Osteocytic Canalicular Networks: Morphological Implications for Altered Mechanosensitivity
Osteocytic Canalicular Networks: Morphological Implications for Altered Mechanosensitivity
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DOI：
10.1021/nn401360u
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发表时间：
2013-09-01
期刊：
影响因子：
17.1
通讯作者：
Busse, Bjoern
中科院分区：
文献类型：
--
作者：
Milovanovic, Petar;Zimmermann, Elizabeth A.;Busse, Bjoern
骨细胞是分布在整个骨基质中的分枝骨细胞，其网络由微米级空腔（陷窝）和许多纳米厚的隧道（小管）组成。骨小管网络的完整性可能影响骨质量并反映其机械感觉潜力。在这项研究中，我们应用酸蚀刻技术嵌入骨标本，允许三维观察的小管网络在一个2D平面定量评估的小管连接在皮质骨标本从年轻人和老年人。我们的研究结果显示，老年人每个骨细胞陷窝的小管数量减少了近30%（N.Ot.Ca/Ot.Lc：老年人15.92 +/- 1.5 vs年轻人22.10 +/- 2.82; p < 0.001）;此外，发现小管数量与以Ca/P比值表示的骨组织年龄呈负相关（p < 0.001）。我们经常观察到这样的现象，即位于骨单位周围的骨细胞小管并不终止于骨单位的骨水泥线边界，而是穿过骨水泥线并扩散到周围的骨基质中，从而建立“外部生根”或“连接”，这可能与骨质量有显著相关性。我们的研究结果表明，老化过程不仅减少了骨单位内的小管网络，而且还显著降低了外部骨单位生根和与周围骨组织连接的可能性。随着年龄的增长，骨小管网络的退化降低了骨细胞之间和骨单位/间质组织之间的连接性，这影响了骨细胞的营养供应，降低了它们的机械敏感性，并导致老年人骨脆性增加。
Osteocytes are ramified bone cells distributed throughout the bone matrix within a network of micrometer-scale cavities (lacunae) and numerous nanometer-thick tunnels (canaliculi). The integrity of the canalicular network might influence bone quality and reflect its mechanosensory potential. In this study, we applied an acid etching technique to embedded bone specimens that allows 3D observation of the canalicular network across a 2D plane to quantitatively assess the canalicular connections in cortical bone specimens from young and aged individuals. Our results showed a nearly 30% reduction in the number of canaliculi per osteocyte lacuna in aged individuals (N.Ot.Ca/Ot.Lc: 15.92 +/- 1.5 in aged vs 22.10 +/- 2.82 in young; p < 0.001); moreover, canalicular number was found to be inversely related to the osteonal tissue age represented by Ca/P ratio (p < 0.001). We frequently observed the phenomenon that canaliculi of osteocytes located near the osteon's periphery did not end at the osteon's cement line boundary but penetrated through the cement line and spread into the surrounding bone matrix, thus establishing an "external rooting" or "connection", which might have significant relevance to bone quality. Our findings showed that not only does the aging process diminish the canalicular network within osteons, but it also significantly reduces the probability of external osteonal rooting and connections with the surrounding bone tissue. Deterioration in the canalicular network with age reduces the connectivity between osteocytes and between osteons/interstitial tissue, which affects the supply of nutrients to osteocytes, degrades their mechanosensitivity, and contributes to increased bone fragility in the elderly.