Vendredi 10 avril à 11h00, salle des séminaires IRPHE
Abstract: Red blood cells (RBCs) are the main component of blood. They are highly deformable due to their membrane properties, the presence of a peripheral spectrin skeleton, as well as the absence of organelles. Of the various methods available such as optical tweezers or microfluidics, atomic force microscopy (AFM) is a technique of choice to measure the mechanical properties of RBCs. However, it requires the cell to be confined or adhered to the underlying substrate. This is known to affect results, but systematic quantification is lacking.
We mapped low to strong non-specific cell-substrate adhesion regimes using Poly-L-Lysine. We demonstrate that substrate adhesion alters the native biconcave shape of the RBC and is accompanied by a significant modification of the effective Young moduli E, with dome-shaped cells exhibiting the greatest stiffness. Rheological measurements reveal that adhesion also affects the transition from solid-like to liquid-like behaviour. These findings help explain the wide discrepancies of E reported in literature. On the one hand, different regimes of membrane deformation are implied depending on adhesion strength. On the other hand, the very low forces in the pN range used to probe these cells are at the limit of what AFM can probe. This also suggests that adhesion strength could directly impact the measurements of other cell types, despite their stronger metabolic activity and more complex adhesive structures.
Agathe Nidriche, post-doctoral researcher at Göttingen University, Institute for X-Rays Physics.