Personne :
Bisson, Francis

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Faculté de médecine, Université Laval
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Voici les éléments 1 - 5 sur 5
  • PublicationRestreint
    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.
  • PublicationRestreint
    Dynamic mechanical stimulations induce anisotropy and improve the tensile properties of engineered tissues produced without exogenous scaffolding
    (Elsevier, 2011-09-01) Germain, Lucie; Parenteau-Bareil, Rémi; Larouche, Danielle; Bisson, Francis; Marcoux, Hugo; Bolduc, Stéphane; Auger, François A.; Gauvin, Robert; Bonnet, Adrien
    Mechanical strength and the production of extracellular matrix (ECM) are essential characteristics for engineered tissues designed to repair and replace connective tissues that are subject to stress and strain. In this study, dynamic mechanical stimulation (DMS) was investigated as a method to improve the mechanical properties of engineered tissues produced without the use of an exogenous scaffold, referred to as the self-assembly approach. This method, based exclusively on the use of human cells without any exogenous scaffolding, allows for the production of a tissue sheet comprised of cells and ECM components synthesized by dermal fibroblasts in vitro. A bioreactor chamber was designed to apply cyclic strain to engineered tissues in order to determine if dynamic culture had an impact on their mechanical properties and ECM organization. Fibroblasts were cultured in the presence of ascorbic acid for 35 days to promote ECM production and allow the formation of a tissue sheet. This sheet was grown on a custom-built anchoring system allowing for easy manipulation and fixation of the tissue in the bioreactor. Following the 35 day period, tissues were maintained for 3 days in static culture (SC), or subjected either to a static mechanical stimulation of 10% strain, or a dynamic DMS with a duty cycle of 10% uniaxial cyclic strain at 1 Hz. ECM was characterized by histology, immunofluorescence labeling and Western blotting. Both static and dynamic mechanical stimulation induced the alignment of assessed cytoskeletal proteins and ECM components parallel to the axis of applied strain and increased the ECM content of the tissues compared to SC. Measurement of the tensile mechanical properties revealed that mechanical stimulation significantly increases both the ultimate tensile strength and tensile modulus of the engineered tissues when compared to the non-stimulated control. Moreover, we demonstrated that cyclic strain significantly increases these parameters when compared to a static-loading stimulation and that mechanical stimulation contributes to the establishment of anisotropy in the structural and mechanical properties of self-assembled tissue sheets.
  • PublicationAccès libre
    Effets de couches nourricières murines et humaines sur la préservation des capacités prolifératrices des cellules épithéliales humaines cultivées in vitro
    (2012) Bisson, Francis; Germain, Lucie
    Les feuillets de cellules épidermiques cultivés en laboratoire sont des substituts cutanés pour le traitement des grands brûlés. Notre équipe a démontré que la couche nourricière de fibrobiastes (CNF) murine accroît la survie des kératinocytes (cellules épidermiques) humains en y maintenant l'expression du facteur de transcription Spl. Notre hypothèse est que l'utilisation d'une CNF irradiée accroit la survie des cellules souches épithéliales cutanées en culture, ce qui permet d'augmenter le potentiel de prolifération et de retarder la différenciation des kératinocytes en culture. Le but de ce projet est d'analyser l'effet des CNF d'origine humaine sur la prolifération et la différenciation des kératinocytes et de comprendre les mécanismes par lesquels Spl influence la survie de ces cellules, notamment en évaluant la régulation de la transcriptase inverse de la télomérase (hTERT). Des kératinocytes ont été cultivés sur une CNF humaine ou murine irradiées ainsi que sans CNF pendant une vingtaine de passages ou jusqu'à différenciation terminale. Des extraits de protéines, d'ARN et de cellules ont été prélevés à chaque passage. Le niveau d'expression de la protéine Spl ainsi que l'activité de la télomérase ont été analysés en fonction des passages. Les résultats obtenus montrent que la CNF humaine possède des caractéristiques similaires à la CNF murine tel que vérifié par le nombre de passages atteints avant différenciation ainsi que par l'expression du facteur de transcription Spl. De plus, il existe une forte corrélation entre l'expression de Spl et le taux de croissance des cellules, ce qui suggère un mécanisme par lequel Spl aiderait la prolifération des kératinocytes. Sans couche nourricière, l'activité de la télomérase et l'expression de Spl sont nettement diminuées. Par contre, les CNF humaines permettent une bonne prolifération des kératinocytes ainsi que le maintien de l'expression de Spl et de l'activité de la télomérase. En conclusion, nos résultats suggèrent que la survie des cellules épithéliales souches en culture passe par des mécanismes moléculaires impliquant Spl et le maintien de l'activité de la télomérase.
  • PublicationAccès libre
    Irradiated human dermal fibroblasts are as efficient as mouse fibroblasts as a feeder layer to improve human epidermal cell culture lifespan
    (Molecular Diversity Preservation International, 2013-02-26) Guérin, Sylvain; Germain, Lucie; Larouche, Danielle; Bisson, Francis; Rochefort, Éloise; Zaniolo, Karine; Damour, Odile; Auger, François A.; Simard-Bisson, Carolyne; Lavoie, Amélie
    A fibroblast feeder layer is currently the best option for large scale expansion of autologous skin keratinocytes that are to be used for the treatment of severely burned patients. In a clinical context, using a human rather than a mouse feeder layer is desirable to reduce the risk of introducing animal antigens and unknown viruses. This study was designed to evaluate if irradiated human fibroblasts can be used in keratinocyte cultures without affecting their morphological and physiological properties. Keratinocytes were grown either with or without a feeder layer in serum-containing medium. Our results showed that keratinocytes grown either on an irradiated human feeder layer or irradiated 3T3 cells (i3T3) can be cultured for a comparable number of passages. The average epithelial cell size and morphology were also similar. On the other hand, keratinocytes grown without a feeder layer showed heavily bloated cells at early passages and stop proliferating after only a few passages. On the molecular aspect, the expression level of the transcription factor Sp1, a useful marker of keratinocytes lifespan, was maintained and stabilized for a high number of passages in keratinocytes grown with feeder layers whereas Sp1 expression dropped quickly without a feeder layer. Furthermore, gene profiling on microarrays identified potential target genes whose expression is differentially regulated in the absence or presence of an i3T3 feeder layer and which may contribute at preserving the growth characteristics of these cells. Irradiated human dermal fibroblasts therefore provide a good human feeder layer for an effective expansion of keratinocytes in vitro that are to be used for clinical purposes.
  • PublicationRestreint
    Contribution of Sp1 to telomerase expression and activity in skin keratinocytes cultured with a feeder layer
    (Wistar Institute of Anatomy and Biology, 2014-06-24) Guérin, Sylvain; Germain, Lucie; Rochette, Patrick J.; Bisson, Francis; Zaniolo, Karine; Paquet, Claudie; Damour, Odile; Bourget, Jean-Michel; Boudreau, François; Landreville, Solange; Auger, François A.
    The growth of primary keratinocytes is improved by culturing them with a feeder layer. The aim of this study was to assess whether the feeder layer increases the lifespan of cultured epithelial cells by maintaining or improving telomerase activity and expression. The addition of an irradiated fibroblast feeder layer of either human or mouse origin (i3T3) helped maintain telomerase activity as well as expression of the transcription factor Sp1 in cultured keratinocytes. In contrast, senescence occurred earlier, together with a reduction of Sp1 expression and telomerase activity, in keratinocytes cultured without a feeder layer. Telomerase activity was consistently higher in keratinocytes grown on the three different feeder layers tested relative to cells grown without them. Suppression of Sp1 expression by RNA inhibition (RNAi) reduced both telomerase expression and activity in keratinocytes and also abolished their long-term growth capacity suggesting that Sp1 is a key regulator of both telomerase gene expression and cell cycle progression of primary cultured human skin keratinocytes. The results of the present study therefore suggest that the beneficial influence of the feeder layer relies on its ability to preserve telomerase activity in cultured human keratinocytes through the maintenance of stable levels of Sp1 expression.