Academic literature on the topic 'Dense collagen'
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Journal articles on the topic "Dense collagen"
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Zou, Chao, Wen Jian Weng, Xu Liang Deng, Kui Cheng, Pi Yi Du, Ge Shen, and Gao Rong Han. "Influence of Collagen Status on Microstructures of Porous Collagen/TCP Composites." Key Engineering Materials 330-332 (February 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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Short, Ben. "Dense collagen kindles invadopodia formation." Journal of Cell Biology 208, no. 3 (February 2, 2015): 252. http://dx.doi.org/10.1083/jcb.2083iti3.
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Keene, D. R., L. Y. Sakai, G. P. Lunstrum, N. P. Morris, and R. E. Burgeson. "Type VII collagen forms an extended network of anchoring fibrils." Journal of Cell Biology 104, no. 3 (March 1, 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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Giraud Guille, Marie Madeleine, Christophe Helary, Sylvain Vigier, and Nadine Nassif. "Dense fibrillar collagen matrices for tissue repair." Soft Matter 6, no. 20 (2010): 4963. http://dx.doi.org/10.1039/c0sm00260g.
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Chicatun, Florencia, Claudio E. Pedraza, Chiara E. Ghezzi, Benedetto Marelli, Mari T. Kaartinen, Marc D. McKee, and Showan N. Nazhat. "Osteoid-Mimicking Dense Collagen/Chitosan Hybrid Gels." Biomacromolecules 12, no. 8 (August 8, 2011): 2946–56. http://dx.doi.org/10.1021/bm200528z.
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Traub, W., L. Zylberberg, V. de Buffrenil, T. Arad, and S. Weiner. "Collagen-apatite complexes in very dense bones." Acta Crystallographica Section A Foundations of Crystallography 58, s1 (August 6, 2002): c172. http://dx.doi.org/10.1107/s0108767302091900.
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Fatiroi, Nurul Syazwanie, Abdul Aziz Jaziri, Rossita Shapawi, Ruzaidi Azli Mohd Mokhtar, Wan Norhana Md Noordin, and Nurul Huda. "Biochemical and Microstructural Characteristics of Collagen Biopolymer from Unicornfish (Naso reticulatus Randall, 2001) Bone Prepared with Various Acid Types." Polymers 15, no. 4 (February 20, 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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Aplin, J. D., S. Campbell, and T. D. Allen. "The extracellular matrix of human amniotic epithelium: ultrastructure, composition and deposition." Journal of Cell Science 79, no. 1 (November 1, 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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Ahmed, Zara, Lydia C. Powell, Navid Matin, Andrew Mearns-Spragg, Catherine A. Thornton, Ilyas M. Khan, and Lewis W. Francis. "Jellyfish Collagen: A Biocompatible Collagen Source for 3D Scaffold Fabrication and Enhanced Chondrogenicity." Marine Drugs 19, no. 8 (July 22, 2021): 405. http://dx.doi.org/10.3390/md19080405.
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Osteoarthritis (OA) is a multifactorial disease leading to degeneration of articular cartilage, causing morbidity in approximately 8.5 million of the UK population. As the dense extracellular matrix of articular cartilage is primarily composed of collagen, cartilage repair strategies have exploited the biocompatibility and mechanical strength of bovine and porcine collagen to produce robust scaffolds for procedures such as matrix-induced chondrocyte implantation (MACI). However, mammalian sourced collagens pose safety risks such as bovine spongiform encephalopathy, transmissible spongiform encephalopathy and possible transmission of viral vectors. This study characterised a non-mammalian jellyfish (Rhizostoma pulmo) collagen as an alternative, safer source in scaffold production for clinical use. Jellyfish collagen demonstrated comparable scaffold structural properties and stability when compared to mammalian collagen. Jellyfish collagen also displayed comparable immunogenic responses (platelet and leukocyte activation/cell death) and cytokine release profile in comparison to mammalian collagen in vitro. Further histological analysis of jellyfish collagen revealed bovine chondroprogenitor cell invasion and proliferation in the scaffold structures, where the scaffold supported enhanced chondrogenesis in the presence of TGFβ1. This study highlights the potential of jellyfish collagen as a safe and biocompatible biomaterial for both OA repair and further regenerative medicine applications.
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Ebelt, Nancy D., Vic Zamloot, Edith Zuniga, Kevin B. Passi, Lukas J. Sobocinski, Cari A. Young, Bruce R. Blazar, and Edwin R. Manuel. "Collagenase-Expressing Salmonella Targets Major Collagens in Pancreatic Cancer Leading to Reductions in Immunosuppressive Subsets and Tumor Growth." Cancers 13, no. 14 (July 16, 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.
Dissertations / Theses on the topic "Dense collagen"
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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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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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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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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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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.
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Chicatun, Florencia. "In vitro generation of a bilayered dense collagen / chitosan hydrogel scaffold as an osteochondral model." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=121353.
Full textAbstract:
Success of osteochondral tissue engineering (TE) requires stratified scaffolds that mimic the biophysicochemical composition of the cellular environment of both the cartilage and subchondral bone. In vitro reconstituted collagen type I (Coll) hydrogels are widely used as biomimetic scaffolds for TE, however due to their highly-hydrated nature they collapse due to gravitational forces (self-compression; SC). Plastic compression (PC) is a method that rapidly enables the generation of dense scaffolds with solid weight percent approaching native tissues values.The aim of this doctoral research was to develop and characterize a bilayered model system for osteochondral TE applications based on the incorporation of a GAG-analog (i.e. chitosan; CTS), within a dense Coll hydrogel, to closely mimic the native extracellular matrix (ECM) of the osteochondral interface. The first objective was to develop and optimize a co-gelling system for the generation of highly-hydrated Coll/CTS hybrid gels with different CTS proportions. PC was shown to be an effective and rapid process able to generate, within minutes, dense Coll/CTS hybrid gels with increased solid weight percent, compressive modulus and resistance to enzymatic degradation, as dictated by CTS content. As a second objective, the effect of CTS incorporation on modulating MC3T3-E1 pre-osteoblast seeded-cell function within dense Coll gels was investigated. Dense Coll/CTS hydrogels supported MC3T3-E1 cell viability, proliferation, and differentiation under osteogenic-inducing conditions. These findings demonstrated that dense Coll/CTS hybrids provide an osteoid-like structure as an in vitro model for bone TE.As a third objective, the effect of CTS incorporation into dense Coll gel discs was investigated to support RCJ3.1C5.18 chondroprogenitors (RCJ) differentiation. Immunohistochemistry for collagen type II, in combination with Safranin O staining and GAG quantification, indicated greater chondroprogenitor differentiation within Coll/CTS scaffolds, compared to Coll alone. The results demonstrated the suitability of dense Coll/CTS scaffolds to be used as in vitro models for cartilage repair. The fourth objective was to develop a bilayered dense Coll/CTS hydrogel with ratios approaching those of Coll/GAGs found in the ECM at the osteochondral interface. In addition, the optimization of the co-culturing conditions to maintain the simultaneous chondro- and osteogenesis was investigated. The results demonstrated the potential of bilayered dense Coll/CTS hydrogels to be used as effective in vitro osteochondral models. As the fifth objective, CTS effect on Coll gel consolidation was investigated by monitoring the spatiotemporal distribution of fluorescent beads using confocal microscopy during Coll/CTS hydrogels consolidation. The Happel model was used to predict the hydraulic permeability of the hydrogels. In addition, the effect of CTS fixed charge on Coll hydrogels was investigated through structural, mechanical and swelling characterizations under isotonic and hypertonic conditions. The results indicate the ability of a charged GAG-analog to tailor the biophysicochemical properties of Coll hydrogels, thus providing a reliable 3D in vitro tissue model for various TE applications. In conclusion, the integrated bilayered dense Coll/CTS construct developed and characterized in this doctoral research effectively provided a tailored in vitro cell culture milieu that closely mimics a complex physiologic ECM to be used as a three-dimensional model and with the potential for clinical use as a biomimetic implant with osteochondral regenerative capacity.Le succès de régénération du tissu ostéochondral requiert le développement des matrices stratifiées afin d'imiter la composition biophysiquechimiques du cartilage et l'os sous-chondral. Les hydrogels de collagène de type I (Coll) reconstitués in vitro sont grandement utilisés en tant que matrices biomimétiques pour le génie tissulaire (GT). En raison de leur nature hautement hydratée s'affaissent à cause des forces gravitationnelles (auto-compression; SC). La compression plastique (CP) est un procédé rapide qui génère des matrices denses avec un pourcentage massique de solide que se rapprochant du taux de solide des tissus naturels. Cette recherche de doctorat a pour but de développer et caractériser un modèle à deux couches pour des applications en GT ostéochondral basés sur l'incorporation de GAGs analogiques (i.e. chitosan; CTS) dans un hydrogel Coll dense afin de reproduire de près la matrice extra-cellulaire (MEC) naturelle de l'interface ostéochondrale. Le premier objectif était de développer et d'optimiser un système co-gélifiant pour la génération de gels hybrides de Coll/CTS hautement hydraté avec diverses proportions de CTS. In a été démontré que la CP est un procédé rapide capable de générer des gels hybrides de Coll/CTS dense avec un taux de solide accru, un module de compression et une résistance à la dégradation enzimatique, le tout dicté par la teneur en CTS.Comme second objectif l'effet de l'incorporation de CTS sur la modulation de la fonction de cellules ensemencées pré-ostéoblastes MC3T3-E1 à l'intérieur de gels Coll denses a été étudié. Les hydrogels de Coll/CTS dense ont permis la viabilité et la prolifération de cellules ainsi que leur différentiation dans des conditions ostéogéniques. Ces résultats démontrent que les hybrides de Coll/CTS denses sont une approche pour l'assemblage de structures de type ostéoïdes en tant que modèle in vitro pour GT. En tant que troisième objectif l'effet de l'incorporation de CTS à des disques de gel Coll dense afin de supporter la différentiation de chondro-progéniteurs RCJ3.1C5.18 (RCJ) a été étudié. L'immunohistochimie du colagène de type II, combiné avec la coloration avec du Safranin O et la quantification des GAGs, ont indiqué que la différentiation des chondro-progéniteurs est meilleures avec les matrices de Coll/CTS. Les résultats ont démontré la pertinence de les hybrides de Coll/CTS denses pour être utilisé comme modèles in vitro pour la réparation du cartilageLe quatrième objectif était de développer une structure à deux couches d'hydrogel de Coll/CTS denses avec des ratios se rapprochant celui de Coll/GAGs se retrouvant dans l'interface ostéochondrale. De plus l'optimisation des conditions de co-culture permettant de supportent les réactions concurrentes de chondrogénèse et d'ostéogénèse. Les résultats démontrent la possibilité d'utiliser les hydrogels de Coll/CTS denses à deux couches en tant que modèles ostéochondraux in vitro. En tant que cinquièmes objectif l'effet des CTS sur la consolidation du gel de colagène a été étudié en surveillant la distribution spatiotemporelle de billes fluorescentes par microscopie confocale. Le modèle de Happel a été utilisé afin de prédire la perméabilité hydraulique des hydrogels. Aussi l'effet de la charge fixe des CTS sur les hydrogels Coll/CTS a été étudié par leur caractérisation structurelle, mécanique et de gonflement dans des conditions isotoniques et hypertoniques. Les résultats ont indiqué la capacité d'un analogue de GAG chargé à s'adapter aux propriétés biophysicochimiques des hydrogels Coll, offrant un modèle de tissus in vitro pour diverses applications de GT. En conclusion la structure à deux couches de Coll/CTS dense développée et caractérisée dans le cadre de ce doctorat a procuré un milieu de culture de cellules in vitro reproduisant la MEC complexe. Cette structure pourrait potentiellement être utilisé cliniquement en tant qu'implant biomimétique avec des capacités régénératrices ostéochondrales.
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Serpooshan, Vahid. "Control of dense collagen gel scaffolds for tissue engineering through measurement and modeling of hydraulic permeability." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97117.
Full textAbstract:
Among various natural biopolymers, type I collagen gels have demonstrated the highest potential as biomimetic scaffolds for tissue engineering (TE). However, the successful application of collagen gels requires a greater understanding of the relationship between their microstructure and physical-mechanical properties. Therefore, a precise method to modulate collagen gel microstructure in order to attain optimal scaffold properties for diverse biomedical applications is necessary. This dissertation describes a new approach to produce collagen gels with defined microstructures, quantified by hydraulic permeability (k), in order to optimize scaffold properties for TE applications. It was hypothesized that the measurement of k can be used to study the role of microstructure in collagen gel properties, as well as cell function and cell-scaffold interactions. Applying increasing levels of plastic compression (PC) to the highly hydrated collagen gels resulted in an increase in collagen fibrillar density, reduced Happel model derived k values, increased gel stiffness, promoted MSC metabolic activity, osteogenic differentiation, and mineral deposition, while cell-induced gel contraction diminished. Thus, collagen gels with lower k and higher stiffness values exhibited greater potential for bone tissue engineering.Correlating between collagen gel microstructure, k, and fibroblast function within collagen gels indicated that increasing the level of PC yielded a reduction in pore size and an increase in fibril bundle diameter. Decrease in k values resulted in a decrease in gel contraction and an increase in cell metabolic activity. An increase in cell density accelerated contraction. Therefore, fibroblast function within collagen gels can be optimised by a balance between the microstructure, k, and cell seeding density.Developing a micromechanical model to measure experimental k of collagen gels during confined compression revealed the formation of a dense collagen lamella at the fluid expulsion boundary, thereby generating a two-layer model. By applying gel mass loss into Darcy's law, experimental k values of the lamella, along with the thickness of lamella (c) and hydrated gel layer (b) were measured. An increase in either compression level or compression time resulted in a decrease in k, decrease in b, and an increase in c. In conclusion, controlled compression of collagen gels can be used to produce multi-layered biomimetic scaffolds with defined microstructures and k in order to attain optimal properties for tissue engineering applications.Parmi les biopolymères naturels couramment utilisés, les gels de collagène de type I se sont révélés être parmi les matrices biomimétiques les plus prometteuses pour l'ingénierie tissulaire. Cependant, le succès des applications thérapeutiques des matrices collagéniques nécessite une meilleure compréhension de la relation entre leur microstructure et leurs propriétés mécaniques. C'est pourquoi une méthode précise permettant de moduler la microstructure du gel de collagène est nécessaire pour pouvoir espérer atteindre les propriétés optimales de la matrice pour des applications médicales diverses. Cette thèse de doctorat décrit le développement et l'évaluation d'une nouvelle approche pour produire des gels de collagène avec une microstructure définie. Cette méthode permet de quantifier la perméabilité hydraulique (k) afin d'optimiser les propriétés de la matrice pour des applications en ingénierie tissulaire. Il a émis l'hypothèse que la mesure de k peut être utilisée pour étudier le rôle de la microstructure dans les propriétés du gel de collagène ainsi que la fonction cellulaire et les interactions matrice-cellules a été formulée.Appliquant des différents niveaux de compression plastique (PC) à des gels de collagène a entraîné une augmentation de la densité de fibrillaire, réduit les valeurs de k dérivées du modèle de Happel, augmentation de la rigidité du gel, stimulé l'activité métabolique des MSC, la différenciation ostéogénique et le dépôt de minéral, alors que la contraction du gel induite par les cellules a été réduite. Ainsi, les gels de collagène qui présentent une valeur de k plus faible et des valeurs de rigidité plus élevées ont présenté un potentiel plus élevé pour des applications en ingénierie tissulaire osseuse. Corréler la microstructure du gel de collagène, la perméabilité, et la fonction des fibroblastes cultivés dans des gels de collagène a indiqué que l'augmentation du niveau de PC résultait en la diminution de la taille des pores et une augmentation du diamètre des faisceaux de fibres. Diminution des valeurs de k résultait en une diminution de la contraction du gel et une augmentation de l'activité cellulaire métabolique. C'est pourquoi la fonction des fibroblastes, cultivés à l'intérieur de matrices de collagène, peut être optimisée en réalisant une balance entre les propriétés de microstructure, définie par k et par la densité cellulaire.Développement d'un modèle micromécanique pour mesurer la valeur expérimentale de k des gels de collagène pendant l'auto-compression radiaire confinée (SC) a révélé la formation d'une lamelle de collagène dense à la limite de l'expulsion de fluide, générant ainsi un model à deux couches. En appliquant la perte de masse de gel à la loi de Darcy, les valeurs expérimentales de k de la lamelle, ainsi que l'épaisseur de la lamelle (c) et hydratée couche de gel (b) ont été mesurés. Une augmentation soit au niveau de compression ou de temps de compression résultait en une diminution de k, diminution de b, et une augmentation de c.En conclusion, la compression contrôlée des gels hydratés de collagène peut être utilisée afin de produire des matrices multicouches biomimétiques présentant une microstructure définie et des valeurs de perméabilité permettant d'atteindre des propriétés optimales pour des applications en ingénierie tissulaire.
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Serpooshan, Vahid. "Control of dense collagen gel scaffolds for tissue engineering through measurement and modelling of hydraulic permeability." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=111921.
Full textAbstract:
Among various natural biopolymers, type I collagen gels have demonstrated the highest potential as biomimetic scaffolds for tissue engineering (TE). However, the successful application of collagen gels requires a greater understanding of the relationship between their microstructure and physical-mechanical properties. Therefore, a precise method to modulate collagen gel microstructure in order to attain optimal scaffold properties for diverse biomedical applications is necessary. This dissertation describes a new approach to produce collagen gels with defined microstructures, quantified by hydraulic permeability ( k), in order to optimize scaffold properties for TE applications. It was hypothesized that the measurement of k can be used to study the role of microstructure in collagen gel properties, as well as cell function and cell-scaffold interactions. Applying increasing levels of plastic compression (PC) to the highly hydrated collagen gels resulted in an increase in collagen fibrillar density, reduced Happel model derived k values, increased gel stiffness, promoted MSC metabolic activity, osteogenic differentiation, and mineral deposition, while cell-induced gel contraction diminished. Thus, collagen gels with lower k and higher stiffness values exhibited greater potential for bone tissue engineering.Correlating between collagen gel microstructure, k, and fibroblast function within collagen gels indicated that increasing the level of PC yielded a reduction in pore size and an increase in fibril bundle diameter. Decrease in k values resulted in a decrease in gel contraction and an increase in cell metabolic activity. An increase in cell density accelerated contraction. Therefore, fibroblast function within collagen gels can be optimised by a balance between the microstructure, k, and cell seeding density.
Developing a micromechanical model to measure experimental k of collagen gels during confined compression revealed the formation of a dense collagen lamella at the fluid expulsion boundary, thereby generating a two-layer model. By applying gel mass loss into Darcy's law, experimental k values of the lamella, along with the thickness of lamella (c) and hydrated gel layer (b) were measured. An increase in either compression level or compression time resulted in a decrease in k, decrease in b, and an increase in c. In conclusion, controlled compression of collagen gels can be used to produce multi-layered biomimetic scaffolds with defined microstructures and k in order to attain optimal properties for tissue engineering applications.
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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.
Full textAbstract:
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
Books on the topic "Dense collagen"
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Hoyle, Denise, and Emma Mason. Denise Hoyle : An Artist at Her Kitchen Table: Collages and Other Works. Bread and Butter Press, 2018.
Find full textBook chapters on the topic "Dense collagen"
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Pavelka, Margit, and 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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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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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, and 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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Park, Hyeree, Derek H. Rosenzweig, and 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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Vedam-Mai, Vinata, Anthony T. Yachnis, Michael Ullman, Saman P. Javedan, and Michael S. Okun. "Fibrous Scarring and Deep Brain Stimulation Lead Implantation." In Deep Brain Stimulation, edited by Laura S. Surillo Dahdah, Padraig O’Suilleabhain, Hrishikesh Dadhich, Mazen Elkurd, Shilpa Chitnis, and 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, and 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.
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Vincent, Maria, Jose Quintero, Henry D. Perry, and 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.
Full textAbstract:
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.
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Ricard-Blum, Sylvie, *. Bernard Dublet, and 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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Lima, Larissa Luana Lopes, Regina Moura de Oliveira, Ana Hester Silva Santos, Maria Eduarda Gomes Freires, Jonatas Monteiro Simião, Alexandrino José de Carvalho Neto, Erasmo de Almeida Júnior, and Émerson de Oliveira Ferreira. "Incidence of metopism in dried skulls of adults from the osteological collection of the faculty of medicine of FAP-Araripina (PE)." In Health and Medicine: Science, Care, and Discoveries. Seven Editora, 2023. http://dx.doi.org/10.56238/sevened2023.004-018.
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During fetal life and childhood, the bones of the skull and face are separated by dense connective tissue membranes with large amounts of collagen fibers that constitute the sutures. One of these is the metopic suture, which joins the two frontal bones in the embryonic period and in the newborn. This suture appears approximately at the end of the second month of intrauterine life between the two ossification centers of the frontal bone, being considered as an anterior extension of the sagittal suture and its total fusion can occur from the end of the first year to the eighth or tenth year of life. , and may persist in adults. The objective of our study was to verify the incidence of metopic suture in dry skulls of adults in the Northeast region of Brazil. A sample of 474 dry skulls of adults, 294 male and 180 female, belonging to the Forensic Anthropology Center of the Faculty of Medicine of FAP-Araripina was used. In general, 84.6% of the skulls did not have a persistent metopic suture, with 3.6% having a complete metopic suture, 10.3% an incomplete metopic suture of the nasion type and 1.5% an incomplete metopic suture of the nasion type. bregma type. Complete metopic suture was more frequent in males (2.3%) than in females (1.3%). Due to the large territorial extension of Brazil and the great miscegenation of the population, in our view, it is necessary to carry out more studies in Brazilian individuals through dry skulls or images, especially if carried out in different regions of our country.
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Hollywood, Eleanor, and Paul Costello. "The renal system." In Clinical Skills in Children's Nursing. Oxford University Press, 2010. http://dx.doi.org/10.1093/oso/9780199559039.003.0020.
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The focus of this chapter is the renal system and the clinical skills that are associated with renal dysfunction. By the end of this chapter you will be knowledgeable in relation to these skills and your new knowledge will be underpinned by up-to-date evidence-based best practice. It is anticipated that you will be able to do the following once you have read and studied this chapter: ● Understand urine sampling techniques and urine testing methods and their significance in clinical practice. ● Understand the various procedures and investigations that the infant, child, or young person may have to endure for renal system evaluation. The urinary system is important in maintaining the correct water and electrolyte concentrations in the body. Waste products and excess water and ions are eliminated from the body in the urine. The kidneys are situated on either side of the vertebral column in the abdomen. The ureter, renal blood vessels, nerves, and lymphatics enter the kidney at a cleft on the medial side called the hilum. The adrenal gland lies on top of the kidney. The outside of each kidney is lined by: ● The renal capsule—a layer of collagen fibres. ● The adipose capsule—a layer of fat. ● The renal fascia—a layer of dense connective tissue. These three layers of tissue protect and support the kidney. The inside of each kidney contains an outer area (the cortex) and an inner area (the medulla). The cortex is lighter in colour compared to the dark reddish-brown medulla. The medulla contains cone-shaped areas of tissue called the medullary pyramids, which point towards the hilum. The cortex extends in between the medullary pyramids forming the renal columns. Urine forms at the tip of the pyramids (papillae) and drains into the minor calyx, then into a larger major calyx. Two or three major calyces join together to form the renal pelvis, a funnel-shaped chamber that leads into the ureter. Nephrons are the functional units of the kidney, the structures where urine is formed.
Conference papers on the topic "Dense collagen"
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Esbona, Karla, David Inman, Sandeep Saha, Kevin Eliceiri, Lee G. Wilke, and 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, and 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, and 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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Esbona, K., DR Inman, S. Saha, LG Wilke, and 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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Coudrillier, Baptiste, Craig Boote, and 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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Coudrillier, Baptiste, Craig Boote, and 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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Mendoza, Maria Gracia Garcia, David R. Inman, Justin J. Jeffery, and 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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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.
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Ziegler, Kimberly A., and 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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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.