Bundy JA, Yang JT, Morscher MA, Steiner RP, Adamczyk MJ, Weiner DS, Jacquet RD, Landis WJ. Induced hypothyroidism alters articular cartilage in skeletally immature miniature swine.
Connect Tissue Res 2021;
62:643-657. [PMID:
33073630 DOI:
10.1080/03008207.2020.1839436]
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Abstract
PURPOSE/AIM
Thyroid hormone has been implicated in the normal growth and development of articular cartilage; however, its effect on a disease state, such as hypothyroidism, is unknown. The purpose of this investigation was to compare normal articular cartilage from proximal femurs of immature miniature swine to proximal femurs from hypothyroid-induced immature miniature swine.
MATERIALS AND METHODS
Two 11-week-old male Sinclair miniature swine were made hypothyroid by administration of 6-propyl-2-thiouracil (PTU) in their drinking water; two control animals did not receive PTU. At 25 weeks of age, the animals were euthanized and their proximal femurs were fixed and decalcified. Samples were sectioned and analyzed by histology to define extracellular matrix (ECM) structure, immunohistochemistry (IHC) to identify types II and X collagen, and histomorphometry to assess articular cartilage mean total and localized height and cell density. Statistics included nested mixed-effects ANOVA with p ≤ 0.05 considered statistically significant.
RESULTS
Compared to controls, hypothyroid articular cartilage demonstrated statistically significant quantitative differences in mean tissue height, mean cell density and type II collagen localized zone height. Qualitative differences in ECM proteoglycans and overall collagen types were also found. Type X collagen was not detected in either hypothyroid or control articular cartilage specimens.
CONCLUSIONS
Significant changes in articular cartilage structure in hypothyroid compared to control immature miniature swine suggest that thyroid hormone is critical in the growth and development of articular cartilage.
CLINICAL SIGNIFICANCE
Understanding articular cartilage development in immature animal models may provide insight into healing or repair of degenerative human articular cartilage.
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