Gannon A R, Nagel T, Bell A P, Avery N C, Kelly D J
Trinity Centre for Bioengineering, Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland; Department of Mechanical and Manufacturing Engineering, School of Engineering, Trinity College Dublin, Dublin, Ireland.
Department of Environmental Informatics, Helmholtz Centre for Environmental Research GmbH - UFZ, Permoserstraße 15, 04318 Leipzig, Germany.
Osteoarthritis Cartilage. 2015 Jun;23(6):975-84. doi: 10.1016/j.joca.2015.02.003. Epub 2015 Feb 11.
To explore how changes to the superficial region (SR) of articular cartilage during skeletal development impact its functional properties. It was hypothesised that a functional superficial region is not present in skeletally immature articular cartilage, and removal of this zone of the tissue would only negatively impact the dynamic modulus of the tissue with the attainment of skeletal maturity.
Porcine osteochondral cores were mechanically tested statically and dynamically with and without their respective superficial regions in confined and unconfined compression at different stages of postnatal development and maturation. A novel combination of histological, biochemical and imaging techniques were utilised to accurately describe changes to the superficial region during postnatal development.
Articular cartilage was found to become stiffer and less permeable with age. The confined and unconfined dynamic modulus significantly decreased after removal of the superficial region in skeletally mature cartilage, whilst no significant change was observed in the 4 week old tissue. Biochemical analysis revealed a significant decrease in overall sGAG content with age (as % dry weight), whilst collagen content significantly increased with age, although the composition of the superficial region relative to the remainder of the tissue did not significantly change with age. Helium ion microscopy (HIM) revealed dramatic changes to the organization of the superficial region with age.
The findings demonstrate that the superficial region of articular cartilage undergoes dramatic structural adaptation with age, which in turn plays a key role in determining the dynamic compressive properties of the tissue.
探讨骨骼发育过程中关节软骨表层区域（SR）的变化如何影响其功能特性。研究假设为骨骼未成熟的关节软骨中不存在功能性表层区域，且去除该组织区域只会在骨骼成熟时对组织的动态模量产生负面影响。
在出生后发育和成熟的不同阶段，对猪的骨软骨核心在有或没有各自表层区域的情况下进行静态和动态力学测试，测试包括受限和非受限压缩。利用组织学、生物化学和成像技术的新组合来准确描述出生后发育过程中表层区域的变化。
发现关节软骨随着年龄增长会变得更硬且渗透性更低。在骨骼成熟的软骨中去除表层区域后，受限和非受限动态模量显著降低，而在4周龄的组织中未观察到显著变化。生化分析显示，随着年龄增长，总体糖胺聚糖（sGAG）含量（以干重百分比计）显著降低，而胶原蛋白含量随年龄显著增加，尽管表层区域相对于组织其余部分的组成并未随年龄发生显著变化。氦离子显微镜（HIM）显示表层区域的组织结构随年龄发生了显著变化。
研究结果表明，关节软骨的表层区域会随着年龄发生显著的结构适应性变化，这反过来在决定组织的动态压缩特性方面起着关键作用。
