Department Seminar of Ran Galinowiecki - Percolation in fibrous gels by active cell contraction dominates tissue mechanical behavior

Wednesday 13.03.2024 at 14:00

Wolfson Building of Mechanical Engineering, Room 206

Percolation in fibrous gels by active cell contraction dominates tissue mechanical behavior

Ran Glinowiecki

M.Sc. student under the supervision of Prof. Ayelet Lesman

School of Mechanical Engineering, Tel-Aviv University, Tel Aviv, Israel

Tissues display unique mechanical behaviors arising from interactions among their microscale components, encompassing living cells and extracellular matrix (ECM) fibers. By contracting, cells alter the architecture, orientation and density of the ECM fibers and can form rigid bands of highly aligned and densified fibers that mechanically connect cells over long distances.

We draw inspiration from the ability of cells to interconnect through contraction by forming rigid ECM bands and ask how such multi-cellular connections influence the global mechanical response of the tissue. We use finite element modeling to simulate contraction of particles that mimic active cell contractility. The particles contract in a 3D hyperelastic continuum with material properties of a fibrin gel, which we then probe in shear. We show that active contraction leads to collective inter-particle mechanical interactions, resulting in global stiffening that emerges at relatively low volume fractions of particles and is not dependent on external loading, rather induced by internal sources. We show that the stiffening effect depends on the nonlinear material properties and is mediated by clustering of bands that percolate the material. Our work leads to a better understanding of the active cellular interactions that mediate rigidity transitions and mechanical stability in living tissues.