On the origin and extent of mechanical variation among cells

TL;DR

This paper proposes a model linking the intrinsic variability in cell rheological properties to the observed distributions of cell stiffness and deformation behaviors, highlighting the stochastic nature of cell mechanics.

Contribution

It introduces a novel hypothesis that the power-law rheology exponent varies among cells, explaining the log-normal distribution of cell stiffness and connecting noise in cytoskeletal relaxation to mechanical variation.

Findings

Power-law rheology is common in cells.

Cell stiffness follows a log-normal distribution.

Variability in rheology exponent explains observed distributions.

Abstract

Investigations of natural variation in cell mechanics within a cell population are essential to understand the stochastic nature of soft-network deformation. Striking commonalities have been found concerning the average values and distribution of rheological parameters of cells: first, attached and suspended cells exhibit power-law rheological behavior; second, cell stiffness is distributed log-normally. A predictive connection between these two near-universal findings has not been reported, to our knowledge. Here we postulate, based on our own and others' experimental reports and leading models of cell rheology, that the exponent that characterizes power-law rheology varies intrinsically among cells as an approximately Gaussian-distributed variable. Besides explaining naturally the log-normal distribution of cell stiffness that is widely observed, this postulate predicts multiple empirically observed relationships from cell deformation studies. Our framework ultimately links inherent noise in postulated relaxation mechanisms of cytoskeletal networks to mechanical variation among cells and cell populations.