A novel microstructural interpretation for the biomechanics of mouse skin derived from multiscale characterization

Barbara Lynch, Stéphane Bancelin, Christelle Bonod-Bidaud, Jean-Baptiste Gueusquin, Florence Ruggiero, Marie-Claire Schanne-Klein, Jean-Marc Allain
Acta Biomaterialia. 2017-03-01; 50: 302-311
DOI: 10.1016/j.actbio.2016.12.051

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Lynch B(1), Bancelin S(2), Bonod-Bidaud C(3), Gueusquin JB(1), Ruggiero F(3), Schanne-Klein MC(2), Allain JM(4).

Author information:
(1)LMS, Ecole Polytechnique, CNRS, Université Paris-Saclay, Palaiseau, France.
(2)LOB, Ecole Polytechnique, CNRS, INSERM, Université Paris-Saclay, Palaiseau, France.
(3)Institut de Génomique Fonctionnelle de Lyon, ENS-Lyon, CNRS, Université de Lyon, Lyon, France.
(4)LMS, Ecole Polytechnique, CNRS, Université Paris-Saclay, Palaiseau, France; Inria, Université Paris-Saclay, Palaiseau, France. Electronic address: .

Skin is a complex, multi-layered organ, with important functions in the
protection of the body. The dermis provides structural support to the epidermal
barrier, and thus has attracted a large number of mechanical studies. As the
dermis is made of a mixture of stiff fibres embedded in a soft non-fibrillar
matrix, it is classically considered that its mechanical response is based on an
initial alignment of the fibres, followed by the stretching of the aligned
fibres. Using a recently developed set-up combining multiphoton microscopy with
mechanical assay, we imaged the fibres network evolution during dermis
stretching. These observations, combined with a wide set of mechanical tests,
allowed us to challenge the classical microstructural interpretation of the
mechanical properties of the dermis: we observed a continuous alignment of the
collagen fibres along the stretching. All our results can be explained if each
fibre contributes by a given stress to the global response. This plastic response
is likely due to inner sliding inside each fibre. The non-linear mechanical
response is due to structural effects of the fibres network in interaction with
the surrounding non-linear matrix. This multiscale interpretation explains our
results on genetically-modified mice with a simple alteration of the dermis
microstructure.STATEMENT OF SIGNIFICANCE: Soft tissues, as skin, tendon or aorta,
are made of extra-cellular matrix, with very few cells embedded inside. The
matrix is a mixture of water and biomolecules, which include the collagen fibre
network. The role of the collagen is fundamental since the network is supposed to
control the tissue mechanical properties and remodeling: the cells attach to the
collagen fibres and feel the network deformations. This paper challenges the
classical link between fibres organization and mechanical properties. To do so,
it uses multiscale observations combined to a large set of mechanical loading. It
thus appears that the behaviour at low stretches is mostly controlled by the
network structural response, while, at large stretches, the fibre inner-sliding

Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


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