Proteoglycans (PGs) are broadly distributed within many soft tissues and, among other roles, often contribute to mechanical properties. Although PGs, consisting of a core protein and glycosaminoglycan (GAG) sidechains, were once hypothesized to regulate stress/strain transfer between collagen fibrils and help support load in tendon, several studies have reported no changes to tensile mechanics after GAG depletion. Since GAGs are known to help sustain nontensile loading in other tissues, we hypothesized that GAGs might help support shear loading in human supraspinatus tendon (SST), a commonly injured tendon which functions in a complex multiaxial loading environment. Therefore, the objective of this study was to determine whether GAGs contribute to the response of SST to shear, specifically in terms of multiscale mechanical properties and mechanisms of microscale matrix deformation. Results showed that chondroitinase ABC (ChABC) treatment digested GAGs in SST while not disrupting collagen fibers. Peak and equilibrium shear stresses decreased only slightly after ChABC treatment and were not significantly different from pretreatment values. Reduced stress ratios were computed and shown to be slightly greater after ChABC treatment compared to phosphate-buffered saline (PBS) incubation without enzyme, suggesting that these relatively small changes in stress values were not due strictly to tissue swelling. Microscale deformations were also not different after ChABC treatment. This study demonstrates that GAGs possibly play a minor role in contributing to the mechanical behavior of SST in shear, but are not a key tissue constituent to regulate shear mechanics.
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July 2017
Research-Article
Multiscale Mechanical Evaluation of Human Supraspinatus Tendon Under Shear Loading After Glycosaminoglycan Reduction
Fei Fang,
Fei Fang
Department of Mechanical Engineering
and Materials Science,
Washington University in St. Louis,
1 Brookings Drive,
Campus Box 1185,
St. Louis, MO 63130
e-mail: fangfei@wustl.edu
and Materials Science,
Washington University in St. Louis,
1 Brookings Drive,
Campus Box 1185,
St. Louis, MO 63130
e-mail: fangfei@wustl.edu
Search for other works by this author on:
Spencer P. Lake
Spencer P. Lake
Department of Mechanical Engineering
and Materials Science,
Washington University in St. Louis,
1 Brookings Drive,
Campus Box 1185,
St. Louis, MO 63130;
and Materials Science,
Washington University in St. Louis,
1 Brookings Drive,
Campus Box 1185,
St. Louis, MO 63130;
Department of Biomedical Engineering,
Washington University in St. Louis,
1 Brookings Drive,
Campus Box 1185,
St. Louis, MO 63130;
Washington University in St. Louis,
1 Brookings Drive,
Campus Box 1185,
St. Louis, MO 63130;
Department of Orthopaedic Surgery,
Washington University in St. Louis,
1 Brookings Drive,
Campus Box 1185,
St. Louis, MO 63130
e-mail: lake.s@wustl.edu
Washington University in St. Louis,
1 Brookings Drive,
Campus Box 1185,
St. Louis, MO 63130
e-mail: lake.s@wustl.edu
Search for other works by this author on:
Fei Fang
Department of Mechanical Engineering
and Materials Science,
Washington University in St. Louis,
1 Brookings Drive,
Campus Box 1185,
St. Louis, MO 63130
e-mail: fangfei@wustl.edu
and Materials Science,
Washington University in St. Louis,
1 Brookings Drive,
Campus Box 1185,
St. Louis, MO 63130
e-mail: fangfei@wustl.edu
Spencer P. Lake
Department of Mechanical Engineering
and Materials Science,
Washington University in St. Louis,
1 Brookings Drive,
Campus Box 1185,
St. Louis, MO 63130;
and Materials Science,
Washington University in St. Louis,
1 Brookings Drive,
Campus Box 1185,
St. Louis, MO 63130;
Department of Biomedical Engineering,
Washington University in St. Louis,
1 Brookings Drive,
Campus Box 1185,
St. Louis, MO 63130;
Washington University in St. Louis,
1 Brookings Drive,
Campus Box 1185,
St. Louis, MO 63130;
Department of Orthopaedic Surgery,
Washington University in St. Louis,
1 Brookings Drive,
Campus Box 1185,
St. Louis, MO 63130
e-mail: lake.s@wustl.edu
Washington University in St. Louis,
1 Brookings Drive,
Campus Box 1185,
St. Louis, MO 63130
e-mail: lake.s@wustl.edu
1Corresponding author.
Manuscript received November 30, 2016; final manuscript received April 26, 2017; published online June 6, 2017. Assoc. Editor: Eric A Kennedy.
J Biomech Eng. Jul 2017, 139(7): 071013 (8 pages)
Published Online: June 6, 2017
Article history
Received:
November 30, 2016
Revised:
April 26, 2017
Citation
Fang, F., and Lake, S. P. (June 6, 2017). "Multiscale Mechanical Evaluation of Human Supraspinatus Tendon Under Shear Loading After Glycosaminoglycan Reduction." ASME. J Biomech Eng. July 2017; 139(7): 071013. https://doi.org/10.1115/1.4036602
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