1School of Engineering and Materials Science, Queen Mary University of London, Mile End Rd., London, E1 4NS, UK.
FASEB J. 2014 Jan;28(1):430-9. doi: 10.1096/fj.13-231894. Epub 2013 Oct 4.
Bone turnover in vivo is regulated by mechanical forces such as shear stress originating from interstitial oscillatory fluid flow (OFF), and bone cells in vitro respond to mechanical loading. However, the mechanisms by which bone cells sense mechanical forces, resulting in increased mineral deposition, are not well understood. The aim of this study was to investigate the role of the primary cilium in mechanosensing by osteoblasts. MLO-A5 murine osteoblasts were cultured in monolayer and subjected to two different OFF regimens: 5 short (2 h daily) bouts of OFF followed by morphological analysis of primary cilia; or exposure to chloral hydrate to damage or remove primary cilia and 2 short bouts (2 h on consecutive days) of OFF. Primary cilia were shorter and there were fewer cilia per cell after exposure to periods of OFF compared with static controls. Damage or removal of primary cilia inhibited OFF-induced PGE2 release into the medium and mineral deposition, assayed by Alizarin red staining. We conclude that primary cilia are important mediators of OFF-induced mineral deposition, which has relevance for the design of bone tissue engineering strategies and may inform clinical treatments of bone disorders causes by load-deficiency.
体内的骨转换受机械力的调节，如源自间质振荡液流 (OFF) 的剪切应力，体外的骨细胞对机械加载有反应。然而，骨细胞感知机械力从而增加矿物质沉积的机制尚不清楚。本研究旨在探讨初级纤毛在成骨细胞机械感知中的作用。MLO-A5 鼠成骨细胞在单层中培养，并接受两种不同的 OFF 方案：5 次短（每天 2 小时）OFF 后对初级纤毛进行形态分析；或用氯醛水合物损伤或去除初级纤毛，然后进行 2 次短（连续两天每天 2 小时）OFF。与静态对照相比，暴露于 OFF 期间，初级纤毛更短，每个细胞的纤毛更少。初级纤毛的损伤或去除抑制了 OFF 诱导的 PGE2 释放到培养基中以及茜素红染色测定的矿物质沉积。我们得出结论，初级纤毛是 OFF 诱导的矿物质沉积的重要介质，这对于骨组织工程策略的设计具有重要意义，并可能为因负荷不足引起的骨疾病的临床治疗提供信息。
