Adachi Taiji, Aonuma Yuki, Taira Keisuke, Hojo Masaki, Kamioka Hiroshi
Department of Mechanical Engineering and Science, Graduate School of Engineering, Kyoto University, Sakyo, Kyoto, Japan.
Biochem Biophys Res Commun. 2009 Nov 20;389(3):495-500. doi: 10.1016/j.bbrc.2009.09.010. Epub 2009 Sep 6.
Bone functional adaptation by remodeling is achieved by harmonized activities of bone cells in which osteocytes in the bone matrix are believed to play critical roles in sensing mechanical stimuli and transmitting signals to osteoclasts/osteoblasts on the bone surface in order to regulate their bone remodeling activities through the lacuno-canalicular network with many slender osteocytic processes. In this study, we investigated the intercellular communication between bone cells, particularly focusing on its directionality, through in vitro observations of the calcium signaling response to mechanical stimulus and its propagation to neighboring cells (NCs). Direct mechanical stimulus was applied to isolated bone cells from chick calvariae, osteocytes (Ocys) and bone surface cells (BSCs) mainly containing osteoblasts, and the percentage of calcium signaling propagation from the stimulated cell to NCs was analyzed. The results revealed that, regardless of the type of stimulated cell, the signaling propagated to BSCs with a significantly higher percentage, implying that calcium signaling propagation between bone cells strongly depends on the type of receiver cell and not the transmitter cell. In addition, in terms of mutual communication between Ocys and BSCs, the percentage of propagation from Ocys to BSCs is significantly higher than that in the opposite direction, suggesting that the calcium signaling mainly propagates asymmetrically with a bias from Ocys in bone matrix to BSCs on bone surfaces. This asymmetric communication between Ocys and BSCs suggests that osteocytic mechanosensing and cellular communications, which significantly affect bone surface remodeling activities to achieve functional adaptation, seem to be well coordinated and active at the location of biologically suitable and mechanically sensitive regions close to the bone surfaces.
通过重塑实现的骨功能适应是由骨细胞的协调活动完成的，其中骨基质中的骨细胞被认为在感知机械刺激以及通过具有许多细长骨细胞突起的腔隙-小管网络将信号传递到骨表面的破骨细胞/成骨细胞以调节其骨重塑活动方面发挥关键作用。在本研究中，我们通过对机械刺激的钙信号反应及其向相邻细胞（NCs）的传播进行体外观察，研究了骨细胞之间的细胞间通讯，尤其关注其方向性。对从鸡颅骨分离的骨细胞、骨细胞（Ocys）和主要包含成骨细胞的骨表面细胞（BSCs）施加直接机械刺激，并分析钙信号从受刺激细胞传播到NCs的百分比。结果显示，无论受刺激细胞的类型如何，信号向BSCs的传播百分比显著更高，这意味着骨细胞之间的钙信号传播强烈依赖于接收细胞的类型而非发送细胞的类型。此外，就Ocys和BSCs之间的相互通讯而言，从Ocys到BSCs的传播百分比显著高于相反方向，这表明钙信号主要以不对称方式传播，偏向于从骨基质中的Ocys到骨表面的BSCs。Ocys和BSCs之间的这种不对称通讯表明，显著影响骨表面重塑活动以实现功能适应的骨细胞机械传感和细胞通讯，似乎在靠近骨表面的生物学适宜且机械敏感区域位置得到了良好协调且活跃。
