The size, shape, and dynamics of cellular blebs

TL;DR

This paper presents a quantitative model for the growth, movement, and dynamics of cellular blebs, integrating pressure, membrane, and cortex interactions to better understand cell motility.

Contribution

It introduces a coupled hydrodynamic model that predicts bleb formation, traveling behavior, and the influence of cortical contraction and healing on bleb dynamics.

Findings

Minimum pressure and membrane length for bleb nucleation identified.

Bleb traveling speed linked to pressure change speed.

Model reproduces experimental observations of bleb behavior.

Abstract

A cellular bleb grows when a portion of the cell membrane detaches from the underlying cortex under the influence of a cytoplasmic pressure. We develop a quantitative model for the growth and dynamics of these objects in a simple two-dimensional setting. In particular, we first find the minimum cytoplasmic pressure and minimum unsupported membrane length for a stationary bleb to nucleate and grow as a function of the membrane-cortex adhesion. We next show how a bleb may travel around the periphery of the cell when the cytoplasmic pressure varies in space and time in a prescribed way and find that the traveling speed is governed by the speed of the pressure change induced by local cortical contraction while the shape of the traveling bleb is governed by the speed of cortical healing. Finally, we relax the assumption that the pressure change is prescribed and couple it hydrodynamically to the cortical contraction and membrane deformation. By quantifying the phase space of bleb formation and dynamics, our framework serves to delineate the range and scope of bleb-associated cell motility and synthesizes a variety of experimental observations.