Decreased bone marrow stromal cells activity involves in unilateral anterior crossbite-induced early subchondral bone loss of temporomandibular joints.

Subchondral bone loss in mandibular condyles was reported to be induced by experimentally created unilateral anterior crossbite (UAC) which altered the occlusal load distribution and hereafter the temporomandibular joint (TMJ) remodelling process. However, the initial cellular responses are poorly understood. In the present study, changes in osteoblast and osteoclast activities in TMJ subchondral bone were investigated using the rats treated with UAC. Forty rats were randomly divided into UAC and control groups, and sampled at 2 weeks after the operation. Subchondral bone loss was evaluated by micro-CT. Osteoclast and osteoblast activities were analyzed by real-time PCR. The osteoblast differentiation of the locally isolated BMSCs from TMJ subchondral bone was assessed by Alizarin red staining. The migration of BMSCs was detected by transwell assays. Compared with the age-matched controls, TMJ subchondral bone loss was observed in the UAC-treated rats (p<0.05). The osteoblast activity evaluated by real-time PCR and osteoblast number revealed by immunohistochemical staining were reduced in the TMJ subchondral bone of UAC rats (p<0.05), and the capability of proliferation, migration and osteoblast differentiation were all decreased in the locally isolated BMSCs from the UAC group (p<0.05). The present data demonstrated an involvement of reduced BMSCs activity in the initiation of the mandibular subchondral bone loss at the early stage of installation of the aberrant prostheses.