Dissertations / Theses on the topic 'Hyaline cartilage'

Mechanical Engineering
M.S.E.
Articular cartilage is hypocellular, aneural, alymphatic, and avascular. In diseased conditions such as osteoarthritis, there is an increase in water content from the average normal of 60-85% to greater than 90%. As cartilage has very little capability for self repair, methods of early detection of degeneration are required, and assessment of water could prove to be a useful diagnostic method. The most explored method for the assessment of water content in cartilage is MRI, but it cannot detect small changes in water content. Other methods such as dry/wet analysis and Karl Fischer titration are destructive. Infrared spectroscopy is extremely sensitive to the chemical composition and molecular structure of the sample. The technique of near infrared spectroscopy (NIRS) has been used for analyses of water in food, pharmaceuticals and skin. The hypothesis that NIR spectra can be used to assess water content in cartilage was investigated here. A model system using bovine nasal cartilage (BNC) to assess water content in hyaline cartilage was developed. The water content was initially determined by finding the integrated areas under the absorbance bands attributable to water centered at 5190 cm-1 and 6890 cm-1, and compared to the gold standard method for water measurement, gravimetric analysis of wet and dry weights.. The integrated areas of the absorbance bands at 5190 cm-1 and 6890 cm-1 , reflective of a combination of bound plus free water, and free water, in the tissues, respectively, were found to correlate with the absolute water content of the tissue. A model system of gelatin with varying amounts of water, representing the primary components of cartilage, collagen and water, was also developed. Regression analysis and partial least square (PLS) models using data from BNC tissues were successfully developed, and demonstrate that NIR spectroscopy can be utilized to quantitatively determine water content in articular cartilage.
Temple University--Theses

Articular cartilage disorders are a leading cause of human disability in many countries around the world. In this work, new techniques and strategies were developed to improve the quality of cartilage produced in vitro by methods of tissue engineering. Chondrocytes were isolated from the hip and knee joints of aborted human foetuses. The cells were expanded and seeded into scaffolds and the seeded scaffolds were cultured in perfusion bioreactors. The quality of the final cartilage constructs was assessed biochemically by measuring their content of glycosaminoglycan (GAG), total collagen and collagen type II and histologically by staining cross-sections of the constructs for GAG, collagen type I and collagen type II. The amount of proteoglycan released in the culture medium was also measured at regular intervals. Proteoglycans from tissue-engineered cartilage and spent culture medium were compared and analysed for degradation and capability of aggregation. During monolayer expansion, the chondrocyte differentiation indices decreased, the cell size increased and the percentage of cells present in G2/S??M phase decreased with the greatest changes occurring during the first passage. Expanding chondrocytes in PGA or PGA??alginate scaffolds produced cells with a higher level of differentiation than monolayer-expanded cells. However, PGA and PGA??alginate could not be justified as suitable systems for the routine expansion of chondrocytes mainly because of the relatively low cell proliferation obtained. Two new methods for seeding of cells into scaffolds were investigated using PGA and PGA??alginate as scaffold materials. Both methods produced high seeding efficiencies and homogeneous distribution of cells. When seeded PGA??alginate scaffolds were cultured in perfusion bioreactors, they produced good quality constructs with higher concentrations of extracellular matrix (ECM) components compared with previously described methods. However, when seeded PGA scaffolds were cultured in perfusion bioreactors, they produced small constructs of poor quality. Investigation of the effect of medium flow rate on the PGA scaffolds showed that a low flow rate was needed at the beginning of the culture to enable the cells to form a framework onto which other synthesised elements could deposit. Applying a gradual increase in medium flow rate to PGA scaffolds cultured in perfusion bioreactors solved the shrinkage problem and produced constructs with quality similar to those produced using PGA??alginate scaffolds. A novel compression bioreactor that mimicked the physiological stimulation of cartilage by joint movement was constructed. Using this bioreactor, compressed constructs showed significantly higher wet weight and higher concentrations of GAG, total collagen and collagen type II compared with non-compressed constructs.

Osteoarthritis (OA) is a highly prevalent, debilitating disease affecting many joints including the knee. Despite the involvement of several tissues, it is believed that the articular cartilage is the primary site of pathogenesis in humans. Within this study, a new scoring system of OA was devised, incorporating the articular cartilage and underlying bone, aimed at providing a more comprehensive means of grading the severity of tissue damage. We examined changes progressively from mild to severe and were able to deduce from the scoring system that bone changes may precede those of the overlying cartilage. Immunohistochemistry was used to assess stem cell marker expression, proliferation and progressive changes within the extracellular matrix of sectioned osteochondral plugs, however no distinct pattern of change could be extrapolated, highlighting the variable nature of this taxing disease. Previous studies have demonstrated the presence of a sub-population of chondroprogenitor cells present in normal hyaline cartilage. We demonstrated in this study that a similar group of cells reside in osteoarthritic articular cartilage. We were able to isolate and expand clonally derived primary cell lines to beyond 50 population doublings whilst maintaining a chondrogenic phenotype, and demonstrated the tri-lineage potential of these cells. That said, a significant amount of variation was observed and it was, therefore, postulated that there may be a smaller cohort of viable cells within this sub-population isolated from osteoarthritic cartilage. A preliminary study was also carried out comparing chondroprogenitors from normal articular cartilage to those isolated from OA tissue. Heterogeneity was again encountered, suggesting that there was a group of OA chondroprogenitors with similar characteristics to the normal cells, which differed from the other less metabolically active cells. This finding was agreeable with the aforementioned postulation. Data from our preliminary integration study was promising as we demonstrated the potential for using these chondroprogenitor cells in combination with other cells whilst achieving successful integration. However, further work is necessary to distinguish between the cell lines with the potential for integration from those that lacked this ability, thereby eliminating the heterogeneity. The presence of viable chondroprogenitor cells in OA tissue challenges the dogma that the tissue is irrecoverable, and opens the scope for regenerative medicine using resident progenitor cells. This is an exciting prospect that could significantly contribute to articular cartilage repair.

En el disseny de dispositius mèdics existeixen diversos casos en els quals és necessària la utilització de superfícies bioactives per aconseguir la integració òptima d’un implant amb el teixit que l’envolta. L’enginyeria de superfícies planteja diferents solucions, tot i així, per algunes aplicacions, l’obtenció d’una unió íntima entre el teixit i l’implant encara és un repte clínic. En aquest treball, presentem una tècnica que permet obtenir superfícies biomimètiques en qualsevol substrat que pugui ser sotmès a modificació per plasma. Com a proba de concepte, hem aplicat la tecnologia desenvolupada en l’obtenció d’un scaffold heterogeni per la regeneració del teixit osteocondral, amb un gran potencial per ser utilitzat com a teràpia regenerativa. Un dels grans reptes en la regeneració osteocondral, és assolir un grau elevat de semblança amb l’estructura articular, des de l’òs subcondral fins a la superfície articular. La nostra metodologia permet la immobilització d’un hidrogel que imita el teixit cartilaginós a la superfície d’una plataforma bioceràmica, la qual reprodueix el teixit ossi. Aquesta última, actuarà com a suport mecànic i punt d’ancoratge a l’òs subcondral, a la vegada que proporcionarà un reservori de ions de calci i de fosfat que ajudaran a la creació del gradient de duresa present en les articulacions. Així doncs, en aquesta tesi hem treballat en el disseny de les diferents parts que conformaran el scaffold. En primer lloc, per tal d’aprofundir en la creació del gradient de duresa, hem estudiat la bioactivitat de diferents substituts ossis bioceràmics comercials, els quals son candidats potencials per ser utilitzats en la construcció del scaffold. A continuació, hem validat la viabilitat del recobriment polimèric obtingut per PECVD en substrats bioceràmics i hem demostrat que no compromet la seva bioactivitat. A més, hem demostrat que la modificació superficial permet l’obtenció d’una interfície estable, que no es veu alterada per canvis fisiològics i permet l’autoensamblatge de l’hidrogel. Els estudis in vitro realitzats demostren que la tecnologia d’immobilització preserva la viabilitat cel·lular, i que la formulació permet la migració cel·lular a més de proporcionar un entorn adequat per la diferenciació condrogènica i osteogènica de cèl·lules mare mesenquimals.
En el diseño de dispositivos médicos existen numerosos casos en los que es necesaria la utilización de superficies bioactivas para lograr la integración óptima de un implante con el tejido que le rodea. La ingeniería de superficies propone diferentes soluciones, sin embargo, en determinadas aplicaciones, la obtención de una unión íntima entre el tejido y el implante aún es un reto clínico. En el presente trabajo, presentamos una técnica que permite la obtención de superficies biomiméticas en cualquier sustrato que pueda ser sometido a modificación por plasma. Como prueba de concepto, hemos aplicado la tecnología desarrollada en la obtención de un scaffold heterogéneo para la regeneración del tejido osteocondral, con un gran potencial para ser usado como terapia regenerativa. Uno de los grandes retos en la regeneración osteocondral, es lograr un grado elevado de semejanza con la estructura articular, desde el hueso subcondral hasta la superficie articular. Nuestra metodología permite la inmovilización de un hidrogel que imita el tejido cartilaginoso en la superficie de una plataforma bioceràmica, la cual reproduce el hueso. Ésta última, actuará como soporte mecánico y punto de anclaje al hueso subcondral, a la vez que proporcionará un reservorio de iones de calcio y fosfato que ayudarán en la creación del gradiente de dureza presente en las articulaciones. Así pues, en esta tesis hemos trabajado en el diseño de las diferentes partes que conformaran el scaffold. En primer lugar, para profundizar en la creación del gradiente de dureza, hemos estudiado la bioactividad de diferentes sustitutos óseos biocerámicos comerciales, los cuales son candidatos potenciales para ser utilizados en la construcción del scaffold. A continuación, hemos validado la viabilidad del recubrimiento polimérico obtenido por PECVD en sustratos biocerámicos y hemos demostrado como no compromete su bioactividad. Además, hemos demostrado como la modificación superficial permite la obtención de una interfaz estable, que no se altera por cambios fisiológicos, la cual permite el autoensamblaje del hidrogel. Los estudios in vitro realizados demuestran que la tecnología de inmovilización preserva la viabilidad celular, y que la formulación permite la migración celular además de proporcionar un entorno adecuado para la diferenciación condrogénica y osteogénica de células madre mesenquimales.
In medical device engineering, there are several cases where there is an imperative need of obtaining bioresponsive surfaces to achieve an optimal integration of a certain biomaterial with the surrounding tissue. Surface engineering has provided different approaches, however for certain applications obtaining an intimate bonding between the tissue and the implant remains a clinical challenge. In this work, we present a newly developed technique that allows the obtention of biomimetic surfaces onto any substrate that can be subject to plasma modification. As a proof of concept, we have applied the technology to obtain a heterogeneous scaffold for osteochondral repair, which has a great potential to be used as regenerative therapy. One of the great challenges in osteochondral repair is achieving a high degree of mimicry of the whole joint structure, from the subchondral bone to the surface of hyaline cartilage. Our methodology allows the immobilization of a cartilage-like hydrogel onto a bone-like bioceramic platform by means of a polymeric coating. The bioceramic acts not only as mechanical support and anchoring point to the subchondral bone, but also it acts as a reservoir of calcium and phosphate ions, which through diffusion help in the creation of the stiffness gradient present in joints. Thus, in the present thesis, we have worked on the design of the different parts that will form the osteochondral heterogeneous scaffold. First, to gain insight into the stiffness gradient creation, we have studied the bioactivity of different commercially available bioceramic bone substitutes, which are potential candidates to be used as bone-like platform. Next, we have validated the viability of the polymeric coating obtained through PECVD in this type of biomaterials and shown how it does not compromise their bioactive properties. Moreover, we have demonstrated how the designed surface modification allows the obtention of a stable interface, which is not disrupted by physiological changes, that enables the subsequent self-assembly of a cartilage-like hydrogel. In vitro studies show how our immobilizing technology preserves cell viability, and that our hydrogel formulation enables cell migration as well as it provides a suitable environment for both chondrogenic and osteogenic differentiation of mesenchymal stem cells.

[ES] El cartílago hialino es un tejido conectivo denso con poca capacidad de auto regeneración cuando es afectado por patologías degenerativas. Por lo tanto, la estimulación eléctrica se ha propuesto como una terapia alternativa no invasiva para mejorar la reparación del cartílago hialino. De acuerdo con esto, este trabajo presenta un enfoque computacional y experimental combinado para entender mejor la biología del cartílago hialino y su respuesta a la estimulación eléctrica usando diferentes modelos in vitro. En primer lugar, se ha desarrollado un modelo mecanobiológico para simular el proceso de osificación endocondral. Por otro lado, se ha evaluado el efecto de la estimulación eléctrica sobre el cartílago hialino en tres escenarios diferentes. Inicialmente se ha analizado la proliferación celular y la síntesis de glicosaminoglicanos de condrocitos cultivados en monocapa y estimulados con campos eléctricos. Luego, se ha realizado un análisis histomorfométrico a explantes de condroepífisis que fueron estimulados eléctricamente. Por último, se ha evaluado el efecto de los campos eléctricos sobre la diferenciación condrogénica de células madre mesenquimales cultivadas en hidrogeles. Los resultados indican que la estimulación eléctrica es un estímulo biofísico prometedor, ya que este tipo de estimulación mejora la viabilidad y la proliferación celular, induce cambios morfológicos en los condrocitos, y estimula la síntesis de las principales moléculas que componen el cartílago hialino, tales como SOX-9, glicosaminoglicanos y agrecan. Además, este proyecto es el primer paso hacia la implementación de un estímulo biofísico alternativo que modifica la dinámica celular de los condrocitos de la placa de crecimiento en condiciones ex vivo. Adicionalmente, este estudio resalta el efecto potencial de los campos eléctricos para inducir el proceso de condrogénesis de células madre mesenquimales cultivadas en condiciones basales. En general, la evaluación de la estimulación eléctrica sobre condrocitos, tejidos y andamios es una herramienta útil que puede contribuir al conocimiento actual de las terapias regenerativas enfocadas en la regeneración del cartílago hialino.
[CAT] El cartílag hialí és un teixit connectiu dens amb poca capacitat d'auto regeneració quan es veu afectat per patologies degeneratives. Per tant, l'estimulació elèctrica s'ha proposat com una teràpia alternativa no invasiva per millorar la reparació del cartílag articular. D'acord amb això, aquest treball presenta un enfoc computacional i experimental combinat per entendre millor la biologia del cartílag hialí i la seva resposta a l'estimulació elèctrica usant diferents models in vitro. En primer lloc, s'ha desenvolupat un model mecanobiològic per simular el procés d'ossificació endocondral. D'altra banda, s'ha avaluat l'efecte de l'estimulació elèctrica sobre el cartílag hialí en tres escenaris diferents. Inicialment s'ha analitzat la proliferació cel·lular i la síntesi de glicosaminoglicans de condròcits cultivats en monocapa i estimulats amb camps elèctrics. Després, s'ha realitzat una anàlisi histomorfomètrica a explants de condroepífisis que van ser estimulats elèctricament. Finalment, s'ha avaluat l'efecte dels camps elèctrics sobre la diferenciació condrogénica de cèl·lules mare mesenquimals cultivades en hidrogels. Els resultats indiquen que l'estimulació elèctrica és un estímul biofîsic prometedor, ja que aquest tipus d'estimulació millora la viabilitat i la proliferació cel·lular, indueix canvis morfològics en els condròcits, i estimula la síntesi de les principals molècules que componen el cartílag hialí, com ara SOX-9, glicosaminoglicans i agrecan. A més, aquest projecte és el primer pas cap a la implementació d'un estímul biofísic alternatiu que modifica la dinàmica cel·lular dels condròcits de la placa de creixement en condicions ex vivo. Addicionalment, aquest estudi ressalta l'efecte potencial dels camps elèctrics per induir el procés de condrogènesi de cèl·lules mare mesenquimals cultivades en condicions basals. En general, l'avaluació de l'estimulació elèctrica sobre condròcits, teixits i scaffolds és una eina útil que pot contribuir al coneixement actual de les teràpies regeneratives enfocades a la regeneració del cartílag hialí.
[EN] Hyaline cartilage is a dense connective tissue with low self-healing capacity when is affected by degenerative pathologies. Therefore, electrical stimulation has been proposed as a possible non-invasive alternative therapy to enhance the restoration of the cartilaginous tissue. Accordingly, this work presents a combined computational and experimental approach to understand better the hyaline cartilage biology and its response to electrical stimulation using different in vitro models. On the one hand, a mechanobiological model was developed to simulate the endochondral ossification process. On the other hand, the electrical stimulation on hyaline cartilage was evaluated in three different scenarios. Initially, cell proliferation and glycosaminoglycans synthesis of chondrocytes, cultured in monolayer and stimulated with electric fields, was analyzed. Then, a histomorphometric analysis was performed to chondroepiphysis explants that were electrically stimulated. Finally, the effects of the electric fields on chondrogenic differentiation of mesenchymal stem cells cultured in hydrogels was assessed. The results indicated that electrical stimulation is a promising biophysical stimulus, due to the fact that this type of stimulation enhances the viability and the proliferation of cells, induces morphological changes in the chondrocytes, and stimulates the synthesis of the main molecules that compose the hyaline cartilage, such as SOX-9, glycosaminoglycans and aggrecan. Moreover, this project is the first step towards the implementation of an alternative biophysical stimulus that modifies the cellular dynamics of growth plate chondrocytes in ex vivo conditions. Additionally, this study highlights the potential effect of electric fields to induce the chondrogenesis process of mesenchymal stem cells cultured in basal conditions. Overall, the assessment of electrical stimulation on chondrocytes, tissues and scaffolds is a useful tool that may contribute to the current knowledge of regenerative therapies focused on hyaline cartilage healing.
To the financial support from COLCIENCIAS – COLFUTURO through the fellowship No. 647 for national doctorates. To the financial support from COLCIENCIAS through the research grant 712-2015 No. 50457. To the financial support from the Spanish Ministry of Economy and Competitiveness through the MAT2016-76039-C4-1-R project.
Vaca González, JJ. (2019). The effect of electric fields on hyaline cartilage: an in vitro and in silico study [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/120023
TESIS

Исследование влияния свинца на скелет человека является актуальной проблемой здравоохранения. Известно, что воздействие свинца вызывает угнетение роста костей путем влияния на гиалиновый хрящ. Кроме того, свинец также может быть одним из экзогенных факторов, вызывающих дегенеративные заболевания позвоночника, приводящие к боли в спине. Остеоартроз дугоотросчатых суставов позвоночника может быть причиной таких болей, однако влияние свинца на суставной хрящ изучено недостаточно. Имеются данные подтверждающие высокую восприимчивость скелета к влиянию свинца в период активного роста, именно поэтому актуальным является исследование воздействия свинца на суставной хрящ дугоотросчатых суставов молодых животных. Целью исследования было выявить особенности воздействия свинца на гиалиновый хрящ дугоотросчатых суставов поясничного отдела позвоночника молодых крыс.

京都大学
新制・課程博士
博士(医学)
甲第23417号
医博第4762号
新制||医||1052(附属図書館)
京都大学大学院医学研究科医学専攻
(主査)教授 松田 秀一特定拠点, 教授 妻木 範行, 教授 安達 泰治
学位規則第4条第1項該当
Doctor of Medical Science
Kyoto University
DFAM

Les lésions de cartilage ne cicatrisent pas spontanément et la réparation de ce tissu est un challenge. Les techniques chirurgicales restant insatisfaisantes, la thérapie cellulaire et l'ingénierie tissulaire sont maintenant envisagées. La transplantation de chondrocytes autologues (TCA) existe déjà mais cette procédure nécessite l'amplification des chondrocytes qui s'accompagne d'une perte du phénotype différencié (dont l'indicateur est le collagène de type II), au profit d'un phénotype fibroblastique (dont l'indicateur est le collagène de type I, retrouvé dans les tissus fibreux). La TCA conduit donc à une greffe de chondrocytes dédifférenciés produisant un fibrocartilage, dont les propriétés mécaniques sont différentes du cartilage hyalin natif. L'objectif de mes travaux était de développer un nouveau kit d'ingénierie tissulaire du cartilage par association de chondrocytes humains, de biomatériaux et d'une sélection de facteurs solubles. Nous avons utilisé le cocktail FGF-2/insuline (FI) pour l'amplification cellulaire et le cocktail BMP-2/insuline/T3 (BIT) pour redifférencier les chondrocytes dans des éponges de collagène. Nos résultats ont montré que cette combinaison permet la synthèse d'une matrice cartilagineuse dans les supports collagène. Cependant, cette synthèse s'est trouvée favorisée en périphérie des éponges cultivées en conditions statiques. Nous avons ensuite utilisé un bioréacteur pour perfuser les éponges et nos résultats ont révélé alors un dépôt plus homogène de cartilage dans ces supports. De manière très intéressante, nous avons aussi observé l'arrêt de l'expression du collagène de type I. Ainsi, notre approche multifactorielle combinant des chondrocytes humains, des biomatériaux collagène, une combinaison FI-BIT et une culture en perfusion permet la reconstruction d'un cartilage non fibrotique

’arthropathie dégénérative est une maladie ayant des répercussions socio-économiques majeures chez l’homme et le cheval. Il n’existe pour l’heure aucun traitement curatif de cette maladie, le cartilage articulaire étant dépourvu de pouvoir de cicatrisation spontané. De nombreux espoirs reposent sur l’utilisation de cellules souches mésenchymateuses (CSM), pour leur potentiel pro-régénératif et anti-inflammatoire. Le premier objectif de cette étude était d’évaluer la tolérance des CSM de sang de cordon ombilical (SCO) et de moelle osseuse (MO) dans des articulations saines. L’étude contrôlée en aveugle menée sur 12 chevaux expérimentaux a démontré que l’injection de CSM-MO provoquait significativement plus de signes de réaction inflammatoire que l’injection de CSM-SCO, et que l’injection des CSM, quelle que soit leur origine, provoquait une réaction inflammatoire discrète à modérée, supérieure à celle d’une injection de placébo, avec une grande variabilité individuelle de sensibilité à une même lignée de cellules. Le second objectif était d’évaluer l’efficacité des CSM-MO et -SCO dans un modèle d’arthropathie induite. L’étude contrôlée en aveugle menée sur 8 chevaux expérimentaux a mis en évidence une réduction significative de la progression des signes indicateurs d’arthropathie à l’imagerie après injection de CSM-MO allogéniques par rapport à l’injection du placébo. Ces résultats encourageants, à considérer à la lumière des limites des études menées, indiquent un effet bénéfique des CSM-MO allogéniques dans la prise en charge de l’arthrose chez le cheval. Ils soulignent la nécessité de poursuivre les recherches afin de confirmer ces résultats, et d’optimiser les effets des CSM à travers leur combinaison à un vecteur ou par une approche acellulaire avec administration des nanovésicules qu’elles sécrètent, et considérées être à l’origine de leurs effets thérapeutiques
Osteoarthritis is a common cause of pain and economic loss in both humans and horses. There is currently no curative treatment for osteoarthritis, because of the lack of spontaneous regenerative capacity of the articular cartilage. Mesenchymal stem cells (MSC) based regenerative medicine comes across as a promising strategy given their pro-regenerative and anti-inflammatory potential. The first objective of this study was to evaluate the safety of umbilical cord blood (UCB) and bone marrow (BM) derived MSC in healthy joints. The blind controlled study conducted on 12 experimental horses showed that the injection of BM-MSC caused significantly more signs of inflammatory reaction than the injection of UCB-MSC, and that the injection of MSC, regardless of their origin, caused a discrete to moderate inflammatory reaction, greater than that of the placebo, with great individual variability in sensitivity to the same cell line. The second objective was to evaluate the efficacy of BM-MSC and UCB-MSC in a model of induced osteoarthritis. The blind controlled study conducted on 8 experimental horses showed a significant reduction in the progression of osteoarthritis associated signs with imaging techniques after injection of allogeneic BM-MSC compared to placebo. These promising results, to be considered in light of the limitations of the studies, indicate a beneficial effect of allogeneic BM-MSC in the management of osteoarthritis in horses. They underline the need for further research to confirm these results, and to optimize the effects of MSC through their combination with a vector or through an acellular approach with administration of the nanovesicles they secrete that ared considered to be responsible for their therapeutic effects

Die rheumatoide Arthritis ist eine chronisch-entzündliche Bindegewebserkrankung mit symmetrischem Befall der Gelenke. Die genaue Ätiologie ist bisher unbekannt. Aktivierte synoviale Fibroblasten sollen durch gesteigerte Adhäsion und Produktion von proinflammatorischen Zytokinen und Matrix-lysierenden Proteasen maßgeblich an der Gelenkdestruktion beteiligt sein. Ziel dieser Arbeit war es, ein neues in-vivo-Knorpeldestruktions-Modell zu etablieren, in welchem unter immunkompetenten Bedingungen, die Invasion und Destruktion von Gelenkknorpel durch die Fibroblasten-Zelllinie LS48 über einen längeren Zeitraum simuliert werden kann. Die am Institut für klinische Immunologie der Medizinischen Fakultät der Universität Leipzig etablierte Zelllinie LS48 wurde in die ipsilateralen Kniegelenke von BALB/c-Mäusen injiziert. Die dadurch induzierte Gewebsdestruktion wurde über zehn Wochen in zweiwöchigem Abstand histopathologisch beurteilt und klassifiziert. Als vergleichende Fibroblasten-Zelllinie wurden nicht-invasive NIH/3T3-Zellen eingesetzt. An Hand der Score-Parameter Zellinvasion, Pannusformation und Knorpeldestruktion wurde eine mäßige bis schwer-wiegende Gewebsdestruktion durch die LS48-Zellen bereits ab der zweiten Untersuchungswoche lichtmikroskopisch nachgewiesen, ohne dass dabei pathologische Effekte in den kontralateralen Kniegelenken aufgetreten sind. Polarisationsmikroskopisch wurden für den Parameter Knorpeldestruktion vergleichbare Ergebnisse erzielt. Damit wurde gezeigt, dass das Modell BALB/c LS48 ein erfolgversprechendes Instrument darstellt, das zur Testung neuer therapeutischer Strategien gegen die Gelenkdestruktion verwendet werden kann. Inwieweit die Auseinandersetzung der LS48-Zellen mit dem spezifischen Immunsystem der BALB/c-Maus Auswirkungen auf den Verlauf der Gewebsdestruktion hat, sollte in weiterführenden Experimenten untersucht werden.

1 Abstract Introduction Autologous transplants of the cartilage tissue from the pinna is commonly used in reconstructive surgery of the nasal skeleton. The present study used animal models to elucidate responses of the auricular cartilage to its damage or transplantation to ectopic sites. Histomorphological analysis of changes observed in auricular cartilage including immunohistochemical study of different isoforms of actin and S-100 proteins was performed. Human articular cartilage prepared by in vitro cultivation using artificial scaffolds was also studied after its transplantation. Aims of the study The aim was to study histological changes and expression of chondrocytic markers (α- SMA and S-100 proteins) in intact, artificially traumatised, or in a human auricular cartilage cultivated in culture medium. An attempt to grow human auricular cartilage chondrocytes implanted in vitro into various types of three dimensional scaffolds aimed at testing chondrocyte survival and phenotype both in the culture and after transplantation to immunodeficient mice. A human auricular cartilage transplanted into the nasal skeleton of patients during a reconstruction surgery should be submitted to a histomorphological examination. Research assumed also comparison of the auricular cartilage responses to a damage,...

The limited intrinsic self-healing capability of articular cartilage requires treatment of cartilage defects. Material assisted and cell based therapies are in clinical practice but tend to result in formation of mechanical inferior fibro-cartilage in long term follow up. If a lesion has not been properly restored degenerative diseases are diagnosed as late sequela causing pain and loss in morbidity. Complex three dimensional tissue models mimicking physiological situation allow investigation of cartilage metabolism and mechanisms involved in repair. A standardized and reproducible model cultured under controllable conditions ex vivo to maintain tissue properties is of relevance for comparable studies. Topic of this thesis was the establishment of an cartilage defect model that allows for testing novel biomaterials and investigate the effect of defined defect depths on formation of repair tissue. In part I an ex vivo osteochondral defect model was established based on isolation of porcine osteochondral explants (OCE) from medial condyles, 8 mm in diameter and 5 mm in height. Full thickness cartilage defects with 1 mm to 4 mm in diameter were created to define ex vivo cartilage critical size after 28 days culture with custom developed static culture device. In part II of this thesis hydrogel materials, namely collagen I isolated from rat tail, commercially available fibrin glue, matrix-metalloproteinase clevable poly(ethylene glycol) polymerized with heparin (starPEGh), methacrylated poly(N-(2-hydroxypropyl) methacrylamide mono-dilactate-poly(ethylene glycol) triblock copolymer/methacrylated hyaluronic acid (MP/HA), thiol functionalized HA/allyl functionalized poly(glycidol) (P(AGE/G)-HA-SH), were tested cell free and chondrocyte loaded (20 mio/ml) as implant in 4 mm cartilage defects to investigate cartilage regeneration. Reproducible chondral defects, 8 mm in diameter and 1 mm in height, were generated with an artificial tissue cutter (ARTcut®) to investigate effect of defect depth on defect regeneration in part III. In all approaches OCE were analyzed by Safranin-O staining to visualize proteoglycans in cartilage and/or hydrogels. Immuno-histological and -fluorescent stainings (aggrecan, collagen II, VI and X, proCollagen I, SOX9, RUNX2), gene expression analysis (aggrecan, collagen II and X, SOX9, RUNX2) of chondrocyte loaded hydrogels (part II) and proteoglycan and DNA content (Part I & II) were performed for detailed analysis of cartilage regeneration. Part I: The development of custom made static culture device, consisting of inserts in which OCE is fixed and deep well plate, allowed tissue specific media supply without supplementation of TGF � . Critical size diameter was defined to be 4 mm. Part II: Biomaterials revealed differences in cartilage regeneration. Collagen I and fibrin glue showed presence of cells migrated from OCE into cell free hydrogels with indication of fibrous tissue formation by presence of proCollagen I. In chondrocyte loaded study cartilage matrix proteins aggrecan, collagen II and VI and transcription factor SOX9 were detected after ex vivo culture throughout the two natural hydrogels collagen I and fibrin glue whereas markers were localized in pericellular matrix in starPEGh. Weak stainings resulted for MP/HA and P(AGE/G)-HA-SH in some cell clusters. Gene expression data and proteoglycan quantification supported histological findings with tendency of hypertrophy indicated by upregulation of collagen X and RunX2 in MP/HA and P(AGE/G)-HA-SH. Part III: In life-dead stainings recruitment of cells from OCE into empty or cell free collagen I treated chondral defects was seen. Separated and tissue specific media supply is critical to maintain ECM composition in cartilage. Presence of OCE stimulates cartilage matrix synthesis in chondrocyte loaded collagen I hydrogel and reduces hypertrophy compared to free swelling conditions and pellet cultures. Differences in cartilage repair tissue formation resulted in preference of natural derived polymers compared to synthetic based materials. The ex vivo cartilage defect model represents a platform for testing novel hydrogels as cartilage materials, but also to investigate the effect of cell seeding densities, cell gradients, cell co-cultures on defect regeneration dependent on defect depth. The separated media compartments allow for systematic analysis of pharmaceutics, media components or inflammatory cytokines on bone and cartilage metabolism and matrix stability
Aufgrund der geringen Selbsheilungsfähigkeit von artikulären Knorpel erfordern Knorpeldefekte eine orthopädische Behandlung. Bislang konnte mit material- oder zellbasierenden Behandlungsstrategien keine funktionelle Regeneration von Knorpeldefekten erreicht werden. In Langzeitstudien zeigt sich vermehrt die Bildung von mechanisch instabilem fibrosen Knorpel. Als Spätfolge nicht vollständig verheilter Knorpeldefekte wird die degenerative Erkrankung Osteoarthrose diagnostiziert. 3-dimensionale Gewebemodelle, die die physiologischen Gegebenheiten nachahmen erlauben einen Einblick in die Mechanismen während der Defektheilung. Dem subchondralen Knochen kommt eine kritische Rolle in der Regeneration nach Mikrofrakturierung zu, weshalb ein Knorpelmodell auf osteochondralen Gewebe basieren sollte. Thema der Arbeit war es ein standardisiertes Knorpeldefektmodell zu etablieren, das die Testung neuer Hydrogelformulierungen sowohl zellfrei als auch zellbeladen hinsichtlich deren Regenerationspotential ermöglicht und den Einfluss der Knorpeldefekttiefe auf die Regeneration zu analysieren. Teil I der Arbeit umfasste die Etablierung des ex vivo osteochondralen Defektmodells, basierend auf der Isolation von porcinen osteochondralen Explantaten (OCE) mit eine Durchmesser von 8 mm und einer Höhe von 5 mm aus der medialen Kondyle. Full thickness Knorpeldefekte mit einem Durchmesser zwischen 1 mm und 4 mm wurden induziert, um den kritischen Defektdurchmesser nach 28 Tagen Kultur in einer neuartigen statischen Kulturplatte zu definieren. In Teil II stand die Testung von Hydrogelen aus Kollagen I isoliert aus Rattenschwänzen, kommerziell erhältlicher Firbrinkleber, Matrix- Metalloproteinase clevable poly(Ethylen Glycol) polymerisiert mit Heparin (starPEGh), methacrylates poly(N-(2-hydroxypropyl) methacrylamid mono-dilactate-poly(Ethylene Glycol) triblock copolymer/methacrylated Hyaluronsäure (MP/HA), thiol functionalisiertes HA/allyl functionalisiertes poly(Glycidol) (P(AGE/G)-HA-SH) als zellfreies oder mit 20 Mio/ml Chondrozyten beladenes Implantat im Knorpeldefekt mit einem Durchmesser von 4 mm im Fokus. Ein automatisiertes Verfahren zur Wundsetzung (ARTcut®) erlaubte in Teil III der Thesis das Kreieren von reproduzierbaren chondralen Defekten mit 4 mm Durchmesser und 1 mm Tiefe in das OCE Modell , um den Einfluss der Defekttiefe auf die Knorpelregeneration zu analysieren. Das Knorpelgewebe des OCE und/oder Hydrogele wurde in allen Experimenten mittels Safranin-O auf Proteoglykangehalt untersucht. Immunhistologische und -fluoreszenzfärbung knorpelspezifischer Marker, Genexpressionsanalysen der Chondrozyten beladenen Hydrogele (Teil II) und Quantifizierung der Proteoglykane und des DNA Gehalts (Teil I & II) folgten nach ex vivo Kultur. Teil I: Die neu entwickelten statischen Kulturkammern setzen sich aus Inserts, in denen das OCE fixiert ist, und einer 6 Well–Platte zusammen. Dadurch wird eine Gewebespezifische Medienversorung mit Knorpelmedium ohne TGF � in den Inserts und Knochenmedium in der Vertiefung der Wellplatte ermöglicht. Die kritische Defektgröße im ex vivo Modell wurde mit 4 mm festgesetzt. Teil II: Biomaterialien als Implantate im Knorpeldefekt zeigten ein materialabhängiges Regenerationspotential. Die Einwanderung von Zellen aus dem OCE in zellfreie Hydrogele resultierte in der Lebend-Tot Färbung bei Kollagen I und Fibrinkleber mit der Tendenz der Synthese von fibrösem Knorpel. Die Chondorzyten beladenen Hydrogele aus Kollagen I und Fibrinkleber zeigten eine homogene Positivfärbung für die hyalinen Proteine Aggrekan, Collagen II und X und des Knorpeltranskriptionsfaktors SOX9, wohingegen die Färbung bei starPEGh lokal in der perizellulären Region lokalisiert war. Die weiteren Materialien MP/HA und P(AGE/G)-HA-SH wiesen eine schwache Positivfärbung an einzelnen Zellclustern auf. Die Genexpressionsanalyse und die Quantifizeirung der Proteoglykane bestätigten die histologischen Ergebnisse mit der Tendenz der Hypertrophie, belegt durch Hochregulierung von Kollagen X und RunX2, bei Chondrozyten eingebettet in MP/HA und P(AGE/G)-HA-SH. Teil III: In der Lebend-Tot Färbung konnte die Einwanderung von Zellen aus dem Knorpel des OCE in den Leerdefekt und zellfreies Kollagen I Hydrogel nachgewisen werden. Separierte und Gewebe spezifische Medienversorgung erwieß sich als kritischer Faktor zur Aufrechterhaltung der Knorpel ECM. Die Anwesenheit des OCE stimuliert Knorpelmatrixsynthese, die für das in vitro kultivierte Chondrozyten beladene Kollagen I nachweislich geringer vorhanden war. Außerdem war die Produktion des hypertrophen Markers Kollagen X im Implantat im OCE weniger stark ausgeprägt als in der in vitro Kultur. Die Unterschiede der Knorpelregeneration deutet auf die Bevorzugung von natürlichen Polymeren gegenüber den synthetisch basierten Hydrogelen hin. Das ex vivo Knorpeldefektmodell stellt eine Platform zur Testung neuer Hydrogelmaterialien als Knorpelimplantate dar. Weiterhin kann das Modell zur Analyse von Zellbesiedelungsstrategien als auch für Zell-Ko-Kulturen im Hinblick auf die Defektregeneration herangezogen werden. Die getrennten Medienreservoire ermöglichen weiterhin die systematische Analyse von Medienkomponenten oder entzündlichen Zytokinen auf die Vitalität und Stabilität von Knochen und Knorpelgewebe