Influence of remodeling on the mineralization of bone tissue
Influence of remodeling on the mineralization of bone tissue
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DOI：
10.1007/s00198-009-0861-x
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发表时间：
2009-06-01
影响因子：
4
通讯作者：
Delmas, P. D.
中科院分区：
文献类型：
--
作者：
Boivin, G.;Farlay, D.;Delmas, P. D.
为了更好地了解治疗方法降低骨折风险、增加骨密度或改变重建的生化标志物的作用机制，不仅有必要分析它们对骨重建、骨量和微结构的组织和细胞效应，而且还有必要讨论它们对反映骨质量的主要参数之一的骨矿化的影响[1]。众所周知，矿化作用在不同的显微区域是不同的，骨结构单元(BSU)的年龄，最近沉积的骨结构单元比旧的要少得多的钙化(图1)。在骨重建过程中，骨吸收后，骨形成是一个多步骤的过程。沉积后，新的基质在沉积后大约5-10天开始矿化，这种原生矿化的线性速率可以通过双四环素标记在体内直接测量。在BSU(皮质骨或松质骨包中的骨粒)完全完成后，次生矿化开始。这一过程包括矿物成分的缓慢和逐渐成熟，包括晶体数量的增加和/或晶体尺寸向其最大尺寸的增大和/或晶体水平的完整性的增加[2-4]。二次矿化逐渐增加了原生矿化过程中沉积的骨基质的矿物含量，后者仅占二次矿化阶段结束时获得的最大矿化度(DMB)的约50%[3，5，6]。最近的研究[7]在一只母羊模型中--其骨骼重建率与人类相似--表明次生矿化大约持续24至30个月。这可能意味着，在使用抗骨质疏松治疗的3年后，次生矿化不会增加。骨矿化影响骨组织的机械强度[8，9]，其对骨显微硬度的贡献是众所周知的[4]。矿化的异质性指数也会影响骨强度。矿化的均质化使骨组织更加脆弱[5]。
To better understand the mechanisms of action of therapies that reduce the risk of fracture, increase bone mineral density, or change the biochemical markers of remodeling, it is necessary not only to analyze their tissue and cellular effects on bone remodeling, bone mass, and microarchitecture but also to discuss their influence on bone mineralization, one of the major parameters reflecting bone quality [1]. Mineralization is known to vary over microscopic regions, with age of the bone structural units (BSUs), the recently deposited ones being much less calcified than the older ones (Fig. 1). During bone remodeling, after bone resorption, bone formation is a multi-step process. Following its deposition, the new matrix begins to mineralize after about 5 to 10 days from the time of deposition and the linear rate of this primary mineralization can be measured directly in vivo using double tetracycline labeling. After full completion of the BSUs (osteons in cortical bone or cancellous packets), a secondary mineralization begins. This process consists of a slow and gradual maturation of the mineral component, including an increase in the number of crystals and/or an augmentation of crystal size toward their maximum dimensions and/or an increase of the perfection at crystal level [2–4]. The secondary mineralization progressively augments the mineral content of bone matrix deposited during primary mineralization, the latter phase representing only about 50% of the maximum degree of mineralization (DMB) obtained at the end of the secondary mineralization phase [3, 5, 6]. Recent studies [7] in a ewe model—whose bone remodeling rate is similar to that in humans—show that secondary mineralization lasts approximately for 24 to 30 months. This could mean that, beyond 3 years of use of an anti-osteoporotic treatment, the secondary mineralization does not increase. Bone mineralization influences the mechanical strength of bone tissue [8, 9] and its contribution to bone microhardness is well known [4]. The heterogeneity index of mineralization also influences bone strength. A homogenization of the mineralization makes the bone tissue more brittle [5].