A comparison of methods to assess cell mechanical properties

Abstract

<p class="first" id="P1">Cell mechanics controls important cellular and subcellular functions, including cell adhesion, migration, polarization, and differentiation, as well as organelle organization, and trafficking inside the cytoplasm. Yet, reported values of cell stiffness and viscosity vary strongly, suggesting disagreements in how results of different methods are obtained or analyzed. To address this issue and illustrate the complementarity of different instruments, we present, analyze, and critically compare measurements conducted by some of the most widely used methods of cell mechanics: atomic force microscopy, magnetic twisting cytometry, particle-tracking microrheology, parallel-plates rheometry, cell monolayer rheology, and the optical stretcher. These measurements highlight that elastic and viscous moduli of MCF-7 breast cancer cells can vary 1,000 fold and 100 fold, respectively. We discuss the sources of these variations, including the level of applied mechanical stress and rate of deformation, the geometry of the probe, the location probed in the cell, and the extracellular microenvironment. </p>