Section of Oral Pathology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan.
J Dent Res. 2013 Apr;92(4):340-5. doi: 10.1177/0022034513476037. Epub 2013 Jan 28.
We investigated the roles of osteocytes in osteoclastic bone resorption during orthodontic tooth movement using the transgenic mice in which osteocytes can be specifically ablated. Because these transgenic mice express the receptor for diphtheria toxin on the cell surfaces of osteocytes, the injection of diphtheria toxin can ablate their osteocytes in vivo. Injection of diphtheria toxin into the transgenic mice significantly increased the number of ablated osteocytes in alveolar bone compared with that in wild-type mice with or without diphtheria toxin injection. Increased numbers of ablated osteocytes were observed from day 4 to day 12 after the injection in alveolar bones as well as in cortical bone of the tibiae. We applied the orthodontic force 4 days after the injection of diphtheria toxin, and the distance of tooth movement on day 12 was significantly smaller in transgenic mice than that in control mice. The numbers of osteoclasts and the quantity of eroded bone surface at the compression site were significantly reduced in the transgenic mice injected with diphtheria toxin than in control mice. These results provide in vivo demonstration of osteocyte involvement in osteoclastic bone resorption during orthodontic tooth movement.
我们使用可以特异性剔除破骨细胞的转基因小鼠，研究了成骨细胞在正畸牙齿移动过程中的破骨细胞骨吸收作用。由于这些转基因小鼠的成骨细胞膜表面表达白喉毒素受体，因此白喉毒素的注射可以在体内剔除其成骨细胞。与未注射白喉毒素或注射白喉毒素的野生型小鼠相比，白喉毒素注射到转基因小鼠中后，牙槽骨中成骨细胞的剔除数量明显增加。在注射后第 4 天至第 12 天，无论是在牙槽骨还是胫骨皮质骨中，被剔除的成骨细胞数量均增加。我们在注射白喉毒素后 4 天施加正畸力，第 12 天时转基因小鼠的牙齿移动距离明显小于对照小鼠。与对照小鼠相比，注射白喉毒素的转基因小鼠破骨细胞数量和受压部位骨吸收表面的数量明显减少。这些结果从体内证明了成骨细胞在正畸牙齿移动过程中的破骨细胞骨吸收作用。
