Mechanical assessment by magnetocytometry of the cytosolic and cortical cytoskeletal compartments in adherent epithelial cells

This study aims at quantifying the cellular mechanical properties based on a partitioning of the cytoskeleton in a cortical and a cytosolic compartments. The mechanical response of epithelial cells obtained by magnetocytometry – a micromanipulation technique which uses twisted ferromagnetic beads specifically linked to integrin receptors – was purposely analysed using a series of two Voigt bodies. Results showed that the cortical cytoskeleton has a faster response (∼1 s) than the cytosolic compartment (∼30 s). Moreover, the two cytoskeletal compartments have specific mechanical properties, i.e., the cortical (resp. cytosolic) cytoskeleton has a rigidity in the range: 49–85 Pa (resp.: 74–159 Pa) and a viscosity in the range 5–14 Pa.s (resp.: 593–1534 Pa.s), depending on the level of applied stress. Depolymerising actin‐filaments strongly modified these values and especially those of the cytosolic compartment. The structural relevance of this two‐compartment partitioning was supported by images of F‐actin structure obtained on the same cells.