Alteration of structural and mechanical properties of the temporomandibular joint disc following elastase digestion

Sepanta Fazaeli, Fereshteh Mirahmadi, Vincent Everts, Theodoor H. Smit, Jan H. Koolstra, Samaneh Ghazanfari*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

2 Citations (Web of Science)

Abstract

The temporomandibular joint disc is a fibrocartilaginous structure, composed of collagen fibers, elastin fibers, and proteoglycans. Despite the crucial role of elastin fibers in load-bearing properties of connective tissues, its contribution in temporomandibular joint disc biomechanics has been disregarded. This study attempts to characterize the structural-functional contribution of elastin in the temporomandibular joint disc. Using elastase, we selectively perturbed the elastin fiber network in porcine temporomandibular joint discs and investigated the structural, compositional, and mechanical regional changes through: (a) analysis of collagen and elastin fibers by immunolabeling and transmission electron microscopy; (b) quantitative analysis of collagen tortuosity, cell shape, and disc volume; (c) biochemical quantification of collagen, glycosaminoglycan and elastin content; and (d) cyclic compression test. Following elastase treatment, microscopic examination revealed fragmentation of elastin fibers across the temporomandibular joint disc, with a more pronounced effect in the intermediate regions. Also, biochemical analyses of the intermediate regions showed significant depletion of elastin (50%), and substantial decrease in collagen (20%) and glycosaminoglycan (49%) content, likely due to non-specific activity of elastase. Degradation of elastin fibers affected the homeostatic configuration of the disc, reflected in its significant volume enlargement accompanied by remarkable reduction of collagen tortuosity and cell elongation. Mechanically, elastase treatment nearly doubled the maximal energy dissipation across the intermediate regions while the instantaneous modulus was not significantly affected. We conclude that elastin fibers contribute to the restoration and maintenance of the disc resting shape and actively interact with collagen fibers to provide mechanical resilience to the temporomandibular joint disc.

Original languageEnglish
Pages (from-to)3228-3240
Number of pages13
JournalJournal of Biomedical Materials Research Part B-applied Biomaterials
Volume108
Issue number8
DOIs
Publication statusPublished - Nov 2020

Keywords

  • ARTICULAR DISC
  • BEHAVIOR
  • COLLAGEN-FIBERS
  • DEGRADATION
  • DISORDERS
  • INTERNAL DERANGEMENT
  • MORPHOLOGY
  • QUANTITATIVE-ANALYSIS
  • RHEUMATOID-ARTHRITIS
  • STEM-CELLS
  • cartilage
  • elastin fiber
  • enzymatic degradation
  • mechanical properties
  • temporomandibular joint disc

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