Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, D-14424 Potsdam, Germany.
Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, D-14424 Potsdam, Germany; ETH Zürich, Laboratory of Applied Mechanobiology, Department of Health Sciences and Technology, CH-8093 Zurich, Switzerland.
J Struct Biol. 2017 Sep;199(3):177-186. doi: 10.1016/j.jsb.2017.07.004. Epub 2017 Aug 1.
During bone formation osteocytes get connected with each other via a dense network of canaliculi within the mineralized bone matrix. Important functions attributed to the osteocyte network include the control of bone remodeling and a contribution to mineral homeostasis. To detect structural clues of the formation and functionality of the network, this study analyzes the structure and orientation of the osteocyte lacuno-canalicular network (OLCN), specifically in relation to the concentric bone lamellae within human osteons. The network structure within 49 osteons from four samples of cortical bone from the femoral midshaft of middle-aged healthy women was determined by a combination of rhodamine staining and confocal laser scanning microscopy followed by computational image analysis. A quantitative evaluation showed that 64±1% of the canalicular length has an angle smaller than 30° to the direction towards the osteon center, while the lateral network - defined by an orientation angle larger than 60° - comprises 16±1%. With the same spatial periodicity as the bone lamellae, both radial and lateral network show variations in the network density and order. However, only the preferred orientation of the lateral network twists when crossing a lamella. This twist agrees with the preferred orientation of the fibrous collagen matrix. The chirality of the twist was found to be individual-specific. The coalignment between network and matrix extends to the orientation of the elongated osteocyte lacunae. The intimate link between OLCN and collagen matrix implies an interplay between osteocyte processes and the arrangement of the surrounding collagen fibers during osteoid formation.
在骨形成过程中，骨细胞通过矿化骨基质内的密集管腔网络相互连接。骨细胞网络的重要功能包括控制骨重塑和有助于矿物质稳态。为了检测网络形成和功能的结构线索，本研究分析了骨陷窝管腔网络（OLCN）的结构和方向，特别是与人类骨单位内的同心骨板层的关系。通过对来自中年健康女性股骨中段皮质骨的四个样本进行罗丹明染色和共聚焦激光扫描显微镜分析，然后进行计算图像分析，确定了 49 个骨单位内的网络结构。定量评估显示，64±1%的管腔长度与朝向骨单位中心的方向的夹角小于 30°，而侧向网络 - 定义为方向角大于 60° - 占 16±1%。与骨板层具有相同的空间周期性，径向和侧向网络都显示出网络密度和有序性的变化。然而，只有当穿过板层时，侧向网络的优选方向才会发生扭曲。这种扭曲与纤维胶原基质的优选方向一致。发现扭曲的手性是个体特异性的。网络和基质之间的共取向延伸到拉长的骨陷窝的取向。OLCN 与胶原基质之间的紧密联系意味着在类骨质形成过程中，骨细胞突起与周围胶原纤维的排列之间存在相互作用。
