Cellular mechanical properties in response to environmental viscosity imaged by Brillouin Microscopy.

An increasing body of research in biomechanics has revealed that the stiffness of the surrounding environment influences cells fate and function. In this context, a recent study showed that cells exposed to highly viscous fluids migrated and spread faster: the viscosity of the surrounding environment thus emerges as a novel potential regulator of key cell functions. To date, however, cellular mechanical responses to this biophysical trigger are widely unconsidered. In this study, we evaluate the mechanical properties of non-cancerous (MCF10A) and highly metastatic cancer (MDA-MB-231) cells grown in fluids of different viscosities by using our custom-built Brillouin Microscope. To achieve this result, we prove that the linewidth of a Brillouin spectrum can serve as a reliable viscosity indicator through an innovative deconvolution method that makes use of a Brillouin Microscope and a Stimulated Brillouin Microscope. Our findings suggest that cancer cells may adapt their internal mechanical properties in response to external media viscosity, thus improving their adaptability to the environment in an active interaction with their surroundings.