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Theses

Confined cell nematics submitted to an orientation field. Applications to differentiation.

Abstract : Group of cells in vivo need to move together in order to achieve physiological function. In particular, some cells are surrounded by extracellular matrix, a meshwork of proteins displaying sizes ranging from nanometers to hundreds of micrometers. In such environments, cells can move altogether directed by mesh orientation. This behaviour has been studied in vitro for simplified systems using guiding cues of different sizes. These studies show that the size of the cue controlled the cell collective motion. However, cell collective motion and the mechanisms involved in systems displaying a mix of different length scales cues are still unclear.In this thesis, we plated cells on substrates that have been textured at two length scales: subcellular microridges making an angle with a wider mesoscopic stripe. We show that the stripe’s width controls a transition at a critical width for the orientation angle of the cells between the two limiting cases. More precisely, middle angle in wider stripes is stabilized by a simple contact guidance effect independent of cell activity while collective cell migration display shear flows close to the edge of stripes. These observations fit a theoretical model we developed based on active matter framework. More interestingly, changing the microscale field orientation allowed us to measure the so-called flow-alignment parameter for the first time in such systems.Understanding these general mechanisms can be relevant in other several contexts in vivo, in particular during myogenesis. By seeding C2C12 mouse myoblasts cells on our previous multiscale system, we observed the self-organization of a 3D “cell cord” in the center of stripes. Due to their particular structures, differentiation was favored compared to classical patterns of the literature showing a real impact of geometrical conditions on cell differentiation processes. We then managed to provide a simple method of muscle differentiation based on cellular self-organization only. This thesis could have outcomes in the tissue engineering field.
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Submitted on : Tuesday, June 28, 2022 - 3:11:11 AM
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  • HAL Id : tel-03706679, version 1

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Thibault Aryaksama. Confined cell nematics submitted to an orientation field. Applications to differentiation.. Theoretical and/or physical chemistry. Université Paris sciences et lettres, 2021. English. ⟨NNT : 2021UPSLS039⟩. ⟨tel-03706679⟩

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