Changes in biomechanical properties of neuronal cells measured by combined atomic force and fluorescence microscopy

We perform combined atomic force (AFM) and fluorescence microscopy measurements to determine how changes in the surrounding environment affect the biomechanical properties of neuronal cells at both the bulk (elastic modulus) and local (elasticity maps) levels. These high-resolution experiments allow us to distinguish between the contributions of the cellular membrane and of different cytoskeletal components to the cell elastic modulus. Our results demonstrate that the dominant mechanism by which the mechanical properties of the neuronal soma changes in response to external temperature is the contractile stiffening of the cytoskeleton induced by the change in myosin II activity. We find a power law relationship between cell elastic modulus and volume, and propose a simple model, based on elastic properties of biopolymer networks, that predicts the observed relationship. These results have significant implications for understanding neuronal functions, as ambient conditions such as external temperature or the stiffness of the growth substrate may change in physiological conditions, for example, under tissue compression or during neuronal growth, cell manipulation, and tissue regeneration.