Personne :
Larouche, Danielle

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Université Laval. Département de chirurgie
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Voici les éléments 1 - 10 sur 38
  • Publication
    Tissue engineering of skin and cornea : Development of new models for in vitro studies
    (Academy of Sciences, 2010-06-02) Guérin, Sylvain; Germain, Lucie; Larouche, Danielle; Bisson, Francis; Paquet, Claudie; Robitaille, Hubert; Auger, François A.; Gaudreault, Manon.; Martel, Israël; Duranceau, Louise; Proulx, Stéphanie; Carrier, Patrick; Simard-Bisson, Carolyne; Fradette, Julie
    Human beings are greatly preoccupied with the unavoidable nature of aging. While the biological processes of senescence and aging are the subjects of intense investigations, the molecular mechanisms linking aging with disease and death are yet to be elucidated. Tissue engineering offers new models to study the various processes associated with aging. Using keratin 19 as a stem cell marker, our studies have revealed that stem cells are preserved in human skin reconstructed by tissue engineering and that the number of epithelial stem cells varies according to the donor's age. As with skin, human corneas can also be engineered in vitro. Among the epithelial cells used for reconstructing skin and corneas, significant age-dependent variations in the expression of the transcription factor Sp1 were observed. Culturing skin epithelial cells with a feeder layer extended their life span in culture, likely by preventing Sp1 degradation in epithelial cells, therefore demonstrating the pivotal role played by this transcription factor in cell proliferation. Finally, using the human tissue-engineered skin as a model, we linked Hsp27 activation with skin differentiation.
  • Publication
    Minimal contraction for tissue-engineered skin substitutes when matured at the air–liquid interface
    (John Wiley & Sons, 2013-06-03) Germain, Lucie; Larouche, Danielle; Auger, François A.; Marcoux, Hugo-Bastien; Gauvin, Robert; Guignard, Rina
    The structural stability of skin substitutes is critical to avoid aesthetic and functional problems after grafting, such as contractures and hypertrophic scars. The present study was designed to assess the production steps having an influence on the contractile behaviour of the tissue-engineered skin made by the self-assembly approach, where keratinocytes are cultured on tissue-engineered dermis comprised of fibroblasts and the endogenous extracellular matrix they organized. Thus, different aspects were investigated, such as the assembly method of the engineered dermis (various sizes and anchoring designs) and the impact of epithelial cell differentiation (culture submerged in the medium or at the air–liquid interface). To evaluate the structural stability at the end of the production, the substitutes were detached from their anchorages and deposited on a soft substrate, and contraction was monitored over 1 week. Collected data were analysed using a mathematical model to characterize contraction. We observed that the presence of a differentiated epidermis significantly reduced the amount of contraction experienced by the engineered tissues, independently of the assembly method used for their production. When the epidermis was terminally differentiated, the average contraction was only 24 4% and most of the contraction occurred within the first 12 h following deposition on the substrate. This is 2.2-fold less compared to when the epidermis was cultured under the submerged condition, or when tissue-engineered dermis was not overlaid with epithelial cells. This study highlights that the maturation at the air–liquid interface is a critical step in the reconstruction of a tissue engineered skin that possesses high structural stability
  • Publication
    Keratin 19 as a stem cell marker in vivo and in vitro
    (Humana Press, 2005-01-01) Fortier, Kristine; Germain, Lucie; Larouche, Danielle; Hayward, Cindy Jean
    The skin is a dynamic tissue in which terminally differentiated keratinocytes are replaced by the proliferation of new epithelial cells that will undergo differentiation. The rapid and continual turnover of skin throughout life depends on a cell population with unique characteristics: the stem cells. These cells are relatively undifferentiated, retain a high capacity for self-renewal throughout their lifetime, have a large proliferative potential, and are normally slow cycling. The long-term regeneration of grafted cultured epidermis indicates that epidermal stem cells are maintained in cultures. In animals they can be identified with 3H-thymidine or bromodeoxyuridine based on their property of slow cycling. The development of markers such as keratin 19 also permits their study in human tissues. In this chapter, protocols to study skin stem cells using their property of slow cycling and their expression of keratin 19 will be described in detail. The methods include the double labeling of tissues for keratin 19 and label-retaining cells (autoradiography of 3H-thymidine) in situ. The labeling of keratin 19 by immunofluorescence of by flow cytometry is described for cells in vitro.
  • Publication
    Dissociation, quantification and culture of normal human merkel cells among epidermal cell populations derived from glabrous and hairy skin sites
    (Springer, 2003-06-23) Germain, Lucie; Larouche, Danielle; Couture, Véronique; Fugère, Claudia.; Guignard, Rina; Fradette, Julie; Caouette-Laberge, Louise; Beauparlant, Annie.; Roy, Alphonse
    Merkel cells constitute a unique population that remains difficult to characterize in human skin because of their scarcity. Our aim was to develop tools for the study of Merkel cells in vitro. As a first step, we evaluated the possibility of harvesting human Merkel cells with the two-step extraction method that is widely used to extract and culture keratinocytes. Merkel cells were identified in the epithelial portion of hairy or glabrous skin biopsies by keratin (K)18 and K20 labeling. The totality of cutaneous epithelial cells were isolated from either hairy or glabrous skin biopsies following enzymatic dissociation of both the epidermis and the hair follicles. Flow cytometry was performed to quantify the small Merkel cell population. The analysis revealed that K18-labeled cells represented between 4.0 and 7.6% of freshly dissociated basal epidermal cells. No significant differences were seen between samples derived from glabrous palmar and hairy anatomic sites from children and adults, respectively. We also reported on the presence of Merkel cells in primary and first subcultures of human epidermal cells. The next step will be to enrich the isolated human Merkel cells and improve their culture conditions. An amplification of the number of Merkel cells will allow further studies to unravel long-standing questions regarding their origin, proliferative capacity, and functions in cutaneous biology
  • Publication
    Considerations in the choice of a skin donor site for harvesting keratinocytes containing a high proportion of stem cells for culture in vitro
    (Butterworth-Heinemann, 2010-12-03) Germain, Lucie; Larouche, Danielle; Paquet, Claudie; Fugère, Claudia.; Genest, Hervé; Auger, François A.; Gauvin, Robert; Têtu, Félix-Andre; Bouchard, Maurice; Roy, Aphonse; Fradette, Julie; Lavoie, Amélie; Beauparlant, Annie.
    The treatment of severely burned patients has benefited from the grafting of skin substitutes obtained by expansion of epithelial cells in culture. The aim of this study was to evaluate whether the anatomic site chosen for harvesting skin had an impact on the quality of the derived cell cultures. Considering that hair follicles contain epithelial stem cells, we compared hairy skin sites featuring different densities and sizes of hair follicles for their capacity to generate high quality keratinocyte cultures. Three anatomic sites from adult subjects were compared: scalp, chest skin and p-auricular (comprising pre-auricular and post-auricular) skin. Keratin (K) 19 was used as a marker to evaluate the proportion of stem cells. Keratinocytes were isolated using the two-step thermolysin and trypsin cell extraction method, and cultured in vitro. The proportion of K19-positive cells harvested from p-auricular skin was about twice that of the scalp. This K19-positive cell content also remained higher during the first subcultures. In contrast to these in vitro results, the number of K19-positive cells estimated in situ on skin sections was about double in scalp as in p-auricular skin. Chest skin had the lowest number of K19-positive cells. These results indicate that in addition to the choice of an adult anatomic site featuring a high number of stem cells in situ, the quality of the cultures greatly depends on the ability to extract stem cells from the skin biopsy
  • Publication
    Vibrissa hair bulge houses two populations of skin epithelial stem cells distinct by their keratin profile
    (Federation of American Societies for Experimental Biology, 2007-12-27) Germain, Lucie; Tong, Xuemei; Larouche, Danielle; Fradette, Julie; Coulombe, Pierre A.
    Defining the properties of postnatal stem cells is of interest given their relevance for tissue homeostasis and therapeutic applications, such as skin tissue engineering for burn patients. In hair follicles, the bulge region of the outer root sheath houses stem cells. We show that explants from the prominent bulge area, but not the bulb, in rodent vibrissa follicles can produce epidermis in a skin model of tissue engineering. Using morphological criteria and keratin expression, we typified epithelial stem cells of vibrissa bulge. Two types of slow-cycling cells (Bb, Bs1) featuring a high colony-forming capacity occur in the bulge. Bb cells are located in the outermost basal layer, express K5, K15, K17, and K19, and feature a loosely organized keratin network. Bs1 cells localize to the suprabasal layers proximal to Bb cells and express K5/K17, corre lating with a network of densely bundled filaments. These prominent bundles are missing in K17-null mice, which lack vibrissa. Atypically, both the Bb and Bs1 keratinocytes lack K14 expression. These findings show heterogeneity within the hair follicle stem cell reposi tory, establish that a subset of slow-cycling cells are suprabasal in location, and point to a special role for K5/K17 filaments in a newly defined subset of stem cells. Our results are discussed in the context of long-term survival of engineered tissues after grafting that requires the presence of stem cells.
  • Publication
    Stem cells of the skin and cornea : their clinical applications in regenerative medicine
    (Rapid Science Publishers, 2011-02-01) Germain, Lucie; Larouche, Danielle; Gauvin, Robert; Proulx, Stéphanie; Fradette, Julie
    Purpose of review: The use of stem cells is of great interest for the treatment of various pathologies and ultimately for the restoration of organ function. Progress pointing towards future treatments of skin and corneal epithelial stem cell defects are reviewed, including the transplantation of living tissue-engineered substitutes. Recent findings: This article focuses on substitutes optimized for permanent replacement of skin and cornea. New skin substitutes for burn care are currently under development. More complex tissue-engineered skin substitutes in which stroma, adipose tissue, capillaries, and neurons are combined with the epithelium are being developed. Some dermal/epidermal substitutes have been applied to the treatment of patients. Cultured corneal epithelial cells have been characterized and more complete corneal substitutes are being designed. Long-term clinical results on the transplantation of cultured corneal stem cells for the treatment of limbal stem cell deficiency have been reported. Summary: Advances in tissue engineering for the development of substitutes that will benefit patients suffering from skin or corneal stem cell deficiencies are reviewed. These products are often a combination of cells, scaffolds and other factors. Key considerations in the development of corneal and skin substitutes for clinical applications are discussed.
  • Publication
    Accès libre
    Évaluation de la relation entre les apports en antioxydants et le niveau d'expression de marqueurs inflammatoires dans le tissu mammaire normal de femmes atteintes du cancer du sein
    (2017) Larouche, Danielle; Diorio, Caroline
    Le régime alimentaire joue un rôle dans le développement du cancer du sein, mais le mode d’action des facteurs nutritionnels sur le tissu mammaire est mal compris. Un des mécanismes potentiels est la création d’un stress oxydatif qui favoriserait le processus tumoral et l’inflammation. Par conséquent, la consommation d’antioxydants pourrait contribuer à réduire l’inflammation dans les tissus et à prévenir le cancer du sein. Cependant, peu d’études ont exploré la relation entre les apports en antioxydants et l’expression de marqueurs inflammatoires dans le tissu mammaire. Ce projet visait à évaluer la relation entre les apports en antioxydants et l’expression de 11 marqueurs inflammatoires dans le tissu mammaire normal de 160 femmes atteintes d’un cancer du sein. Les données alimentaires ont été obtenues par un questionnaire de fréquence alimentaire auto-administré mesurant les apports alimentaires et la prise de suppléments de l’année précédente. L’expression des marqueurs inflammatoires a été évaluée par immunohistochimie. La corrélation entre les apports en antioxydants et l’expression des marqueurs inflammatoires a été analysée par le coefficient de corrélation partiel de Spearman. Les analyses ont été effectuées pour l’ensemble de l’échantillon et pour les femmes pré-ménopausées et post-ménopausées prises séparément. Après la correction de Bonferroni, les apports élevés en bêta-tocophérol corrélaient avec une diminution de l’expression de l’IL-10 pour l’ensemble de l’échantillon (r=-0,26) et chez les femmes post-ménopausées (r=-0,39). Parmi toutes les femmes, les apports en zinc corrélaient négativement avec l’expression de l’IL-10 (r=-0,26) et parmi les femmes post-ménopausées, les apports en sélénium corrélaient négativement avec l’expression de la lactoferrine (r=-0,39). Aucune association significative n’a été observée chez les femmes pré-ménopausées. Nos résultats suggèrent que le bêta-tocophérol, le zinc et le sélénium pourraient agir sur le tissu mammaire par des mécanismes affectant l’expression de certains marqueurs inflammatoires et que ceci serait influencé par le statut ménopausique.
  • Publication
    Accès libre
    Expression of C4.4A in an in vitro human tissue-engineered skin model
    (Hindawi, 2017-09-07) Germain, Lucie; Larouche, Danielle; Rochette-Drouin, Olivier; Ploug, Michael; Jacobsen, Benedikte
    A multi-LU-domain-containing protein denoted C4.4A exhibits a tightly regulated membrane-associated expression in the suprabasal layers of stratified squamous epithelia such as skin and the esophagus, and the expression of C4.4A is dysregulated in various pathological conditions. However, the biological function of C4.4A remains unknown. To enable further studies, we evaluated the expression of C4.4A in monolayer cultures of normal human keratinocytes and in tissue-engineered skin substitutes (TESs) produced by the self-assembly approach, which allow the formation of a fully differentiated epidermis tissue. Results showed that, in monolayer, C4.4A was highly expressed in the centre of keratinocyte colonies at cell-cell contacts areas, while some cells located at the periphery presented little C4.4A expression. In TES, emergence of C4.4A expression coincided with the formation of the stratum spinosum. After the creation of a wound within the TES, C4.4A expression was observed in the suprabasal keratinocytes of the migrating epithelium, with the exception of the foremost leading keratinocytes, which were negative for C4.4A. Our results are consistent with previous data in mouse embryogenesis and wound healing. Based on these findings, we conclude that this human TES model provides an excellent surrogate for studies of C4.4A and Haldisin expressions in human stratified epithelia.
  • Publication
    Identification of epithelial stem cells in vivo and in vitro using keratin 19 and BrdU
    (Humana Press, 2010-01-01) Germain, Lucie; Larouche, Danielle; Paquet, Claudie; Simard-Bisson, Carolyne; Lavoie, Amélie
    Progress in the identification of skin stem cells and the improvement of culture methods open the possibility to use stem cells in regenerative medicine. Based on their quiescent nature, the development of label retention assays allowed the localization of skin stem cells in the bulge region of the pilosebaceous units and in the bottom of rete ridges in glabrous skin. The development of markers such as keratin 19 also permits their study in human tissues. In this chapter, protocols to identify skin stem cells based on their slow-cycling property and their expression of keratin 19 will be described in detail. The methods include the labeling of skin stem cells within mouse or rat tissues in vivo, the labeling of proliferative human cells in vitro using 5-bromo-2-deoxyuridine (BrdU), and the detection of keratin 19 and BrdU by immunofluorescence or immunoperoxidase staining.