Alison E. Patteson: 0000-0002-4004-1734

J. M. Schwarz: 0000-0001-9880-9999

Document Type



Spring 3-18-2020




National Science Center, Poland under Grant, National Institutes of Health

Funding ID

UMO-2017/26/D/ST4/00997, NSF DMR-1720530, NSF CMMI-154857, NIH R01 EB017753, NSF-DMR-CMMT-1507938, NSF-DMR-CMMT-1832002, NSF-PHY-PoLS-1607416


We thank an anonymous reviewer for queries which led to an analysis of the stretching and bending regimes in Section III. MCG acknowledges useful discussions with Matthias Merkel and Daniel Sussman, while JMS acknowledges useful exchanges with Dennis Discher and Tom Lubensky. KP acknowledges partial support from the National Science Center, Poland under Grant: UMO-2017/26/D/ST4/00997. AEP, AvO, and PAJ were supported by NSF DMR-1720530, NSF CMMI-154857 and NIH R01 EB017753. JMS acknowledges financial support from NSF-DMR-CMMT-1507938, NSF-DMR-CMMT-1832002, and from NSF-PHY-PoLS-1607416.

Official Citation

Gandikota, M. C., Pogoda, Katarzyna, van Oosten, Anne, Engstrom, T. A., Patteson, A. E., Janmey, P. A., and Schwarz, J. M. Loops versus lines and the compression stiffening of cells. Retrieved from https://par.nsf.gov/biblio/10178787. Soft Matter 16.18 Web. doi:10.1039/C9SM01627A.




Both animal and plant tissue exhibit a nonlinear rheological phenomenon known as compression stiffening, or an increase in moduli with increasing uniaxial compressive strain. Does such a phenomenon exist in single cells, which are the building blocks of tissues? One expects an individual cell to compression soften since the semiflexible biopolymer-based cytoskeletal network maintains the mechanical integrity of the cell and in vitro semiflexible biopolymer networks typically compression soften. To the contrary, we find that mouse embryonic fibroblasts (mEFs) compression stiffen under uniaxial compression via atomic force microscopy studies. To understand this finding, we uncover several potential mechanisms for compression stiffening. First, we study a single semiflexible polymer loop modeling the actomyosin cortex enclosing a viscous medium modeled as an incompressible fluid. Second, we study a two-dimensional semiflexible polymer/fiber network interspersed with area-conserving loops, which are a proxy for vesicles and fluid-based organelles. Third, we study two-dimensional fiber networks with angular-constraining crosslinks, i.e. semiflexible loops on the mesh scale. In the latter two cases, the loops act as geometric constraints on the fiber network to help stiffen it via increased angular interactions. We find that the single semiflexible polymer loop model agrees well with the experimental cell compression stiffening finding until approximately 35% compressive strain after which bulk fiber network effects may contribute. We also find for the fiber network with area-conserving loops model that the stress–strain curves are sensitive to the packing fraction and size distribution of the area-conserving loops, thereby creating a mechanical fingerprint across different cell types. Finally, we make comparisons between this model and experiments on fibrin networks interlaced with beads as well as discuss implications for single cell compression stiffening at the tissue scale.

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Creative Commons Attribution 3.0 License
This work is licensed under a Creative Commons Attribution 3.0 License.

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