A distinctive patchy osteomalacia characterises Phospho1-deficient mice
A distinctive patchy osteomalacia characterises Phospho1-deficient mice
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DOI：
10.1111/joa.12628
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发表时间：
2017-08-01
影响因子：
2.4
通讯作者：
Farquharson, Colin
中科院分区：
文献类型：
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作者：
Boyde, Alan;Staines, Katherine A.;Farquharson, Colin
磷酸酶PHOSPHO1参与了生物矿化的启动。Phosphone1基因敲除(KO)小鼠的骨骼显示出组织学上的骨软化，伴有频繁的长骨弯曲和自发性骨折：它们含有较少的矿物质，矿物质晶体较小。然而，磷酸盐消融对骨的微尺度结构的影响还没有完全阐明。取野生型和磷脂酰肌醇缺失型(KO)小鼠(25~32周龄)的胫骨和股骨，包埋于PMMA中，切割抛光，制成近纵切面。使用20KV背散射电子(BSE)成像技术研究块表面，并在碘染色后再次显示未矿化的基质和细胞成分。对于3D表征，我们使用了X射线微层析成像。用硬质合金铣刀打开暴露骨内膜表面的骨，用碱性细菌链霉蛋白酶洗涤剂、5%过氧化氢和7%次氯酸钠溶液浸泡，以产生3D表面，用于3D BSE扫描电子显微镜(SEM)研究。在Phosphy 1 KO小鼠体内，致密的皮质和松质骨基质的广泛区域不包含显著的矿物和/或显示出受阻的矿化前沿，其特征是骨内单独矿化的类钙球石融合失败。与周围正常矿化骨相比，Phosphone1KO小鼠未钙化基质的破骨吸收减弱。这种异常生物矿化的程度和位置在动物、对侧肢体和解剖部位之间差别很大。然而，最常见的表现是皮质中许多横向血管管周围的骨骼中矿化几乎完全失败。总而言之，扫描电子显微镜显示矿化前锋有缺陷和广泛的斑片状骨软化症，这是以前没有发现的。这些数据进一步证实了这种磷酸酶在生理性骨骼矿化中的作用。
The phosphatase PHOSPHO1 is involved in the initiation of biomineralisation. Bones in Phospho1 knockout (KO) mice show histological osteomalacia with frequent bowing of long bones and spontaneous fractures: they contain less mineral, with smaller mineral crystals. However, the consequences of Phospho1 ablation on the microscale structure of bone are not yet fully elucidated. Tibias and femurs obtained from wild-type and Phospho1 null (KO) mice (25-32weeks old) were embedded in PMMA, cut and polished to produce near longitudinal sections. Block surfaces were studied using 20kV backscattered-electron (BSE) imaging, and again after iodine staining to reveal non-mineralised matrix and cellular components. For 3D characterisation, we used X-ray micro-tomography. Bones opened with carbide milling tools to expose endosteal surfaces were macerated using an alkaline bacterial pronase enzyme detergent, 5% hydrogen peroxide and 7% sodium hypochlorite solutions to produce 3D surfaces for study with 3D BSE scanning electron microscopy (SEM). Extensive regions of both compact cortical and trabecular bone matrix in Phospho1 KO mice contained no significant mineral and/or showed arrested mineralisation fronts, characterised by a failure in the fusion of the calcospherite-like, separately mineralising, individual micro-volumes within bone. Osteoclastic resorption of the uncalcified matrix in Phospho1 KO mice was attenuated compared with surrounding normally mineralised bone. The extent and position of this aberrant biomineralisation varied considerably between animals, contralateral limbs and anatomical sites. The most frequent manifestation lay, however, in the nearly complete failure of mineralisation in the bone surrounding the numerous transverse blood vessel canals in the cortices. In conclusion, SEM disclosed defective mineralising fronts and extensive patchy osteomalacia, which has previously not been recognised. These data further confirm the role of this phosphatase in physiological skeletal mineralisation.