Measuring cell adhesion forces with the atomic force microscope at the molecular level

In the past 25 years many techniques have been developed to
characterize cell adhesion and to quantify adhesion forces. Atomic
force microscopy (AFM) has been used to measure forces in the
pico-newton range, an experimental technique known as force
spectroscopy. We modified such an AFM to measure adhesion forces
between live cells or between cells and surfaces. This strategy
required functionalizing the surface of the sensors for
immobilizing the cell. We used Dictyostelium discoideum cells which
respond to starvation by surface expression of the adhesion
molecule csA and consequent aggregation to measure the adhesion
force of a single csA-csA bond. Relevant experimental parameters
include the duration of contact between the interacting surfaces,
the force against which this contact is maintained, the number and
specificity of interacting adhesion molecules and the constituents
of the medium in which the interaction occurs. This technology also
permits the measurement of the viscoelastic properties of single
cells or cell layers. Copyright (C) 2002 S, Karger AG, Basel.