There are number of evidences indicating that both tumour micro-environment and mechanics are playing an important role in the malignant transformation of cells and resistance to treatment. We try to take into account these important issues (micro-environment and mechanics) by developing original techniques enabling to precisely control cell micro-environment, including the applied mechanical...
En cas de sécheresse, l'eau contenue dans les circuits hydrauliques du xylème des arbres est soumise à des pressions très négatives. Des bulles de cavitation peuvent alors se former, initiant une embolie d'air qui se propage, conduisant à l'arrêt de la circulation de la sève. Des observations sur des feuilles réelles ont montré que l'embolie progresse par une succession de longs arrêts et de...
Bacterial motility and intestinal mucus quality have both been shown to be important issues related with different pathologies (diabeta, obesity, IBD...). In this context, I aim at understanding the properties of bacterial exploration in such environments which could open new ways for treatments and cure.
To study this complex medical problematic with a physicist eye, I was led to...
Cell adhesion proteins are transmembrane proteins that play a crucial role in the binding of cells to one another, as well as to the extracellular matrix that surrounds them. Cell adhesion proteins can typically organize into clusters that can take various forms, from circular patches to long linear structures. Here, we propose that the tilt between the extracellular protein domain and the...
Cell shape changes are crucial for many biological processes, including cell division and motility. Such shape changes are fueled by the dynamics of the actin cortex, which can reshape the cell membrane. The mechanisms of these shape changes are difficult to decipher in the complex environment of the living cell. Therefore, biomimetic experiments coupling reconstituted membranes and actin...
Clotting is the process by which the flow of blood is stopped after an injury. This process may occur pathologically, in both arteries and veins. In the venous system, the severe forms are called Venous Thromboembolic Events which include Deep Vein Thrombosis and Pulmonary Embolism. Today, 50% of recurrent Venous Thromboembolic Events remain unexplained. Hypercoagulability is likely due to a...
In recent years, there has been a growing interest in understanding the mechanical behavior of cells. To gain an in-depth understanding of the physical properties of cells, such as their mass, elasticity, and viscosity, we developed and improved novel techniques allowing to perform single cell measurements for these quantities. These techniques involve the use of micro-mechanical oscillators,...
Biological tissues self-organise thanks to patterning processes coupled to cellular mechanical interactions, which play a fundamental role in driving coordinated cell movements. Here I will discuss how polarity-oriented active mechanical forces drive collective cell motion in three dimensions. I will introduce the framework of « interacting active surfaces », which describe cell aggregates as...
Epithelial tissues play fundamental roles in living organisms. The mechanical behaviour of epithelial tissues involves interactions of many elements. Traditionally it is believed that genes and biochemistry instruct mechanics. Recently, it is becoming clear that mechanics also feeds back onto and drives gene expression and biochemical signalling, but how mechanical feedback affects tissue...
Understanding the interplay between electrical coupling, mechanical stimuli and transcription factors in the context of muscle cell differentiation is a challenge for mechanobiology and muscle tissue engineering. We aim to determine the correlation between mechanical and geometrical constraints and spatially resolved differentiation, focusing on single cell scale. I will present my research...
L’intestin est au centre des investigations en organogénèse depuis que Caspar Friedrich Wolf posa en 1769 les bases de l’embryologie moderne dans son « De Formatione Intestinorum ». Alors que le XXème siècle nous a livré une vision quasi exclusivement génétique du développement des organes, on comprend aujourd’hui que le génome code pour des ensembles de propriétés macroscopiques physiques –...
During their final transformation, insects emerge from the pupal case and within a few minutes, they deploy their wings for the very first time. Wings expand from a compact, pleated structure, to form a planar, rigid wing blade that allows flight. The deployment is powered by an increase of internal pressure, and by the subsequent injection of hemolymph into the deployable wing...
Biological tissues remodelling occurs through bio-chemical signalling and mechanical processes. In such complex biological systems, unravelling the contribution of a given parameter, for instance cell-cell adhesion regulation, therefore represents a huge challenge. In order to work in a simplified framework, we use adhesive emulsions as a biomimetic system of adhesive tissues, where each oil...
The evolutionary emergence of the primitive gut in Metazoa is one of the decisive events that conditioned the major evolutionary transition leading to the origin of animals. It is thought to have been intimately associated with endomesoderm specification in multicellular tissue and its invagination (i.e. gastrulation). However, the biochemical signals underlying endomesoderm specification and...
Multiphoton microscopy has demonstrated unique advantages for imaging embryonic development in vivo, including deep imaging or the ability to combine nonlinear fluorescence excitation with label-free contrast mechanisms, such as second or third harmonic generation. However, the acquisition speed is often a critical limitation for multiscale imaging or for investigating fast biological...
Microstructured surfaces offer powerful platforms to investigate single cell adhesion, migration and contractility. Micropattern lattices have been successfully used to control the cell contractile apparatus [1], the cell motion [2,3], and also to study the regulation between integrins and Rho-family GTPases (or Src-familiy kinases) adhesion signaling pathways [4,5]. Two-state micropattern,...
Cells mechanical reflects a signature of the cell state, in health and disease. Various techniques have been developed to measure cell viscoelasticity, which is inherently dependent on the timescale of measurement. While several works report data at medium to short timescales (from seconds to microseconds), few are the techniques that allow viscoelastic measurement at long timescales (minutes...
Introduction: Focal adhesions (FAs) are the anchoring point which link the actin cytoskeleton to the extracellular matrix and though which cells sense their environment. Several proteins are involved in FAs assembly, stabilization and disassembly but their roles are still not fully understood. The vinculin protein is force-dependently recruited and is suspected to be responsible for FAs...
Nous proposons une technique de nanorhéologie des globules rouges basée sur les rotors moléculaires, sondes fluorescentes de viscosité. Nous identifions le DASPI, un rotor moléculaire adapté à l’hémoglobine, qui pénètre spontanément dans les globules rouges. Sa sensibilité à la viscosité dans les fluides simples le rend attractif pour l’étude de pathologies érythrocytaires caractérisées par la...
In a tissue, cells that are in direct physical contact with each other can exchange ions or molecules via protein clusters called gap junctions, that form channels across the membranes of adjacent cells. Artificial systems that mimic cellular tissues can be used as a way to overcome the complexity of cell-cell communication in biological tissues. For this, a simplified biomimetic approach,...
Morphological traits of 3D multicellular complexes can reliably discriminate features and gene functions[1]. Many ways exist for probing the morphology of 3D cellular complexes, with different degrees of spatial resolution and invasiveness. Brillouin Light Scattering[2] is in that matter a particularly interesting option because it is label-free and can perform measurements at a spatial...
