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Personne :
Gauvin, Robert

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Gauvin

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Robert

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Université Laval. Faculté de médecine

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ncf12139335

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Voici les éléments 1 - 5 sur 5
  • PublicationRestreint
    Tissue reorganization in response to mechanical load increases functionality
    (2005-02-28) Bergeron, François; Langelier, Ève.; Grenier, Guillaume.; Germain, Lucie; Larouche, Danielle; Dupuis, Daniel; Rancourt, Denis; Auger, François A.; Gauvin, Robert; Baker, Kathleen; Rémy-Zolghadri, Murielle
    In the rapidly growing field of tissue engineering, the functional properties of tissue substitutes are recognized as being of the utmost importance. The present study was designed to evaluate the effects of static mechanical forces on the functionality of the produced tissue constructs. Living tissue sheets reconstructed by the self-assembly approach from human cells, without the addition of synthetic material or extracellular matrix (ECM), were subjected to mechanical load to induce cell and ECM alignment. In addition, the effects of alignment on the function of substitutes reconstructed from these living tissue sheets were evaluated. Our results show that tissue constructs made from living tissue sheets, in which fibroblasts and ECM were aligned, presented higher mechanical resistance. This was assessed by the modulus of elasticity and ultimate strength as compared with tissue constructs in which components were randomly oriented. Moreover, tissue-engineered vascular media made from a prealigned living tissue sheet, produced with smooth muscle cells, possessed greater contractile capacity compared with those produced from living tissue sheets that were not prealigned. These results show that the mechanical force generated by cells during tissue organization is an asset for tissue component alignment. Therefore, this work demonstrates a means to improve the functionality (mechanical and vasocontractile properties) of tissues reconstructed by tissue engineering by taking advantage of the biomechanical forces generated by cells under static strain.
  • PublicationRestreint
    A novel cylindrical biaxial computer-controlled bioreactor and biomechanical testing device for vascular tissue engineering
    (Mary Ann Liebert, 2009-04-22) Zaucha, Michael T.; Germain, Lucie; Raykin, Julia; Auger, François A.; Wan, William; Gauvin, Robert; Michaels, Thomas E.; Gleason, Rudolph L.
    It is becoming evident that tissue-engineered constructs adapt to altered mechanical loading, and that specific combinations of multidirectional loads appear to have a synergistic effect on the remodeling. However, most studies of mechanical stimulation of engineered vascular tissue engineering employ only uniaxial stimulation. Here we present a novel computer-controlled bioreactor and biomechanical testing device designed to precisely and simultaneously control mean and cyclic values of transmural pressure (at rates up to 1 Hz and ranges of 40 mmHg), luminal flow rate, and axial length (or load) applied to gel-derived, scaffold-derived, and self-assembly-derived tissue-engineered blood vessels during culture, while monitoring vessel geometry with a resolution of 6.6 μm. Intermittent monitoring of the extracellular matrix and cells is accomplished on live tissues using multi-photon confocal microscopy under unloaded and loaded conditions at multiple time-points in culture (on the same vessel) to quantify changes in cell and extracellular matrix content and organization. This same device is capable of performing intermittent cylindrical biaxial biomechanical testing at multiple time-points in culture (on the same vessel) to quantify changes in the mechanical behavior during culture. Here we demonstrate the capabilities of this new device on self-assembly-derived and collagen-gel-derived tissue-engineered blood vessels.
  • PublicationRestreint
    A novel single-step self-assembly approach for the fabrication of tissue-engineered vascular constructs
    (Mary Ann Liebert, 2009-12-28) Germain, Lucie; Ahsan, Taby; Larouche, Danielle; Auger, François A.; Gauvin, Robert; Dubé, Jean; Tanguay, Robert M.; Lévesque, Philippe
    There is a clinical need for a functional tissue-engineered blood vessel because small-caliber arterial graft (<5 mm) applications are limited by the availability of suitable autologous vessels and suboptimal performances of synthetic grafts. This study presents an analysis of the mechanical properties of tissue-engineered vascular constructs produced using a novel single-step self-assembly approach. Briefly, the tissue-engineered vascular media were produced by culturing smooth muscle cell in the presence of sodium l-ascorbate until the formation of a cohesive tissue sheet. This sheet was then rolled around a tubular support to create a media construct. Alternatively, the tissue-engineered vascular adventitia was produced by rolling a tissue sheet obtained from dermal fibroblasts or saphenous vein fibroblasts. The standard self-assembly approach to obtain the two-layer tissue-engineered vascular constructs comprising both media and adventitia constructs consists of two steps in which tissue-engineered vascular media were first rolled on a tubular support and a tissue-engineered vascular adventitia was then rolled on top of the first layer. This study reports an original alternative method for assembling tissue-engineered vascular constructs comprising both media and an adventitia in a single step by rolling a continuous tissue sheet containing both cell types contiguously. This tissue sheet was produced by growing smooth muscle cells alongside fibroblasts (saphenous vein fibroblasts or dermal fibroblasts) in the same culture dish separated by a spacer, which is removed later in the culture period. The mechanical strength assessed by uniaxial tensile testing, burst pressure measurements, and viscoelastic behavior evaluated by stepwise stress relaxation tests reveals that the new single-step fabrication method significantly improves the mechanical properties of tissue-engineered vascular construct for both ultimate tensile strength and all the viscoelastic moduli.
  • PublicationRestreint
    Surface topography induces 3D self-orientation of cells and extracellular matrix resulting in improved tissue function
    (RSC Pub., 2009-01-15) Guillemette, Maxime.; Cui, Bo; Germain, Lucie; Roy, Emmanuel; Veres, Teodor; Auger, François A.; Giasson, Claude J.; Gauvin, Robert; Esch, Mandy B.; Carrier, Patrick; Deschambeault, Alexandre; Dumoulin, Michel; Toner, Mehmet
    The organization of cells and extracellular matrix (ECM) in native tissues plays a crucial role in their functionality. However, in tissue engineering, cells and ECM are randomly distributed within a scaffold. Thus, the production of engineered-tissue with complex 3D organization remains a challenge. In the present study, we used contact guidance to control the interactions between the material topography, the cells and the ECM for three different tissues, namely vascular media, corneal stroma and dermal tissue. Using a specific surface topography on an elastomeric material, we observed the orientation of a first cell layer along the patterns in the material. Orientation of the first cell layer translates into a physical cue that induces the second cell layer to follow a physiologically consistent orientation mimicking the structure of the native tissue. Furthermore, secreted ECM followed cell orientation in every layer, resulting in an oriented self-assembled tissue sheet. These self-assembled tissue sheets were then used to create 3 different structured engineered-tissue: cornea, vascular media and dermis. We showed that functionality of such structured engineered-tissue was increased when compared to the same non-structured tissue. Dermal tissues were used as a negative control in response to surface topography since native dermal fibroblasts are not preferentially oriented in vivo. Non-structured surfaces were also used to produce randomly oriented tissue sheets to evaluate the impact of tissue orientation on functional output. This novel approach for the production of more complex 3D tissues would be useful for clinical purposes and for in vitro physiological tissue model to better understand long standing questions in biology.
  • PublicationAccès libre
    Impact of cell source on human cornea reconstructed by tissue engineering
    (IOVS, 2009-06-01) Giasson, Claude-J.; Guérin, Sylvain; Germain, Lucie; Audet, Caroline; Giroux-Talbot, Mariève; Auger, François A.; Gauvin, Robert; Carrier, Patrick; Deschambeault, Alexandre
    Purpose: To investigate the effect of the tissue origin of stromal fibroblasts and epithelial cells on reconstructed corneas in vitro. Methods: Four types of constructs were produced by the self-assembly approach using the following combinations of human cells: corneal fibroblasts/corneal epithelial cells, corneal fibroblasts/skin epithelial cells, skin fibroblasts/corneal epithelial cells, skin fibroblasts/skin epithelial cells. Fibroblasts were cultured with ascorbic acid to produce stromal sheets on which epithelial cells were cultured. After 2 weeks at the air-liquid interface, the reconstructed tissues were photographed, absorption spectra were measured, and tissues were fixed for histologic analysis. Cytokine expression in corneal- or skin-fibroblast-conditioned media was determined with the use of protein array membranes. The effect of culturing reconstructed tissues with conditioned media, or media supplemented with a cytokine secreted mainly by corneal fibroblasts, was determined. Results: The tissue source from which epithelial and mesenchymal cells were isolated had a great impact on the macroscopic and histologic features (epithelium thickness and differentiation) and the functional properties (transparency) of the reconstructed tissues. The reconstructed cornea had ultraviolet-absorption characteristics resembling those of native human cornea. The regulation of epithelial differentiation and thickness was mesenchyme-dependent and mediated by diffusible factors. IL-6, which is secreted in greater amounts by corneal fibroblasts than skin fibroblasts, decreased the expression of the differentiation marker DLK in the reconstructed epidermis. Conclusions: The tissue origin of fibroblasts and epithelial cells plays a significant role in the properties of the reconstructed tissues. These human models are promising tools for gaining a thorough understanding of epithelial-stromal interactions and regulation of epithelia homeostasis.