Résumé
The aim of this work is to provide a rheological description of biomimetic tissues in microfluidic confinement, as a simplified model for the flow of cellular tissues observed in complex physiological problems such as in embryogenesis or tumor metastasis. The prototissues were conceived by the controlled assembly of giant unillamelar vesicles (GUV), mediated by the inclusion of the biotin-streptavidin pair, and displayed tuneable mechanical properties and typical sizes [1]. The prototissues were mechanically probed in a “pipette-aspiration” inspired microfluidic chip, under controlled pressure conditions (creep test) [2]. The penetration length inside the constriction (lc) was measured for increasing applied pressures, as shown in the figure. We reported a viscoelastic response, which was well captured by a generalized Kelvin-Voigt fluid model. While the inferred rheological parameters did not show a significant dependence on the GUV-GUV adhesion strength, we observed a strain-stiffening behavior for increasing applied pressures. Complementary flow velocimetry allowed us to quantify the prototissue effective permeability and to identify spatial reorganizations taking place within the prototissue at the vesicle level.