Extracellular fluid viscosity influences the mechanics and migration of MDA ‐ MB ‐231 cells in a macromolecule‐dependent manner

Cells constantly experience the ubiquitous mechanical cue of extracellular fluid (ECF) viscosity, which dictates essential cell functions across physiological and pathophysiological conditions. Recent studies have linked increased ECF viscosity to the enhanced migratory capacity of cells across a wide range of environments. The mechanical properties of cells have been shown to regulate cell motility. As ECF viscosity is mechanical, the resulting increased cell migration due to ECF viscosity could be mediated by modulated cellular mechanoresponses. In this work, we varied extracellular fluid viscosity through addition of methylcellulose (MC) or polyvinylpyrrolidone (PVP) to the cell culture media. Cell morphology and migration parameters were quantified from phase-contrast microscopy images and were measured as a function of extracellular fluid viscosity and/or osmotic shocks. We also utilized a microfluidic cell deformation device and Brillouin microscopy to measure the mechanical properties of cells as a function of extracellular fluid viscosity. We demonstrated that increased ECF viscosity leads to changes in cell mechanical properties and invasive potential in a macromolecule-dependent manner.