Variable-Angle Total Internal Reflection Fluorescence Microscopy: Towards a New Way to Probe Single Cell Adhesion Strength
Résumé
Total Internal Reflection Fluorescence (TIRF) microscopy is a widespread technique used to study cellular process occurring near the contact region with the glass substrate. In this framework, we have recently proposed a new strategy to investigate adhesion strength at the single cell level (Biophysical Journal, 111, 2016, p1316-1327 and AIMS Biophysics, 4, 2017, p438-450). This approach involves variable-angle Total Internal Reflection Fluorescence Microscopy (vaTIRFM). vaTIRFM allows to map in real time, the cell topography (i.e. the membrane-substrate separation distance) with a nanometric axial resolution, and the effective refractive index of the cell cortex. Topography and refractive index are two key parameters allowing to observe close contacts related to focal adhesion process, and non-specific membrane/substrate interactions for example to highlight the crucial role of glycocalyx. vaTIRFM can also be used to get the profile of the potential energy related to membrane/substrate interactions, from which it is possible to extract an energy of adhesion. We have recently emphasized the benefits of vaTIRFM for different cancer cells in adhesion on various substrates, or by blocking the adhesion and/or the migration signaling pathways using integrin antagonists.