Personne : Rochette-Drouin, Olivier
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Département de chirurgie, Faculté de Médecine, Université Laval
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- PublicationAccès libreElectric potential across epidermis and its role during wound healing can be studied by using an in vitro reconstructed human skin(S-N Publications, 2012-02-28) Plante, Michel; Germain, Lucie; Roberge, Charles; Auger, François A.; Gauvin, Robert; Dubé, Jean; Rochette-Drouin, Olivier; Goulet, Daniel; Lévesque, Philippe; Bourdages, Michel; Moulin, VéroniqueBackground : After human epidermis wounding, transepithelial potential (TEP) present in nonlesional epidermis decreases and induces an endogenous direct current epithelial electric field (EEF) that could be implicated in the wound re-epithelialization. Some studies suggest that exogenous electric stimulation of wounds can stimulate healing, although the mechanisms remain to be determined. The Problem : Little is known concerning the exact action of the EEF during healing. The mechanism responsible for TEP and EEF is unknown due to the lack of an in vitro model to study this phenomenon. Basic Science Advances : We carried out studies by using a wound created in a human tissue-engineered skin and determined that TEP undergoes ascending and decreasing phases during the epithelium formation. The in vitro TEP measurements over time in the wound were corroborated with histological changes and with in vivo TEP variations during porcine skin wound healing. The expression of a crucial element implicated in Na+ transport, Na+/K+ ATPase pumps, was also evaluated at the same time points during the re-epithelialization process. The ascending and decreasing TEP values were correlated with changes in the expression of these pumps. The distribution of Na+/K+ ATPase pumps also varied according to epidermal differentiation. Further, inhibition of the pump activity induced a significant decrease of the TEP and of the re-epithelization rate. Clinical Care Relevance : A better comprehension of the role of EEF could have important future medical applications regarding the treatment of chronic wound healing. Conclusion : This study brings a new perspective to understand the formation and restoration of TEP during the cutaneous wound healing process.
- PublicationRestreintTranscatheter heart valve crimping and the protecting effects of a polyester cuff(Elsevier Masson, 2016-07-22) Germain, Lucie; Zegdi, Rachid; Mao, Jifu; lin, Jing; Guidoin, Robert; Zhang, Ze; Rochette-Drouin, Olivier; how, D.; Guan, X.; Bruneval, Patrick; Wang, LuIntroduction - Prior to deployment, the percutaneous heart valves must be crimped and loaded into sheaths of diameters that can be as low as 6 mm for a 23 mm diameter valve. However, as the valve leaflets are fragile, any damage caused during this crimping process may contribute to reducing its long-term durability in vivo. Material and method Bovine pericardium percutaneous valves were manufactured as follows. The leaflets were sutured on a nitinol frame. A polyester cuff fabric served as a buffer between the pericardium and the stent. Two valves were crimped and one valve was used as control. The valves were examined in gross observation and micro-CT scan and then the leaflets were processed for histology and analyzed in scanning electron microscopy, light microscopy and transmission electron microscopy. Result Crimping of the valves resulted in the increase thickness of the leaflets and there was no evidence of additional delamination. The heavy prints of the stents were irregularly distributed on the outflow surface in the crimped devices and were shallow and did not penetrate throughout the thickness of the leaflets. However, the wavy microscopy of collagen fiber bundles was well preserved. They were found to remain individualized without any agglutination as shown by the regular banding appearance. Conclusion Crimping of self-deployable valves per se caused only minor damages to the leaflets. However, the procedure could be refined in order to minimize areas of high pressure and swelling of the tissue that can be accompanied with flow surface disruption and increase of the hydraulic conductance. The incorporation of a polyester buffer serves to prevent the deleterious effects that may be caused if the pericardium tissue were in direct contact with the nitinol stent.
- PublicationRestreintRestoration of the transepithelial potential within tissue-engineered human skin in vitro and during the wound healing process in vivo(Mary Ann Liebert, 2010-08-05) Plante, Michel; Germain, Lucie; Roberge, Charles; Auger, François A.; Gauvin, Robert; Dubé, Jean; Goulet, Daniel; Rochette-Drouin, Olivier; Bourdages, Michel; Lévesque, Philippe; Moulin, VéroniqueNormal human epidermis possesses a transepithelial potential (TEP) that varies in different parts of the body (10–60 mV). The role of TEP in normal epidermis is not yet identified; but after skin injury, TEP disruption induces an endogenous direct current electric field (100–200 mV/mm) directed toward the middle of the wound. This endogenous electric field could be implicated in the wound healing process by attracting cells, thus facilitating reepithelialization. However, little is known on the restoration of the TEP during human skin formation and wound healing. In this study, the variations in TEP and Na+/K+ ATPase pump expression during the formation of the epithelium were investigated in vitro using human tissue-engineered human skin (TES) reconstituted by tissue engineering and in vivo with a porcine wound healing model. Results showed that TEP undergoes ascending and decreasing phases during epithelium formation in TES as well as during wound repair within TES. Similar results were observed during in vivo reepithelialization of wounds. The ascending and decreasing TEP values were correlated with changes in the expression of Na+/K+ ATPase pump. The distribution of Na+/K+ ATPase pumps also varied according to epidermal differentiation. Taken together, these results suggest that the variations in the expression of Na+/K+ ATPase pump over time and across epidermis would be a determinant parameter of the TEP, dictating a cationic transport during the formation and restoration of the epidermis. Therefore, this study brings a new perspective to understand the formation and restoration of TEP during the cutaneous wound healing process. This might have important future medical applications regarding the treatment of chronic wound healing.
- PublicationRestreintHuman keratinocytes respond to direct current stimulation by increasing intracellular calcium : preferential response of poorly differentiated cells(Liss, 2012-02-24) Plante, Michel; Germain, Lucie; Roberge, Charles; Auger, François A.; Gauvin, Robert; Dubé, Jean; Goulet, Daniel; Rochette-Drouin, Olivier; Bourdages, Michel; Lévesque, Philippe; Moulin, VéroniqueA direct current (DC) endogenous electric field (EF) is induced in the wound following skin injury. It is potentially implicated in the wound healing process by attracting cells and altering their phenotypes as indicated by the response to an EF of keratinocytes cultured as individual cells. To better define the signalization induced by a direct current electric field (DCEF) in human keratinocytes, we took advantage of an in vitro model more representative of the in vivo situation since it promotes cell–cell interactions and stratification. Human keratinocytes were grown into colonies. Their exposure to a DCEF of physiological intensity induced an increase of intracellular calcium. This variation of intracellular calcium resulted from an extracellular calcium influx and was mediated, at least in part, by the L-type voltage-gated calcium channel. The increase in intracellular calcium in response to a DCEF was however not observed in all the cells composing the colonies. The intracellular calcium increase was only detected in keratinocytes that didn't express involucrin, a marker of differentiated cells. These results indicate that DCEF is able to induce a specific calcium response in poorly differentiated keratinocytes. This study brings a new perspective for the understanding of the signaling mechanism of endogenous EF in reepithelialization, a critical process during skin wound healing.
- PublicationAccès libreExpression of C4.4A in an in vitro human tissue-engineered skin model(Hindawi, 2017-09-07) Germain, Lucie; Larouche, Danielle; Rochette-Drouin, Olivier; Ploug, Michael; Jacobsen, BenedikteA multi-LU-domain-containing protein denoted C4.4A exhibits a tightly regulated membrane-associated expression in the suprabasal layers of stratified squamous epithelia such as skin and the esophagus, and the expression of C4.4A is dysregulated in various pathological conditions. However, the biological function of C4.4A remains unknown. To enable further studies, we evaluated the expression of C4.4A in monolayer cultures of normal human keratinocytes and in tissue-engineered skin substitutes (TESs) produced by the self-assembly approach, which allow the formation of a fully differentiated epidermis tissue. Results showed that, in monolayer, C4.4A was highly expressed in the centre of keratinocyte colonies at cell-cell contacts areas, while some cells located at the periphery presented little C4.4A expression. In TES, emergence of C4.4A expression coincided with the formation of the stratum spinosum. After the creation of a wound within the TES, C4.4A expression was observed in the suprabasal keratinocytes of the migrating epithelium, with the exception of the foremost leading keratinocytes, which were negative for C4.4A. Our results are consistent with previous data in mouse embryogenesis and wound healing. Based on these findings, we conclude that this human TES model provides an excellent surrogate for studies of C4.4A and Haldisin expressions in human stratified epithelia.
- PublicationAccès libreLa dynamique du potentiel trans-épithélial au cours de la cicatrisation de la peau(2012) Rochette-Drouin, Olivier; Germain, Lucie; Moulin, VéroniqueLe potentiel trans-épithélial (PTE) représente la différence de charges qui existe dans un tissu étanche composé de cellules pluristratifiées. La distribution inégale de certains ions à travers l'épiderme est responsable de sa présence dans la peau. Des mesures de PTE ont été effectuées à différents temps lors de la genèse de l'épiderme ainsi que durant la réépithélialisation d'une plaie sur un modèle de peau humaine reconstruite par génie tissulaire. L'intensité du PTE varie en fonction du temps dans les deux conditions et cette cinétique a été confirmée au cours de la réépithélialisation d'une plaie sur un modèle in vivo. L'expression des pompes Na⁺/K⁺ ATPase varie elles aussi en fonction du temps et l'utilisation de l'amiloride, un inhibiteur du transport cationique, module négativement la cinétique du PTE par rapport au groupe témoin en plus de retarder la réépithélialisation de la plaie.
- PublicationRestreintA Floating Thrombus Anchored at the Proximal Anastomosis of a Woven Thoracic Graft Mimicking a Genuine Aortic Dissection(Begell House, 2015-01-01) Germain, Lucie; Bondarenko, Olexandr; Fu, Yijun; Bourget, Jean-Michel; Guidoin, Robert; Verdant, Alain; Zhang, Ze; Liu, Bing; Lin, Jing; Li, Bin; Rochette-Drouin, Olivier; Guzman, Randolph; Douville, Yvan; Wang, Lu; Jing, ZaipingAn aortoesophageal fistula following surgery for a ruptured 6.6-cm thoracic aneurysm in a 69-year-old female was repaired using a 34-mm woven prosthetic graft. A follow-up computed tomography (CT) scan at 10 days postoperatively revealed a dissection-like picture in the region of the graft, which was treated conservatively. The patient eventually died from sepsis and multiorgan failure. At autopsy, the graft was retrieved in situ and studied by detailed gross, microscopy, and scanning electron microscopy (SEM) examination. Gross observation confirmed that the dissection resulted from the rolling of the internal capsule downstream. A massive thrombus anchored at the proximal anastomosis and held by a narrow head was also noted. The thrombus demonstrated reorganization in the area of the anastomosis, with a false lumen in its distal half. The reminder of the thrombus consisted of layered fibrin. After gross examination, the fabric graft was found to be flawless. Additional detailed studies were also done using microscopy, SEM, and gross examination.