Integer topological defects of cell monolayers -- mechanics and flows

Abstract

Monolayers of anisotropic cells exhibit long-ranged orientational order and topological defects. During the development of organisms, orientational order often influences morphogenetic events. However, the linkage between the mechanics of cell monolayers and topological defects remains largely unexplored. This holds specifically at the time scales relevant for tissue morphogenesis. Here, we build on the physics of liquid crystals to determine material parameters of cell monolayers. In particular, we use a hydrodynamical description of an active polar fluid to study the steady-state mechanical patterns at integer topological defects. Our description includes three distinct sources of activity: traction forces accounting for cell-substrate interactions as well as anisotropic and isotropic active nematic stresses accounting for cell-cell interactions. We apply our approach to C2C12 cell monolayers in small circular confinements, which form isolated aster or spiral topological defects. By analyzing the velocity and orientational order fields in spirals as well as the forces and cell number density fields in asters, we determine mechanical parameters of C2C12 cell monolayers. Our work shows how topological defects can be used to fully characterize the mechanical properties of biological active matter.

arXiv comment41 pages, 11 figures

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Cited by in corpus (11)

• Quantifying material properties of cell monolayers by analyzing integer topological defects
• Active morphogenesis of patterned epithelial shells
• Introduction to topological defects: from liquid crystals to particle physics
• Theory of nematic and polar active fluid surfaces
• Controlling topological defects and contractile flow in confined nematic cell population
• Properties of twisted topological defects in 2D nematic liquid crystals
• Morphodynamics of Active Nematic Fluid Surfaces
• Cells around the corner
• Density-polarity coupling in confined active polar films: asters, spirals, and biphasic orientational phases
• Spontaneous flow created by active topological defects
• Noise-induced transitions from contractile to extensile active stress in isotropic fluids