Tracking displacements of intracellular organelles in response to nanomechanical forces

The living cell is under constant influence of mechanical forces from its environment. These forces affect many aspects of the cell´s behaviour, including morphology, growth, cell differentiation, protein synthesis and cell death. In this study we show how mechanical stress perturbs the intracellular structures of the cell and induces mechanical responses. In order to correlate mechanical perturbations to cellular responses, we used a combined fluorescence-atomic force microscope (AFM) to produce nanomechanical perturbations while simultaneously tracking the real-time motion of fluorescently labelled mitochondria in live cells. Feature point tracking was then used to analyze and quantify the structural displacements. Following indentation from the AFM tip, the average mitochondrial displacement showed an increase of -40% in comparison to the natural movement. These results show how mitochondrial structures that are far away from the point of force (up to ~40 mum) are instantaneously affected by extracellular perturbations.