Personne : Veres, Teodor
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Département de chirurgie, Faculté de médecine, Université Laval
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- PublicationAccès libreRecent advances in the development of tissue-engineered vascular media made by self-assembly(Elsevier, 2013-06-05) Guillemette, Maxime.; Laterreur, Véronique; Germain, Lucie; Ruel, Jean; Miville Godin, Caroline; Bourget, Jean-Michel; Mounier, Maxence; Veres, Teodor; Auger, François A.; Gauvin, RobertThere is a lack of an optimal transplant material for small calibre blood vessels. This could be overcome by tissue engineering. The optimal construct is to be derived from autologous cells and present mechanical resistance comparable to the gold standard, autologous vessels such as the internal mammary artery or the saphenous vein. Our laboratory has developed the self-assembly approach to produce tissue sheets that can be rolled into such vessel substitutes. Over the years, many improvements have been made to the technique to facilitate smooth muscle cell culture and to produce vascular media substitutes with higher circumferential mechanical resistance.
- PublicationRestreintSurface 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, MehmetThe 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 libreAlignment of cells and extracellular matrix within tissue-engineered substitutes(Intech, 2013-01-01) Guillemette, Maxime.; Germain, Lucie; Bourget, Jean-Michel; Veres, Teodor; Auger, François A.Most of the cells in our body are in direct contact with extracellular matrix (ECM) components which constitute a complex network of nano-scale proteins and glycosaminoglycans. Those cells constantly remodel the ECM by different processes. They build it by secreting different proteins such as collagen, proteoglycans, laminins or degrade it by producing factors such as matrix metalloproteinase (MMP). Cells interact with the ECM via specific receptors, the integrins . They also organize this matrix, guided by different stimuli, to generate patterns, essential for tissue and organ functions. Reciprocally, cells are guided by the ECM, they modify their morphology and phenotype depending on the protein types and organization via bidirectional integrin signaling [2-4]. In the growing field of tissue engineering , control of these aspects are of the utmost importance to create constructs that closely mimic native tissues. To do so, we must take into account the composition of the scaffold (synthetic, natural, biodegradable or not), its organization and the dimension of the structure. The particular alignment patterns of ECM and cells observed in tissues and organs such as the corneal stroma, vascular smooth muscle cells (SMCs), tendons, bones and skeletal muscles are crucial for organ function. SMCs express contraction proteins such as alpha-smoothmuscle (SM)-actin, desmin and myosin  that are essential for cell contraction . To result in vessel contraction, the cells and ECM need to be organized in such a way that most cells are elongated in the same axis. For tubular vascular constructs, it is suitable that SMCs align in the circumferential direction, as they do in vivo [7, 8]. Another striking example of alignment is skeletal muscle cells that form long polynuclear cells, all elongated in the same axis. Each cell generates a weak and short contraction pulse but collectively, it results in a strong, long and sustained contraction of the muscle and, in term, a displacement of the member. In the corneal stroma, the particular arrangement of the corneal fibroblasts (keratocytes) and ECM is essential to keep the transparency of this tissue [9-13]. Tendons also present a peculiar matrix alignment relative to the muscle axis. It gives a substantial resistance and exceptional mechanical properties to the tissue in that axis [14, 15]. Intervertebral discs , cartilage , dental enamel , and basement membrane of epithelium are other examples of tissues/organs that present peculiar cell and matrix organization. By reproducing and controlling those alignment patterns within tissue-engineered substitutes, a more physiological representation of human tissues could be achieved. Taking into account the importance of cell microenvironment on the functionality of tissue engineered organ substitutes, one can assume the importance of being able to customise the 3D structure of the biomaterial or scaffold supporting cell growth. To do so, some methods have been developed and most of them rely on topographic or contact guidance. This is the phenomenon by which cells elongate and migrate in the same axis as the ECM. Topographic guidance was so termed by Curtis and Clark  to include cell shape, orientation and movement in the concept of contact guidance described by Harrison  and implemented by Weiss [21, 22]. Therefore, if one can achieve ECM alignment, cells will follow the same pattern. Inversely, if cells are aligned on a patterned culture plate, the end result would be aligned ECM deposition . The specific property of tissues or materials that present a variation in their mechanical and structural properties in different axis is called anisotropy. This property can be evaluated either by birefringence measurements [24, 25], mechanical testing in different axis , immunological staining of collagen or actin filaments  or direct visualisation of collagen fibrils using their self-fluorescence around 488 nm [27, 28]. Several techniques have been recently developed to mimic the specific alignment of cells within tissues to produce more physiologically relevant constructs. In this chapter, we will describe five different techniques, collagen gel compaction, electromagnetic field, electro‐spinning of nanofibers, mechanical stimulation and microstructured culture plates.
- PublicationRestreintMicrostructured human fibroblast-derived extracellular matrix scaffold for vascular media fabrication(John Wiley & Sons, Inc, 2016-04-28) Guillemette, Maxime.; Tondreau, Maxime; Laterreur, Véronique; Germain, Lucie; Miville-Godin, Caroline; Ruel, Jean; Mounier, Maxence; Tremblay, Catherine; Labbé, Raymond; Bourget, Jean-Michel; Veres, Teodor; Auger, François A.; Gauvin, RobertIn the clinical and pharmacological fields, there is a need for the production of tissue-engineered small-diameter blood vessels. We have demonstrated previously that the extracellular matrix (ECM) produced by fibroblasts can be used as a scaffold to support three-dimensional (3D) growth of another cell type. Thus, a resistant tissue-engineered vascular media can be produced when such scaffolds are used to culture smooth muscle cells (SMCs). The present study was designed to develop an anisotropic fibroblastic ECM sheet that could replicate the physiological architecture of blood vessels after being assembled into a small diameter vascular conduit. Anisotropic ECM scaffolds were produced using human dermal fibroblasts, grown on a microfabricated substrate with a specific topography, which led to cell alignment and unidirectional ECM assembly. Following their devitalization, the scaffolds were seeded with SMCs. These cells elongated and migrated in a single direction, following a specific angle relative to the direction of the aligned fibroblastic ECM. Their resultant ECM stained for collagen I and III and elastin, and the cells expressed SMC differentiation markers. Seven days after SMCs seeding, the sheets were rolled around a mandrel to form a tissue-engineered vascular media. The resulting anisotropic ECM and cell alignment induced an increase in the mechanical strength and vascular reactivity in the circumferential direction as compared to unaligned constructs.