Interaction of Pulp and Periodontal Ligament in Treatment of Trauma

Regenerative medicine has limitations of stem cell amplification and immune rejection that make it difficult to ap-ply in emergency treatment, such as that required for trauma. We have transplanted DPSCs or conditioned medium (CM; secretome accumulation) in animal models and found evidence for pulp regenerative potential, with these findings caused by various trophic effects of DPSCs and CM. Trauma affects various tissues, all of which require regeneration, and there is a need to evaluate trophic effects in trauma models. To examine this issue, we made a canine teeth complete dislocation model, removed the dental pulp and periodontal ligament, performed DPSC transplantation and retransplantation, and ob-served the regenerative response of periodontal tissues. These results suggest that pulp regeneration is important for regen-eration of periodontal ligament in a complete dislocation model. In short, these results indicate the need to focus on cross talk between dental pulp and periodontal tissues. Thus, we added DPSC-CM to periodontal ligament cells and investigated whether a trophic effect would occur in regenerated tissues. The results of this study suggest that migration and proliferation were promoted by trophic effects of DPSC-CM, suggesting regeneration of dental pulp. Next, we performed coculture of dental pulp and periodontal ligament to observe changes in trophic factors by cross talk between these tissues. The results of the current study showed that both VEGF and HGF were highly expressed, suggesting a synergistic effect. Tissue regen-eration after trauma was found to be caused by the trophic effect of CM, promotion of proliferation, migration and antire-sorptive activity. This effect may be enhanced by crosstalk between the pulp and the periodontal ligament, and VEGF and HGF are candidates for this effect.