Concentration-Dependent Cellular Uptake of Graphene Oxide Quantum Dots Promotes the Odontoblastic Differentiation of Dental Pulp Cells via the AMPK/mTOR Pathway

Abstract

As zero-dimension nanoparticles, graphene oxide quantum dots (GOQDs) have broad potential for regulating cell proliferation and differentiation. However, such regulation of dental pulp cells (DPSCs) with different concentrations of GOQDs is insufficiently investigated, especially on the molecular mechanism. The purpose of this study was to explore the effect and molecular mechanism of GOQDs on the odontoblastic differentiation of DPSCs and to provide a theoretical basis for the repair of pulp vitality by pulp capping. CCK-8, immunofluorescence staining, alkaline phosphatase activity assay and staining, alizarin red staining, qRT-PCR, and western blotting were used to detect the proliferation and odontoblastic differentiation of DPSC coculturing with different concentrations of GOQDs. The results indicate that the cellular uptake of low concentration of GOQDs (0.1, 1, and 10 μg/mL) could promote the proliferation and odontoblastic differentiation of DPCSs. Compared with other concentration groups, 1 μg/mL GOQDs show better ability in such promotion. In addition, with the activation of the AMPK signaling pathway, the mTOR signaling pathway was inhibited in DPSCs after coculturing with GOQDs, which indicates that low concentrations of GOQDs could regulate the odontoblastic differentiation of DPSCs by the AMPK/mTOR signaling pathway.

Functional extracellular vesicles from SHEDs combined with gelatin methacryloyl promote the odontogenic differentiation of DPSCs for pulp regeneration

“…Alizarin red staining revealed that compared to CM-EV and the control group, OM-EV substantially incorporated into the formation growth of mineralized nodules, particularly on day 14. The ALP is commonly regarded as an early marker of odontogenic differentiation and is noticeably expressed after one week of induction [ 21 , 34 , 35 ]. Therefore, we performed ALP staining and ALP activity detection only on day 7.…”

“…A series of studies have revealed that the promotion of odontoblast differentiation by EVs from dental mesenchymal stem cells may be achieved through regulating multiple signaling pathways (such as Wnt/β-catenin [ 32 ], p38/MAPK [ 13 ], and TGF-β/smads [ 15 ]) by microRNA, and proteins were carried by EVs. In a previous article by our team, we also suggested the correlation between the AMPK/mTOR pathway and the odontogenic differentiation of DPSCs [ 21 ]. The obtained results of pathway analysis and Western blotting revealed that the activation of the AMPK/mTOR pathway may play a pivotal role in regulating the odontogenic differentiation of DPSCs by OM-EV.…”

“…The required informed consent was obtained from individuals and their parents. Dental pulp was appropriately harvested from extracted teeth under aseptic conditions and then digested to isolate SHEDs as elucidated in Refs [ 21 , 22 ]. The SHEDs were cultured in high-glucose Dulbecco’s modified Eagle medium (DMEM, Gibco, Grand Island, USA) supplemented with 10% fetal bovine serum (FBS, Gibco) and 1% penicillin/streptomycin (P/S; Gibco, USA) at 37 °C.…”

Effects of different signaling pathways on odontogenic differentiation of dental pulp stem cells: a review

“…After 14-day odontoblastic differentiation, the expression level of phosphorylated AMPK increased, while the expression level of phosphorylated mTOR decreased. This indicated that GOQDs would activate the AMPK signaling pathways but inhibit the mTOR signaling pathways in DPSCs (Lin et al, 2023). Xu et al (2021) found that NaF promoted osteo/odontogenic differentiation of DPSCs by suppressing the PI3K/AKT/mTOR signaling pathways.…”