Mechanical, compositional, and structural properties of the mouse patellar tendon with changes in biglycan gene expression

Dourte, LeAnn M.; Pathmanathan, Lydia; Mienaltowski, Michael J.; Jawad, Abbas F.; Birk, David E.; Soslowsky, Louis J.

doi:10.1002/jor.22372

Cited by 64 publications

(71 citation statements)

References 31 publications

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“…To our knowledge, these parameters have not been analyzed in traditional compound decorin- and biglycan-null models where expression was absent from conception. However, an analysis of decorin-null [16] and biglycan-null [20] tendons suggest that the inferior mechanical properties after acute knockout of both decorin and biglycan expression were substantially less than that expected based on additive effects observed in traditional decorin and biglycan knockout tendons [16, 20]. …”

Section: Discussionmentioning

confidence: 99%

“…Tendons from decorin knockout mice have decreased viscoelastic properties including larger and faster stress relaxation [17], decreased strain rate sensitivity [18], but no change in elastic properties [19]. Biglycan-null tendons demonstrated less alteration in mechanical properties than the decorin-null mice, however, tensile dynamic modulus was increased when expression was reduced [20]. Structurally, decorin deficiency manifests with irregularly contoured large diameter collagen fibrils [21] and biglycan-null [22] tendons have an increased range of collagen fibril diameter and irregular profile in mouse tendon and smaller average fibril diameter [8].…”

Section: Introductionmentioning

confidence: 99%

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Decorin and biglycan are necessary for maintaining collagen fibril structure, fiber realignment, and mechanical properties of mature tendons

et al. 2017

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The small leucine-rich proteoglycans (SLRPs), decorin and biglycan, are key regulators of collagen fibril and matrix assembly. The goal of this work was to elucidate the roles of decorin and biglycan in tendon homeostasis. Our central hypothesis is that decorin and biglycan expression in the mature tendon would be critical for the maintenance of the structural and mechanical properties of healthy tendons. Defining the function(s) of these SLRPs in tendon homeostasis requires that effects in the mature tendon be isolated from their influence on development. Thus, we generated an inducible knockout mouse model that permits genetic ablation of decorin and biglycan expression in the mature tendon, while maintaining normal expression during development. Decorin and biglycan expression were knocked out in the mature patellar tendon with the subsequent turnover of endogenous SLRPs deposited prior to induction. The acute absence of SLRP expression was associated with changes in fibril structure with a general shift to larger diameter fibrils in the compound knockout tendons, together with fibril diameter heterogeneity. In addition, tendon mechanical properties were altered. Compared to wild-type controls, acute ablation of both genes resulted in failure of the tendon at lower loads, decreased stiffness, a trend toward decreased dynamic modulus, as well as a significant increase in percent relaxation and tissue viscosity. Collagen fiber realignment was also increased with a delayed and slower in response to load in the absence of expression. These structural and functional changes in response to an acute loss of decorin and biglycan expression in the mature tendon demonstrate a significant role for these SLRPs in adult tendon homeostasis.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Decorin and biglycan are necessary for maintaining collagen fibril structure, fiber realignment, and mechanical properties of mature tendons

et al. 2017

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“…Twenty specimens from each group designated for dynamic viscoelastic testing were subjected to a testing protocol as described previously [13,14,40]. Tendons were first preloaded and preconditioned for 10 cycles to 1.5% grip strain at 0.25 Hz.…”

Section: Dynamic Viscoelastic Testingmentioning

confidence: 99%

“…In addition, the dynamic modulus jE*j (defined as the stress amplitude divided by the strain amplitude) and the phase angle d (between the stress and strain) were computed at each frequency and strain level. The dynamic modulus (jE*j) represents how difficult the material is to deform under dynamic loading, while the tangent of the phase angle (tan d) is the ratio of loss over storage moduli [13,14,40,42]. Comparisons were made using one-way ANOVA for each parameter with post-hoc Bonferroni tests to correct for family-wise error associated with multiple comparisons.…”

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confidence: 99%

Collagen V-heterozygous and -null supraspinatus tendons exhibit altered dynamic mechanical behaviour at multiple hierarchical scales

et al. 2016

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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.

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“…8, 14, 31, 34, 38 This behavior is modulated by the structure and composition of the tissue, which can vary widely between (Achilles versus patellar) and within tendons (insertion versus midsubstance). 8, 12, 13, 16 Generally, tendon is made primarily of a hierarchical collagen structure, with collagen fibrils that bundle to form fibers which bundle to form tendon. 36 Collagen fibers, and the surrounding glycosaminoglycans (GAGs), are thought to be the primary load-bearing structure in tendon.…”

Section: Introductionmentioning

confidence: 99%

Diabetes Alters Mechanical Properties and Collagen Fiber Re-Alignment in Multiple Mouse Tendons

et al. 2014

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Tendons function to transfer load from muscle to bone through their complex composition and hierarchical structure, consisting mainly of type I collagen. Recent evidence suggests that type II diabetes may cause alterations in collagen structure, such as irregular fibril morphology and density, which could play a role in the mechanical function of tendons. Using the db/db mouse model of type II diabetes, the diabetic skin was found to have impaired biomechanical properties when compared to the non-diabetic group. The purpose of this study was to assess the effect of diabetes on biomechanics, collagen fiber re-alignment, and biochemistry in three functionally different tendons (Achilles, supraspinatus, patellar) using the db/db mouse model. Results showed that cross-sectional area and stiffness, but not modulus, were significantly reduced in all three tendons. However, the tendon response to load (transition strain, collagen fiber re-alignment) occurred earlier in the mechanical test, contrary to expectations. In addition, the patellar tendon had an altered response to diabetes when compared to the other two tendons, with no changes in fiber realignment and decreased collagen content at the midsubstance of the tendon. Overall, type II diabetes alters tendon mechanical properties and the dynamic response to load.

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Mechanical, compositional, and structural properties of the mouse patellar tendon with changes in biglycan gene expression

Cited by 64 publications

References 31 publications

Decorin and biglycan are necessary for maintaining collagen fibril structure, fiber realignment, and mechanical properties of mature tendons

Decorin and biglycan are necessary for maintaining collagen fibril structure, fiber realignment, and mechanical properties of mature tendons

Collagen V-heterozygous and -null supraspinatus tendons exhibit altered dynamic mechanical behaviour at multiple hierarchical scales

Diabetes Alters Mechanical Properties and Collagen Fiber Re-Alignment in Multiple Mouse Tendons

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