Nano-mechanical mapping of interdependent cell and ECM mechanics by AFM force spectroscopy.

Extracellular matrix (ECM), as a dynamic component of the tissue, influences cell behavior and plays an important role in cell mechanics and tissue homeostasis. Reciprocally, this three-dimensional scaffold is dynamically, structurally and mechanically modified by cells. In the field of biophysics, the independent role of cell and ECM mechanics has been largely investigated; however, there is a lack of experimental data reporting the interdependent interplay between cell and ECM mechanics, measured simultaneously. Here, using Atomic Force Microscopy (AFM) we have characterized five different decellularized matrices diverse in their topography, ECM composition and stiffness and cultured them with normal and pathological fibroblasts (scar and Dupuytren's). We investigated the change in topography and elasticity of these matrices due to cell seeding, by using AFM peak force imaging and mechanical mapping, respectively. We found normal fibroblasts soften these matrices more than pathological fibroblasts, suggesting that pathological fibroblasts are profoundly influencing tissue stiffening in fibrosis. We detected different ECM composition of decellularized matrices used here influences fibroblast stiffness, thus highlighting that cell mechanics not only depends on ECM stiffness but also on their composition. We used confocal microscopy to assess fibroblasts invasion and found pathological fibroblasts were invading the matrices deeper than normal fibroblasts.