Multiscale nature of cell rearrangement caused by collective cell migration

Viscoelasticity and cell jamming state transition

“…Pajic-Lijakovic and Milivojevic (2019c;2021) applied this concept to a long-time rearrangement of dense cellular systems. The effective temperature, in this case, represents a product of cell mobility and has been expressed as (where is the cell average speed) (Pajic-Lijakovic and Milivojevic, 2021). The effective temperature decreases from the convective to the damped-conductive regime.…”

“…The viscoelasticity of multicellular systems changes from a regime to regime by increasing the cell packing density accompanied with change of cell mobility. The convective regime accounts for two states of viscoelasticity: a viscoelastic liquid and viscoelastic solid, depending primarily on the magnitude of cell velocity and the state of cell-cell adhesion contacts (Pajic-Lijakovic and Milivojevic, 2021). Higher cell velocities and weak cell-cell adhesion contacts lead to pronounced liquid-like behavior while lower cell velocities and stronger cell-cell adhesion contacts ensure solid-like behavior (Pajic-Lijakovic and Milivojevic., 2019c;2021).…”

“…Single-cell movement within a stream induces generation of local shear strain rate equal to and local volumetric strain rate (where Ĩ is identity tensor) (Pajic-Lijakovic and Milivojevic, 2021). Both strain rates are supposed to be constant during a short-time relaxation cycle and changes from cycle to cycle.…”

“…Further increase in cell packing density additionally reduced cell movement which leads to the anomalous nature of energy dissipation during cell rearrangement (Nnetu et al, 2013; Pajic-Lijakovic and Milivojevic, 2021). Transition from the conductive to the damped-conductive regime occurs for T eff → 0 and consequently, for the Young’s modulus E → 0 under these conditions.…”

“…Normal stress is primarily accumulated within a core region of migrating cell clusters during their movement through the dense environment (Pajic-Lijakovic and Milivojevic, 2019a;2021) and during collisions of migrating cell fronts (Nnetu et al, 2012). The normal residual stress accumulation is responsible for the increase in cell packing density (Trepat et al, 2009) and reduction of cell mobility (Pajic-Lijakovic and Milivojevic, 2021) and on that base for the jamming state transition (Pajic-Lijakovic, 2021). The theoretical consideration accounts for: characterization of the established regimes by cell velocities, the rate of cell packing density change and the viscoelasticity at a supracellular level.…”