title: Collagen V-heterozygous and -null supraspinatus tendons exhibit altered dynamic mechanical behaviour at multiple hierarchical scales.
abstract: Tendons function using a unique set of mechanical properties governed by the extracellular matrix and its ability to respond to varied multi-axial loads. Reduction of collagen V expression, such as in classic Ehlers-Danlos syndrome, results in altered fibril morphology and altered macroscale mechanical function in both clinical and animal studies, yet the mechanism by which changes at the fibril level lead to macroscale functional changes has not yet been investigated. This study addresses this by defining the multiscale mechanical response of wild-type, collagen V-heterozygous and -null supraspinatus tendons. Tendons were subjected to mechanical testing and analysed for macroscale properties, as well as microscale (fibre re-alignment) and nanoscale (fibril deformation and sliding) responses. In many macroscale parameters, results showed a dose-dependent response with severely decreased properties in the null group. In addition, both heterozygous and null groups responded to load faster than in wild-type tendons via earlier fibre re-alignment and fibril stretch. However, the heterozygous group exhibited increased fibril sliding, while the null group exhibited no fibril sliding. These studies demonstrate that dynamic responses play an important role in determining overall function and that collagen V is a critical regulator in the development of these relationships.
authors: McKay Orthopaedic Research Laboratory , University of Pennsylvania , 424 Stemmler Hall, 36th and Hamilton Walk, Philadelphia, PA 19104-6081 , USA.
authors: Brianne K
authors: BK
authors: Connizzo
authors: School of Biomedical Engineering, Science and Health Systems , Drexel University , 3141 Chestnut Street, Philadelphia, PA 19104 , USA.
authors: Lin
authors: L
authors: Han
authors: Department of Molecular Pharmacology and Physiology , Morsani College of Medicine, University of South Florida , Tampa, FL 33612 , USA.
authors: David E
authors: DE
authors: Birk
authors: McKay Orthopaedic Research Laboratory , University of Pennsylvania , 424 Stemmler Hall, 36th and Hamilton Walk, Philadelphia, PA 19104-6081 , USA.
authors: Louis J
authors: LJ
authors: Soslowsky
keywords: Ehlers–Danlos syndrome; fibril sliding; multiscale mechanics; re-alignment; supraspinatus; tendon