Experimental bone metastasis model of the oral and maxillofacial region

Metastasis of the oral and maxillofacial region frequently causes serious morbidity. Despite the importance of the clinical problem, little is known about the pathophysiological mechanisms of this metastatic process. Therefore, we examined whether the intracardiac injection of human breast cancer cells reproductively leads to jaw metastases developing an adequate experimental model. Human breast cancer MDA-MB-231 (MDA-231) cells (1 x 10⁵) were injected into the left heart ventricle of 4-week-old, female nude mice. Jaw metastases were examined radiographically and histologically 4 weeks after the cancer cell inoculation. At this time, the nude mice showed a marked body weight loss and cachexia. Osteolytic bone metastases were commonly observed in limbs, vertebral bone, pelvis and scapulae. In maxillofacial bones, breast cancer cells metastasized in 11 of 12 nude mice (91.7%). The lesions were radiographically determined at the mandible (11/12), maxilla (8/12) and zygomatic arch (2/12). Metastasis frequently occurred at the molar and angle regions of the mandible and at the palatal suture as well as around the root of the incisal teeth of the maxilla respectively. Histological examination revealed that numerous osteoclasts were present along the trabecular bone surfaces with aggressive bone resorption. This experimental model may be useful not only for the investigation of the mechanism of jaw metastasis formation but also for the screening of potential therapeutic agents for osteolytic bone metastasis.