European Synchrotron Radiation Facility , 38000 Grenoble , France.
Department of Chemistry, University of Copenhagen , 2100 Copenhagen Ø , Denmark.
ACS Nano. 2019 Jun 25;13(6):6421-6430. doi: 10.1021/acsnano.8b08478. Epub 2019 May 22.
The osteocyte lacuno-canalicular network (LCN) is essential for bone remodeling because osteocytes regulate cell recruitment. This has been proposed to occur through liquid-flow-induced shear forces in the canaliculi. Models of the LCN have thus far assumed that it contains canaliculi connecting the osteocyte lacunae. However, here, we reveal that enlarged spaces occur at places where several canaliculi cross; we name these spaces canalicular junctions. We characterize them in detail within mice cortical bone using synchrotron nanotomography at two length scales, with 50 and 130 nm voxel size, and show that canalicular junctions occur at a density similar to that of osteocyte lacunae and that canalicular junctions tend to cluster. Through confocal laser scanning microscopy, we show that canalicular junctions are widespread as we have observed them in cortical bone from several species, even though the number density of the canalicular junctions was not universal. Fluid flow simulations of a simple model system with and without a canalicular junction clearly show that liquid mass transport and flow velocities are altered by the presence of canalicular junctions. We suggest that these canalicular junctions may play an important role in osteocyte communication and possibly also in canalicular fluid flow. Therefore, we believe that they constitute an important component in the bone osteocyte network.
骨细胞陷窝-小管网络 (LCN) 对于骨重塑是必不可少的，因为骨细胞调节细胞募集。这被认为是通过小管中的液流诱导剪切力来实现的。因此，LCN 的模型迄今为止假设它包含连接骨细胞陷窝的小管。然而，在这里，我们揭示了在几个小管交叉的地方会出现扩大的空间；我们将这些空间命名为小管连接。我们使用同步加速器纳米断层扫描术在两个长度尺度上（体素大小为 50 和 130nm）对小鼠皮质骨中的小管连接进行了详细的特征描述，并表明小管连接的密度与骨细胞陷窝的密度相似，并且小管连接倾向于聚集。通过共聚焦激光扫描显微镜，我们表明小管连接是广泛存在的，正如我们在来自几种物种的皮质骨中观察到的那样，尽管小管连接的数量密度不是普遍存在的。具有和不具有小管连接的简单模型系统的流体流动模拟清楚地表明，液体质量传输和流速会因小管连接的存在而发生变化。我们认为这些小管连接可能在骨细胞通讯中发挥重要作用，并且可能在小管液流中也发挥重要作用。因此，我们认为它们是骨细胞网络中的一个重要组成部分。
