Short-term binding of fibroblasts to fibronectin: optical tweezers experiments and probabilistic analysis.

Olivier Thoumine, Pierre Kocian, Arlette Kottelat, Jean-Jacques Meister
European Biophysics Journal. 2000-09-22; 29(6): 398-408
DOI: 10.1007/s002490000087

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1. Eur Biophys J. 2000;29(6):398-408.

Short-term binding of fibroblasts to fibronectin: optical tweezers experiments
and probabilistic analysis.

Thoumine O(1), Kocian P, Kottelat A, Meister JJ.

Author information:
(1)Biomedical Engineering Laboratory, Swiss Federal Institute of Technology,
Lausanne.

The biophysical properties of the interaction between fibronectin and its
membrane receptor were inferred from adhesion tests on living cells. Individual
fibroblasts were maintained on fibronectin-coated glass for short time periods
(1-16 s) using optical tweezers. After contact, the trap was removed quickly,
leading to either adhesion or detachment of the fibroblast. Through a stochastic
analysis of bond kinetics, we derived equations of adhesion probability versus
time, which fit the experimental data well and were used to compute association
and dissociation rates (k+ = 0.3-1.4 s(-1) and koff = 0.05-0.25 s(-1),
respectively). The bond distribution is binomial, with an average bond number <
or = 10 at these time scales. Increasing the fibronectin density (100-3000
molecules/microm2) raised k+ in a diffusion-dependent manner, leaving koff
relatively unchanged. Increasing the temperature (23-37 degrees C) raised both k+
and koff, allowing calculation of the activation energy of the chemical reaction
(around 20 kBT). Increasing the compressive force on the cell during contact (up
to 60 pN) raised k+ in a logarithmic manner, probably through an increase in the
contact area, whereas koff was unaffected. Finally, by varying the pulling force
to detach the cell, we could distinguish between two adhesive regimes, one
corresponding to one bond, the other to at least two bonds. This transition
occurred at a force around 20 pN, interpreted as the strength of a single bond.

DOI: 10.1007/s002490000087
PMID: 11081401 [Indexed for MEDLINE]

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