Measurement of heterogeneity in subcellular live-cell rigidity using a stretchable micropost array platform

Cell stiffness together with other cell functional responses are recognized for their sensitiveness to external stimuli including biochemical and mechanical signals. It was shown that the stiffness over the cell body is heterogeneous, and the subcellular stiffness may correlate with other intracellular activities such as the cytoskeleton reorganization and the contractility dynamics. Here we reported a novel subcellular stiffness measurement strategy implemented by a cell stretching platform we recently developed. Our strategy involved a microfabricated array of the micropost structure integrated onto a stretchable silicone-based elastomeric membrane in order to apply global equibiaxial cell stretch. The simultaneous subcellular cell deformations under a stretching force profile reflected the mechanical properties of the adherent cells. Furthermore, we devised a computational scheme based on the finite element theory and the optimization techniques to convert the measurement results to the corresponding spatial stiffness of live-cells. We quantified the correlations between cell area, contractile force and the cell stiffness. Collectively, this work provided an effective and high resolution measurement strategy for the heterogeneity in subcellular live-cell stiffness profile that will help elucidate the intracellular mechanical responses and the related pathogenesis and developmental processes.