Contribution of glycosaminoglycans to viscoelastic tensile behavior of human ligament

Abstract

The viscoelastic properties of human ligament potentially guard against structural failure, yet the microstructural origins of these transient behaviors are unknown. Glycosaminoglycans (GAGs) are widely suspected to affect ligament viscoelasticity by forming molecular bridges between neighboring collagen fibrils. This study investigated whether GAGs directly affect viscoelastic material behavior in human medial collateral ligament (MCL) by using nondestructive tensile tests before and after degradation of GAGs with chondroitinase ABC (ChABC). Control and ChABC treatment (83% GAG removal) produced similar alterations to ligament viscoelasticity. This finding was consistent at different levels of collagen fiber stretch and tissue hydration. On average, stress relaxation increased after incubation by 2.2% (control) and 2.1% (ChABC), dynamic modulus increased after incubation by 3.6% (control) and 3.8% (ChABC), and phase shift increased after incubation by 8.5% (control) and 8.4% (ChABC). The changes in viscoelastic behavior after treatment were significantly more pronounced at lower clamp-to-clamp strain levels. A 10% difference in the water content of tested specimens had minor influence on ligament viscoelastic properties. The major finding of this study is that mechanical interactions between collagen fibrils and GAGs are unrelated to tissue-level viscoelastic mechanics in mature human MCL. These findings narrow the possible number of extracellular matrix molecules that have a direct contribution to ligament viscoelasticity.

Controlling the Fibroblastic Differentiation of Mesenchymal Stem Cells Via the Combination of Fibrous Scaffolds and Connective Tissue Growth Factor

“…46 Many GAG molecules also contribute to the maintenance of proper tissue viscoelasticity. 53,55 The upregulation of HAS3 gene expression (Fig. 4D) by exogenous CTGF suggests the improved ability of cells to synthesize HA.…”

Influence of Decorin on the Mechanical, Compositional, and Structural Properties of the Mouse Patellar Tendon

“…Immediately following, the tendon was subjected to 10 sinusoidal strain cycles (frequency sweep) at 0.01, 0.1, 1, 5, and 10 Hz with an amplitude of 0.125% (Fig. 1) [17]. The stress relaxation and frequency sweep were repeated at 6 and 8%.…”

Tendon Fascicles Exhibit a Linear Correlation Between Poisson's Ratio and Force During Uniaxial Stress Relaxation

“…Samples were preconditioned by applying 10 cycles of a triangular displacement profile to 3.0% clamp-to-clamp strain at a strain rate of 0.5%/s. Samples were allowed to recover for 10 min after preconditioning [19]. Stress relaxation testing was then performed, with a ramping strain rate of 0.5%/s, a maximum strain of 3%, and a relaxation time of 300 s. The force at 300 s was within 95% of the equilibrium force.…”