC) provenientes do C.C.Z., serviram de grupos controles. Os animais foram avaliados clinica e radiologicamente. Foi colhido líquido sinovial dos animais operados e de outros 20 cães controles submetidos às cirurgias por diferentes causas. Para estudo morfológico, os fragmentos de cartilagens foram corados com H&E e Picrossirius. A gravidade do escore histológico da OA foi quantificada através da coloração com Safranina O. Analisou-se citocinas próinflamatórias (IL-6, TNF-alfa) e a quimiocina CCL2/MCP-1 nos líquidos sinoviais. RESULTADOS: Todos os cães tinham o teste de movimento da gaveta e exame de compressão da mesa tibial positivos. Achados radiográficos correlacionaram-se com maior tempo de RLCCr. Cartilagem articular de animais normais (NC) exibiram superfície preservada, disposição ordenada dos condrócitos e integridade da rede de colágeno. Exames histológicos em animais do grupo RLCCr < 20 mostraram irregularidades na superfície articular, diminuição no número de condrócitos e remodelamento de fibras de colágeno. No grupo > 20, observou-se osteófitos e irregularidades evidentes nas superfícies articulares. A gravidade do escore de acometimento histológico traduziu-se por intensa diminuição celular na superfície articular, com presença de clusters de condrócitos na região intermediária da cartilagem e total desorganização da rede de fibras de colágeno. A quimiocina CCL2/MCP-1 esteve aumentada no grupo com menos de 20 dias de lesão, enquanto a IL-6 foi mais expressiva nos animais operados tardiamente. CONCLUSÃO: O modelo experimental espontâneo de OA canino, estudado em dois tempos, é um instrumento original e útil para estudo da patogênese da osteoartrite, além de ter o mérito de preservar a integridade física dos animais de laboratório / INTRODUCTION and OBJECTIVE: Osteoarthritis (OA) is a frequent and severe rheumatic disease of unknown pathogenesis. We described an original experimental model of OA, analyzing the consequences of spontaneous cranial cruciate ligament rupture (RLCCr), occurred at two different times. METHOD: Twenty male animals, younger than 5 years old (20 to 45kg) with RLCCr were submitted to arthrotomy for articular stability and had cartilage fragments removed for analysis. The Group RLCCR < 20 (10 animals) was operated before 20 days and Group RLCCR > 20 (10 animals) after 20 days of beginning of lesion. Seven animals with pre-existent OA which died without any reason, and 7 normal animals (NC) from Service of Zoonosis Control were the control groups. The animals were submitted to clinical and radiological evaluations. Synovial fluid were collected from operated dogs and from another 20 control animals, submitted for surgical procedures for any reason. For the morphological study, the cartilage fragments were stained with H&E and Picrossirus. The score for OA severity was quantified using Safranin-O staining. Inflammatory cytokines (IL-6 and TNF alfa) and chemiokine CCL2/MCP-1 were measured in sinovial fluid. RESULTS: At physical examination, all the dogs had positive drawer and the tibial plateau compression tests. Knee Radiographic data showed that narrowing of joint space, osteophytes and erosions were more prominent in Group RLCCr> 20 animals. Articular cartilage of normal animals (NC) revealed preserved cartilage surface, organized disposition of chondrocytes and integrity of collagen net. Histological exams done in animals from Group RLLCr > 20 showed irregularities on articular surface, reduction of the number of chondrocytes and collagen fibers remodeling. Animals from Group RLCCR > 20 exhibited deep fibrillations, presence of chondrocytes clusters at intermediate area of cartilage, osteophytes and and total disorganization of the collagen fibers net. Chemiokine CCL2/MCP-1 was found overexpressed in dogs operated less than 20 days, while IL-6 was increased in late surgical group. CONCLUSION: The spontaneous model of canine RLCCr, studied at two distinct times, is an original and useful tool to understand pathogenesis of OA. Furthermore, the procedure preserves the animal integrity, becoming an Ethical laboratorial procedure

A instabilidade do ombro é a incapacidade de manter a cabeça umeral centralizada na fossa glenóide. Os requisitos para o diagnóstico clínico incluem história clínica, exame físico geral e testes objetivos para avaliar a presença e o grau de instabilidade do ombro. O objetivo do presente trabalho é comparar os achados por imagem das alterações anatômicas da artrotomografia computadorizada multislice com a artrorressonância magnética na avaliação da instabilidade do ombro correlacionando com os achados artroscópicos assim como verificar a eficácia da artrotomografia computadorizada multislice na avaliação das alterações anatômicas relacionadas com a instabilidade do ombro. Trata-se de um estudo prospectivo onde, inicialmente, 30 pacientes com o diagnóstico clínico de instabilidade do ombro foram submetidos à artrotomografia computadorizada com cortes de espessura de 0,5 mm e reconstrução a cada 3 mm e à artrorressonância magnética nas seqüências convencionais ponderadas em T1 e T2 com e sem saturação de gordura. Comparado com a artroscopia, a artrorressonância magnética mostrou uma sensibilidade de 93,33% para lesão labral superior, 96,30% para lesão labral anterior e 83,3% para lesão labral ântero-superior e a artrotomografia computadorizada multislice mostrou uma sensibilidade de 90%, 88,89% e 77,78%, respectivamente. A sensibilidade da artrorressonância magnética para lesão de cartilagem articular foi de 16,67% comparado com uma sensibilidade 33,30% da artrotomografia computadorizada multislice. A artrorressonância magnética e artrotomografia computadorizada multislice mostraram a mesma sensibilidade para detecção da lesão de Hill-Sachs (100%), lesão labral ântero-inferior (100%), anormalidades capsulares (88,89%) e lesões de Bankart ósseo (80%). Com base nos resultados, concluímos que a artrorressonância magnética é um método de acurácia superior à artroTCMS na avaliação das lesões labrais ântero-superior, superior e anterior e que a artrotomografia computadorizada multislice mostrou-se eficaz nas estruturas relacionadas à instabilidade, com resultados semelhantes à Artro- RM para o diagnóstico de lesões labrais ântero-inferiores (ALPSA e Bankart), lesões de Hill-Sachs, redundância capsular e Bankart ósseo, sendo superior à artro-RM no diagnóstico de lesões de cartilagem articular / Shoulder instability is characterized by the incapacity to keep the humeral head centered within the glenoid fossa. Clinical diagnosis should include a history of prior events, a complete physical examination, and a set of objective tests to evaluate the presence and extent of shoulder instability. This study aims to compare the imaging of anatomical deformities seen in shoulder instability by employing both multislice computerized tomography (MSCT) arthrography and magnetic resonance arthrography (MRA). A correlation between those images and the arthroscopic findings was important to determining the efficacy of MSCT arthrography in the assessment of shoulder instability. The 30 patients in this prospective study, who had had a previous clinical diagnosis of shoulder instability, underwent CT arthrography using 0.5 mm-thick slices with reconstructions every 3 mm, and T1- and T2-weighted sequential MR imaging arthrography with and without fat saturation. MRA was shown to be 93.33 % sensitive in detecting superior labral lesion, 96.30% in anterior labral lesion, and 83.3% sensitive in anterosuperior labral lesion, whereas the respective results for MSCT arthrography were 90%, 88.89%, and 77.78%. MRA and MSCT arthrography afforded 16.67% and 33.30% sensitivity for joint cartilage injury, respectively. Both techniques were equally sensitive in detecting Hill-Sachs lesion (100%), anteroinferior labral lesion (100%), capsular abnormalities (88.89%), and bony Bankart lesions (80%). The results herein led us to conclude that MRA is more accurate than MSCT arthrography in assessing anterosuperior, superior (SLAP) and anterior labral lesions and the MSCT arthrography had good results in the evaluation of the structures related to shoulder instability. Both methods yielded equivalent results for Hill-Sachs, ALPSA and Bankart lesions. The MSCT arthrography furnished better results than MRA in the diagnosis of articular cartilage lesions

Articular cartilage, also called shock absorber, is a complex living soft tissue that covers gliding surfaces of joint and enables the joint to withstand weight bearing from human. Since there is no direct blood supply in the articular cartilage, it is generally hard to be repaired itself when it is injured. Although there have been several approaches to the repair of injured articular cartilage, current medical treatment is not able to give patients satisfactory treatment. Ultrasound has been used as one of physical therapy tools. Recently, there have been frequent reports that ultrasound has beneficial effect on the repair of bone fracture and soft tissue healing including articular cartilage. Although there have been appreciation of beneficial effect of ultrasound therapeutically, its mechanism is not fully understood and under investigation. From literature review, several researches tried to find optimal conditions of ultrasound such as intensity, frequency and duration on the repair of articular cartilage and it was reported that more effective ultrasound dose was found. However, different reports have different optimized ultrasound dose. It might be due to the variations of the type of ultrasound wave, intensity, frequency and duration as well as the different condition of experimental samples. Therefore, low intensity pulsed ultrasound (LIPUS) was investigated on the repair of articular cartilage and chondrocyte migration from this study. Also, optimal conditions of LIPUS dose on chondrocyte migration were investigated for the repair of articular cartilage.

Osteoarthritis (OA) is a disease that has significant individual, social, and economic impact worldwide. Although many etiologies lead to the eventual development of OA, one potentially treatable cause is the acute articular cartilage (AC) injury. These injuries are common and have a poor inherent healing capacity, leading to the formation of OA. In an effort to repair AC injuries several treatment strategies have been developed but none have proven completely successful. Studies examining AC tissue-engineering strategies have suggested that those with the most potential for success involve the introduction of autogenous or allogenous cells to the site of injury. These strategies are designed to encourage creation of a matrix with the appropriate characteristics of normal AC. However, development of a completely successful repair method has proven difficult because the biomechanical properties of normal AC are not easy to replicate, a cell source with the appropriate functional characteristics has not been optimized, and the problem of effective incorporation of a repair construct into the host tissue remains unresolved. In an effort to more fully understand the cartilage repair process, this work first focused on the development and utilization of an in vitro human explant model of AC to study the ability of seeded human chondrocytes to integrate into an AC defect. Further work elucidated the gene expression patterns of cultured adult human chondrocytes and human mesenchymal stem cell (MSC)-derived chondrocytes. Results from this work determined that cultured human chondrocytes were able to adhere to articular cartilage defects in a viable in vitro explant model and produce a matrix containing collagen type II. However, further work with the in vitro expanded chondrocytes revealed that these cells have increased expression of collagen type I which promotes the formation of a less durable fibrocartilagenous tissue. This unfavorable expression persisted despite placing the chondrocytes in an environment favoring a chondrocytic phenotype. Further work with MSC-derived chondrocytes demonstrated a similar and unfavorable production of collagen type I. This work represented an important first step towards a treatment for acute AC lesions but it is clear that further work to optimize the culture microenvironment is still required. / Experimental Surgery

Thesis (M.S.)--Mississippi State University. Department of Agricultural and Biological Engineering. / Title from title screen. Includes bibliographical references.

Habilitation-Thesis--Cologne. / Includes bibliographical references (p. 45-48) and index.

published_or_final_version / Dental Surgery / Master / Master of Dental Surgery

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