Modelling the rheology of living cell cytoplasm: poroviscoelasticity and fluid-to-solid transition
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10237_2024_Article_1854.pdf
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Author(s)
Thekkethil, Namshad
Köry, Jakub
Guo, Ming
Stewart, Peter S.
Hill, Nicholas A.
Luo, Xiaoyu
Date Issued
July 8, 2024
Journal
Biomechanics and Modeling in Mechanobiology
Publisher
Springer Science and Business Media LLC
Citation
Thekkethil, N., Köry, J., Guo, M. et al. Modelling the rheology of living cell cytoplasm: poroviscoelasticity and fluid-to-solid transition. Biomech Model Mechanobiol (2024).
Version
Final published version
Abstract
Eukaryotic cell rheology has important consequences for vital processes such as adhesion, migration, and differentiation. Experiments indicate that cell cytoplasm can exhibit both elastic and viscous characteristics in different regimes, while the transport of fluid (cytosol) through the cross-linked filamentous scaffold (cytoskeleton) is reminiscent of mass transfer by diffusion through a porous medium. To gain insights into this complex rheological behaviour, we construct a computational model for the cell cytoplasm as a poroviscoelastic material formulated on the principles of nonlinear continuum mechanics, where we model the cytoplasm as a porous viscoelastic scaffold with an embedded viscous fluid flowing between the pores to model the cytosol. Baseline simulations (neglecting the viscosity of the cytosol) indicate that the system exhibits seven different regimes across the parameter space spanned by the viscoelastic relaxation timescale of the cytoskeleton and the poroelastic diffusion timescale; these regimes agree qualitatively with experimental measurements. Furthermore, the theoretical model also allows us to elucidate the additional role of pore fluid viscosity, which enters the system as a distinct viscous timescale. We show that increasing this viscous timescale hinders the passage of the pore fluid (reducing the poroelastic diffusion) and makes the cytoplasm rheology increasingly incompressible, shifting the phase boundaries between the regimes.
MIT Department
Massachusetts Institute of Technology. Department of Mechanical Engineering
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DOI of Published Version
https://doi.org/10.1007/s10237-024-01854-2
