The nanomorphology of cell surfaces of adhered osteoblasts

TL;DR

This study uses scanning ion conductance microscopy to characterize the nanoscale surface features and dynamics of osteoblast cells, revealing membrane ruffles, protrusions, and fluctuation behaviors relevant to adhesion and migration.

Contribution

It provides a detailed 3D nanomorphological analysis of osteoblast surfaces, highlighting dynamic membrane features and their relation to cell adhesion and migration.

Findings

Dynamic membrane ruffles contribute to surface corrugation.

Anticorrelation between excess surface area and adhesion area.

Edge heights of lamellipodia range from 100 to 300 nm.

Abstract

Functionality of living cells is inherently linked to subunits with dimensions on the nanoscale. In case of osteoblasts the cell surface plays a particularly important role for adhesion and spreading which are crucial properties with regard to bone implants. Here we present a comprehensive characterization of the 3D nanomorphology of living as well as fixed osteoblastic cells using scanning ion conductance microscopy (SICM) which is a nanoprobing method largely avoiding forces. Dynamic ruffles are observed, manifesting themselves in characteristic membrane protrusions. They contribute to the overall surface corrugation which we systematically study by introducing the relative 3D excess area as a function of projected adhesion area. A clear anticorrelation is found upon analysis of ~40 different cells on glass as well as on amine covered surfaces. At the rim of lamellipodia characteristic edge heights between 100 nm and ~300 nm are observed. Power spectral densities of membrane fluctuations show frequency-dependent decay exponents in excess of -2 on living osteoblasts. We discuss the capability of apical membrane features and fluctuation dynamics in aiding assessment of adhesion and migration properties on a single-cell basis.