Hydraulic fracturing in cells and tissues: fracking meets cell biology

The animal body is fundamentally made of water. A small fraction of this water is freely flowing in blood and lymph, but most of it is trapped in hydrogels such as the extracellular matrix (ECM), the cytoskeleton, and chromatin. Besides providing a medium for biological molecules to diffuse, water trapped in hydrogels plays a fundamental mechanical role. This role is well captured by the theory of poroelasticity, which explains how any deformation applied to a hydrogel causes pressure gradients and water flows, much like compressing a sponge squeezes water out of it. Here we review recent evidence that poroelastic pressures and flows can fracture essential biological barriers such as the nuclear envelope, the cellular cortex, and epithelial layers. This type of fracture is known in engineering literature as hydraulic fracturing or "fracking"Peer ReviewedPostprint (author's final draft

Porous-based rheological model for tissue fluidisation

It has been experimentally observed that cells exhibit a fluidisation process when subjected to a transient stretch, with an eventual recovery of the mechanical properties upon removal of the applied deformation. This fluidisation process is characterised by a decrease of the storage modulus and an increase of the phase angle. We propose a rheological model which is able to reproduce this combined mechanical response. The model is described in the context of continua and adapted to a cell-centred particle system that simulates cell–cell interactions. Mechanical equilibrium is coupled with two evolution laws: (i) one for the reference configuration, and (ii) another for the porosity or polymer density. The first law depends on the actual strain of the tissue, while the second assumes different remodelling rates during porosity increase and decrease. The theory is implemented on a particle based model and tested on a stretching experiment. The numerical results agree with the experimental measurements for different stretching magnitudes.Peer ReviewedPostprint (author's final draft

Hydraulic fracturing in cells and tissues: fracking meets cell biology

The animal body is largely made of water. A small fraction of body water is freely flowing in blood and lymph, but most of it is trapped in hydrogels such as the extracellular matrix (ECM), the cytoskeleton, and chromatin. Besides providing a medium for biological molecules to diffuse, water trapped in hydrogels plays a fundamental mechanical role. This role is well captured by the theory of poroelasticity, which explains how any deformation applied to a hydrogel causes pressure gradients and water flows, much like compressing a sponge squeezes water out of it. Here we review recent evidence that poroelastic pressures and flows can fracture essential biological barriers such as the nuclear envelope, the cellular cortex, and epithelial layers. This type of fracture is known in engineering literature as hydraulic fracturing or 'fracking'

Mesoscale physical principles of collective cell organization

We review recent evidence showing that cell and tissue dynamics are governed by mesoscale physical principles. These principles can be understood in terms of simple state diagrams in which control variables include force, density, shape, adhesion and self-propulsion. An appropriate combination of these physical quantities gives rise to emergent phenomena such as cell jamming, topological defects and underdamped waves. Mesoscale physical properties of cell assemblies are found to precede and instruct biological functions such as cell division, extrusion, invasion and gradient sensing. These properties are related to properties of biomolecules, but cannot be predicted from biochemical principles. Thus, biological function is governed by emergent mesoscale states that can be predicted by a simple set of physical properties

Durotaxis

In this Primer, Sunyer and Trepat introduce durotaxis, the mode of migration by which cells follow gradients of extracellular matrix stiffness

Hydraulic fracturing in cells and tissues: fracking meets cell biology

The animal body is largely made of water. A small fraction of body water is freely flowing in blood and lymph, but most of it is trapped in hydrogels such as the extracellular matrix (ECM), the cytoskeleton, and chromatin. Besides providing a medium for biological molecules to diffuse, water trapped in hydrogels plays a fundamental mechanical role. This role is well captured by the theory of poroelasticity, which explains how any deformation applied to a hydrogel causes pressure gradients and water flows, much like compressing a sponge squeezes water out of it. Here we review recent evidence that poroelastic pressures and flows can fracture essential biological barriers such as the nuclear envelope, the cellular cortex, and epithelial layers. This type of fracture is known in engineering literature as hydraulic fracturing or ‘fracking’

Living cells on the move

Spectacular collective phenomena such as jamming, turbulence, wetting, and waves emerge when living cells migrate in groups.Comment: Peer-reviewed version before editorial edit