How cells tiptoe on adhesive surfaces before sticking

TL;DR

This study reveals that monocytic cell membranes exhibit nanometer-scale undulations that facilitate initial contact and sensitivity to surface topography during adhesion, advancing understanding of early cell-surface interactions.

Contribution

The paper uncovers the dynamic membrane undulations and their role in cell surface sensing and adhesion initiation, providing new insights into cell topography interactions.

Findings

Membrane undulations have 5 nm amplitude and 5-10 s lifetime.

Cells detect surfaces at 50 nm separation, amplifying membrane fluctuations.

Membrane contact involves a 30-40 nm separation decreasing over seconds.

Abstract

Cell membranes are studded with protrusions that were thoroughly analyzed with electron microscopy. However, the nanometer-scale three-dimensional motions generated by cell membranes to fit the topography of foreign surfaces and initiate adhesion remain poorly understood. Here, we describe the dynamics of surface deformations displayed by monocytic cells bumping against fibronectin-coated surfaces. We observed membrane undulations with typically 5 nm amplitude and 5-10 second lifetime. Cell membranes behaved as independent units of micrometer size. Cells detected the presence of foreign surfaces at 50 nm separation, resulting in time-dependent amplification of membrane undulations. Molecular contact then ensued with apparent cell-membrane separation of 30-40 nm, and this distance steadily decreased during the following tens of seconds. Contact maturation was associated with in-plane egress of bulky molecules and robust membrane fluctuations. Thus, membrane undulations may be the major determinant of cell sensitivity to substrate topography, outcome of interaction and initial kinetics of contact extension