Personne :
Laroche, Gaétan

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Université Laval. Département de génie des mines, de la métallurgie et des matériaux
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Voici les éléments 1 - 6 sur 6
  • Publication
    Accès libre
    Electrode cleanliness impact on the surface treatment of fluoropolymer films for a long-lasting plasma process
    (Elsevier, 2020-09-16) Gélinas, Alex; Laroche, Gaétan; Laurent, Morgane
    A dielectric barrier discharge in a continuous process configuration is used to coat the surface of polymer films. The effect of the growth of a coating layer on top of the uncovered electrode with regards to the physicochemical properties of the film treatment is studied. Plasma electrical parameters such as power density (−2) and voltage (kV) are monitored during a typical cycle, which is comprised between two electrode cleanings. In addition, the surface energy and chemistry are determined at chosen time-points of the process by contact angle measurements with two liquids and X-ray photoelectron spectroscopy (XPS). Based on these analyses, no major modification of the coated polymer physicochemical properties was attributed to the deposition of an organic layer on top of the bare electrodes after the equivalent of 1 h of continuous treatment.
  • Publication
    Accès libre
    Dynamics of endothelial cell responses to laminar shear stress on surfaces functionalized with fibronectin-derived peptides
    (American Chemical Society, 2018-10-11) Duchesne, Carl; Ruel, Jean; Tremblay, Catherine; Juneau, Pierre-Marc; Beland, Ariane V.; Garnier, Alain; Ling, Si Da; Boulanger, Mariève D.; Laroche, Gaétan; Hoesli, Corinne A.; Gaillet, Bruno
    Surface endothelialization could improve the long-term performance of vascular grafts and stents. We previously demonstrated that aerosol-generated fibronectin-derived peptide micropatterns consisting of GRGDS spots over a WQPPRARI background increase endothelial cell yields in static cultures. We developed a novel fluorophore-tagged RGD peptide (RGD-TAMRA) to visualize cell–surface interactions in real-time. Here, we studied the dynamics of endothelial cell response to laminar flow on these peptide-functionalized surfaces. Endothelial cells were exposed to 22 dyn/cm² wall shear stress while acquiring time-lapse images. Cell surface coverage and cell alignment were quantified by undecimated wavelet transform multivariate image analysis. Similar to gelatin-coated surfaces, surfaces with uniform RGD-TAMRA distribution led to cell retention and rapid cell alignment (∼63% of the final cell alignment was reached within 1.5 h), contrary to the micropatterned surfaces. The RGD-TAMRA peptide is a promising candidate for endothelial cell retention under flow, and the spray-based micropatterned surfaces are more promising for static cultures.
  • Publication
    Accès libre
    RGD and BMP-2 mimetic peptides crosstalk enhances osteogenic commitment of human bone marrow stem cells
    (Elsevier, 2016-03-18) Bilem, Ibrahim; Laroche, Gaétan; Plawinski, Laurent; Chevallier, Pascale; Stone, E.; Durrieu, Marie-Christine
    Human bone marrow mesenchymal stem cells (hBMSCs) commitment and differentiation are dictated by bioactive molecules sequestered within their Extra Cellular Matrix (ECM). One common approach to mimic the physiological environment is to functionalize biomaterial surfaces with ECM-derived peptides able to recruit stem cells and trigger their linage-specific differentiation. The objective of this work was to investigate combinatorial effects of RGD and BMP-2 mimetic peptides on the osteogenic commitment of hBMSCs, without supplementing the media with pro-osteogenic factors. The RGD peptide promotes cell adhesion via cell transmembrane integrin receptors, while the BMP-2 peptide, corresponding to residues 73-92 of Bone Morphogenetic Protein-2, was shown to induce hBMSCs osteoblast differentiation. The immobilization of peptides on aminated glass was ascertained by X-ray Photoelectron Spectroscopy (XPS), the density of grafted peptides was quantified by fluorescence microscopy and the surface roughness was evaluated using Atomic Force Microscopy (AFM). The osteogenic commitment of hBMSCs cultured on RGD and/or BMP-2 surfaces was characterized by immunohistochemistry using STRO-1 as specific stem cells marker and Runx-2 as an earlier osteogenic marker. Biological results showed that the osteogenic commitment of hBMSCs was enhanced on bifunctionalized surfaces as compared to surfaces containing BMP-2, while on RGD surfaces cells mainly preserved their stemness character. These results demonstrated that RGD and BMP-2 mimetic peptides act synergistically to enhance hBMSCs osteogenesis without supplementing the media with osteogenic factors. These findings contribute to the development of biomimetic materials, allowing a deeper understanding of signaling pathways that govern the transition of stem cells towards the osteoblastic lineage.
  • Publication
    Accès libre
    Grafting of a model protein on lactide and caprolactone based biodegradable films for biomedical applications
    (Taylor & Francis, 2014-01-23) Larrañaga, Aitor; Laroche, Gaétan; Guay-Bégin, Andrée-Anne; Chevallier, Pascale; Sabbatier, Gad; Fernández, Jorge; Sarasua, José-Ramón
    Thermoplastic biodegradable polymers displaying elastomeric behavior and mechanical consistency are greatly appreciated for the regeneration of soft tissues and for various medical devices. However, while the selection of a suitable base material is determined by mechanical and biodegradation considerations, it is the surface properties of the biomaterial that are responsible for the biological response. In order to improve the interaction with cells and modulate their behavior, biologically active molecules can be incorporated onto the surface of the material. With this aim, the surface of a lactide and caprolactone based biodegradable elastomeric terpolymer was modified in two stages. First, the biodegradable polymer surface was aminated by atmospheric pressure plasma treatment and second a crosslinker was grafted in order to covalently bind the biomolecule. In this study, albumin was used as a model protein. According to X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), albumin was efficiently immobilized on the surface of the terpolymer, the degree of albumin surface coverage (ΓBSA) reached ~35%. Moreover, gel permeation chromatography (GPC) studies showed that the hydrolytic degradation kinetic of the synthesized polymer was slightly delayed when albumin was grafted. However, the degradation process in the bulk of the material was unaffected, as demonstrated by Fourier transform infrared (FTIR) analyses. Furthermore, XPS analyses showed that the protein was still present on the surface after 28 days of degradation, meaning that the surface modification was stable, and that there had been enough time for the biological environment to interact with the modified material.
  • Publication
    Accès libre
    Fibronectin-modified surfaces for evaluating the influence of cell adhesion on sensitivity of leukemic cells to siRNA nanoparticles
    (London Future Medicine, 2016-04-13) Valencia-Serna, Juliana; Laroche, Gaétan; Chevallier, Pascale; Bahadur K.C., Remant; Uludağ, Hasan
    Aim: This study aimed to create fibronectin (FN)-grafted polymeric surfaces to investigate the influence of leukemic cell adhesion on siRNA treatment. Materials & methods: FN was grafted on plasma-treated PTFE surfaces using chemical crosslinkers. Adhesion and growth of chronic myeloid leukemia K562 cells on modified surfaces were investigated. The silencing effect of siRNA/lipid-polymers nanoparticles on cells grown on FN-grafted surfaces was evaluated. Results: Crosslinker-mediated immobilization showed significant FN grafting on surfaces, which provided K562 cell adhesion and growth advantage. siRNA nanoparticle silencing was similarly effective on FN-adhered and suspension-growing K562 cells. Conclusion: This study provided initial data to develop a cell-adhesive system to investigate therapeutic effects on leukemic cells. The response of chronic myeloid leukemia cells to siRNA nanoparticles was independent on cell attachment.
  • Publication
    Accès libre
    Single or mixed tethered peptides to promote hMSC differentiation toward osteoblastic lineage
    (American Chemical Society, 2018-11-27) Padiolleau, Laurence; Chanseau, Christel; Laroche, Gaétan; Durrieu, Stephanie; Chevallier, Pascale; Durrieu, Marie-Christine
    The commitment and differentiation of human mesenchymal stem cells (hMSCs) are guided by bioactive molecules within the extracellular matrix. Among the various approaches to design biomaterials, the functionalization of biomaterial surfaces with peptides from the sequence of proteins from the extracellular matrix is quite common. The purpose of this functionalization is to recruit hMSCs and promote their differentiation into the appropriate lineage. The aim of this work was to investigate the influence of RGD and FHRRIKA peptides and peptide sequences taken from bone morphogenic protein (BMP-2) and histone H4 (osteogenic growth peptide; OGP) either tethered alone or as a mixture on the surface of a model material and to also examine the level of hMSC osteogenic commitment without using a differentiation medium. Grafting of the different peptides was assessed by X-ray photoelectron spectroscopy (XPS), while their surface density was quantified by fluorescence microscopy, and their surface properties were assessed by atomic force microscopy (AFM) and contact angle (CA). The osteogenic commitment of hMSCs cultured on the different surfaces was characterized by immunohistochemistry using Runx-2 as an earlier osteogenic marker and OPN, a late osteogenic marker, and by RT-qPCR through the expression of ColI-a1, Runx-2, and ALP. Biological results show that the osteogenic commitment of the hMSCs was increased on surfaces tethered with a mixture of peptides. Results indicate that tethered peptides in the range of pmol mm–2 were indeed effective in inducing a cellular response after 2 weeks of cell culture without using an osteogenic media. These findings contribute to the research efforts to design biomimetic materials able to induce a response in human stem cells through tethered bioactive molecules for bone tissue engineering.