Séminaire

Vendredi 11 Juin 2021 à 11h00.

Biomimetic emulsions probe the role of adhesion in tissue mechanics

''We use tissue-mimetic systems to understand the physical basis of collective remodeling in biological tissues. In particular, we focus on the interplay between adhesion and mechanical forces and how it controls the emergence of tissue architecture during morphogenesis. To do so, we use biomimetic emulsions that were shown to reproduce the minimal mechanical and adhesive properties of cells in biological tissues. These emulsions are stabilized with phospholipids and can be functionalized with binders to induce specific interactions between the droplets. We study the elasto-plastic behavior of these systems under an applied mechanical perturbation, by flowing them in 2D microfluidic constrictions. Image analysis then allows us to distinguish between an elastic response, in which the droplets deform while maintaining their neighborhood, and a plastic response, in which droplets rearranged their positions irreversibly. We found that while the presence of adhesion does not affect the global topology of rearrangements of the droplets, it slows down the local dynamics of individual rearrangements. As a result, droplets exhibit larger deformations and are globally aligned with the direction of tissue elongation. This process could be the signature of an adhesion-induced polarization mechanism in elongating tissues.
In parallel to this in vitro approach, we use oil droplets as force sensors in vivo, in developing zebrafish embryos. In particular, the injection of biocompatible oil droplets in their olfactory placode allows us to measure the presence of anteroposterior compressive forces that can contribute to axone elongation of the olfactory neurons. Further studies will be conducted in order to obtain the full force map in the placode and decipher the origin of the forces driving axonal growth.

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