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Personne :
Fradette, Julie

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Fradette

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Julie

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Université Laval. Département de chirurgie

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ncf11860418

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Voici les éléments 1 - 5 sur 5
  • PublicationRestreint
    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
  • PublicationRestreint
    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.
  • PublicationRestreint
    IFATS Collection : using human adipose-derived stem/stromal cells for the production of new skin substitutes
    (AlphaMed Press, 2008-07-10) Germain, Lucie; Vincent, Caroline; Trottier, Valérie; Marceau-Fortier, Guillaume; Fradette, Julie
    The ability to harvest and culture stem cell populations from various human postnatal tissues is central to regenerative medicine applications, including tissue engineering. The discovery of multipotent mesenchymal stem cells within the stromal fraction of adipose tissue prompted their use for the healing and reconstruction of many tissues. Here, we examined the influence of adipose-derived stem/stromal cells (ASCs) on skin's regenerative processes, from a tissue engineering perspective. Using a self-assembly approach, human skin substitutes were produced. They featured a stromal compartment containing human extracellular matrix endogenously produced from either dermal fibroblasts or adipose-derived stem/stromal cells differentiated or not toward the adipogenic lineage. Human keratinocytes were seeded on each stroma and cultured at the air-liquid interface to reconstruct a bilayered skin substitute. These new skin substitutes, containing an epidermis and a distinctive stroma devoid of synthetic biomaterial, displayed characteristics similar to human skin. The influence of the type of stromal compartment on epidermal morphogenesis was assessed by the evaluation of tissue histology, the expression of key protein markers of the epidermal differentiation program (keratin [K] 14, K10, transglutaminase), the expression of dermo-epidermal junction components (laminins, collagen VII), and the presence of basement membrane and hemidesmosomes. Our findings suggest that adipose-derived stem/stromal cells could usefully substitute dermal fibroblasts for skin reconstruction using the self-assembly method. Finally, by exploiting the adipogenic potential of ASCs, we also produced a more complete trilayered skin substitute consisting of the epidermis, the dermis, and the adipocyte-containing hypodermis, the skin's deepest layer. Disclosure of potential conflicts of interest is found at the end of this article.
  • PublicationAccès libre
    Human post-natal stem cells in organs produced by tissue engineering for clinical applications
    (Nova Biomedical Books, 2008-01-01) Germain, Lucie; Larouche, Danielle; Auger, François A.; Fradette, Julie
    This chapter will focus on the clinical applications of post-natal stem cells. Massive tissue loss frequently requires grafting for proper healing. Considering that there is a shortage of organ donors, the expansion of cells in vitro and the reconstruction of tissues or organs constitute a very valuable alternative solution. The first clinical application of such tissues has been the autologous culture of epidermal cells for the treatment of burn patients, and will be presented herein. Since the cutaneous epithelium forms squames that are lost, it is continuously renewed every 28 days and its long-term regeneration depends on stem cells. The importance of preserving stem cells during in vitro expansion and after grafting will thus be discussed. Clinical applications of cultured cells from other tissues, such as limbal stem cells for corneal epithelium (surface of the eye) replacement, will also be reviewed. Finally, the development of new promising technologies and methods taking advantage of other sources of stem cells that could be isolated after birth from tissues such as adipose depots will also be presented.
  • PublicationRestreint
    Evolution of three dimensional skin equivalent models reconstructed in vitro by tissue engineering
    (2009-03-01) Auxenfans, Celine; Germain, Lucie; Auger, François A.; Lequeux, Charlotte; Fradette, Julie; Kinikoglu, Beste; Bechetoille, Nicolas; Braye, Fabienne; Damour, Odile
    Since the culture of keratinocytes on feeder layers, research to produce skin equivalents has been motivated by the challenge of treating large burns and chronic wounds and by European regulations which both require proof of the innocuousness and the effectiveness of cosmetic products, and which forbid animal testing. The dynamism in fundamental research, dermocosmetology and the pharmaceutical industry has led to the evolution and complexification of reconstructed skin. The Collagen-GAG-Chitosan sponge, as well as the self-assembly model, allow dermal reconstruction in which the neosynthesized extracellular matrix contains all of the desired macromolecules. It is deposited forming an ultrastructurally organised architecture. The quality of the dermis obtained allows the development and regeneration of a pluristratified and differentiated epidermis firmly anchored by an organised dermal-epidermal junction. Evolution of reconstructed skin into models which are more and more similar to the physiological skin results in higher graft take rates in the treatment of burns and chronic wounds, and brings to research, to dermocosmetology and to the pharmaceutical industry, a wide range of products such as pigmented, endothelialized, immunocompetent, and now adipose reconstructed skins. The present review will mainly concentrate on the latest developments in skin engineering and will mostly concern the studies carried out by our groups.