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Mechanics of a Fiber Network Within a Non-Fibrillar Matrix: Model and Comparison with Collagen-Agarose Co-gels

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Abstract

While collagen is recognized as the predominant mechanical component of soft connective tissues, the role of the non-fibrillar matrix (NFM) is less well understood. Even model systems, such as the collagen-agarose co-gel, can exhibit complex behavior, making it difficult to identify relative contributions of specific tissue constituents. In the present study, we developed a two-component microscale model of collagen-agarose tissue analogs and used it to elucidate the interaction between collagen and NFM in uniaxial tension. Collagen fibers were represented with Voronoi networks, and the NFM was modeled as a neo-Hookean solid. Model predictions of total normal stress and Poisson’s ratio matched experimental observations well (including high Poisson’s values of ~3), and the addition of NFM led to composition-dependent decreases in volume change and increases in fiber stretch. Because the NFM was more resistant to volume change than the fiber network, extension of the composite led to pressurization of the NFM. Within a specific range of parameter values (low shear modulus and moderate Poisson’s ratio), the magnitude of the reaction force decreased relative to this pressurization component resulting in a negative (compressive) NFM stress in the loading direction, even though the composite tissue was in tension.

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Acknowledgments

The authors gratefully acknowledge the financial support of the National Institutes of Health (R01-EB005813 and F32-EB012352), the National Science Foundation (GRFP), and the American Heart Association (11PRE5410003).

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No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.

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  1. Department of Biomedical Engineering, University of Minnesota, 7-105 Nils Hasselmo Hall, 312 Church Street SE, Minneapolis, MN, 55455, USA

    Spencer P. Lake, Mohammad F. Hadi, Victor K. Lai & Victor H. Barocas

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  1. Spencer P. Lake
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  2. Mohammad F. Hadi
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Correspondence to Victor H. Barocas.

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Associate Editor Laura Suggs oversaw the review of this article.

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Lake, S.P., Hadi, M.F., Lai, V.K. et al. Mechanics of a Fiber Network Within a Non-Fibrillar Matrix: Model and Comparison with Collagen-Agarose Co-gels. Ann Biomed Eng 40, 2111–2121 (2012). https://doi.org/10.1007/s10439-012-0584-6

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