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Tissue engineering of cartilage using a mechanobioreactor exerting simultaneous mechanical shear and compression to simulate the rolling action of articular joints

Authors

  • Kifah Shahin,

    1. School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney NSW, Australia
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  • Pauline M. Doran

    Corresponding author
    1. Faculty of Life and Social Sciences, Swinburne University of Technology, PO Box 218, Hawthorn, Melbourne, VIC 3122, Australia; telephone: +61-3-9214-8573; fax: +61-3-9819-0574
    • Faculty of Life and Social Sciences, Swinburne University of Technology, PO Box 218, Hawthorn, Melbourne, VIC 3122, Australia; telephone: +61-3-9214-8573; fax: +61-3-9819-0574
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Abstract

The effect of dynamic mechanical shear and compression on the synthesis of human tissue-engineered cartilage was investigated using a mechanobioreactor capable of simulating the rolling action of articular joints in a mixed fluid environment. Human chondrocytes seeded into polyglycolic acid (PGA) mesh or PGA–alginate scaffolds were precultured in shaking T-flasks or recirculation perfusion bioreactors for 2.5 or 4 weeks prior to mechanical stimulation in the mechanobioreactor. Constructs were subjected to intermittent unconfined shear and compressive loading at a frequency of 0.05 Hz using a peak-to-peak compressive strain amplitude of 2.2% superimposed on a static axial compressive strain of 6.5%. The mechanical treatment was carried out for up to 2.5 weeks using a loading regime of 10 min duration each day with the direction of the shear forces reversed after 5 min and release of all loading at the end of the daily treatment period. Compared with shaking T-flasks and mechanobioreactor control cultures without loading, mechanical treatment improved the amount and quality of cartilage produced. On a per cell basis, synthesis of both major structural components of cartilage, glycosaminoglycan (GAG) and collagen type II, was enhanced substantially by up to 5.3- and 10-fold, respectively, depending on the scaffold type and seeding cell density. Levels of collagen type II as a percentage of total collagen were also increased after mechanical treatment by up to 3.4-fold in PGA constructs. Mechanical treatment had a less pronounced effect on the composition of constructs precultured in perfusion bioreactors compared with perfusion culture controls. This work demonstrates that the quality of tissue-engineered cartilage can be enhanced significantly by application of simultaneous dynamic mechanical shear and compression, with the greatest benefits evident for synthesis of collagen type II. Biotechnol. Bioeng. 2012; 109:1060–1073. © 2011 Wiley Periodicals, Inc.

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