Topological transitions, turbulent-like motion and long-time-tails driven by cell division in biological tissues

TL;DR

This paper reveals that cell division in biological tissues induces turbulent-like flow patterns with topological transitions and long-time correlations, resembling inertial turbulence despite low Reynolds numbers.

Contribution

It demonstrates that cell division and apoptosis generate turbulent-like flows and long-lived vortices in tissues, with energy spectra matching Kolmogorov scaling and novel long-time tail behavior.

Findings

Cell division drives directed cell motion for hours.

Flow patterns exhibit Kolmogorov $k^{-5/3}$ energy spectrum.

Long-lived vortices cause $t^{-1/2}$ decay in velocity correlations.

Abstract

The complex spatiotemporal flow patterns in living tissues, driven by active forces, have many of the characteristics associated with inertial turbulence even though the Reynolds number is extremely low. Analyses of experimental data from two-dimensional epithelial monolayers in combination with agent-based simulations show that cell division and apoptosis lead to directed cell motion for hours, resulting in rapid topological transitions in neighboring cells. These transitions in turn generate both long ranged and long lived clockwise and anticlockwise vortices, which gives rise to turbulent-like flows. Both experiments and simulations show that at long wavelengths the wave vector ($k$) dependent energy spectrum $E(k) \approx k^{-5/3}$, coinciding with the Kolmogorov scaling in fully developed inertial turbulence. Using theoretical arguments and simulations, we show that long-lived vortices lead to long-time tails in the velocity auto-correlation function, $C_v(t) \sim t^{-1/2}$, which has the same structure as in classical 2D fluids but with a different scaling exponent.