Promoting dentinogenesis of DPSCs through inhibiting microRNA-218 by using magnetic nanocarrier delivery

The purposes of this study are to explore the roles of microRNA-218 (miR-218) delivered by a newly designed magnetic nanocarrier: GCC-Fe₃O₄ (GCC-Fe) in dentinogenesis potentials of human dental pulp stem cells (DPSCs).

Human DPSCs were obtained from impacted wisdom teeth of healthy donors under the permission of National Taiwan University Hospital institutional review board (NTUH IRB). Meanwhile, the transfection efficiency of GCC-Fe was evaluated. After transfecting miR-218 (GFm) and miR-218 inhibitor (GFmi) into DPSCs for 24 h, the dentinogenesis potentials of DPSCs were then evaluated with Alizarin Red S (ARS) staining with or without induction for 1, 4, and 9 days. Possible signaling pathway was further investigated by Western Blotting.

We found that the magnetic GCC-Fe₃O₄ nanocarrier was serum endurable with about 90% transfection efficiency in DPSCs under normal culture condition. Results of ARS staining indicated that miR-218 was negatively regulating dentinogenesis potentials of DPSCs after induction. When the miR-218 inhibitor was delivered, calcium deposits in DPSCs were increased significantly. We also discovered that the effects of miR-218 were further regulated through the MAPK/ERK pathway.

We identified that miR-218 had a negative regulation role in the dentinogenesis of DPSCs. By inhibiting miR-218, the mineralization potentials of DPSCs were promoted after induction. In addition, we also confirmed that the highly efficient magnetic GCC-Fe₃O₄ nanocarrier not only was suitable for gene manipulation in biomedical studies, but also ideal for future clinical applications due to its serum endurable property.