To investigate how cells sense stiffness in settings structurally similar to native extracellular matrices, we designed a synthetic fibrous material with tunable mechanics and user-defined architecture. In contrast to flat hydrogel surfaces, these fibrous materials recapitulated cell–matrix interactions observed with collagen matrices including stellate cell morphologies, cell-mediated realignment of fibres, and bulk contraction of the material. Increasing the stiffness of flat hydrogel surfaces induced mesenchymal stem cell spreading and proliferation; however, increasing fibre stiffness instead suppressed spreading and proliferation for certain network architectures. Lower fibre stiffness permitted active cellular forces to recruit nearby fibres, dynamically increasing ligand density at the cell surface and promoting the formation of focal adhesions and related signalling. These studies demonstrate a departure from the well-described relationship between material stiffness and spreading established with hydrogel surfaces, and introduce fibre recruitment as a previously undescribed mechanism by which cells probe and respond to mechanics in fibrillar matrices.
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This work was supported in part by grants from the National Institutes of Health (grant numbers EB000262, EB001046, HL115553, GM74048, AR056624) and Center for Engineering Cells and Regeneration of the University of Pennsylvania. B.M.B. acknowledges financial support from a Ruth L. Kirschstein National Research Service Award (EB014691) and NIH Pathway to Independence Award (HL124322). We would like to thank N. Wang for helpful discussions. We would also like to acknowledge support from the Penn Regional Nanotechnology Facility and the BME Core Facilities at Boston University.
The authors declare no competing financial interests.
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Baker, B., Trappmann, B., Wang, W. et al. Cell-mediated fibre recruitment drives extracellular matrix mechanosensing in engineered fibrillar microenvironments. Nature Mater 14, 1262–1268 (2015). https://doi.org/10.1038/nmat4444
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