A graphene oxide-copper nanocomposite for the regeneration of the dentin-pulp complex: An odontogenic and neurovascularization-inducing material

Dentin–pulp complex tissue engineering is a promising novel therapy in endodontics. Materials currently used in regenerative endodontics, e.g., calcium hydroxide and mineral trioxide aggregate, do not ensure full regeneration of the dentin–pulp complex, especially in terms of neurovascular induction. In this study, we fabricated a water-soluble graphene oxide–copper nanocomposite (GO-Cu) and investigated its odontogenic and neurovascularization-inducing abilities by means of dental pulp stem cells (DPSCs). Low-dose (≤10 µg/mL) GO-Cu had no effect on DPSC viability and promoted proliferation and adhesion. DPSCs treated with GO-Cu differentiated into odontoblasts and secreted larger amounts of vascular endothelial growth factor (VEGF) and glia-derived neurotrophic factor (GDNF) just as when they were cultured on a GO-Cu–coated calcium phosphate cement (CPC/GO-Cu) scaffold. Human umbilical vein endothelial cells treated with GO-Cu showed more tube formation, higher VEGF expression, and a stronger migratory ability. In addition, immunomodulatory genes, including indoleamine 2,3-dioxygenase (IDO), human leukocyte antigen G (HLA-G), and hepatocyte growth factor (HGF), were upregulated in DPSCs by the GO-Cu treatment. When CPC/GO-Cu was transplanted subcutaneously into nude mice, dentin–pulp complex–like structures formed expressing dentin sialophosphoprotein (DSPP), CD31, and GAP43, and the mineralized area and blood vessel numbers were greater in the CPC/GO-Cu group than CPC-alone group. These results show odontogenic and neurovascularization-inducing abilities of GO-Cu and suggest its promising application in regenerative endodontics.