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Berthod, François

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Berthod

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François

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Université Laval. Département de chirurgie

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Voici les éléments 1 - 10 sur 20
  • PublicationAccès libre
    Le génie tissulaire au service de la compréhension du vivant
    (Société des Périodiques Flammarion, 2003-10-15) Germain, Lucie; Auger, François A.; Berthod, François; Goulet, Francine; Moulin, Véronique
    Le génie tissulaire est un nouveau domaine, qui permet l’étude des mécanismes physiologiques du vivant. Il s’agit d’une technologie fondée sur la capacité des cellules vivantes, en présence ou non de biomatériaux, à s’assembler en un tissu tridimensionnel. Elle constitue une voie intéressante ouvrant aux chercheurs la possibilité de considérer les cellules dans un contexte proche de celui retrouvé in vivo. Cet article résume les travaux en génie tissulaire menés par le laboratoire d’organogenèse expérimentale (LOEX) au cours des dernières années, dans le but de comprendre certains des mécanismes physiologiques et pathologiques de l’organisme humain. Ainsi, la cicatrisation cutanée, mais aussi les cellules souches, l’angiogenèse et les interactions cellulaires sont des secteurs ayant profité de l’apport du génie tissulaire.
  • PublicationRestreint
    Tissue-engineered human skin substitutes developed from collagen-populated hydrated gels : clinical and fundamental applications
    (Springer, 1998-11-01) Germain, Lucie; Auger, François A.; Rouabhia, Mahmoud; Berthod, François; Goulet, Francine; Moulin, Véronique
    The field of tissue engineering has opened several avenues in biomedical sciences, through ongoing progress. Skin substitutes are currently optimised for clinical as well as fundamental applications. The paper reviews the development of collagen-populated hydrated gels for their eventual use as a therapeutic option for the treatment of burn patients or chronic wounds: tools for pharmacological and toxicological studies, and cutaneous models for in vitro studies. These skin substitutes are produced by culturing keratinocytes on a matured dermal equivalent composed of fibroblasts included in a collagen gel. New biotechnological approaches have been developed to prevent contraction (anchoring devices) and promote epithelial cell differentiation. The impact of dermo-epidermal interactions on the differentiation and organisation of bio-engineered skin tissues has been demonstrated with human skin cells. Human skin substitutes have been adapted for percutaneous absorption studies and toxicity assessment. The evolution of these human skin substitutes has been monitored in vivo in preclinical studies showing promising results. These substitutes could also serve as in vitro models for better understanding of the immunological response and healing mechanism in human skin. Thus, such human skin substitutes present various advantages and are leading to the development of other bio-engineered tissues, such as blood vessels, ligaments and bronchi.
  • PublicationAccès libre
    What is new in mechanical properties of tissue-engineered organs
    (Springer, 1999-01-01) Germain, Lucie; Auger, François A.; Berthod, François; Goulet, Francine
    Tissue engineering is a promising new field based on expertise in cell biology, medicine and mechanical engineering. It raises exciting hopes of producing autologous tissue substitutes to replace altered organs. This challenge involves highly specialized technology in order to provide the proper shape to the tissue and promote the maintenance of its native physiological properties. Primary cell populations may lose some of their functional and morphological properties in vitro in the absence of a proper environment. In order to maintain cell integrity, a three-dimensional matrix that mimics the in vivo environment as closely as possible was developed, according to the type of tissue produced [1, 5, 18, 26, 27, 29, 34, 35].
  • PublicationRestreint
    Use of in vitro reconstructed skin to cover skin flap donor site
    (Academic Press, 2002-04-12) Li, Hui; Germain, Lucie; Xu, Wen; Damour, Odile; Auger, François A.; Berthod, François
    Background: The skin flap technique is widely used in reconstructive surgery for the coverage of deep burns of the face, neck, and joints. Facial deformities and joint contractures are avoided by transplanting vascularized full-thickness skin on wounds. The major drawback of this technique is the injury inflicted upon the donor site, which corresponds to a third degree burn. The usual technique to cover the flap donor site is the transplantation of split-thickness autografts. In the case of patients with deep and extensive burns, the harvesting of good quality autografts is often difficult because of multiple scars. In order to avoid additional trauma to the patient by split-thickness skin harvesting, we have experimented the use of a new model ofin vitroreconstructed skin graft for flap donor site coverage in a mouse model. Materials and methods: The reconstructed skin was grafted on the back of nude mice at the skin flap donor site, while flap was used to cover a wound generated on joint of the posterior leg. Results: A 100% graft take was achieved (16 mice were used) and a limited contraction of the reconstructed skin was observed 30 days posttransplantation (78% of the initial surface area of the graft remained). Histological analysis of the graft demonstrated healing of a well differentiated epidermis laying on a dense dermis. Conclusions: Since this technique would prevent additional trauma to the patient while achieving a good healing of the wound, it may be a useful approach in the coverage of skin flap donor site in humans.
  • PublicationRestreint
    Engineering human tissues for in vivo applications
    (New York Academy of Sciences, 2002-06-01) Germain, Lucie; Auger, François A.; Berthod, François; Goulet, Francine; Moulin, Véronique
    Tissue engineering is a rapidly developing field. This technology could offer a new alternative for wound repair and organ replacement. It is based on the ability of living cells, with or without biomaterials, to be assembled as three-dimensional tissues. The in vivo applications extend from specialized dressings that improve host tissue repair (e.g., ulcer) to permanent grafts that restore the function of the tissue (e.g., skin grafting for burn patients).
  • PublicationRestreint
    How to achieve early vascularization of tissue-engineered skin substitutes
    (Mary Ann Liebert, 2010-01-01) Germain, Lucie; Auger, François A.; Berthod, François; Pouliot, Roxane
    Background: The coverage of deep and extensive burns with autologous tissue-engineered skin is a promising strategy to improve the cosmetic aspect and functionality of the skin, compared to the transplantation of simple epithelial sheets. Indeed, a dermal compartment could markedly help to prevent hypertrophic scar formation and to strengthen the dermal–epidermal junction while increasing skin suppleness and pliability. The Problem: The thickness of the dermis could be a limitation to the survival of the tissue after transplantation, since its vascularization can take up to 2 weeks to occur through neovascularization. This delay could lead to graft necrosis. Basic/Clinical Science Advances: To overcome this problem, the reconstruction of a preformed network of branching capillaries in the dermis before grafting has proven to be an efficient solution in connecting to the host's vasculature in less than 4 days after grafting. The formation of this capillary-like network is achieved by the coculture of human fibroblasts and endothelial cells in a collagen sponge for a 1-month in vitro maturation period. The successful inosculation process between human capillaries and the host's vasculature was demonstrated after grafting onto nude mice. Clinical Care Relevance: In addition to autologous epithelial sheets and split-thickness autografts, this endothelialized reconstructed skin made of the patient's own cells could be a valuable additional strategy to permanently cover deep wounds. Conclusion: The reconstruction in tissue-engineered organs of a capillary-like network made of the patient's own cells before grafting is a promising approach to promote their early vascularization.
  • PublicationRestreint
    Principles of living organ reconstruction by tissue engineering
    (Marcel Dekker, 2004-01-01) Germain, Lucie; Auger, François A.; Berthod, François; Goulet, Francine; Moulin, Véronique
    Tissue engineering is a novel sector arising from the biomaterial field, which is developing rapidly as a result of the dramatic cIinicalneed for organ replacement,since there is unfortunately an ever-growing lack of organs for transplantation. Various approaches are presently being developed in different laboratories and companies based on the utilization of biomaterials, extracellular matrix components, and cellsto produce substitutesto aJlowthe replacement of wounded or diseased tissues. Theorgan reconstructionby tissue engineering presented in this chapter are of living tissues. This concept entails that the various cells incorporated in our constructs or tissues are not only readily dividing, but also metabolically active. Thus, mesenchymal cells (fibroblasts, smooth muscle cells) incorporated into the stromal component of these substitutes are also significantly involved in the reorganization of the extracellular matrix. Furthermore, the interactions between the mesenchymal cells and the epithelial cells improve the very nature, structure, and function of the resulting organ. Lastly, the presence of living cells, within the in vitro engineered tissues, adds the benefit of tissue remodeling and healing after transplantation in vivo. The source of cells that can be used for tissue reconstruction is dictated by the foreseen application. Autologous cells will be necessary for the production of living tissue substitutes when striving for permanent replacement of organs in order to prevent any histocompatibility mismatch and the ensuing predictable rejection (e.g., skin grafting for full-thickness burns). However, the rejection process has been shown to vary with the type of cells involved, and it may be possible to graft allogeneic engineered tissue under some appropriate conditions. But in such cases as keratinocytes, dentritic cells and endothelial cells that are privileged targets for rejection, autologous ceIls are necessary to permanently replace tissues encompassing these cells. ln sharp contrast, when the living tissue substitute is destined to improve wound healing, such as in the case of uIcers,allogeneic cells are sufficientsince they act as a temporary coverage, enhancing the natural healing process, and will be replaced over time by cells from the receiver. The firststep in reconstructing a living organ by tissue engineering in vitro is the isolation and culture of each cell type. The most stringent conditions must be met during this step since it has a direct impact on the quality of the desired tissue engineered product. The ideal cellsource for tissue reconstructionshouldprovide celIswith extensive proliferation potential (self-renewal capacity) and appropriate differentiation abilities (able to give rise to a differentiated progeny). Each cell culture method must be characterized in such a manner to ensure that the isolation method and culture conditions (e.g., culturé medium and growth factors) during the growth as weil as during the maturation period are the most appropriate to conserve cell purity and phenotype. This chapter wilI focus on the various approachesdevelopedover the years by the Laboratoire d'Organogénèse Expérimental (LOEX) (Hôpital du Saint-Sacrement, Chauq, Quebec) to obtain three-dimensional tissues such as reconstructed epidermis, skin, blood vessel, comea, bronchi, and ligament.
  • PublicationRestreint
    Comparative study of bovine, porcine and avian collagens for the production of a tissue engineered dermis
    (Elsevier, 2011-06-17) Germain, Lucie; Parenteau-Bareil, Rémi; Gauvin, Robert; Cliche, Simon.; Gariépy, Claude; Berthod, François
    Combining bovine collagen with chitosan followed by freeze-drying has been shown to produce porous scaffolds suitable for skin and connective tissue engineering applications. In this study collagen extracted from porcine and avian skin was compared with bovine collagen for the production of tissue engineered scaffolds. A similar purity of the collagen extracts was shown by electrophoresis, confirming the reliability of the extraction process. Collagen was solubilized, cross-linked by adding chitosan to the solution and freeze-dried to generate a porous structure suitable for tissue engineering applications. Scaffold porosity and pore morphology were shown to be source dependant, with bovine collagen and avian collagen resulting into the smallest and largest pores, respectively. Scaffolds were seeded with dermal fibroblasts and cultured for 35 days to evaluate the suitability of the different collagen–chitosan scaffolds for long-term tissue engineered dermal substitute maturation in vitro. Cell proliferation and scaffold biocompatibility were found to be similar for all the collagen–chitosan scaffolds, demonstrating their capability to support long-term cell adhesion and growth. The scaffolds contents was assessed by immunohistochemistry and showed increased deposition of extracellular matrix by the cells as a function of time. These results correlate with measurements of the mechanical properties of the scaffolds, since both the ultimate tensile strength and tensile modulus of the cell seeded scaffolds had increased by the end of the culture period. This experiment demonstrates that porcine and avian collagen could be used as an alternative to bovine collagen in the production of collagen–chitosan scaffolding materials.
  • PublicationRestreint
    Multiple applications of tissue-engineered human skin
    (Thieme, 2001-01-01) Carlos, A.; Germain, Lucie; Auger, François A.; López Valle, Carlos Antonio; Berthod, François; Goulet, Francine; Moulin, Véronique
    The progress in tissue engineering has lead to the development of tri-dimensional tissues that can be used in vitro for various applications. Different methods have been designed to produce reconstructed dermis or skin in vitro. This chapter describes the human skin models and substitutes with respect to the evolution of their complexity as well as some of their potential applications. Dermal fibroblasts or myofibroblasts included in floating collagen gels produce useful wound healing models. Bi-layered human skin constructs comprising both the dermis and the epidermis could serve. for fundamental (eg. cell-matrix interactions) or applied (e.g. dermatoabsorption) studies. Another skin substitute is produced by seeding keratinocytes on fibroblasts. cultured in a collagen-chondroitin 4-6 sulfates and. chitosan sponge. The addition of endothelial cells to this model lead to the formation of capillary-like structure in the dermis. Finally, a method of human reconstructed skin production by the "auto-assembly" approach is presented. This model is developped from cells that produce their own extracellular matrix. No synthetic material or exogenous matrix is added. Thus, it could be completely autologous. Tissue engineered skin is an attractive tissue for gene therapy. Cells could be transplanted safely in vitro, evaluated for gene expression before their incorporation in reconstructed tissue and grafting in vivo. Of particular importance will be skin stem cells that have a long term regeneration potential and that can he cultured in vitro. The progress accomplished in tissue. engineering of skin is now applied to the reconstruction of other tissues and more complex organs such as ligaments, bronchi, bladder, cornea and blood vessels. These tissues could provide therapeutic alternatives in organ transplantation as well as models for varions in vitro applications.
  • PublicationAccès libre
    Markers for an In vitro skin substitute
    (Artech House, 2018-02-01T16:41:46Z) Germain, Lucie; Jean, Jessica; Larouche, Danielle; Berthod, François; Pouliot, Roxane; Maguire, Tim; Novik, Eric
    The tissue engineering self-assembly approach allows the production of skin substitutes comprising both the dermis and epidermis, using methods promoting the secretion and organization of a dense extracellular matrix by skin cells. In a reconstructed epidermis, all cellular layers of the native tissue are present. An evaluation of the expression and localization of a number of specific protein markers revealed that the self-assembled, tissue-engineered skin substitute shares some common features with normal human skin, such as the expression of Ki-67, keratins 10 and 14, filaggrin, involucrin, transglutaminase, DLK, a3-integrin subunit, laminin-S, and collagens I, II, 1V, and VII. At the ultrastructural level, many differentiation markers can be observed, including desmosomes, as well as an organized basement membrane presenting hemidesmosomes, lamina densa, and lamina lucida. In this chapter, protocols to generate skin substitutes by the self-assembly approach will be presented and the methods including the labeling of the principal skin differentiation markers by immunofluorescence will be examined.