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Auswahl der wissenschaftlichen Literatur zum Thema „Collagène dense“
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Zeitschriftenartikel zum Thema "Collagène dense"
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Zou, Chao, Wen Jian Weng, Xu Liang Deng, Kui Cheng, Pi Yi Du, Ge Shen und Gao Rong Han. „Influence of Collagen Status on Microstructures of Porous Collagen/TCP Composites“. Key Engineering Materials 330-332 (Februar 2007): 495–98. http://dx.doi.org/10.4028/www.scientific.net/kem.330-332.495.
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Two starting collagens, sponge and floc collagen, were used to prepare collagen/tricalcium phosphate (TCP) composites. The resulting composites were porous and had 200μm pore size. However, there was a difference in the microstructure of the pore walls for the composites derived from the two collagens, the pore walls in sponge collagen/TCP composite were still porous and had 200 nm micropores size, TCP particles were trapped in collagen matrices. While floc collagen/TCP composite had smooth and dense walls in which TCP particles were embedded. The difference could be attributed to the starting collagen with different status. Sponge collagen has a soft structure, which easily becomes disassembled fibrils during alkali treatment, the disassembled fibrils are integrated again to form a dense morphology for pore walls after freeze-drying. While floc collagen has already a low disassembly degree, the alkali treatment could not be able to separate the fibrils, this remains as micropores in pore walls after freeze-drying. Both porous composites are significant in bone tissue engineering or regeneration. MTT test results showed the two composites had good cytocompatibility, and sponge collagen/TCP composite was somewhat better than floc collagen/TCP composite, which could result from that micropores derived roughness in pore walls of sponge collagen/TCP composite is suitable for cell growth.
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Aplin, J. D., S. Campbell und T. D. Allen. „The extracellular matrix of human amniotic epithelium: ultrastructure, composition and deposition“. Journal of Cell Science 79, Nr. 1 (01.11.1985): 119–36. http://dx.doi.org/10.1242/jcs.79.1.119.
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Ultrastructural comparisons have been made between human amnion extracellular matrix in tissue and cell culture. Immunochemical analysis of matrix deposited by monolayers of cultured amnion epithelial cells has also been undertaken. The basal cell surfaces are highly invaginated with an associated basal lamina that is more electron dense at the distal tips of basal cell processes where hemidesmosomes are frequent. Immediately below the lamina densa is a zone rich in collagen bundles. In the underlying stroma two types of fibril predominate, one striated of 50 nm diameter and one of 18 nm diameter. The observations suggest that at gestational term the epithelial cells are still active in the production of matrix. Secretion appears to occur into invaginations in the basal cell surface where a loosely organized mixture of stromal-type and basal laminal-type aggregates is formed. In culture on plastic, cells also deposit a mixture of basal laminal (type IV collagen + laminin) and stromal (collagens type I + III) components as well as fibronectin. However, segregation into a true basal lamina with underlying stroma does not occur in vitro, suggesting the need for an organized subcellular template to complete matrix morphogenesis. The in vitro and in vivo evidence suggest that the epithelium contributes to the subjacent dense collagenous zone as well as to the basal lamina.
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Keene, D. R., L. Y. Sakai, G. P. Lunstrum, N. P. Morris und R. E. Burgeson. „Type VII collagen forms an extended network of anchoring fibrils.“ Journal of Cell Biology 104, Nr. 3 (01.03.1987): 611–21. http://dx.doi.org/10.1083/jcb.104.3.611.
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Type VII collagen is one of the newly identified members of the collagen family. A variety of evidence, including ultrastructural immunolocalization, has previously shown that type VII collagen is a major structural component of anchoring fibrils, found immediately beneath the lamina densa of many epithelia. In the present study, ultrastructural immunolocalization with monoclonal and monospecific polyclonal antibodies to type VII collagen and with a monoclonal antibody to type IV collagen indicates that amorphous electron-dense structures which we term "anchoring plaques" are normal features of the basement membrane zone of skin and cornea. These plaques contain type IV collagen and the carboxyl-terminal domain of type VII collagen. Banded anchoring fibrils extend from both the lamina densa and from these plaques, and can be seen bridging the plaques with the lamina densa and with other anchoring plaques. These observations lead to the postulation of a multilayered network of anchoring fibrils and anchoring plaques which underlies the basal lamina of several anchoring fibril-containing tissues. This extended network is capable of entrapping a large number of banded collagen fibers, microfibrils, and other stromal matrix components. These observations support the hypothesis that anchoring fibrils provide additional adhesion of the lamina densa to its underlying stroma.
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Jaziri, Abdul Aziz, Rossita Shapawi, Ruzaidi Azli Mohd Mokhtar, Wan Norhana Md Noordin und Nurul Huda. „Physicochemical and Microstructural Analyses of Pepsin-Soluble Collagens Derived from Lizardfish (Saurida tumbil Bloch, 1795) Skin, Bone and Scales“. Gels 8, Nr. 8 (27.07.2022): 471. http://dx.doi.org/10.3390/gels8080471.
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Reducing food waste is critical for sustainability. In the case of fish processing, more than sixty percent of by-products are generated as waste. Lizardfish (Saurida tumbil Bloch, 1795) is an economically important species for surimi production. To address waste disposal and maximize income, an effective utilization of fish by-products is essential. This study aims to isolate and characterize pepsin-soluble collagens from the skin, bone and scales of lizardfish. Significant differences (p < 0.05) in the yields of collagen were noted with the highest yield recorded in pepsin-soluble skin collagen (PSSC) (3.50 ± 0.11%), followed by pepsin-soluble bone collagen (PSBC) (3.26 ± 0.10%) and pepsin-soluble scales collagen (PSCC) (0.60 ± 0.65%). Through SDS–polyacrylamide gel electrophoresis, the presence of two alpha chains were noted and classified as type I. From Fourier transform infrared spectroscopy (FTIR) analysis, the triple-helix structure of the collagen was maintained. The X-ray diffraction and UV visible spectra characteristics of the lizardfish collagens in this study are similar to the previously reported fish collagens. In terms of thermostability, PSSC (Tmax = 43.89 °C) had higher thermostability in comparison to PSBC (Tmax = 31.75 °C) and PSCC (Tmax = 30.54 °C). All pepsin-soluble collagens were highly soluble (>70%) in acidic conditions (particularly at pH 4.0) and at low sodium chloride concentrations (0–30 g/L). Microstructural analysis depicted that all extracted collagens were multi-layered, irregular, dense, sheet-like films linked by random coiled filaments. Overall, pepsin-soluble collagens from lizardfish skin, bone and scales could serve as potential alternative sources of collagens.
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Fatiroi, Nurul Syazwanie, Abdul Aziz Jaziri, Rossita Shapawi, Ruzaidi Azli Mohd Mokhtar, Wan Norhana Md Noordin und Nurul Huda. „Biochemical and Microstructural Characteristics of Collagen Biopolymer from Unicornfish (Naso reticulatus Randall, 2001) Bone Prepared with Various Acid Types“. Polymers 15, Nr. 4 (20.02.2023): 1054. http://dx.doi.org/10.3390/polym15041054.
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Biopolymer-like collagen has great industrial potential in terms of its excellent properties, such as strong biocompatibility, high degradability, and low antigenicity. Collagen derived from fish by-products is preferable as it is safer (free from transmittable diseases) and acceptable to most religious beliefs. This study aimed to characterize the unicornfish (Naso reticulatus Randall, 2001) bone collagens prepared with different type of acids, i.e., acetic acid, lactic acid, and citric acid. A higher yield (Y) (p < 0.05) was obtained in the citric-acid-soluble collagen (CASC) (Y = 1.36%), followed by the lactic-acid-soluble collagen (LASC) (Y = 1.08%) and acetic-acid-soluble collagen (AASC) (Y = 0.40%). All extracted collagens were classified as type I due to the presence of 2-alpha chains (α1 and α2). Their prominent absorption spectra were located at the wavelengths of 229.83 nm to 231.17 nm. This is similar to wavelengths reported for other fish collagens. The X-ray diffraction (XRD) and infrared (IR) data demonstrated that the triple-helical structure of type I collagens was still preserved after the acid-extraction process. In terms of thermal stability, all samples had similar maximum transition temperatures (Tmax = 33.34–33.51 °C). A higher relative solubility (RS) of the unicornfish bone collagens was observed at low salt concentration (0–10 g/L) (RS > 80%) and at acidic condition (pH 1.0 to pH 3.0) (RS > 75%). The extracted collagen samples had an irregular and dense flake structure with random coiled filaments. Overall, bones of unicornfish may be used as a substitute source of collagen.
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Matarsim, Nur Nadiah, Abdul Aziz Jaziri, Rossita Shapawi, Ruzaidi Azli Mohd Mokhtar, Wan Norhana Md Noordin und Nurul Huda. „Type I Collagen from the Skin of Barracuda (Sphyraena sp.) Prepared with Different Organic Acids: Biochemical, Microstructural and Functional Properties“. Journal of Functional Biomaterials 14, Nr. 2 (03.02.2023): 87. http://dx.doi.org/10.3390/jfb14020087.
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This study was carried out to compare the extractability and characteristics of barracuda (Sphyraena sp.) skin collagen using various organic acids. Acetic-solubilized collagen (ASBS), lactic-solubilized collagen (LSBS) and citric-solubilized collagen (CSBS) yielded 6.77 g/100 g, 10.06 g/100 g and 8.35 g/100 g, respectively, and those yields were significantly different (p < 0.05). All acid-solubilized collagens were considered as type I because of their two alpha chains (α1 and α2) detected in acrylamide gel after electrophoresis. Ultraviolet–visible (UV–vis) analysis confirmed that ASBS, LSBS and CSBS had similar absorption peaks (230.5 nm) and the results were in accordance with other fish collagens. Under infrared (IR) and X-ray diffraction (XRD) analysis, the triple helical structure of type I collagens extracted from barracuda skin was maintained. From a thermostability study, all type I collagens showed a higher maximum transition temperature (Tmax = 40.16 to 41.29 °C) compared to other fish skin collagens. In addition, the functional properties of the extracted collagens revealed the ASBS had higher water and oil absorption capacities than the CSBS and LSBS samples. The highest level of the emulsion ability index (EAI) (>200 m2/g) was detected under acidic conditions (pH 4), while lower EAIs were recorded under the alkaline (pH 10) and neutral treatments (pH 7). All type I collagens had a higher relative solubility (>60%) at a low pH test but the solubility level sharply decreased at a neutral pH. In addition to this, a lower concentration of NaCl (0–20 g/L) showed the higher percentage of solubility (>60%) while adding over 30 g/L of NaCl decreased solubility (>40%). From a microstructural test, all type I samples had an irregular and dense flake structure with random coiled filaments. Overall, collagen extracted from the barracuda skin may be applied as an alternative collagen from an industry perspective.
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Ebelt, Nancy D., Vic Zamloot, Edith Zuniga, Kevin B. Passi, Lukas J. Sobocinski, Cari A. Young, Bruce R. Blazar und Edwin R. Manuel. „Collagenase-Expressing Salmonella Targets Major Collagens in Pancreatic Cancer Leading to Reductions in Immunosuppressive Subsets and Tumor Growth“. Cancers 13, Nr. 14 (16.07.2021): 3565. http://dx.doi.org/10.3390/cancers13143565.
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Therapeutic resistance in pancreatic ductal adenocarcinoma (PDAC) can be attributed, in part, to a dense extracellular matrix containing excessive collagen deposition. Here, we describe a novel Salmonella typhimurium (ST) vector expressing the bacterial collagenase Streptomyces omiyaensis trypsin (SOT), a serine protease known to hydrolyze collagens I and IV, which are predominantly found in PDAC. Utilizing aggressive models of PDAC, we show that ST-SOT selectively degrades intratumoral collagen leading to decreases in immunosuppressive subsets, tumor proliferation and viability. Ultimately, we found that ST-SOT treatment significantly modifies the intratumoral immune landscape to generate a microenvironment that may be more conducive to immunotherapy.
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Walchli, C., M. Koch, M. Chiquet, B. F. Odermatt und B. Trueb. „Tissue-specific expression of the fibril-associated collagens XII and XIV“. Journal of Cell Science 107, Nr. 2 (01.02.1994): 669–81. http://dx.doi.org/10.1242/jcs.107.2.669.
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Interstitial collagen fibrils form the supporting scaffold of all connective tissues. The synthesis of this framework is subject to a precise spatial and temporal regulation in order to meet the mechanical needs of every tissue type. A subgroup of non-fibrillar collagens termed FACIT seems to play a role in this regulation by providing specific molecular bridges between fibrils and other matrix components. Collagens XII and XIV represent such FACIT molecules and occur preferentially in tissues containing banded type I collagen fibrils. We have used the techniques of indirect immunofluorescence and in situ hybridization to investigate the expression patterns of the two molecules during chicken embryonic development. We detected specific differences in these patterns, which may be related to the respective functions of the two proteins within the connective tissues. Collagen XIV was expressed at very few sites in the 6-day-old embryo, but occurred in virtually every collagen I-containing tissue (skeletal muscle, cardiac muscle, gizzard, tendon, periosteum, nerve) by the end of embryonic development. In contrast, collagen XII was fairly abundant in the 6-day-old embryo but was, at later stages, restricted to only a few dense connective tissue structures (bone, tendon, gizzard). Thus, our results suggest that collagen XII and collagen XIV serve different functions during embryonic development although their structures are highly similar.
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Itoh, Yoshifumi, Noriko Ito, Hideaki Nagase, Richard D. Evans, Sarah A. Bird und Motoharu Seiki. „Cell Surface Collagenolysis Requires Homodimerization of the Membrane-bound Collagenase MT1-MMP“. Molecular Biology of the Cell 17, Nr. 12 (Dezember 2006): 5390–99. http://dx.doi.org/10.1091/mbc.e06-08-0740.
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Pericellular degradation of interstitial collagens is a crucial event for cells to migrate through the dense connective tissue matrices, where collagens exist as insoluble fibers. A key proteinase that participates in this process is considered to be membrane-type 1 matrix metalloproteinase (MT1-MMP or MMP-14), but little is known about the mechanism by which it cleaves the insoluble collagen. Here we report that homodimerization of MT1-MMP through its hemopexin (Hpx) domain is essential for cleaving type I collagen fibers at the cell surface. When dimerization was blocked by coexpressing either a membrane-bound or a soluble form of the Hpx domain, cell surface collagenolytic activity was inhibited in a dose-dependent manner. When MMP-13, a soluble collagenase active as a monomer in solution, was expressed as a membrane-anchored form on the cell surface, homodimerization was also required to cleave collagen. Our results introduce a new concept in that pericellular collagenolysis is regulated by correct molecular assembly of the membrane-anchored collagenase, thereby governing the directionality of the cell to migrate in tissue.
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Short, Ben. „Dense collagen kindles invadopodia formation“. Journal of Cell Biology 208, Nr. 3 (02.02.2015): 252. http://dx.doi.org/10.1083/jcb.2083iti3.
Der volle Inhalt der QuelleDissertationen zum Thema "Collagène dense"
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Lama, Miléna. „Structure-properties relationship in dense collagen gels produced by injection of spray-dried collagen“. Electronic Thesis or Diss., Sorbonne université, 2019. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2019SORUS559.pdf.
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Injecter des gels denses de collagène pour obtenir des matériaux 3D, biomimétiques en termes d’architecture et de propriétés mécaniques, est un enjeu pour la régénération tissulaire car cela pourrait éviter des chirurgies lourdes. Des solutions de collagène très concentrées ont la capacité de former des mésophases dont la géométrie mime celle des tissus biologiques. Ainsi, il est possible d’obtenir des gels de collagène en 3D possédant une meilleure tenue mécanique, sans utiliser de réticulant chimique qui peut induire des inflammations. Cependant, l’injection de solutions de collagène très concentrées est empêchée par l’augmentation drastique de leur viscosité. Comment associer biomimétisme et injectabilité de gels denses de collagène ? Nous proposons de concentrer des solutions acides de collagène par atomisation, produisant des billes denses de collagène. Une simple pesée de ces billes permet de déterminer la concentration des gels. Mélangées à un solvant aqueux, elles sont injectées dans un moule imitant un défaut tissulaire. La fibrillogénèse, induite in vitro dans les solutions de collagène, forme des gels rigides. Les microscopies optique et électroniques révèlent des organisations issues de l’auto-assemblage du collagène à l’échelle macroscopique, selon la concentration en collagène (de 3wt% à 8wt%). Le comportement mécanique des gels imite celui des tissus biologiques, et est fortement lié à l’ultrastructure des fibrilles de collagène. Cette étude ouvre des perspectives dans le domaine de la régénération tissulaire en dessinant le cadre d’une librairie tissulaire, contenant des matériaux en collagène biomimétiques, injectables et denses, permettant l’usage de procédures chirurgicales moins invasivesInjection of dense collagen to obtain 3D biomimetic scaffolds in terms of structure and mechanical properties is challenging for regenerative medicine since it would avoid open-surgery. It is well-known that highly concentrated collagen solutions can form liquid crystal mesophases with tissue-like geometries. Thus, it is possible to obtain 3D collagen gels in vitro with better mechanical properties, without widely used chemical crosslinkers that may lead to inflammatory responses. Nevertheless, the injection of highly concentrated collagen solutions is unlikely due to their high viscosity.How to combine biomimetism and injectability of dense collagen gels?To achieve this goal we concentrate acidic collagen solutions by spray-drying, forming dense collagen beads. A simple weighing of the beads determines the concentration of the gels. Mixed with an aqueous solvent, the beads are injected into a mold mimicking a tissue defect. The fibrillogenesis in vitro is induced within the collagen solutions that transform into stiff gels. Electron and polarized light microscopies show organizations resulting from collagen self-assembly at macroscopic length scale depending on the collagen concentration i.e. from 3wt% to 8wt%. Mechanical tests results reveal tissue-like properties strongly linked to collagen fibrils ultrastructure. This study opens perspectives in tissue repair in setting the framework of a library made of biomimetic (anisotropic, dense and stiff) and injectable collagen gels, enabling minimally invasive procedures
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Camman, Marie. „Hydrogels de collagène dense structurés par impression 3D pour modéliser la matrice extracellulaire musculaire et cardiaque dans la Dystrophie Musculaire de Duchenne“. Electronic Thesis or Diss., Sorbonne université, 2022. http://www.theses.fr/2022SORUS447.
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La myopathie de Duchenne est une maladie génétique rare caractérisée par une dégénération progressive des muscles striés notamment squelettiques et cardiaque. A l’échelle de la cellule, l’absence de dystrophine perturbe l'intégrité de la membrane plasmique, la signalisation cellulaire et par conséquent la contraction musculaire. A l’échelle du tissu, ces changements se traduisent par une faiblesse musculaire et par une perturbation de la matrice extracellulaire qui se rigidifie, perd son organisation anisotrope et devient peu poreuse. La matrice joue un rôle essentiel dans l’évolution de la maladie et est souvent négligée dans les modèles existants. Ainsi, ce projet de thèse a eu pour but de développer un nouveau modèle tissulaire cardiaque et musculaire prenant en compte ces modifications structurelles de la matrice pour améliorer la compréhension de la pathologie et générer un modèle physiologique pour tester des molécules thérapeutiques. Tout d’abord, un modèle de matrice extracellulaire saine a été généré par impression 3D de collagène de type I dense. Les paramètres ont été ajustés pour reproduire la matrice physiologique, à savoir une rigidité de 10 kPa, de l’anisotropie et de la porosité. L’impression de collagène dense permet à la fois d’aligner les molécules de collagène et de générer une porosité intrinsèque dans l’hydrogel de collagène. Ensuite, son pendant pathologique a pu être développé en modifiant les paramètres d’impression et de gélification du collagène pour obtenir une matrice de rigidité 50 kPa, isotrope et non poreuse. In vivo, les cellules musculaires et cardiaques sont physiologiquement agencées sous forme de fuseaux. Cette morphologie particulière a été reproduite au sein des matrices développées en créant un pore cylindrique par moulage qui a été colonisé par les cellules. L’enjeu est de recréer au sein de ces pores un microtissu jointif pour mimer les conditions physiologiques. En utilisant des cardiomyocytes dérivés de cellules souches pluripotentes induites humaines ou des myoblastes murins, nous avons respectivement obtenu des microtissus cardiaques et musculaires au contact de matrices saines ou pathologiques. Pour le microtissu musculaire, les cellules saines ensemencées dans la matrice pathologique montrent un stress du à l’hypoxie, associé à un ralentissement du cycle cellulaire et une moins bonne différentiation en myotubes. Pour le microtissu cardiaque, les cellules ensemencées dans le modèle pathologique ont montré une moins bonne contraction sous stimulation. Par ailleurs, les matrices ont été adaptées à une puce microfluidique pour assurer la perfusion de milieu de culture par les pores créés par l’impression 3D. Cette perfusion permet d’améliorer la diffusion de l’oxygène et des nutriments au sein du modèle. Ces nouveaux modèles de tissu cardiaque et musculaire permettent de prendre en compte les interactions cellule/cellule mais aussi cellule/matrice dans l’évolution de la pathologie. Ainsi, les différentes combinaisons entre matrice saine/pathologique et cellules saines/mutées permettrait à l’avenir de mieux comprendre la pathologie et de trouver des stratégies thérapeutiques adaptéesDuchenne Muscular Dystrophy is a rare genetic disease characterized by progressive degeneration of striated muscles, notably skeletal and cardiac. At the cellular level, the absence of dystrophin disturbs the integrity of the plasma membrane, cell signaling, and consequently muscle contraction. At the tissue level, these changes result in muscle weakness and a disturbance of the extracellular matrix which becomes rigid and loses its anisotropic organization with reduced porosity. The matrix plays a crucial role in the evolution of the disease and is often neglected in existing models. The matrix plays a crucial role in the evolution of the disease and is often neglected in existing models. This project aims to develop a new tissue model that considers these structural changes in ECM to improve our understanding of the pathology and discover novel therapeutic solutions. First, the 3D printing of dense type I collagen generated a healthy extracellular matrix model. Its parameters were adjusted to reproduce the physiological matrix, i.e., a stiffness of 10 kPa, anisotropy, and porosity. Dense collagen printing allows collagen molecules alignment and generates porosity. Then, its pathological counterpart could be synthesized by modifying the printing and gelling parameters of collagen to get a matrix with a 50 kPa stiffness, isotropic, and non-porous. In vivo, the muscle and heart cells are physiologically arranged in bundles. A cellularized cylindrical pore generated by molding reproduced this morphology within the matrices. To mimic the physiological conditions, the challenge was to recreate a joined microtissue with densely-packed cells within these pores. We obtained a cardiac and a muscular microtissue with both types of matrices (healthy or pathological) using human cardiomyocytes derived from induced pluripotent stem cells or murine myoblasts. For the muscle microtissue, the healthy cells seeded in the pathological matrix showed high stress due to hypoxia, associated with cell cycle arrest and weak differentiation into myotubes. For the cardiac microtissue, cells seeded in the pathological model had irregular beatings when stimulated. In addition, the matrices were adapted to a microfluidic chip to ensure the perfusion of the culture medium through the pores created by the 3D printing. This perfusion enhances nutrient and oxygen diffusion in the model. These new cardiac and muscular tissue models take into account cell/cell and cell/matrix interactions in the evolution of the pathology. Thus, the different combinations between healthy/pathological matrix and healthy/mutated cells will allow us a better understanding of the pathology to discover novel and adapted therapeutic strategies
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Metzmacher, Iris. „Enzymatic Degradation and Drug Release Behavior of Dense Collagen Implants“. Diss., lmu, 2005. http://nbn-resolving.de/urn:nbn:de:bvb:19-45495.
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Ghezzi, Chiara Elia. „Dense collagen-based tubular tissue constructs for airway tissue engineering“. Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114489.
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To date, only engineered tissues of planar geometry, such as epidermal and dermal layer substitutes, have successfully reached the market, mainly due to their relative low complexity and simple geometry. In contrast, the mechanical and functional requirements of tubular tissues are more stringent compared to planar tissues. Tubular tissues, which are the main components of several biological systems (e.g. circulatory, urinary or respiratory), not only present an increased complexity in geometry and tissue architecture, they are also populated by mixed cell types. In addition, these are continuously exposed to cyclic mechanical stimuli, which modulate cellular responses and ultimately the functionality of the tissues. Therefore, the understanding and the ability to reproduce physiologically equivalent environments are critical to generate mechanically and biologically functional neo-tissues or tissue models. The aim of this doctoral research was to produce and characterize 3D DC-based tubular constructs as tissue models for airway tissue engineering in physiologically relevant culture conditions. The first objective was to develop DC-based constructs and evaluate, in real-time, the responses of seeded fibroblasts to PC and to culturing with the DC environment; the fabrication and characterization of mesenchymal stem cell (MSC) seeded multilayered DC-SF-DC hybrids; and to evaluate the differentiation of MSCs cultured within multilayered DC-SF-DC hybrids.The second objective was to develop and characterize cell-seeded tubular dense collagen constructs (TDCCs) with bioinspired mechanical properties.The third objective was to implement tubular dense collagen-based constructs as an airway tissue model through the evaluation of airway smooth muscle cell (ASMC) responses within TDCC under physiological mechanical stimuli, and the development of a multilayered tubular dense collagen-silk fibroin construct (TDC-SFC) that mimicked airway tract architecture in order to study MSC responses under physiological mechanical stimulation.By providing ASMCs with a physiologically equivalent niche, and through pulsatile flow stimulation, in vitro, ASMCs exhibited their native orientation, maintained their contractile phenotype and enhanced the mechanical properties of the TDCC through matrix remodelling. The ability of TDC-SFC to transfer physiological pulsatile stimulation to resident MSCs resulted in native-like cell orientation (i.e. parallel to circumferential strain), and induced MSC contractile phenotype expression.In conclusion, the tubular dense collagen-based constructs developed and implemented, in this doctoral dissertation, effectively provided an in vitro airway tissue model for potential preclinical studies to mimic physiological and pathological conditions (e.g. inflammatory and degenerative diseases) in a relevant biomechanical environment, as alternatives to simple tissue culture techniques or complex animal models.À ce jour, seuls les tissus synthétisés de forme plane, comme les substituts dermiques et épidermiques, ont réussi à percer le marché, surtout en raison de leur complexité relativement faible et de leur géométrie simple. À l'opposé, les exigences mécaniques et fonctionnelles des tissus tubulaires imposent un plus grand nombre de contraintes que les tissus planaires. Principales composantes de plusieurs systèmes biologiques (circulatoire, urinaire ou respiratoire), les tissus tubulaires sont non seulement plus complexes sur le plan de la géométrie et de l'architecture tissulaire, mais ils sont aussi composés de cellules de différents types. De plus, ils sont continuellement exposés à des stimuli mécaniques cycliques. Voilà pourquoi il est essentiel de comprendre les milieux physiologiquement équivalents et de pouvoir les reproduire si on veut obtenir des néotissus ou des modèles tissulaires fonctionnels sur le plan mécanique et biologique.La présente recherche de doctorat visait donc à produire et à caractériser des constructions tubulaires 3D à base de CD, les tissus des voies respiratoires dans des conditions de culture physiologiquement pertinentes. Le premier objectif était de concevoir des constructions à base de CD et d'évaluer la réaction des fibroblastes ensemencés à la CP et à la culture dans un milieu à base de CD; de fabriquer et de caractériser des hybrides multicouches CD-fibroïne-CD ensemencés de cellules souches mésenchymateuses (CSM); et d'évaluer la différenciation.Le deuxième objectif de la présente recherche était de concevoir et de caractériser des constructions tubulaires faites de collagène dense (CTCD). Le troisième objectif était d'implanter des constructions tubulaires à base de CD comme modèle tissulaire des voies respiratoires par l'évaluation de la réponse des cellules musculaires lisses (CML) des voies respiratoires dans les CTCD en présence de stimuli mécaniques physiologiques.En leur fournissant une niche physiologiquement équivalente, et grâce à la stimulation de l'écoulement pulsatoire, in vitro, les CML des voies respiratoires ont pris leur orientation naturelle, maintenu leur phénotype contractile et amélioré les propriétés mécaniques de la CTCD grâce au remodelage matriciel. La capacité de la CTCD à transférer la stimulation physiologique pulsatile aux CSM résidentes a donné une orientation des cellules s'apparentant à leur orientation naturelle et induit l'expression phénotypique.En conclusion, les constructions tubulaires à base de collagène dense qui ont été développées et implantées sont parvenues à fournir in vitro un modèle tissulaire des voies respiratoires pour d'éventuelles études précliniques visant à reproduire les conditions physiologiques et pathologiques.
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Oliveira, Stéphanie de. „Hydrogels denses collagène/acide hyaluronique par biofabrication pour le développement d’un nouveau modèle in vitro d’Annulus Fibrosus“. Electronic Thesis or Diss., Sorbonne université, 2023. http://www.theses.fr/2023SORUS307.
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La dégénérescence du disque intervertébral est une pathologie irréversible entraînant des maux de dos intenses. Les disques intervertébraux sont composés de trois parties : le Nucleus Pulposus (NP) situé au centre, entouré par l’Annulus Fibrosus (AF) et deux plateaux cartilagineux de part et d’autre. La dégénérescence du disque est caractérisée par une baisse d’hydratation du NP qui devient fibreux et ne joue plus son rôle d’absorbeur de chocs. Les forces exercées par le NP sur l’AF vont le rompre provoquant l’écoulement du NP ce qui génère une hernie discale. De nombreux traitements ont été développés mais ils ne permettent pas de freiner la dégénérescence du disque. Ceci est dû en partie à une méconnaissance de la maladie. La plupart des modèles animaux sont quadrupèdes et ne reproduisent pas les caractéristiques de la pathologie humaine. C’est pourquoi il est essentiel de développer de nouveaux modèles in vitro utilisant des cellules humaines. De plus, des biomatériaux à bases de polymères naturels semblent être les plus adéquats pour le développement de tels modèles car ils sont le support naturel des cellules. Ce projet de thèse a eu pour but de développer un nouveau modèle d’Annulus Fibrosus. Pour cela, deux biopolymères présents dans le tissu natif ont été sélectionnés : l’acide hyaluronique qui apporte l’hydratation au disque et le collagène qui sert de support aux cellules. Dans un premier temps, une encre imprimable reproduisant la matrice extracellulaire de l’AF a été développée. Pour cela, une étude physicochimique a été effectuée sur les interactions collagène I/acide hyaluronique (HA). Lorsqu’ils sont mélangés, ces deux biopolymères forment des complexes poly-ioniques (CPIs) du fait de leurs charges opposées. Ces CPIs précipitent et ne permettent pas d’obtenir une encre homogène. L’inhibition des CPIs est efficace à des pH très acides (pH 1) en présence de sels mais ces conditions sont incompatibles avec la survie cellulaire. En modulant le pH et la force ionique, nous avons découvert une nouvelle méthode pour formuler une encre collagène/HA homogène. En se plaçant proche du point isoélectrique du collagène (pH 5,5) et en présence de NaCl, des fibrilles de collagène se forment en solution. Dans ces conditions, les interactions avec l’HA sont inhibées et les CPIs ne se forment pas. Il est ensuite possible de former des hydrogels de collagène fibrillaire par remontée de pH à 7 et de photo réticuler l’HA pour obtenir des hydrogels avec des propriétés physiques optimisées. Le second objectif était de générer le modèle in vitro d’Annulus Fibrosus. L’AF étant un tissu anisotrope, nous avons procédé à une impression 3D de solutions denses de collagène pour induire son alignement. Deux stratégies ont été adoptées pour cette étude. (i) L’encre précédemment formulée en phase diluée a été utilisée à plus haute concentration (30 mg.mL-1 en collagène, 7,5 mg.mL-1 en HA) avec un ratio collagène/HA de 4 pour 1 comme c’est le cas dans l’AF natif. Cette encre est imprimée en bain de gélification (PBS 2X, NaOH 10-3M) et photo-réticulée sous lumière verte en présence d’éosine Y. (ii) Une seconde encre a été formulée composée de collagène concentré imprimée dans le bain de gélification. Après imprégnation avec l’HA, la photoréticulation a été effectuée. Les deux méthodes ont permis d’obtenir des lamelles d’hydrogels anisotropes avec une structure ressemblant à celle de l’AF et des propriétés rhéologiques intéressantes (G’ = 6kPa). Ces lamelles ont été cellularisées avec des fibroblastes en reproduisant leur environnement natif confiné entre deux couches imprimées. La viabilité cellulaire et la morphologie des cellules étaient similaires à celles observées dans le tissu natif après 14 jours de culture. Si les propriétés mécaniques n’ont pas été atteintes, la bioactivité, la structure et l’anisotropie des matériaux développés lors de cette thèse ont été proches du tissu natif, les validant en tant que modèle 3D de l’Annulus FibrosusThe intervertebral disc degeneration is an irreversible pathology leading to low back pain. The intervertebral disc is composed of three tissues: the Nucleus Pulposus located in the center, surrounded by the Annulus Fibrosus (AF) and two cartilaginous plates located above and below. Disc degeneration is characterized by a hydration loss of the Nucleus Pulposus (NP), which becomes fibrous and no longer acts as a shock absorber. The forces exerted by the NP on the AF break it, causing the leakage of the NP leading to disc herniation. Several drug and surgical treatments have been developed but none stops or slows down the disc degeneration. This is due to a lack of knowledge of this disease. Most animal models are quadrupedal and do not reproduce the characteristics of the human pathology. This is why it is essential to develop novel in vitro models using human cells. Furthermore, biomaterials based on natural polymers are the most suitable for the development of three-dimensional in vitro models because these biopolymers are the natural support of cells. In order to mimic a complete intervertebral disc, it is essential to reproduce the three parts of this tissue. This thesis project aimed to develop a novel model of Annulus Fibrosus. For this purpose, two biopolymers present in the native tissue were selected: hyaluronic acid which gives hydration to the disc and collagen which is the natural support of cells. The first objective of this thesis was devoted to the formulation of a printable ink to reproduce the AF extracellular matrix. To do this, a physicochemical study was carried out on collagen/hyaluronic acid (HA) interactions. After mixing, these two biopolymers form polyionic complexes (PICs) and precipitate due to their opposite charges. So, a homogeneous ink cannot be obtained. Inhibition of PICs formation is effective at very acidic pH (pH 1) in with salt addition. Nevertheless, these conditions are incompatible with cell survival. By modulating the pH and ionic strength, we discovered a new method to formulate a homogeneous collagen/HA ink. Using a collagen solution close to its isoelectric point (pH 5.5) in presence of NaCl, we triggered the formation of collagen fibrils in solution. Interactions with HA are inhibited in these conditions and PICs are not formed anymore. Then, a fibrillary collagen hydrogel can be formed by raising the pH to 7 and HA can be crosslinked to obtain hydrogels with optimized physical properties. The second objective was to design the in vitro model of Annulus Fibrosus. Since AF is an anisotropic tissue, we 3D printed dense collagen solutions to induce alignment. Indeed, the shearing of dense solutions during printing aligns collagen. Two strategies were tested in this study. (i) The ink previously formulated was used at high concentration (30 mg.mL-1 for collagen, 7.5 mg.mL-1 for HA) with a 4:1 collagen/hyaluronic acid ratio to resemble the native AF. This ink was printed in a gelation bath (2X PBS, 10-3M NaOH) and photocrosslinked under green light (eosin Y used as photo initiator). (ii) A second ink was used, only composed of concentrated collagen and printed in the same gelling bath. Then, an impregnation process with HA was carried out followed by the photocrosslinking with green light. The two methods allowed the production of anisotropic lamellae with structural features resembling those of AF as well as interesting rheological properties (G' = 6kPa). These lamellae were cellularized with fibroblasts confined between two printed layers. Cell viability and morphology were similar to that observed within the native tissue. If the physiological mechanical properties were not reached, biocompatibility, bioactivity, structure and anisotropy of these biomaterials were close to the native tissue, this allows to validate them as a novel 3D model of Annulus Fibrosus
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Alekseeva, T. „Introducing controllable 3D features into dense collagen constructs for tissue engineering applications“. Thesis, University College London (University of London), 2012. http://discovery.ucl.ac.uk/1344165/.
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Plastic compression of collagen is based on unidirectional expulsion of fluid from hydrated collagen gel. The process results in dense collagen sheet, with higher density of collagen at the fluid leaving surface (FLS) than non-FLS. Compression process is completely cell-independent and at the same time cell-friendly. However, engineered tissues should replicate not only components of tissues in vivo (extracellular matrix and cells) but also their complex micro-architecture. Therefore the aim of this work was to develop collagen-based scaffolds with controllable micro-architecture for biomedical and tissue engineering applications using plastic compression (PC) of collagen. The objectives of this project were: i. to test formation of progressively opening channels in the PC collagen, ii. to investigate stable and predictable PC collagen patterning, iii. to adapt PC method in a upward-flow system as a route to process automation, iv. to investigate formation of channels using in layered PC collagen constructs. Two approaches were used in this work. Firstly, internal channels were introduced using lost fibre approach, where soluble glass fibres are incorporated in the scaffold and leave channel when dissolved. Shape and potentially progression of the channels’ opening is controlled by the shape of the template. The shape of the fibres was altered from cylindrical to conical in a controlled manner and incorporated into the PC constructs, resulting in conically-shaped channels, giving predictable internal 3D structures. The second approach relied on formation of dense collagen zone at the fluid leaving surface of the compressed collagen constructs. Formation of the densely packed collagen zone at the fluid leaving surface is essential for stable and faithful pattern formation in the process of micro-moulding. This finding has been applied in a novel upward-flow compression system to create channels using a ‘roofing’ technique. ‘Roof’ is formed by a compression of a new collagen gel on top of a patterned one; process results in open lumen channels. This appears to be due to a combination of the small dimension of the grooves in the base layer and viscosity of the collagen in the upper layer. This work demonstrates a new, previously unknown level of subtlety by which collagen fibrils can be packed and aggregated due to directional fluid flow. The outcome of this work is important for understanding pattern formation in PC collagen in vitro and potentially tissue morphogenesis in vivo. It also introduces new generation of implantable living tissue equivalents with complex micro-architecture. The multi-well compression technique has already been implemented in semi-automative working station for biomedical applications.
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Gobeaux, Frédéric. „PHASES DENSES DE COLLAGÈNE DE TYPE I :TRANSITION ISOTROPE/CHOLESTÉRIQUE, FIBRILLOGENÈSE ET MINÉRALISATION“. Phd thesis, Université Pierre et Marie Curie - Paris VI, 2007. http://tel.archives-ouvertes.fr/tel-00337402.
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L'objectif de ce travail consiste en l'étude in vitro des phénomènes d'autoassemblage des molécules de collagène de type I en phases denses. Dans un premier temps nous nous sommes consacrés à l'étude de solutions colloïdales de collagène solubilisé en milieu acide. Nous avons étudié la transition isotrope/cholestérique ainsi que la structure de la phase cristal-liquide obtenue à l'aide de la microscopie optique à lumière polarisée et de la diffusion des rayons X aux petits angles. De plus, nous avons décrit les propriétés rhéologiques de ces solutions à l'aide d'expériences en régime oscillant en géométrie cône-plan. Ensuite, nous avons cherché à déterminer l'influence de quelques paramètres physicochimiques simples sur la formation de gels fibrillaires à partir des solutions acides (la « fibrillogenèse »). Ces gels ont été caractérisés par diffusion des rayons X et microscopie électronique à transmission sur coupes ultrafines. Enfin, nous présentons quelques expériences de minéralisation de ces matrices fibrillaires ordonnées ; nous y montrons comment nous avons réussi à obtenir une phase minérale coalignée avec la phase organique. Ce travail s'inscrit dans un contexte plus large de compréhension de la morphogenèse tissulaire et de la synthèse de biomatériaux ordonnés.
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Alcock, Rebekah D. „Dietary collagen intake and sources for support of dense connective tissues in athletes“. Thesis, Australian Catholic University, 2019. https://acuresearchbank.acu.edu.au/download/735dcbe3102bcc4d19ddd84efe04e7267e078206d002757b8221417651e13847/5376764/Alcock_2019_Dietary_collagen_intake_and_sources_for_Redacted.pdf.
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Intake of dietary sources of collagen may support the synthesis of collagen in varying tissues, with the availability of key amino acids being a likely contributor to its effectiveness. This study analyzed commonly consumed preparations of bone broth (BB) to assess the amount and consistency of its amino acid content. Commercial and laboratory prepared samples, made with standardized and variable (non-standardized) protocols were analyzed for key amino acids (glycine, lysine, proline, leucine, hydroxyproline and hydroxylysine). The main finding of the study was that amino acid concentrations in BB made to a standardized recipe were significantly lower for hydroxyproline, glycine, proline; P = 0.003 and hydroxylysine, leucine and lysine; P = 0.004 than those provided by a potentially therapeutic dose (20 g) of reference collagen supplements (P > 0.05). There was large variability in the amino acid content of BB made to non-standardized recipes, with the highest levels of all amino acids found within the café prepared varieties. For standardized preparations, commercial BB were lower in all amino acids than the self-prepared varieties. There were no differences (P > 0.05) in the amino acid content of different batches of BB when prepared according to a standardized recipe. If the intake of collagen precursors is proven to support the synthesis of new collagen in vivo, it’s unlikely that bone broth can provide a consistently reliable source of key amino acids. Focus on the provision of key amino acids from dietary sources should continue to focus on the standard sources currently being researched.
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Collignon, Anne-Margaux. „Utilisation de cellules souches pulpaires combinées à une matrice de collagène pour la réparation osseuse cranio-faciale Strategies developed to induce, direct, and potentiate bone healing Accelerated craniofacial bone regeneration through dense collagen gel scaffolds seeded with dental pulp stem cells Mouse Wnt1-CRE-RosaTomato dental pulp stem cells directly contribute to the calvarial bone regeneration process Early angiogenesis detected by PET imaging with 64Cu-NODAGA-RGD is predictive of bone critical defect repair“. Thesis, Sorbonne Paris Cité, 2018. http://www.theses.fr/2018USPCB113.
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La région cranio-faciale est particulièrement vulnérable aux pertes de structures. Sa localisation et sa visibilité font qu'une atteinte entraîne des troubles, aussi bien physiques (alimentation, phonation...) que psychologiques (intégrité de la personne...). Les traitements actuels (régénération osseuse guidée, autogreffe osseuse ou allogreffe) sont particulièrement invasifs et présentent un taux d'échec élevé. Tout cela affecte fortement la qualité de vie du patient. De plus, le coût direct de ces traitements est important pour les systèmes de santé et le patient. Il existe donc un réel besoin de développer des traitements innovants basés sur des approches biomimétiques d'ingénierie tissulaire pour la régénération/réparation osseuse. L'objectif de ce travail est de développer une approche d'ingénierie tissulaire pour la réparation/régénération de tissus osseux cranio-faciaux lésés. Il est basé sur l'utilisation de matrices cellularisées avec des cellules souches mésenchymateuses issues de la pulpe dentaire : les Dental Pulp Stem Cells (DPSCs). De nombreux travaux ont démontré la grande plasticité de ces cellules, qui dérivent initialement de la crête neurale, mais aussi leur rôle trophique dans la réparation de tissus lésés par leur capacité de différenciation ostéogénique et chondrocytaire. Par ailleurs, ces cellules présentent des propriétés pro-angiogéniques supérieures aux cellules mésenchymateuses de la moelle osseuse (MSCs) et l'accès à cette réserve est aisé puisqu'elles peuvent être obtenues à partir de dents extraites. Dans ce contexte, nous avons à ce jour utilisé des matrices denses de collagène contenant des cellules souches pulpaires pour régénérer un tissu osseux crânien après réalisation de défauts critiques. L'objectif est d'induire très précocement une néo-angiogenèse favorisant à court terme la survie des cellules implantées, puis de stimuler leur maintien à long terme au sein du néo-tissu implanté, pour enfin provoquer une ostéoformation. Nous avons, ainsi, pu étudier et valider différents aspects de cette thématique : .1 L'impact positif de l'utilisation de matrices denses de collagène comme support ostéoconducteur, .2 Le suivi à long terme des cellules après implantation in vivo .3 L'impact positif d'un pré-traitement à l'hypoxie sur i/ la survie des cellules après implantation in vivo ii/ la potentialisation de leur apport pour la régénération/réparation osseuse en orientant leur différenciation vers une voie ostéoblastique, .4 L'apport significatif des techniques d'imageries pour le suivi des animaux grâce à la tomographie par émission de positons (utilisation de traceurs spécifiques de la minéralisation au sein des matrices et de la néo-angiogenèse) et au microscanner à rayons X (suivi cinétique de la qualité et de la quantité de matrice osseuse régénérée), .5 La validation et la confirmation de l'ensemble de ces résultats par l'histologie. Ainsi, ces résultats nous ont permis de répondre à l'objectif de travail et de perfectionner certains aspects de la composante cellulaire. Toutefois, il reste nécessaire d'optimiser le biomatériau lui-même. Il est en effet envisageable d'améliorer les matrices de collagène compressées que nous utilisons actuellement, en y intégrant par exemple des céramiques bioactives. En perspective, potentialiser les biomatériaux des matrices et combiner les DPSCs avec un support plus adapté à leur survie et à leur croissance permettrait d'améliorer considérablement la cicatrisation osseuse. Ces dernières années, l'étude des cellules souches a progressé d'approche in vitro vers l'in vivo. Les modèles in vivo établis pour étudier ces cellules dans le domaine cranio-facial ont déjà apporté des renseignements et ce travail s'inscrit dans leur continuité en cherchant à concevoir des stratégies adaptées pour l'utilisation future des DPSCs en ingénierie tissulaireThe craniofacial area is particularly vulnerable to structural loss. Its location and visibility make a loss causes disorders, both physical (food, phonation...) than psychological (integrity of the person...). Current treatments (autografts, allografts or synthetic bone grafts) are particularly invasive and have a high failure rate. All this strongly affects the quality of life of the patient. In addition, the cost of these treatments is significant for the health systems and the patient. Therefore, there is a real need to develop innovative treatments based on biomimetic tissue approaches for bone repair. The purpose of this thesis is to develop a tissue engineering approach for the repair/regeneration of injured cranial-facial bone tissue. It is based on the use of cellularized scaffolds with mesenchymal stem cells derived from the dental pulp: Dental Pulp Stem Cells (DPSCs). Many studies have demonstrated the high plasticity of these cells, which initially derive from the neural crest, but also their trophic ability in the repair of damaged tissues by their osteogenic and chondrocyte differentiation capacity. Moreover, these cells have better's pro-angiogenic properties than mesenchymal cells of the bone marrow (MSCs) and access to this reserve is easy since they can be obtained from extracted teeth. In this context, we have used dense collagen scaffolds seeded with DPSCs to regenerate cranial bone tissue on critical defects model. The objective is to induce a very early neo-angiogenesis for improved short-term survival of implanted cells, then stimulate the long-term maintenance of cells in the implanted neo-tissue, finally to cause osteoformation. We were able to study and validate various aspects of this theme: 1- The positive impact of the use of dense collagen scaffold as osteoconductive support, 2- Long-term follow-up of the cells after implantation in vivo (thanks to the use of a cell line constitutively expressing an intracellular fluorescence protein), 3- The positive impact of a pre-treatment with hypoxia on i/ the survival of the cells after implantation in vivo ii/ their contribution to bone regeneration / repair by orienting their differentiation towards an osteoblastic pathway, 4- The significant contribution of imaging techniques for the monitoring of animals (less sacrifice and longitudinal follow-up...) thanks to positron emission tomography (use of specific tracers of the mineralization within the scaffolds and neo-angiogenesis) and X-ray microscanner (kinetic monitoring of the quality and quantity of regenerated bone matrix) 5- Validation and confirmation of all these results by histology. Thus, these different results allowed us to respond to the working hypothesis and optimize some aspects of the cellular component. However, it remains necessary to optimize the biomaterial itself. It is indeed possible to improve the compressed collagen scaffolds that we currently use, for example by incorporating bioactive ceramics such as bioglasses or hydroxyapatite. In recent years, the study of stem cells has progressed from in vitro to in vivo. The in vivo models established to study these cells in the craniofacial area have already provided valuable information and this work is a continuation of these previous studies by seeking to build on better strategies (right characterization, environment oriented...) for the future use of DPSCs for tissue engineering purposes. In view of this work, potentiating the biomaterials of the scaffolds and combining the DPSCs with a support more adapted to their survival and their growth would considerably improve bone healing, as well as bone regeneration / repair
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Marelli, Benedetto. „In vitro mineralization of an osteoid-like dense collagen construct for bone tissue engineering“. Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=106503.
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Bone tissue engineering (BTE) has emerged as a promising solution to heal the millions of people worldwide that suffer from bone degenerative pathologies and bone fractures. Since bone is a biocomposite of type I collagen nanofibres (namely osteoid) reinforced with nanocrystals of carbonated hydroxylapatite (CHA), reconstituted type I collagen gels are an attractive choice as scaffolds for BTE. However, to date, the design of a collagenous bone-like construct ready to be implanted is far from being accomplished, as collagen matrices are difficult to mineralize. The aim of this doctoral research was to design and evaluate strategies to rapidly achieve an acellular mineralization of an osteoid-like dense collagen gel for potential applications in bone regeneration. It was hypothesized that the collagen fibrillar density (CFD) affects the microenvironment and the physical properties of the framework of collagen gels. To test this hypothesis, and as a first objective, the mineralization of collagen gel with increasing CFDs was investigated in simulated body fluid (SBF). Collagen gels with physiologically relevant CFDs led to greater extent of mineralization, when compared to highly hydrated gels. It was therefore proposed that the increase in gel CFD led to a more physiological microenvironment, which facilitated the mineral formation and validated the proposed osteoid model. As a second objective, the mineralization of dense collagen (DC) gels was enhanced and accelerated by mimicking the role of anionic non collagenous proteins (NCPs) in the native osteoid, which act as CHA nucleators. Two strategies were implemented: first, the influence of collagen fibrillization pH on the extent of DC gel mineralization was investigated. Since the collagen molecule is slightly positively charged at physiological pH, it was hypothesized that it would be more negatively charged if formed in an alkaline environment, i.e., above its isoelectric point. This hypothesis was validated by investigating the electrostatic properties of collagen gels formed at physiological pH (7.4) and at pH values of 8.2 and 9.0. The effect of alkaline fibrillization pH on DC gel mineralization was evident by the extensive mineralization and the soft to hard transition of the gels by day 14 in SBF. Second, anionic fibroin derived polypeptides (Cs) were introduced, for the first time as easily produced alternatives to NCPs. Apatite was formed within 6 hours in SBF and by day 7, CHA crystals were homogenously distributed throughout the roll gels resulting also in a transition from soft-to-hard tissue-like response to compressive testing. As a third objective, a bioinorganic approach to enhance and accelerate the mineralization of collagen was developed. DC gels were combined with silica-based 45S5 bioactive glass of micron- and nano-sized particles (μBG and nBG, respectively) to investigate the effect of an osteoconductive and osteoinductive bioactive glass on collagen mineralization. DC-μBG gels conditioned in SBF resulted in the extensive mineralization of the collagenous framework. Furthermore, the effect of nBG on the mineralization of DC and its effect on seeded pre-osteoblastic cells, were also investigated. Compared to μBG, nBG particles resulted in an enhanced and accelerated mineralization of the collagen matrix when immersed in SBF. Apatite formation was immediately detected within as processed DC-nGB hybrid gels, and by day 7 there was a 13 fold increase in the hybrid gel scaffold compressive modulus. The metabolic activity of MC3T3-E1 cells was affected by the presence of nBG, indicating accelerated osteogenic differentiation in the absence of osteogenic supplements, suggesting the potential of DC-nBG scaffolds to be used as cell-seeded constructs. In conclusion, since the role of the collagen framework microstructure on its mineralization has been previously ignored, the present doctoral dissertation provides new insights into collagen mineralization.Des millions de personnes dans le monde souffrent de maladies osseuses. Les techniques chirurgicales actuelles font appel à l'autogreffe, à l'allogreffe, à la xénogreffe et à la greffe de matériaux artificiels. Cependant, comme ces interventions comportent plusieurs inconvénients, l'ingénierie tissulaire de l'os (ITO) est apparue comme une solution prometteuse. Comme l'os est un biocomposite constitué de nanofibres de collagène de type I renforcées de nanocristaux d'hydroxylapatite carbonatée (HAC), les gels de collagène de type I représentent un choix attrayant pour la production de ces matrices. Toutefois, la minéralisation in vivo de ces matrices de collagène est difficile et la minéralisation in vitro n'est obtenue qu'après avoir soustrait les matrices des contraintes physiologiques, ce qui limite leur utilisation.Ces travaux s'appuyaient sur l'hypothèse selon laquelle la densité en fibrine du collagène (DFC) influe sur le microenvironnement et les propriétés physiques de la charpente de gels de collagène. Afin de vérifier cette hypothèse, et d'atteindre l'objectif premier de l'essai, la minéralisation de gel de collagène d'une DFC croissante a été réalisée dans du liquide organique simulé (LOS). Les gels de collagène d'une DFC physiologique ont permis d'obtenir une plus grande minéralisation et a aussi influé sur les propriétés électrostatiques des gels. Cette découverte suggère donc que l'augmentation de la DF du gel de collagène a permis de créer un microenvironnement plus physiologique, ce qui a facilité la formation minérale et a permis de valider le modèle proposé. Comme deuxième objectif, la minéralisation de gels de collagène dense a été améliorée et accélérée en reproduisant le rôle des protéines anioniques (PANC) au sein des ostéoïdes indigènes. Deux stratégies ont été mises en œuvre : étude de l'influence du pH des fibrines du collagène et de polypeptides anioniques dérivés de la fibroïne. Premièrement, la charge de la molécule de collagène étant légèrement positive dans un milieu doté d'un pH physiologique l'hypothèse est que un milieu dont le pH se situe au-dessus de son point isoélectrique, a été posée et validée. L'effet du pH alcalin durant la formation de fibrines sur la minéralisation du gel de collagène dense a été constaté par la quantité d'HAC formée; la matrice s'était largement minéralisée au jour 3. De plus, la minéralisation a significativement augmenté le module apparents des gels, rendant les structures autoportantes. Deuxièmement, la minéralisation de gels de collagène dense additionnés de 10 % poids de polypeptides anioniques dérivés de la fibroïne a été évaluée dans du LOS. De l'apatite s'était formée dans les 6 heures et des cristaux d'HAC étaient distribués de façon homogène dans les rouleaux de gels au jour 3.Le troisième objectif a été la mise au point d'une approche bio-inorganique en vue d'améliorer et d'accélérer la minéralisation du collagène. Des gels de collagène dense ont été additionnés de micro- et de nanoparticules de verre bioactif (μBG et nBG, respectivement) 45S5 à base de silice. Les gels de collagène dense additionnés de μBG préparés dans un LOS ont produit une importante minéralisation de la matrice de collagène. De plus, l'effet des nBG sur la minéralisation du collagène dense et son effet sur des cellules préostéoblastiques ensemencées ont aussi été étudiés. La formation d'apatite a immédiatement été détectée par la présence de gels hybrides de collagène dense contenant des nBG. Au jour 7, le module à la compression de la construction de gel hybride était 13 fois plus élevé. De plus, l'activité métabolique des MC3T3 cellules a été altérée par la présence des nBG, indiquant une différenciation ostéogénique accélérée en l'absence de suppléments ostéogéniques.En conclusion, le rôle des matrices de collagène à microstructures dans la minéralisation ayant été ignoré jusqu'ici, la présente dissertation doctorale jette un nouvel éclairage sur la minéralisation du collagène.
Buchteile zum Thema "Collagène dense"
1
Le Touze, Anne. „Scars in Pediatric Patients“. In Textbook on Scar Management, 397–404. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-44766-3_46.
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AbstractPhysiological healing process is not much different in children, but the resulting scar is very rich in collagen and very dense. Therefore, when dealing with children, it is necessary to be aware of these particularities and to “guide” the scaring process to avoid disgracious and disabling scars.
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Pavelka, Margit, und Jürgen Roth. „Dense Connective Tissue: Collagen Bundles in the Cornea“. In Functional Ultrastructure, 282–83. Vienna: Springer Vienna, 2010. http://dx.doi.org/10.1007/978-3-211-99390-3_145.
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Weinberg, Crispin B., Kimberlie D. O’Neil, Robert M. Carr, John F. Cavallaro, Bruce A. Ekstein, Paul D. Kemp, Mireille Rosenberg, Jose P. Garcia, Michael Tantillo und Shukri F. Khuri. „Matrix Engineering: Remodeling of Dense Fibrillar Collagen Vascular Grafts in Vivo“. In Tissue Engineering, 190–98. Boston, MA: Birkhäuser Boston, 1993. http://dx.doi.org/10.1007/978-1-4615-8186-4_18.
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Ricard-Blum, Sylvie, *. Bernard Dublet und Michel van der Rest. „Collagen VII and the formation of anchoring fibrils“. In Unconventional Collagens, 25–41. Oxford University PressOxford, 2000. http://dx.doi.org/10.1093/oso/9780198505457.003.0003.
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Abstract Collagen VII was first isolated from chorioamniotic membranes by limited pepsin digestion and was termed long-chain collagen (LC) before being referred to as collagen VII [911, see 7, 8, 9 for reviews]. Collagen VII is the major structural component of anchoring fibrils [691, 724], the specialized fibrous structures located immediately beneath the lamina densa of many epithelia and which are critical for epidermal-dermal adhesion. Table 12 gives the Swiss Prot database entries for collagen VII.
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Park, Hyeree, Derek H. Rosenzweig und Showan N. Nazhat. „Dense collagen-based scaffolds for soft tissue engineering applications“. In Tissue Engineering Using Ceramics and Polymers, 771–802. Elsevier, 2022. http://dx.doi.org/10.1016/b978-0-12-820508-2.00010-6.
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Colby, Georgina. „Collage and the Anxiety of Self-description: Blood and Guts in High School“. In Kathy Acker. Edinburgh University Press, 2016. http://dx.doi.org/10.3366/edinburgh/9780748683505.003.0002.
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Chapter 2 addresses Acker’s practice of collage, and the anxiety of self-description. Blood and Guts in High School is positioned in relation to both the Dadaist collage and montage practices of artists such as Hannah Höch at the beginning of the twentieth century, and the subversive publications of the 1960s and 1970s: mimeographed magazines, and the punk and post-punk medium of Xeroxed publications. The original manuscript of Blood and Guts in High School housed in the archive possesses a different materiality to the published version of the novel. The materiality of the text in its collage and typographic experimentation is situated in a counter position to the language and hegemonic discourses within which Janey, the voice of the text, is imprisoned. Drawing on Acker’s practices of illegibility, and Denise Riley’s work on language and affect, the chapter argues that Blood and Guts in High School, through its experimental form, reveals the anxiety of self-description that Janey experiences within conventional language structures. Illustration, experimental typography, non-referential language, and the use of the poetic, function in Blood and Guts in High School as sites of an alternate language that emerges through compositional form and experimental forms of iteration.
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Alexander, Neal. „Basil Bunting’s Regional Modernism“. In Late Modernism and the Poetics of Place, 52–80. Edinburgh University Press, 2022. http://dx.doi.org/10.3366/edinburgh/9781474484404.003.0003.
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This chapter contends that Basil Bunting’s magnum opus, the long poem Briggflatts (1966), has too often been misread as a poem that is elementally ‘rooted’ in the poet’s home region of Northumbria. His regional modernism is characterised both by the imaginative centrality of northern landscapes and cultural paradigms, and by the refraction of such local and regional attachments through a self-consciously international modernist poetics. Bunting’s poem is a deliberately eccentric poetic autobiography that both enacts the expression of a secure regional identity and suspends any such existential anchoring through its formal disjunctions and dense collage of incommensurable places and times. Moreover, at the level of theme and content, Briggflatts is profoundly concerned with experiences of displacement and transience, foregrounding vagrancy as a characteristically modern mode of being-in-the-world.
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Adachi, Eijiro, Ian Hopkinson und Toshihiko Hayashi. „Basement-Membrane Stromal Relationships: Interactions between Collagen Fibrils and the Lamina Densa“. In International Review of Cytology, 73–156. Elsevier, 1997. http://dx.doi.org/10.1016/s0074-7696(08)62476-6.
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Vedam-Mai, Vinata, Anthony T. Yachnis, Michael Ullman, Saman P. Javedan und Michael S. Okun. „Fibrous Scarring and Deep Brain Stimulation Lead Implantation“. In Deep Brain Stimulation, herausgegeben von Laura S. Surillo Dahdah, Padraig O’Suilleabhain, Hrishikesh Dadhich, Mazen Elkurd, Shilpa Chitnis und Richard B. Dewey, 137–40. Oxford University Press, 2020. http://dx.doi.org/10.1093/med/9780190647209.003.0028.
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Deep brain stimulation (DBS) has emerged in recent years as a powerful surgical modality for the treatment of several movement disorders as well as neuropsychiatric syndromes. Despite its clinical efficacy, the mode of action of DBS and the cellular responses to this therapy remain unclear. This chapter presents an unusual case from the DBS Brain Tissue Network at the University of Florida of prominent tissue response to DBS. The patient was a 74-year-old man with idiopathic Parkinson disease, status post bilateral STN DBS leads. Neuropathologic examination of the tissue surrounding the distal lead tip of the right DBS using immunohistochemistry revealed a dense, collagen-filled fibrous sheath. There was no intraoperative bleeding during the procedure, and this finding was confirmed by postoperative imaging. Further, there was no perioperative decline in this patient’s condition. It is likely that the fibrous capsule resulted in less than optimal clinical benefit, which was previously reported in this patient. This severe type of exaggerated tissue response to DBS leads has not been observed in other cases in our Brain Bank network and has not been reported previously in the literature, to our knowledge.
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Vincent, Maria, Jose Quintero, Henry D. Perry und James M. Rynerson. „Biofilm Theory for Lid Margin and Dry Eye Disease“. In Ocular Surface Diseases - Some Current Date on Tear Film Problem and Keratoconic Diagnosis. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.89969.
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Blepharitis and dry eye disease have long been viewed as two distinct diseases with overlapping presentations and separate etiologies. Evaporative dry eye, although frequently associated with aqueous deficiency, is also considered a separate entity. We propose viewing dry eye, both evaporative and insufficiency, as the natural sequelae of chronic blepharitis induced by biofilm. We suggest describing this one chronic disease as dry eye blepharitis syndrome (DEBS). The disease process begins when normal flora bacteria colonize the lid margin beginning shortly after birth. This colonization accompanies the development of a biofilm on the lid margin. As years pass, the biofilm matures, and the increased bacterial population initiates the production of inflammatory virulence factors, such as exotoxins, cytolytic toxins, and super-antigens, which persist on the lid margin for the rest of the patient’s life. These virulence factors cause early follicular inflammation and later, meibomian gland dysfunction followed by aqueous insufficiency, and finally, after many decades, loss of the dense collagen in the tarsal plate. We proposed four stages of DEBS, which correlate with the clinical manifestations of folliculitis (anterior blepharitis), meibomitis (meibomian gland dysfunction), lacrimalitis (aqueous deficiency), and lid structure damage evidenced by increased lid laxity resulting in entropion, ectropion, and floppy eyelid syndrome.
Konferenzberichte zum Thema "Collagène dense"
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Esbona, Karla, David Inman, Sandeep Saha, Kevin Eliceiri, Lee G. Wilke und Patricia J. Keely. „Abstract 1116: Response to cyclooxygenase-2 inhibition is regulated by collagen dense stroma“. In Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA. American Association for Cancer Research, 2014. http://dx.doi.org/10.1158/1538-7445.am2014-1116.
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Garcia Mendoza, Maria Gracia, David Inman, Suzanne M. Ponik und Patricia J. Keely. „Abstract 2345: The collagen-dense tumor microenvironment increases neutrophil recruitment in mouse mammary carcinoma“. In Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA. American Association for Cancer Research, 2015. http://dx.doi.org/10.1158/1538-7445.am2015-2345.
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Hong, Hyeonjun, Hyeonji Kim, Seonjin Han, Hong Kyun Kim, Dong-Woo Cho und Dong Sung Kim. „Development of dense collagenous construct mimicking native corneal stroma based on collagen compression process“. In 2018 IEEE International Conference on Cyborg and Bionic Systems (CBS). IEEE, 2018. http://dx.doi.org/10.1109/cbs.2018.8612178.
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Coudrillier, Baptiste, Craig Boote und Thao D. Nguyen. „Effects of the Scleral Collagen Structure on the Biomechanical Response of the Optic Nerve Head“. In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80540.
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The sclera is a fiber-reinforced material composed of dense superimposed lamellae of type I collagen fibrils embedded in a matrix of elastin and proteoglycan. Recent Wide-Angle X-ray Scattering (WAXS) experiments (Meek, 2009) showed that the collagen lamellae are strongly aligned circumferentially in the region closest to the optic nerve head (ONH). The collagen structure was more disperse and heterogeneous away from the peripapillary region. The collagen structure of the sclera directly influences its material stiffness properties and therefore the level of strain transmitted to the tissues of the ONH, which is the primary site of damage in glaucoma. The effects of the fiber structure on the ONH biomechanics have been studied on the monkey eye (Girard, 2009), but not on the human eye. Recent work evaluating the influence of the human sclera on ONH biomechanics approximated the scleral behavior as linear elastic (Sigal, 2009) or hyperelastic orthotropic (Eilaghi, 2009).
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Coudrillier, Baptiste, Craig Boote und Thao D. Nguyen. „Modeling the Effect of the Experimentally-Derived Collagen Structure on the Mechanical Anisotropy of the Human Sclera“. In ASME 2011 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/sbc2011-53272.
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The sclera is the main load-bearing structure of the eye. It must be sufficiently stiff to maintain the shape and dimensions of the eye under acute elevation of intraocular pressure (IOP). These properties stem from the fiber-reinforced structure of the sclera, which contains dense superimposed lamellae of type I collagen fibrils embedded in matrix of proteoglycans and elastin. Recently, wide-angle X-ray diffraction [1] (WAXS) was used to map the fibrillar arrangement and distribution of collagen over posterior human sclera [2]. The results showed that the peripapillary region, immediately adjacent to the optic nerve head (ONH) had a larger amount of collagen and a circumferential collagen structure. The collagen structure in the mid-posterior region was more heterogeneous. The collagen structure of the sclera directly influences its material stiffness properties and therefore the level of strain transmitted to the tissues of the optic nerve head, which is the primary site of damage in glaucoma. Models inspired from the microstructure are needed to evaluate the contribution of the collagen structure on the mechanical properties. Earlier modeling efforts have treated the sclera as a homogenous, isotropic, linear elastic [3] or hyperelastic material [4, 5]. Girard et al. recently added the effect of the collagen structure using a nonlinear anisotropic model [6]. The authors fit their model for the collagen orientation and distribution to mechanical inflation data of the posterior sclera.
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Esbona, K., DR Inman, S. Saha, LG Wilke und PJ Keely. „Abstract P1-03-04: Response to cyclooxygenase-2 inhibition is regulated by collagen dense stroma“. In Abstracts: Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium; December 8-12, 2015; San Antonio, TX. American Association for Cancer Research, 2016. http://dx.doi.org/10.1158/1538-7445.sabcs15-p1-03-04.
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Ziegler, Kimberly A., und Thao D. Nguyen. „Modeling Study Incorporating Depth-Dependent Transverse Reinforcement due to Variation in Collagen Lamellae Interweaving in Corneal Tissue“. In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80771.
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The cornea is crucial for maintaining refraction and focusing ability of the eye. Small alterations in mechanical behavior of the tissue can cause changes in curvature and structure of the cornea, having adverse affects on visual acuity. Since the corneal stroma makes up 90% of corneal thickness and contains a majority of the tissue’s collagen content, it is considered the dominant contributor to the tissue’s mechanical strength and stiffness, which originates from a complex fiber-reinforced structure [1]. It has been shown that collagen lamellae (comprised of type I collagen fibrils) within a dense, proteoglycan-rich matrix, are highly interwoven in the anterior third of the cornea and the degree of interweaving decreases significantly through the thickness with relatively no interweaving observed in the posterior third [1]. The interwoven structure also varies within the plane of the tissue, gradually increasing from a planar arrangement in the central cornea to a highly interwoven arrangement near the limbus [2].
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Mendoza, Maria Gracia Garcia, David R. Inman, Justin J. Jeffery und Patricia J. Keely. „Abstract C09: The collagen-dense tumor microenvironment recruits tumor promoting Ly6G+Ly6C+ neutrophils in mouse mammary carcinoma“. In Abstracts: AACR Special Conference: The Function of Tumor Microenvironment in Cancer Progression; January 7-10, 2016; San Diego, CA. American Association for Cancer Research, 2016. http://dx.doi.org/10.1158/1538-7445.tme16-c09.
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Malmgren, R. „LUMI-AGGREGOMETER STUDIES OF THE INITIAL ATP-SECRETION FROM COLLAGEN-ADHERENT PLATELETS“. In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1643550.
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We have earlier, with the use of a lumi-aggregometer and sub-aggregating doses of collagen (0.2-0.8 ug/ml PRP), been able to detect the initial, aspirin-insensitive secretion of ATP from the collagen-adherent platelets, and to correlate this secretion to the doses of collagen, and onset and degree of subsequent shape change of non-adherent platelets (Malmgren, Thromb Res 4:445, 1986). The present study shows, that 200 ATU of hirudin,which reduced near-maximal aggregation and ATP-secretion induced by high collagen doses (2.5 ug/ml PRP) from 3.35 ± 0.2 uM to 2.85 ± 0.1 uM, did neither reduce the secreted amount of ATP that were 82.5 ± 15 nM in control samples and 90 ± 27.5 nM in hirudin-treated samples, nor reduce platelet shape change when platelets were challenged with 0.31 ug collagen /ml PRP. (200 ATU hirudin completely abolished an equal degree of platelet shape change induced by 0.01 U thrombin). Assuming that 3 % of the platelets in PRP were actually adhering to the collagen fibrils, the secreted amount corresponds to 14.6 ±0.04 pmoles ATP/106adheringplatelets, amounts which closely represented 100 % of their dense granule content. The finding confirms that hirudin does not inhibit platelet adhesion and also indicates, that thrombin-mediated activation of secretory pathways appears not to be involved during the initial phase of platelet-collagen interactions.Dipyridamole (DPA) and dibutyryl cAMP (DBcAMP) inhibited ATP-secretion and platelet aggregation in a dose-dependent manner at high collagen concentrations, but only DBcAMP caused a dose-dependent reduction of ATP secretion (IC50 =10-4 M) induced by sub-aggregating doses of collagen. DPA was devoid of effect in this respect and thus did not inhibit platelet adhesion.Yohimbine, dihydroergotamine and phentolamine reduced ATP-secretion induced by sub-aggregating collagen doses in the mentioned rank order of potency, and with IC50 values in the micromolar range. Ketanserin, ritanserin and propranolol were devoid of effect. The findings suggest that the initial collagen-plate-let interaction involve alfareceptor-mediated mechanisms that may encompass adhesion, while DBcAMP probably interacts with secretory mechanisms connected to phosphatidylinositol turnover.
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Harley, Brendan A. C. „Collagen Scaffold-Membrane Composites for Mimicking Orthopedic Interfaces“. In ASME 2011 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/sbc2011-54026.
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Tendons are specialized connective tissues that transmit load between bone and muscle, and whose microstructural and compositional features underlie their function. The biological solution to the problem of connecting relatively compliant tendon to stiffer (∼2 orders of magnitude) bone is a gradient interface zone ∼100μm wide. Over the tendon-bone-junction (TBJ) a linear transition takes place in the ECM inorganic:organic (mineral:collagen) ratio as well as mineral crystallinity from that of tendon to bone. While small TBJ injuries can heal via regeneration, severe defects undergo repair-mediated healing characterized by fibrocartilagenous scar tissue with inferior biomechanical and functional properties. Severe TBJ injuries are common in athletes, the elderly, and following severe craniofacial and extremity trauma. Many tendon injuries (i.e. supraspinatus injuries), particularly those associated with acute trauma, are prone to occur at the TBJ due to high levels of region-specific stress concentrations; rotator cuff tendons injuries, one of the most common TBJ injuries, exhibit re-tears at rates as high as 94%. The scale of such defects and current poor clinical results suggest the need for a biomaterial solution that can mimic the dynamic heterogeneities of the native insertion and tendon body to induce rapid, functional regeneration. Three-dimensional collagen-GAG (CG) scaffolds have been successfully used clinically to regenerate large soft tissue defects (skin, peripheral nerves); they act by mimicking the native extracellular matrix (ECM) of the damaged tissue to prevent wound contraction and scar tissue synthesis. However these scaffolds have not traditionally been used for orthopedics due to an inability to recapitulate two critical features of orthopedic tissues: multiscale structural complexity, biomechanical properties. While the multi-scale properties of tendon itself cannot be currently replicated, nature provides an alternative paradigm: core-shell composites. Plant stems combine a porous core with a dense shell to aid osmotic transport (core) while maintaining sufficient tensile/bending stiffness (shell); many bird beaks use core-shell designs to efficiently enhance compressive strength. Here we describe development of three biomaterial engineering approaches to create the next generation of regeneration templates for tendon insertion injuries: composite, spatially patterned CG biomaterials.