Aim: Bone marrow-derived cells have abilities of cell migration and differentiation into teeth and related tissues/organs, especially into periodontal ligament fibroblast cells. In this examination using a bone marrow transplantation model, we examined the effect of orthodontic mechanical stress to the transplanted bone marrow-derived cell migration into periodontal tissues.

Materials and methods: Bone marrow derived cells from green fluorescence protein (GFP) transgenic mice were transplanted into 8 week-old female C57BL/6 immunocompromised recipient mice, which had undergone 10 Gy of lethal whole-body irradiation. After successful transplantation (about one month period), the mice received orthodontic mechanical stress using the Waldo method 5 times in 5 weeks. After that, the regional tissues were removed and fixed in formalin fixative. Paraffin-embedded sections were immunohistochemically analyzed using a Dako Envision+Kit-K4006 (Dako, Glostrup, Denmark) and a primary anti-GFP-polyclonal rabbit antibody (#598; 1/500; MBL, Nagoya, Japan).

Results: The immunohistochemistry revealed that GFP-positive cells were detected in the periodontal tissues, both in the experimental and control specimens. In the experimental group, there were numerous GFP-positive cells appearing in the experimental periodontal tissues which received intermittent stimulation of orthodontic mechanical stress, but there were few GFP-positive cells in the control specimens. Thus, these data indicated that orthodontic mechanical stress acts as a possible promoting factor of transplanted bone marrow-derived cell migration into periodontal tissues, and of differentiation to fibroblasts and capillary endothelial cells.

Conclusions: This phenomenon suggests that the possibility of short-term orthodontic treatment with of transplantation of bone marrow cells.

Conflict of interest: None declared.