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Cellular nanoscale stiffness patterns governed by intracellular forces

Abstract

Cell stiffness measurements have led to insights into various physiological and pathological processes1,2. Although many cellular behaviours are influenced by intracellular mechanical forces3,4,5,6 that also alter the material properties of the cell, the precise mechanistic relationship between intracellular forces and cell stiffness remains unclear. Here we develop a cell mechanical imaging platform with high spatial resolution that reveals the existence of nanoscale stiffness patterns governed by intracellular forces. On the basis of these findings, we develop and validate a cellular mechanical model that quantitatively relates cell stiffness to intracellular forces. This allows us to determine the magnitude of tension within actin bundles, cell cortex and plasma membrane from the cell stiffness patterns across individual cells. These results expand our knowledge on the mechanical interaction between cells and their environments, and offer an alternative approach to determine physiologically relevant intracellular forces from high-resolution cell stiffness images.

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All the data supporting the findings of this study are available within the article or its Supplementary Information files, or from the corresponding authors on reasonable request.

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Acknowledgements

We acknowledge M. P. Sheetz for helpful discussions, E. Bryant for help in setting up imaging and cell culture, T. Iskratsch and V. Stevenin for help with fibroblast culture and treatment, X. Chen for help with instrumentation, T. P. Stossel and F. Nakamura for providing M2 cells, L. Chasin for providing CHO cells and L. P. Alonso-Sarduy for culturing them. This work is supported by the NIH Director’s New Innovator Award Program (1DP2-EB018657), the Rowland Fellows Program and the Wyss Institute for Biologically Inspired Engineering at Harvard University.

Author information

N.M. carried out AFM and fluorescence imaging and contributed to cantilever design, improvement of imaging protocols, data analysis and development of mechanical models. C.F. demonstrated proof of principle for the AFM imaging method and contributed to the development of imaging protocols. J.A.J.-M. contributed to the AFM and fluorescence imaging and to the development of mechanical models. K.V.T. contributed to AFM and florescence imaging, and development of imaging protocols. D.E.I. contributed to the development of mechanical models, experimental design and discussions. O.S. contributed to the cantilever design, development of mechanical models, experimental design and data analysis. O.S. and N.M. wrote the manuscript with input from all coauthors.

Correspondence to Ozgur Sahin.

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Competing interests

O.S. is a co-inventor on US Patents US7302833B2 and US7404314B2 assigned to Stanford University, which are related to the methods used this work. O.S. founded Big Apple Nano, Inc.

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Supplementary Information

Supplementary Figures 1–12, Supplementary Notes 1–3 and Supplementary References 1 and 2

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Fig. 1: Imaging nanoscale stiffness of cells.
Fig. 2: Stiffness of load-bearing cytoskeletal components.
Fig. 3: Cell stiffness patterns along actin bundles.
Fig. 4: Cell stiffness patterns across the cortex.
Fig. 5: Measuring physiologically relevant intracellular forces from the stiffness images.