Personne : Mayrand, Dominique
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LOEX, Centre de Recherche FRSQ du Centre Hospitalier Affilié Universitaire de Québec, Université Laval
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- PublicationAccès libreÉtude des interactions entre les myofibroblastes et les cellules endothéliales au cours de la cicatrisation cutanée(2011) Mayrand, Dominique; Moulin, VéroniqueLa cicatrisation cutanée est un système complexe qui regroupe différents processus biologiques comme l'hémostase, l'inflammation, Pangiogenèse et la synthèse matricielle. Les myofibroblastes sont au coeur de ce système et bien que plusieurs fonctions aient été associées aux myofibroblastes, on en sait peu sur la relation qu'ils entretiennent avec les autres cellules impliquées dans la formation du tissu de granulation. Nous avons exploré la possibilité que les myofibroblastes influencent le développement angiogénique au cours de la cicatrisation cutanée. Les fibroblastes sont connus pour avoir des propriétés proangiogéniques, mais nous avons observé à l'aide d'un modèle tridimensionnel in vitro à base de fibrine que la différenciation vers un phénotype myofibroblastique permet aux cellules d'accroître leur potentiel proangiogénique. Ce potentiel proangiogénique acquis n'est pas dû à une augmentation de la sécrétion de facteurs de croissance associés à Pangiogenèse comme le VEGF ou le bFGF, mais serait plutôt associé à une augmentation de la sécrétion d'inhibiteurs des métalloprotéinases dont TIMP-1 au cours des premières étapes du développement angiogénique, et plus tardivement par la sécrétion de TIMP-3. TIMP-1 est connu pour son effet proangiogénique alors que TIMP-3, identifié comme un inhibiteur de Pangiogenèse, permet la stabilisation du réseau vasculaire évitant ainsi sa régression. Nous avons également observé que les myofibroblastes produisaient dans le surnageant de culture des microparticules capables d'induire la prolifération des cellules endothéliales et des fibroblastes. Ces microparticules, qui contiennent du VEGF et du bFGF, ne résultent pas d'un processus apoptotique, mais d'une activation suite à l'induction par un ou des médiateur(s) contenu(s) dans les fluides corporels, représentés par le sérum et le plasma sanguin. Ces microparticules sont connues comme étant des médiateurs permettant le transfert direct entre cellules d'un ensemble de molécules bioactives. Leur présence démontre qu'il existe un réseau de communication intercellulaire spécialisé au sein du processus de cicatrisation. En conclusion, nous avons montré que les myofibroblastes, déjà associés à la synthèse de la matrice extracellulaire, sont également favorables au développement angiogénique et à la prolifération cellulaire. Chacune de ces fonctions contribue à la formation du tissu de granulation et par conséquent, elles sont importantes dans le processus de cicatrisation cutanée.
- PublicationAccès libreImpact of TNF and IL-1β on capillary networks within engineered human adipose tissues(Royal Society of Chemistry, 2016-04-27) Proulx, Maryse; Maux, Amandine; Safoine, Meryem; Aubin, Kim; Fradette, Julie; Mayrand, DominiqueInflammation is a normal phase of the wound healing process, which likely occurs following tissue transplantation. For reconstructive surgery purposes, engineered adipose tissues represent promising alternatives to autologous fat grafts. It is therefore important to study the impact of an inflammatory microenvironment on the cellular functions of the different cell types comprised within matrix-rich reconstructed tissues. In this study, human reconstructed adipose tissues (hrATs) featuring a preformed capillary network formed by microvascular endothelial cells (hMVECs) were produced from adipose-derived stem/stromal cells (ASCs) by the self-assembly approach of tissue engineering. We hypothesized that a prolonged inflammatory context, mediated by tumor necrosis factor (TNF) and interleukin-1β (IL-1β), would impact hrATs' secretory profile and mediate detrimental effects on the microvascular network in vitro. Analysis of conditioned media established tissue responsiveness through the increased secretion of monocyte chemoattractant protein-1 (up to 23 fold), interleukin-6 (up to 69 fold) and angiopoietin-1 (up to 2.7 fold) after 3 and 6 days of cytokine exposure, along with a significant reduction in adiponectin secretion. Imaging of the preformed capillary network within the hrATs revealed increased disorganization in the presence of TNF/IL-1β, featuring a less extended and less ramified network with apoptotic hMVECs in the remaining capillary structures. These results indicate that a prolonged inflammatory context can be deleterious to the capillary network featured by in vitro engineered tissues. Strategies aiming at preserving the integrity of the vascular network will help develop substitutes that are better suited to face inflammatory conditions upon grafting.
- PublicationAccès libreShedding of microparticles by myofibroblasts as mediator of cellular cross-talk during normal wound healing(Liss, 2010-06-07) Messier, Hugo; Genest, Hervé; Moulin, Véronique; Martinez, Maria Carmen; Mayrand, Dominique; Lopez-Vallé, Carlos AntonioInteractions between cells are a crucial mechanism to correctly heal a wounded tissue. Myofibroblasts have a central role during healing but their means to communicate with other cells is unknown. Microparticles (MP) have demonstrated a potential role as mediators of cellular interactions during various diseases. We have analyzed the production of MP by normal (Wmyo) and pathological (hypertrophic scar, Hmyo) myofibroblasts and human dermal fibroblasts (Fb) when treated with serum or plasma as examples of body fluids. We have shown that the presence of these body fluids induced a very significant increase in MP production by Wmyo while no MP production was denoted for Hmyo and Fb. These effects were at least due to thermally sensitive protein(s) with a molecular mass >30 kDa. Furthermore, the increase in MP production was not linked to an increase in apoptotic Wmyo. MP characterization showed that VEGF and FGF2 were present in MP and that endothelial and (myo)fibroblast cell growth can be stimulated by MP treatment. We postulated that MP production by myofibroblasts could modulate mesenchymal cell growth and angiogenesis during normal healing.
- PublicationAccès libreShort-term post-implantation dynamics of in vitro engineered human microvascularized adipose tissues(Elsevier Science Publishers, 2018-10-01) Boisvert, Annie; Vincent, Caroline; Proulx, Maryse; Aubin, Kim; Trottier, Valérie; Fradette, Julie; Mayrand, DominiqueEngineered adipose tissues are developed for their use as substitutes for tissue replacement in reconstructive surgery. To ensure a timely perfusion of the grafted substitutes, different strategies can be used such as the incorporation of an endothelial component. In this study, we engineered human adipose tissue substitutes comprising of functional adipocytes as well as a natural extracellular matrix using the self-assembly approach, without the use of exogenous scaffolding elements. Human microvascular endothelial cells (hMVECs) were incorporated during tissue production in vitro and we hypothesized that their presence would favor the early connection with the host vascular network translating into functional enhancement after implantation into nude mice in comparison to the substitutes that were not enriched in hMVECs. In vitro, no significant differences were observed between the substitutes in terms of histological aspects. After implantation, both groups presented numerous adipocytes and an abundant matrix in addition to the presence of host capillaries within the grafts. The substitutes thickness and volume were not significantly different between groups over the short-term time course of 14 days (d). For the microvascularized adipose tissues, human CD31 staining revealed a human capillary network connecting with the host microvasculature as early as 3 d after grafting. The detection of murine red blood cells within human CD31+ structures confirmed the functionality of the human capillary network. By analyzing the extent of the global vascularization achieved, a tendency towards increased total capillary network surface and volume was revealed for prevascularized tissues over 14 d. Therefore, applying this strategy on thicker reconstructed adipose tissues with rate-limiting oxygen diffusion might procure added benefits and prove useful to provide voluminous substitutes for patients suffering from adipose tissue loss or defects.
- PublicationRestreintHigh definition confocal imaging modalities for the characterization of tissue-engineered substitutes(Springer, 2018-04-01) Fradette, Julie; Mayrand, DominiqueOptimal imaging methods are necessary in order to perform a detailed characterization of thick tissue samples from either native or engineered tissues. Tissue-engineered substitutes are featuring increasing complexity including multiple cell types and capillary-like networks. Therefore, technical approaches allowing the visualization of the inner structural organization and cellular composition of tissues are needed. This chapter describes an optical clearing technique which facilitates the detailed characterization of whole-mount samples from skin and adipose tissues (ex vivo tissues and in vitro tissue-engineered substitutes) when combined with spectral confocal microscopy and quantitative analysis on image renderings.
- PublicationAccès libreOxidative activity of 17β-hydroxysteroid dehydrogenase on testosterone in male abdominal adipose tissues and cellular localization of 17β-HSD type 2(North-Holland, 2015-06-26) Fouad Mansour, Mohamed; Boulet, Marie Michèle; Poirier, Donald; Luu The, Van; Brochu, Gaétan; Cianflone, Katherine M.; Lebel, Stefane; Pelletier, Mélissa; Fradette, Julie; Tchernof, André; Mayrand, DominiqueTestosterone can be converted into androstenedione (4-dione) by 17β-hydroxysteroid dehydrogenase (HSD) activity likely performed by 17β-HSD type 2. Our objective was to evaluate the rate of testosterone conversion to 4-dione as well as expression and localization of 17β-HSD type 2 in omental (OM) vs. subcutaneous (SC) adipose tissues of men. Formation of 4-dione from testosterone was significantly higher in homogenates (p ≤ 0.001) and explants (p ≤ 0.01) of OM than SC tissue. Microscopy analyses and biochemical assays in cell fractions localized the enzyme in the vasculature/endothelial cells of adipose tissues. Conversion of testosterone to 4-dione was weakly detected in most OM and/or SC preadipocyte cultures. Positive correlations were found between 17β-HSD type 2 activity in whole tissue and BMI or SC adipocyte diameter. We conclude that conversion of testosterone to 4-dione detected in abdominal adipose tissue is caused by 17β-HSD type 2 which is localized in the vasculature of the adipose compartment.
- PublicationAccès libreCreating capillary networks within human engineered tissues: impact of adipocytes and their secretory products(Elsevier, 2014-09-30) Vincent, Caroline; Proulx, Maryse; Aubin, Kim; Fradette, Julie; Mayrand, DominiqueThe development of tissue-engineered substitutes of substantial volume is closely associated with the need to ensure rapid vascularization upon grafting. Strategies promoting angiogenesis include the in vitro formation of capillary-like networks within engineered substitutes. We generated both connective and adipose tissues based on a cell sheet technology using human adipose-derived stromal cells. This study evaluates the morphology and extent of the capillary networks that developed upon seeding of human microvascular endothelial cells during tissue production. We posited that adipocyte presence/secretory products could modulate the resulting capillary network when compared to connective substitutes. Analyses including confocal imaging of CD31-labeled capillary-like networks indicated slight differences in their morphological appearance. However, the total volume occupied by the networks as well as the frequency distribution of the structure’s volumes were similar between connective and adipose tissues. The average diameter of the capillary structures tended to be 20% higher in reconstructed adipose tissues. Quantification of pro-angiogenic molecules in conditioned media showed greater amounts of leptin (15×), angiopoietin-1 (3.4×) and HGF (1.7×) secreted from adipose than connective tissues at the time of endothelial cell seeding. However, this difference was attenuated during the following coculture period in endothelial cell-containing media, correlating with the minor differences noted between the networks. Taken together, we developed a protocol allowing reconstruction of both connective and adipose tissues featuring well-developed capillary networks in vitro. We performed a detailed characterization of the network architecture within engineered tissues that is relevant for graft assessment before implantation as well as for in vitro screening of angiogenic modulators using three-dimensional models.
- PublicationAccès libreEnhancing repair of full-thickness excisional wounds in a murine model : impact of tissue-engineered biological dressings featuring human differentiated adipocytes(Elsevier, 2015-04-29) Laterreur, Véronique; Maux, Amandine; Gagné, Valérie; Moulin, Véronique; Fradette, Julie; Morissette Martin, Pascal; Mayrand, DominiquePromotion of skin repair for acute or chronic wounds through the use of tissue-engineered products is an active field of research. This study evaluates the effects mediated by tissue-engineered biological dressings containing human in vitro-differentiated adipocytes and adipose-derived stromal cells (ASCs). Re-epithelialization, granulation tissue formation and neovascularization of full-thickness cutaneous wounds were specifically assessed using a murine model featuring a fluorescent epidermis. In comparison with wounds that did not receive an adipocyte-containing biological dressing, treated wounds displayed a slight but significantly faster wound closure based on macroscopic observations over 18 days. Non-invasive imaging of GFP-expressing keratinocytes determined that the kinetics of re-epithelialization were similar for both groups. Treated wounds featured thicker granulation tissues (1.7-fold, P < 0.0001) enriched in collagens (1.3-fold, P < 0.0104). In addition, wound cryosections labeled for detection of CD31-expressing cells indicated a 2.2-fold (P < 0.0002) increased neovascularization for the treated wounds at the time of terminal biopsy. This is in accordance with the secretion of pro-angiogenic factors detected in media conditioned by the dressings. Taken together, these results establish that a new type of engineered substitutes featuring a mixture of adipocytes and ASCs can promote cutaneous healing when applied as temporary dressings, suggesting their potential relevance for chronic wound management studies.
- PublicationRestreintAngiogenic properties of myofibroblasts isolated from normal human skin wounds(Rapid Science Publishers, 2012-02-18) Langlois, Amélie; Roy, Michel; Larochelle, Sébastien; Genest, Hervé; Moulin, Véronique; Laforce-Lavoie, Audrey; Mayrand, DominiqueDuring wound healing, angiogenesis plays a crucial role in inducing adequate perfusion of the new tissue, thereby allowing its survival. This angiogenic process contributes to the formation of granulation tissue, alongside myofibroblasts. Myofibroblasts are cells specialized in wound contraction and synthesis of new extracellular matrix. Fibroblasts, considered by some to be at the origin of myofibroblasts, have already been shown to promote neovascularization. Thus, we hypothesized that myofibroblasts play a key role during angiogenic development in wound healing. We isolated myofibroblasts from normal human skin wounds and dermal microvascular endothelial cells (HDMVEC) and fibroblasts from skin. Using an in vitro fibrin-based model, we compared the proangiogenic activity of wound myofibroblasts to that of fibroblasts in the presence of HDMVEC. By immunostaining with collagen IV antibodies, we observed the formation of a capillary network significantly more developed when HDMVEC were cultured with myofibroblasts compared to the network formed in the presence of fibroblasts. The differences between these cell types did not result from a differential secretion of Vascular Endothelial Growth Factor or basic Fibroblast Growth Factor. However, in the presence of myofibroblasts, a significant decrease in matrix metalloproteinase activity was observed. This finding was correlated with a significant increase in Tissue Inhibitor of MetalloProteinase (TIMP)-1 and TIMP-3. Furthermore, inhibition of TIMP-1 secretion using shRNA significantly decreased myofibroblasts induced angiogenesis. These results led to the hypothesis that normal wound myofibroblasts contribute to the vascular network development during wound healing. Our data emphasize the critical role of wound myofibroblasts during healing.