TY - JOUR
T1 - Alteration of structural and mechanical properties of the temporomandibular joint disc following elastase digestion
AU - Fazaeli, Sepanta
AU - Mirahmadi, Fereshteh
AU - Everts, Vincent
AU - Smit, Theodoor H.
AU - Koolstra, Jan H.
AU - Ghazanfari, Samaneh
N1 - Publisher Copyright:
© 2020 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials published by Wiley Periodicals, Inc.
PY - 2020/11
Y1 - 2020/11
N2 - 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.
AB - 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.
KW - ARTICULAR DISC
KW - BEHAVIOR
KW - COLLAGEN-FIBERS
KW - DEGRADATION
KW - DISORDERS
KW - INTERNAL DERANGEMENT
KW - MORPHOLOGY
KW - QUANTITATIVE-ANALYSIS
KW - RHEUMATOID-ARTHRITIS
KW - STEM-CELLS
KW - cartilage
KW - elastin fiber
KW - enzymatic degradation
KW - mechanical properties
KW - temporomandibular joint disc
U2 - https://doi.org/10.1002/jbm.b.34660
DO - https://doi.org/10.1002/jbm.b.34660
M3 - Article
SN - 1552-4973
VL - 108
SP - 3228
EP - 3240
JO - Journal of Biomedical Materials Research Part B-applied Biomaterials
JF - Journal of Biomedical Materials Research Part B-applied Biomaterials
IS - 8
ER -