Dental pulp is critical to maintain the vitality of a tooth. Regeneration of pulpo-dentinal complex is of great interest to treat pulpitis and pulp necrosis. In this study, through three-dimensional spheroid culture, a group of unique multipotent stem cells were identified from mouse dental papilla called multipotent dental pulp regenerative stem cells (MDPSCs). MDPSCs exhibited enhanced osteogenic/odontogenic differentiation capabilities and could form regenerative dentin and neurovascular-like structures that mimicked the native teeth in vivo. Further analysis revealed that CD24a was the bona fide marker for MDPSCs, and their expansion was highly dependent on the expression of a key transcriptional factor, Sp7. Last, CD24a+ cells could be detected in primary dental papilla in mice and human, suggesting that MDPSCs resided in their native niches. Together, our study has identified a previously unidentified group of multipotent pulp regenerative stem cells with defined molecular markers for the potential treatment of pulpitis and pulp necrosis.

Low-temperature dry reforming of methane (DRM) can avoid the sintering of nickel and reduce the cost of the process. However, inefficient activation of CO 2 and oxidization of Ni 0 hamper the catalytic performance of Ni-based catalysts at low temperatures. Herein, a Ni/ZrO 2 catalyst was prepared and used in the DRM reaction, which exhibited stable activity at low temperatures (400, 320 and 300 °C) for 10 h, with CH 4 and CO 2 turnover frequencies of 0.26 and 0.18 s −1 at 320 °C, respectively. The presence of Ni 0 species and oxygen vacancies promotes the activation of CO 2 at 300 °C, proved by CO 2 temperature-programmed oxidation (CO 2 -TPO). Combined with O 2 temperature-programmed decomposition (O 2 -TPD), C 18 O 2 -DRM, in situ X-ray photoelectron spectroscopy (XPS), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) results, after CH 4 decomposition on the Ni 0 site, the resultant C would react with nearby surface oxygen species and lattice oxygen species of ZrO 2 , forming CO and an oxygen vacancy. The oxygen vacancy nearby Ni 0 species with more electron transfer would promote the activation of CO 2 . This work highlights the importance of CO 2 activation and emphasizes the key role of the synergistic effect between Ni 0 species and the oxygen vacancy in enhancing the stability of catalysts over low-temperature DRM reactions.