The size, shape, and dynamics of cellular blebs

¹ A*STAR Institute of High Performance Computing - 1 Fusionopolis Way, #16-16, Singapore 138632, Singapore
² Mechanobiology Institute, National University of Singapore - 5A Engineering Drive 1, Singapore 117411, Singapore
³ School of Engineering and Applied Sciences, Department of Physics, Harvard University 29 Oxford Street, Cambridge, MA 02138, USA

^(a) lm@seas.harvard.edu (corresponding author)

Received: 15 September 2012
Accepted: 28 September 2012

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.