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Personne :
Germain, Lucie

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Germain

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Lucie

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Université Laval. Département de chirurgie

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ncf11846565

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Voici les éléments 1 - 10 sur 173
  • 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
    Production of bioengineered cancer tissue constructs in vitro : epithelium–mesenchyme heterotypic interactions
    (Tissue Culture Association, 2001-07-01) Tremblay, Nathalie; Germain, Lucie; Wang, Chang Shu; Auger, François A.; Têtu, Bernard; Goulet, Francine
    A few models have been established to study cancer cells in vitro. However, the cellular interactions have rarely been studied specifically using bioengineered cancer constructs combining human carcinoma cells and tumor-associated fibroblasts. We developed an in vitro model of tridimensional bioengineered cancer tissue constructs (bCTC) by seeding mammary epithelial cancer cells or normal keratinocytes over a mesenchymal layer containing tumor-derived fibroblastic cells or normal skin fibroblasts. After the introduction of epithelial cells, each construct was cultured for another 10 d. Histologic analyses showed that carcinoma cell lines could invade the subjacent mesenchymal layer and that the capacity to migrate was related to the invasive potential of cancer cells and the type of fibroblasts used, while noninvasive populations did not. Of the tested epithelial cells, MDA-MB-231 and, to a lesser degree, HDQ-P1 cell lines were invasive, and the invasion was deeper into the mesenchymal component containing tumor-derived fibroblasts. However, with normal skin fibroblasts, the mesenchymal layer was degraded twice faster than with tumor-derived fibroblastic cells. MDA-MB-231 cells and normal keratinocytes induced the highest level of gelatinase B, and the level was lowest with the MCF-7 cell line. The activated form of gelatinase B was, however, induced to the highest levels in the keratinocyte-seeded bCTC containing tumor-derived but not normal fibroblasts. MDA-MB-231 was the only epithelial cancer cell line whose activity of gelatinase A was reduced when cocultured with tumor-derived fibroblasts but not under normal fibroblast stimulation. Finally, a 50/48-kDa gelatinase band has been observed in bCTCs with noninvasive epithelial cells only. Our study demonstrates the selective secretion of gelatinases according to the phenotype of the cells seeded in the various bCTCs.
  • PublicationRestreint
    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
  • 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
    In vivo remodeling of fibroblast-derived vascular scaffolds implanted for 6 months in rats
    (Hindawi, 2016-11-24) Tondreau, Maxime; Laterreur, Véronique; Germain, Lucie; Vallières, Karine; Ruel, Jean; Tremblay, Catherine; Bourget, Jean-Michel; Auger, François A.; Gauvin, Robert; Lacroix, Dan.
    There is a clinical need for tissue-engineered small-diameter (<6 mm) vascular grafts since clinical applications are halted by the limited suitability of autologous or synthetic grafts. This study uses the self-assembly approach to produce a fibroblast-derived decellularized vascular scaffold (FDVS) that can be available off-the-shelf. Briefly, extracellular matrix scaffolds were produced using human dermal fibroblasts sheets rolled around a mandrel, maintained in culture to allow for the formation of cohesive and three-dimensional tubular constructs, and decellularized by immersion in deionized water. The FDVSs were implanted as an aortic interpositional graft in six Sprague-Dawley rats for 6 months. Five out of the six implants were still patent 6 months after the surgery. Histological analysis showed the infiltration of cells on both abluminal and luminal sides, and immunofluorescence analysis suggested the formation of neomedia comprised of smooth muscle cells and lined underneath with an endothelium. Furthermore, to verify the feasibility of producing tissue-engineered blood vessels of clinically relevant length and diameter, scaffolds with a 4.6 mm inner diameter and 17 cm in length were fabricated with success and stored for an extended period of time, while maintaining suitable properties following the storage period. This novel demonstration of the potential of the FDVS could accelerate the clinical availability of tissue-engineered blood vessels and warrants further preclinical studies.
  • PublicationRestreint
    The tissue-engineered human cornea as a model to study expression of matrix metalloproteinases during corneal wound healing
    (Elsevier BV, 2015-11-22) Guérin, Sylvain; Germain, Lucie; Couture, Camille; Zaniolo, Karine; Lake, Jennifer; Patenaude, Julien; Carrier, Patrick
    Corneal injuries remain a major cause of consultation in the ophthalmology clinics worldwide. Repair of corneal wounds is a complex mechanism that involves cell death, migration, proliferation, differentiation, and extracellular matrix (ECM) remodeling. In the present study, we used a tissue-engineered, two-layers (epithelium and stroma) human cornea as a biomaterial to study both the cellular and molecular mechanisms of wound healing. Gene profiling on microarrays revealed important alterations in the pattern of genes expressed by tissue-engineered corneas in response to wound healing. Expression of many MMPs-encoding genes was shown by microarray and qPCR analyses to increase in the migrating epithelium of wounded corneas. Many of these enzymes were converted into their enzymatically active form as wound closure proceeded. In addition, expression of MMPs by human corneal epithelial cells (HCECs) was affected both by the stromal fibroblasts and the collagen-enriched ECM they produce. Most of all, results from mass spectrometry analyses provided evidence that a fully stratified epithelium is required for proper synthesis and organization of the ECM on which the epithelial cells adhere. In conclusion, and because of the many characteristics it shares with the native cornea, this human two layers corneal substitute may prove particularly useful to decipher the mechanistic details of corneal wound healing.
  • PublicationRestreint
    Localization of merkel cells at hairless and hairy human skin sites using keratin 18
    (National Research Council of Canada, 1995-09-01) Michel, Martine; Germain, Lucie; Godbout, Marie-Josée; Fradette, Julie
    Les cellules de Merkel sont des cellules cutanées particulières, possédant non seulement des granules de sécrétion contenant des neuropeptides, mais également des desmosomes et des tonofilaments formés des kératines 8, 18, 19 et 20. Les cellules de Merkel sont plutôt rares dans la peau d'adulte. Toutefois, elles ont été observées en plus grande quantité dans les régions sans poils, telles la paume des mains et la plante des pieds. Leur présence a aussi été rapportée dans les follicules pileux. Les cellules de Merkel sont souvent innervées par des fibres nerveuses sensorielles et on leur reconnaît un rôle de mécanorécepteurs dans la peau. Toutefois, leur origine et fonction précises ne sont pas encore clairement établies. Le but de cette étude était de localiser les cellules de Merkel dans des régions anatomiques pourvues ou non de follicules pileux, par immunohistochimie avec les anticorps Ks18.174 et Ks19.1 respectivement dirigés contre les kératines 18 et 19. Dans la paume des mains et la plante des pieds, les cellules de Merkel ont été identifiées dans la couche basale de l'épiderme, à la base des papilles. Pour étudier la localisation des cellules de Merkel dans une région possédant des poils, nous avons choisi la peau provenant de réduction mammaire car on y trouve de petits follicules pileux représentatifs des poils couvrant une grande partie de notre corps. Des cellules de Merkel ont été observées dans l'épiderme interfolliculaire et dans le follicule pileux, où elles ont été localisées dans la région de l'isthme.Mots clés : peau, humain, cellule de Merkel, kératines, follicule pileux.
  • PublicationRestreint
    Rescue of the transcription factors Sp1 and NFI in human skin keratinocytes through a feeder-layer-dependent suppression of the proteasome activity
    (Academic Press, 2012-03-12) Masson-Gadais, Bénédicte; Guérin, Sylvain; Germain, Lucie; Rochette, Patrick J.; Duval, Céline; Gaudreault, Manon.; Vigneault, François; Touzel-Deschênes, Lydia
    Co-culturing human skin keratinocytes along with a feeder layer has proven to considerably improve their proliferative properties by delaying massive induction of terminal differentiation. Through a yet unclear mechanism, we recently reported that irradiated 3T3 (i3T3) fibroblasts used as a feeder layer increase the nuclear content of Sp1, a positive transcription factor (TF) that plays a critical role in many cellular functions including cell proliferation, into both adult skin keratinocytes and newborn skin keratinocytes. In this study, we examined the influence of i3T3 on the expression and DNA binding of NFI, another TF important for cell proliferation and cell cycle progression, and attempted to decipher the mechanism by which the feeder layer contributes at maintaining higher levels of these TFs in skin keratinocytes. Our results indicate that co-culturing both adult skin keratinocytes and newborn skin keratinocytes along with a feeder layer dramatically increases glycosylation of NFI and may prevent it from being degraded by the proteasome.
  • PublicationRestreint
    Biliary epithelial and hepatocytic cell lineage relationships in embryonic rat liver as determined by the differential expression of cytokeratins, α-fetoprotein, albumin, and cell surface-exposed components
    (Waverly Press, 1988-09-01) Germain, Lucie; Marceau, Normand; Blouin, Marie-Josée
    The differentiation patterns of epithelial cells in fetal rat liver were analyzed in situ and in primary culture by indirect immunofluorescence microscopy using polyvalent and monoclonal antibodies directed against cytokeratins with molecular weights of 55,000 (CK55), 52,000 (CK52), and 39,000 (CK39) and against vimentin, albumin, α-fetoprotein, and surface-exposed components of bile ductular cells (BDS7) and hepatocytes (HES6). The anti-CK52 antibody, which reacted with biliary ductal cells in the liver of adult rats (Germain et al., Cancer Res., 45: 673, 1985; Germain et al., Cancer Res., 48: 368–378, 1988), stained essentially all of the epithelial cells of embryonic day 12 (E12) rat liver. The anti-BDS7 antibody reacted with a few cell foci, which enlarged and became more numerous at later developmental ages. At E12 essentially all of the cells were positive for albumin and α-fetoprotein but did not express HES6. In fact HES6 was not detected until E15 in cells with the morphology of immature hepatocytes. By E18 staining with anti-HES6 reached the level of that observed on adult rat hepatocytes. Liver cells isolated from E12 rats were seeded on fibronectin-treated dishes and their response to various combinations of growth- and differentiation-promoting factors was evaluated with respect to their capacity to express either the hepatocytic or the bile ductular phenotype. In medium supplemented with serum, insulin, dexamethasone, and dimethyl sulfoxide, the E12 cells were capable of differentiating in culture to mimic over a 6-day period the sequential phenotypic changes which occur in vivo during normal hepatoontogeny, namely the loss of CK52 and the appearance of HES6. In contrast, the addition of sodium butyrate to the above supplement mixture resulted in the massive expression of BDS7. To further assess the developmental potential of fetal rat liver cells toward the biliary epithelial cell lineage, the in vitro assay was performed using cells isolated from livers of E18 rats and also from 2-day-old (P2) and P14 rats. While a slight expression of BDS7 was induced in cell culture from E18 liver, essentially no expression was observed in cells from postnatal livers. These findings strongly suggest that the emerging hepatic tissue in rat embryo is composed of bipotential progenitor epithelial cells that are capable of differentiating along either the hepatocytic or biliary epithelial cell lineage. These observations constitute a clear demonstration of the plasticity of liver differentiation and also provide a striking example of environmental influences on liver progenitor cell differentiation.
  • PublicationAccès libre
    What's New in Human Wound-Healing Myofibroblasts?
    (springerLink, 1999-01-01) Germain, Lucie; Garrel, Dominique A.; Castilloux, G.; Auger, François A.; O'Connor-McCourt, Maureen; Moulin, Véronique
    During wound healing and fibrocontractive diseases, clinical and experimental investigations have shown that fibroblastic cells acquire some morphological and biochemical features similar to those of smooth muscle cells [33]. These modified fibroblasts, called myofibroblasts, express de novo α-SM actin temporarily during wound healing and permanently in fibrotic situations, such as hypertrophic scars or fibromatosis. Myofibroblasts are thought to be involved in contraction and have been observed in practically all fibrotic conditions involving retraction and reorganization of connective tissues