Doctor--Philosophy--Graduate school of arts and sciences, Collumbia university (sic), 2000. / Bibliogr. p. 252-267.

Texte remanié de: Th.--Antioch university, 1984. / Bibliogr. p. 38-44.

Reproduction de : Thèse doctorat : Sciences : Automatique : Metz : 2004. / Titre provenant de l'écran-titre. Notes bibliographiques.

Thèses (M.Sc.)--Université de Sherbrooke (Canada), 1999. / Titre de l'écran-titre (visionné le 20 juin 2006). Publié aussi en version papier.

Texte remanié de: Thèse--Lettres--Paris IV, 1981. / Bibliogr. p. 307-311. Index. Résumé en anglais.

Thèse (M.Sc.)--Université Laval, 2004. / Titre de l'écran-titre (visionné le 12 juillet 2005). Bibliogr.

Proefschrift--Universiteit van Amsterdam, 1998. / Bibliogr. p. 272-282. Index. Résumé en anglais.

Tableau d’honneur de la Faculté des études supérieures et postdoctorales, 2022 / La greffe de peau autologue chez les grands brûlés est une technique répandue, mais souvent limitée lorsque le patient présente une petite surface disponible pour le prélèvement des greffons. Les substituts de peaux bilamellaires autoassemblés (PRB) permettent de pallier cette limitation, mais leur production est longue. Le but de cette étude est donc d'optimiser la méthode pour réduire le délai nécessaire avant la première greffe. Pour cela, nous souhaitons développer une technique de décellularisation et d'entreposage de dermes allogéniques produits par autoassemblage. Notre hypothèse est que les PRB produites avec les dermes reconstruits décellularisés (DRD) sont comparables aux PRB préparées avec le protocole du LOEX (Germain et al., 2018) présentement en essai clinique. Nos objectifs sont de trouver les conditions permettant d'éliminer les résidus allogéniques des dermes décellularisés et de les recellulariser de manière à soutenir la différenciation épidermique et la formation de la jonction dermoépidermique. Nous avons déterminé que l'utilisation de deux cycles de choc osmotique avec 0,4 mg/mL de DNAse permet de réduire la quantité résiduelle d'ADN allogénique en dessous de 50ng/mg de tissu sec. L'entreposage d'un mois permet de complémenter cette décellularisation en diminuant la dose de DNAse nécessaire à 0,2mg/mL. En testant différentes populations pour la formation matricielle et densités de fibroblastes pour la recellularisation de DRD, nous avons déterminé que la recellularisation d'une matrice riche en collagène avec une faible densité de fibroblastes (10 000 f/cm$^2$) permet d'obtenir des PRB similaires histologiquement aux PRB standards. Cette recellularisation permet également de regagner les glycosaminoglycanes et l'épaisseur perdues lors de la décellularisation. En conclusion, la méthode de décellularisation utilisée est efficace pour l'atteinte des seuils établis par la littérature et complémentée par l'entreposage des DRD. La recellularisation de ces matrices permet l'obtention de PRB de manière accélérée par rapport à la méthode classique. Le tout est adapté pour une translation clinique. / Autologous skin grafting in burn patients is a widespread technique, but often limited when patients have a small area available for graft harvesting. Self-assembled skin substitutes (SASS) can overcome this limitation, but their production is time consuming. The aim of this study is therefore to optimize the method in order to reduce the time required before the first graft. To this end, we aim to develop a technique for decellularization and storage of allogeneic dermis produced by the self-assembly approach. Our hypothesis is that SASS produced with decellularized reconstructed dermis (DRD) are comparable to autologous SASS prepared with the LOEX protocol(Germain et al., 2018) currently in clinical trial. Our objectives are to find conditions to remove allogeneic residues from decellularized dermis and recellularize it in a way that supports epidermal differentiation and dermal-epidermal junction formation. We determined that the use of two cycles of osmotic shock with 0.4 mg/mL DNAse reduces the residual amount of allogeneic DNA below 50 ng/mg of dry tissue. Storage for one month helps this decellularization by reducing the dose of DNAse required to 0.2 mg/mL. By testing different fibroblast populations and densities for recellularization, we determined that recellularization of a collagen-rich matrix with a low fibroblast density (10 000 f/cm2) yields SASS histologically similar to standard SASS. This recellularization also allows the retrieval of the glycosaminoglycans and thickness lost during decellularization. In conclusion, the decellularization method used is effective in meeting the thresholds established in the literature and is complemented by DRD storage. The recellularization of these matrices allows the obtention of SASS in an accelerated manner compared to the conventional method. This is suitable for clinical translation.

Habilitation à diriger des recherches : Automatique et Informatique industrielle : Lille 1 : 2003. / N° d'ordre (Lille 1) : 395. Curriculum vitae. Bibliogr. p. 124-128. Liste des publications.

Tissue characterization is a major step in tissue mechanobiological studies. By characterization methods, tissue quality i.e. the combination of tissue structural, compositional and mechanical properties, is determined. This research focuses on mechanical characterization methods. Among all mechanical characterization methods, we propose those ones which are: 1) Non-destructive, (i.e. that reserves the capability of doing other characterization tests at the end of mechanical test; and, 2) In-line, (that enables tissue progression observation during experiment, and without transferring the specimen from one apparatus to another). However, in-line characterization raises the question of whether conducting tissue observation methods during experimentation modifies tissue progression over time. Therefore, the purpose of this study was to deepen our knowledge about the parameters which could affect tissue quality during mechanical testing. This requires a better understanding of viscoelasticity and viscoplasticity, two key behaviors of tissue, affecting the impact of these parameters (e.g. tissue quality, stimulation parameters) on the response of live tissue to biophysical stimuli. Thus, the objectives of this study were: 1. To review the literature to find information about two mechanical behaviors of tissue i.e. viscoelasticity and viscoplasticity, and the way they affect tissue properties 2. To investigate whether diagnostic tests, as mechanical characterization tests to observe tissue properties, affect tissue progression We explain that viscoelasticity and viscoplasticity of tissue originate from structure and components of the extracellular matrix. We also describe the way they affect tissue dynamic competition between repair, enzymatic degradation and mechanical degradation of the extracellular matrix. Moreover, we specify some tissue stimulation parameters, such as stimulation control type or stimulus history, which could affect tissue progression in response to biophysical stimuli because of viscoelasticity and viscoplasticity. Moreover, by conducting a series of 3-day experiments on frshly extracted tendons, we investigated whether applying "stress relaxation" tests at physiological amplitudes affects tissue response. We divided the tendons into two groups based on the characterization protocol (24 and 0 stress relaxation tests each day), and compared the progression of these groups over time. The stress relaxation tests at physiological amplitude modified tissue response to mechanical stimuli in vitro . In general, the modulus increased for 0 stress relaxation tests, while it first decreased and then increased slightly for 24 stress relaxation tests each day. The difference of mechanical properties between the two groups was significant. Therefore, applying stress relaxation tests at physiological amplitude during the rest periods between mechanical stimuli can affect live tissue progression over time. Therefore, it is essential to take into account the viscoelasticity and viscoplasticity of tissue while developing a stimulation protocol for bioreactor studies or clinical applications.