Graphene Oxide Quantum Dots-Induced Mineralization via the Reactive Oxygen Species-Dependent Autophagy Pathway in Dental Pulp Stem Cells

As an important recycling and degradation system, autophagy is considered to be critical in regulating stem cell differentiation. It has been shown that graphene oxide quantum dots (GOQDs) are a robust biological labelling tool for stem cells with little cytotoxicity. In this study, we explored the role of autophagy in regulating the impact of GOQDs on the odontoblastic differentiation of DPSCs during autophagy. Western blotting and immunofluorescence staining were used to evaluate the autophagic activity of DPSCs. Quantitative PCR, alizarin red S staining, and alkaline phosphatase staining were used to examine DPSC odontoblastic differentiation. The impacts of ROS scavengers on autophagy induction and reactive oxygen species (ROS) levels were also measured. Lentiviral vectors carrying Beclin1 siRNA sequences, as well as autophagy inhibitors (3-MA and bafilomycin A1), were used to inhibit autophagy. Initial exposure to GOQDs increased autophagic activity and enhanced DPSC mineralization. Autophagy inhibition suppressed GOQD-induced odontoblastic differentiation. Moreover, GOQD treatment induced autophagy in a ROS-dependent manner. GOQDs promoted differentiation, which could be modulated via ROS-induced autophagy.