Research article summary (published 23 Sep 2009):

The role of fluctuations and stress on the effective viscosity of cell aggregates.

Full Abstract

Cell aggregates are a tool for in vitro studies of morphogenesis, cancer invasion, and tissue engineering. They respond to mechanical forces as a complex rather than simple liquid. To change an aggregate's shape, cells have to overcome energy barriers. If cell shape fluctuations are active enough, the aggregate spontaneously relaxes stresses ("fluctuation-induced flow"). If not, changing the aggregate's shape requires a sufficiently large applied stress ("stress-induced flow"). To capture this distinction, we develop a mechanical model of aggregates based on their cellular structure. At stress lower than a characteristic stress tau*, the aggregate as a whole flows with an apparent viscosity eta*, and at higher stress it is a shear-thinning fluid. An increasing cell-cell tension results in a higher eta* (and thus a slower stress relaxation time t(c)). Our constitutive equation fits experiments of aggregate shape relaxation after compression or decompression in which irreversibility can be measured; we find t(c) of the order of 5 h for F9 cell lines. Predictions also match numerical simulations of cell geometry and fluctuations. We discuss the deviations from liquid behavior, the possible overestimation of surface tension in parallel-plate compression measurements, and the role of measurement duration.

Author information

Author/s: Marmottant, Philippe (P); Mgharbel, Abbas (A); Käfer, Jos (J); Audren, Benjamin (B); Rieu, Jean-Paul (JP); Vial, Jean-Claude (JC); van der Sanden, Boudewijn (B); Marée, Athanasius F M (AF); Graner, François (F); Delanoë-Ayari, Hélène (H);

Affiliation: Laboratoire de Spectrométrie Physique, Unité Mixte de Recherche 5588, Université Grenoble I and Centre National de la Recherche Scientifique, 140 Avenue de la Physique, F-38402 Martin d'Hères Cedex, France.

Journal and publication information

Publication Type: Journal Article

Journal: Proceedings of the National Academy of Sciences of the United States of America (Proc Natl Acad Sci U S A), published in United States. (Language: eng)

Reference: 2009-Oct; vol 106 (issue 41) : pp 17271-5

Dates: Created 2009/10/15; Completed 2009/11/03; Revised 2009/11/06;

PMID: 19805170, status: MEDLINE (last retrieval date: 11/9/2009, IMS Date: )

Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.

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MeSH headings (categories)

This article was linked to the MESH Headings shown below.

Animals Biomechanics - physiology Cell Aggregation - physiology Cell Cycle - physiology Cell Line, Tumor - cytology; physiology Cell Size Cells - cytology

Cells - cytology Compressive Strength Elasticity Emulsions Mice Stress, Mechanical Viscosity

Associated Chemicals: Emulsions (0)

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