title: The high-throughput phenotyping of the viscoelastic behavior of whole mouse intervertebral discs using a novel method of dynamic mechanical testing.
abstract: Intervertebral disc (IVD) degeneration is highly correlated with lower back pain, and thus understanding the mechanisms of IVD degeneration is critical for the treatment of this disease. Utilizing mouse models to probe the mechanisms of degeneration is especially attractive due to the ease of manipulating mouse models and the availability of transgenics. Yet characterizing the mechanical behavior of mice IVDs remain challenging due to their minute size (approximately 540 μm in height and 1080 μm(2) in cross sectional area). We have thus developed a simple method to dynamically characterize the mechanical properties of intact mouse IVDs. The IVDs were dissected with the endplates intact, and dynamically compressed in the axial direction at 1% and 5% peak strains at 1 Hz. Utilizing this novel approach, we examined the effects of in vitro ribosylation and trypsin digestion for 24 or 72 h on the viscoelastic behavior of the whole murine IVD. Trypsin treatment resulted in a decrease of proteoglycans and loss of disc height, while ribosylation had no effect on structure or proteoglycan composition. The 72 h ribosylation group exhibited a stiffening of the disc, and both treatments significantly reduced viscous behavior of the IVDs, with the effects being more pronounced at 5% strain. Here we demonstrate a novel high-throughput method to mechanically characterize murine IVDs and detect strain-dependent differences in the elastic and the viscous behavior of the treated IVDs due to ribose and trypsin treatments.
authors.affiliation: Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, United States.
authors.forename: Jennifer W
authors.initials: JW
authors.lastname: Liu
authors.affiliation: Department of Orthopaedic Surgery, Washington University in St. Louis, 660 South Euclid Avenue, Box 8233, St. Louis, MO 63110, United States.
authors.forename: Adam C
authors.initials: AC
authors.lastname: Abraham
authors.affiliation: Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, United States; Department of Orthopaedic Surgery, Washington University in St. Louis, 660 South Euclid Avenue, Box 8233, St. Louis, MO 63110, United States; Department of Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO, United States. Electronic address: tangs@wustl.edu.
authors.forename: Simon Y
authors.initials: SY
authors.lastname: Tang
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D004195:Disease Models, Animal; D004548:Elasticity; D007403:Intervertebral Disc / Q000503:physiopathology; D055959:Intervertebral Disc Degeneration / Q000150:complications / Q000503:physiopathology*; D017116:Low Back Pain / Q000209:etiology / Q000503:physiopathology; D051379:Mice; D008810:Mice, Inbred C57BL; D010641:Phenotype; D014783:Viscosity
keywords: Dynamic compression; Intervertebral disc degeneration; Murine model; Ribosylation; Trypsin