Personne : Beauparlant, Annie.
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Faculté de médecine, Université Laval
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- PublicationRestreintConsiderations in the choice of a skin donor site for harvesting keratinocytes containing a high proportion of stem cells for culture in vitro(Butterworth-Heinemann, 2010-12-03) Germain, Lucie; Larouche, Danielle; Paquet, Claudie; Fugère, Claudia.; Genest, Hervé; Auger, François A.; Gauvin, Robert; Têtu, Félix-Andre; Bouchard, Maurice; Roy, Aphonse; Fradette, Julie; Lavoie, Amélie; Beauparlant, Annie.The treatment of severely burned patients has benefited from the grafting of skin substitutes obtained by expansion of epithelial cells in culture. The aim of this study was to evaluate whether the anatomic site chosen for harvesting skin had an impact on the quality of the derived cell cultures. Considering that hair follicles contain epithelial stem cells, we compared hairy skin sites featuring different densities and sizes of hair follicles for their capacity to generate high quality keratinocyte cultures. Three anatomic sites from adult subjects were compared: scalp, chest skin and p-auricular (comprising pre-auricular and post-auricular) skin. Keratin (K) 19 was used as a marker to evaluate the proportion of stem cells. Keratinocytes were isolated using the two-step thermolysin and trypsin cell extraction method, and cultured in vitro. The proportion of K19-positive cells harvested from p-auricular skin was about twice that of the scalp. This K19-positive cell content also remained higher during the first subcultures. In contrast to these in vitro results, the number of K19-positive cells estimated in situ on skin sections was about double in scalp as in p-auricular skin. Chest skin had the lowest number of K19-positive cells. These results indicate that in addition to the choice of an adult anatomic site featuring a high number of stem cells in situ, the quality of the cultures greatly depends on the ability to extract stem cells from the skin biopsy
- PublicationRestreintDissociation, quantification and culture of normal human merkel cells among epidermal cell populations derived from glabrous and hairy skin sites(Springer, 2003-06-23) Germain, Lucie; Larouche, Danielle; Couture, Véronique; Fugère, Claudia.; Guignard, Rina; Fradette, Julie; Caouette-Laberge, Louise; Beauparlant, Annie.; Roy, AlphonseMerkel cells constitute a unique population that remains difficult to characterize in human skin because of their scarcity. Our aim was to develop tools for the study of Merkel cells in vitro. As a first step, we evaluated the possibility of harvesting human Merkel cells with the two-step extraction method that is widely used to extract and culture keratinocytes. Merkel cells were identified in the epithelial portion of hairy or glabrous skin biopsies by keratin (K)18 and K20 labeling. The totality of cutaneous epithelial cells were isolated from either hairy or glabrous skin biopsies following enzymatic dissociation of both the epidermis and the hair follicles. Flow cytometry was performed to quantify the small Merkel cell population. The analysis revealed that K18-labeled cells represented between 4.0 and 7.6% of freshly dissociated basal epidermal cells. No significant differences were seen between samples derived from glabrous palmar and hairy anatomic sites from children and adults, respectively. We also reported on the presence of Merkel cells in primary and first subcultures of human epidermal cells. The next step will be to enrich the isolated human Merkel cells and improve their culture conditions. An amplification of the number of Merkel cells will allow further studies to unravel long-standing questions regarding their origin, proliferative capacity, and functions in cutaneous biology
- PublicationRestreintLa médecine régénératrice : les cellules souches, les interactions cellulaires et matricielles dans la reconstruction cutanée et cornéenne par génie tissulaire(Elsevier Masson, 2008-06-02) Germain, Lucie; Larouche, Danielle; Paquet, Claudie; Auger, François A.; Proulx, Stéphanie; Carrier, Patrick; Lavoie, Amélie; Beauparlant, Annie.Le génie tissulaire vise à produire des tissus ou organes in vitro pour le remplacement permanent des tissus endommagés. À cette fin, la production de tissus autologues possède l’avantage d’éviter tout risque de rejet suite à leur transplantation sur un patient. La maîtrise des conditions de culture des cellules souches humaines postnatales est essentielle à la réalisation de tels tissus. Il est aussi souhaitable que leur organisation histologique et leur fonctionnalité se rapprochent de celles des tissus natifs. De plus, les cellules souches jouent un rôle essentiel au niveau du remplacement des cellules épithéliales différenciées dans les tissus qui doivent constamment se renouveler, tels que la peau et la cornée. Nous avons décrit une méthode qui permet de produire des organes vivants in vitro à partir de cellules humaines postnatales sans ajouter de biomatériaux. Cette méthode d’auto-assemblage repose sur la capacité qu’ont les cellules mésenchymateuses de s’organiser en tissu en présence des conditions de culture adéquates. Grâce à différentes techniques, ces tissus peuvent ensuite être assemblés en organes plus complexes tels que les vaisseaux sanguins, les valves cardiaques, la peau ou encore la cornée. Ces divers tissus pourront éventuellement être utilisés pour le remplacement d’organes malades ou endommagés et fourniront de nouvelles alternatives pour la médecine régénératrice de demain. Cet article de revue sera concentré sur la peau et la cornée. L’importance d’utiliser des conditions d’isolement et de culture qui permettent de conserver les cellules souches et de contrôler l’organisation des tissus afin d’assurer la qualité et la fonctionnalité des organes reconstitués par génie tissulaire sera discutée.
- PublicationRestreintHuman epithelial stem cells persist within tissue-engineered skin produced by the self-assembly approach(Mary Ann Liebert, 2013-02-15) Germain, Lucie; Goyer, Benjamin; Larouche, Danielle; Kim, Dong Hyun; Paquet, Claudie; Fugère, Claudia.; Dunnwald, Martine; Robitaille, Hubert; Sauvé, Sarah; Desgagné, Maxime; Fradette, Julie; Lavoie, Amélie; Beauparlant, Annie.; Pouliot, RoxaneTo adequately and permanently restore organ function after grafting, human tissue-engineered skin substitutes (TESs) must ultimately contain and preserve functional epithelial stem cells (SCs). It is therefore essential that a maximum of SCs be preserved during each in vitro step leading to the production of TESs such as the culture process and the elaboration of a skin cell bank by cryopreservation. To investigate the presence and functionality of epithelial SCs within the human TESs made by the self-assembly approach, slow-cycling cells were identified using 5′-bromo-2′-deoxyuridine (BrdU) in the three-dimensional construct. A subset of basal epithelial cells retained the BrdU label and was positive for the SC-associated marker keratin 19 within TESs after a chase of 21 days in culture post-BrdU labeling. Moreover, keratinocytes harvested from TESs gave rise to SC-like colonies in secondary monolayer subcultures, indicating that SCs were preserved within TESs. To evaluate the effect of cryopreservation with dimethyl sulfoxide and storage in liquid nitrogen on SCs, human epithelial cells were extracted from skin samples, amplified in culture, and used to produce TESs, before cryopreservation as well as after thawing. We found that the proportion and the growth potential of epithelial SCs in monolayer culture and in TESs remained constant before and after cryopreservation. Further, the functionality of these substitutes was demonstrated by successfully grafting human TESs on athymic mice for 6 months. We conclude that human epithelial skin SCs are adequately preserved upon human tissue reconstruction. Thus, these TESs produced by the self-assembly approach are suitable for clinical applications.
- PublicationRestreintNormal human merkel cells are present in epidermal cell populations isolated and cultured from glabrous and hairy skin sites(Elsevier Science, 2015-12-08) Caouette, Louise; Germain, Lucie; Larouche, Danielle; Couture, Véronique; Fugère, Claudia.; Guignard, Rina; Fradette, Julie; Roy, Alphonse; Beauparlant, Annie.The Merkel cell is a highly specialized cell that primarily acts as a slowly adapting mechanoreceptor. Merkel cells are scarce in normal skin but can be identified by the expression of distinct keratin filaments. Merkel cells constitute a very unique population and many questions still remain as to their origin, number, proliferative capacity, and functions in cutaneous biology. The dissociation of epidermal cells from skin is a widely used technique to extract and culture keratinocytes. We took advantage of a two-step extraction method to quantify keratin-20-expressing Merkel cells among total cutaneous cells obtained from either hairy or glabrous skin biopsies. Flow cytometry analysis revealed that keratin-20-labeled Merkel cells represent between 3.6% and 5.7% of freshly dissociated basal epidermal cells. No significant differences were seen between samples derived from glabrous palmar and hairy anatomic sites, from children and adult, respectively. We also report on the presence of Merkel cells in primary and first subcultures of epidermal cells indicating their capacity to remain viable after extraction from skin of various anatomic sites. To our knowledge, this is the first demonstration of nontumorigenic human Merkel cells in culture in vitro. The persistence of a small number of Merkel cells in culture suggests that, with the development of appropriate culture conditions, these cells could be amplified and further studied to unravel long-standing questions relative to their paracrine function or epithelial origin.