Force mapping in epithelial cell migration

TLDR

The study compares traction forces produced by MDCK cells in subconfluent epithelia versus isolated cells following hepatocyte growth factor treatment. Dynamic traction forces were measured with a high‑density array of elastomeric microfabricated pillars, and real‑time mechanical activity was estimated by multiple‑particle tracking at 2 µm resolution, using differentiated MDCK cells. The measurements revealed that forces are strongest at the epithelial edge, that hepatocyte growth factor enhances motility and scattering, and that edge traction stresses exceed those of single cells, suggesting collective behavior.

Abstract

We measure dynamic traction forces exerted by epithelial cells on a substrate. The force sensor is a high-density array of elastomeric microfabricated pillars that support the cells. Traction forces induced by cell migration are deduced from the measurement of the bending of these pillars and are correlated with actin localization by fluorescence microscopy. We use a multiple-particle tracking method to estimate the mechanical activity of cells in real time with a high-spatial resolution (down to 2 μm) imposed by the periodicity of the post array. For these experiments, we use differentiated Madin-Darby canine kidney (MDCK) epithelial cells. Our data provide definite information on mechanical forces exerted by a cellular assembly. The maximum intensity of the forces is localized on the edge of the epithelia. Hepatocyte growth factor promotes cell motility and induces strong scattering activity of MDCK cells. Thus, we compare forces generated by MDCK cells in subconfluent epithelia versus isolated cells after hepatocyte growth factor treatment. Maximal-traction stresses at the edge of a monolayer correspond to higher values than those measured for a single cell and may be due to a collective behavior.