QUANTIFYING CELL ADHESION USING SINGLE-CELL FORCE SPECTROSCOPY - Life at the Nanoscale: Atomic Force Microscopy of Live Cells - page 214

10.3.3.4 Elasc properes of the cell

The slope of the approach F-D curve in the contact region ( Fig. 10.4b , dashed
ellipse E) is inluenced by the elastic properties of the cell. Organized actin
ilaments of the cell cortex can substantially inluence the elastic properties
of most cell types.

10.3.3.5 Detachment work

The detachment work, W D , corresponds to the work required to detach the

cell from the substrate. W D is extracted from F-D curves by measuring the

area enclosed by retraction curve and baseline ( Fig. 10.4 ; hatched area). W D

is not only determined by the overall adhesion established between cell and
substrate, but is also substantially inluenced by the elastic properties of the
cell. Because of their length, often tens of micrometres, membrane nanotubes
signiicantly contribute to the W D .

10.3.4 AFM-Based SCFS—State of the Art

Pioneering AFM-based SCFS experiments with living mammalian cells
quantiied cell-cell adhesion between trophoblasts and uterine epithelial
cells to model interactions occurring during embryo implantation. 31 In
another early study, Lehenkari analysed adhesion between osteoblasts/

osteoclasts and different RGD-containing ligands. 32 In other studies,
endothelial cell-leukocyte adhesion 54,55 has been investigated, and the
contribution of integrin- and selectin-mediated interactions to this adhesion
was demonstrated using blocking antibodies. These experiments have
provided insights into the mechanisms underlying adhesive interactions
between leukocytes and endothelium that are crucial to initiate the process
of transmigration during inlammatory response. Adhesive interactions
between endothelial cells and leukocytes involve LFA (lymphocyte function-
associated molecule)-1-ICAM (intercellular adhesion molecule) 33,56 and
A

et al.

B

1 -integrin-VCAM (vascular cell adhesion molecule). 57 Interactions
between these two proteins were explored at the single-molecule level.
Thereby, bond-speciic parameters such as bond dissociation rates could
be determined. Recently, homophilic JAM-A (junctional adhesion molecule)
interactions were characterized, and a role of LFA-1 in their regulation was
shown. 58 Homophilic and heterophilic N-, E- and VE-cadherin interactions
were characterized at the single-molecule level using SCFS. 46,59 Furthermore,
adhesive interactions of cell surface integrins with nanopatterned RGD-
peptide-coated substrates were quantiied revealing insights into the spatial
organization of RGD ligands. 60

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