Improvement of dentinogenesis of irreversible pulpitis-derived DPSCs

Objectives: Adult stem/progenitor cells play a critical role in maintaining and repairing the tissues/organs. The utility of adult stem/progenitor cells for cell-based therapy has been also clearly recognized. Clinically, irreversible pulpitis tissue is entirely removed, and replaced totally by root canal treatment with artificial root canal materials. Regeneration of infected pulp tissue leads the induction of reparative dentin formation to maintain the physiological condition. In this study we aimed to find out not only a defective mechanism, but also an improvement of the dentinogenesis of dental pulp stem cells (DPSCs) in inflamed condition. Methods: We isolated DPSCs from irreversible pulpitis tissue (DPSCs-IP), and compared the stem cell properties to DPSCs from healthy pulp tissue (DPSCs-HP). Treatment of tumor necrosis factor alpha (TNFα) and interferon gamma (IFNγ) were assayed to evaluate the effect on dentinogenesis of DPSCs-IP. Results: DPSCs-IP expressed lower property of colony formation, population doubling, cell proliferation, multidifferentiation capacity including in vitro and in vivo dentinogenesis, in vitro adipogenesis, in vitro neural cell differentiation when compared to DPSCs-HP. TNFα reduced more sever dentiogenesis of DPSC-IP by Alizarin Red staining and odontoblast-specific gene expression assay. On the other hand, IFNγ treatment induced in vitro dentiogenesis of DPSCs-IP. Conclusion: Taken together, these results indicated not only that TNFα acts, at least in part, as a defective factor on dentinogenesis of DPSCs, but also that IFNγ has a capable of improving defective property of dentinogenesis of DPSCs-IP.