# Glassy Dynamics in Models of Confluent Tissue with Mitosis and Apoptosis

## TL;DR

This study investigates how cell division and death influence the glassy, slow-moving behavior of confluent tissues, revealing that low cell cycling rates can lead to glass-like states despite ongoing cell turnover.

## Contribution

The paper introduces a simulation-based analysis showing that low cell cycling rates can produce glassy tissue dynamics, reconciling experimental observations with theoretical models.

## Key findings

- Glass-like tissue states occur at low cell cycling rates.
- Cell birth and death rates contribute additively to tissue fluidity.
- Subdiffusive cell displacements indicate caging behavior.

## Abstract

Recent work on particle-based models of tissues has suggested that any finite rate of cell division and cell death is sufficient to fluidize an epithelial tissue. At the same time, experimental evidence has indicated the existence of glassy dynamics in some epithelial layers despite continued cell cycling. To address this discrepancy, we quantify the role of cell birth and death on glassy states in confluent tissues using simulations of an active vertex model that includes cell motility, cell division, and cell death. Our simulation data is consistent with a simple ansatz in which the rate of cell-life cycling and the rate of relaxation of the tissue in the absence of cell cycling contribute independently and additively to the overall rate of cell motion. Specifically, we find that a glass-like regime with caging behavior indicated by subdiffusive cell displacements can be achieved in systems with sufficiently low rates of cell cycling.