A GelMA hydrogel co-loaded with ursolic acid, ferulic acid and naringin facilitates dentin regeneration by providing a multi-component odontogenic microenvironment

Dental caries is a prevalent bacterial infectious disease, yet current clinical treatments remain limited because conventional restorative materials provide only mechanical filling and fail to induce dental tissue regeneration. Herein, we developed a composite gelatin methacryloyl (GelMA) hydrogel system (Gel/UFN) co-loaded with three active components from traditional Chinese medicine, including ursolic acid (UA), ferulic acid (FA) and naringin (Nar), to remodel the carious microenvironment and promote dentin remineralization and vascularized pulp-dentin-like tissue formation. Gel/UFN showed excellent biocompatibility and favorable physicochemical and mechanical properties for dental applications, supporting adhesion and proliferation of human dental pulp stem cells (hDPSCs). Functionally, Gel/UFN significantly inhibited Streptococcus mutans (S. mutans) growth and biofilm formation, downregulated inflammatory cytokine expression and promoted the migration and angiogenesis of human umbilical vein endothelial cells (HUVECs). More importantly, Gel/UFN upregulated odontogenesis-related genes in hDPSCs, thereby enhancing odontogenic differentiation, alkaline phosphatase activity, collagen maturation and regenerative mineralization. In vivo, Gel/UFN exhibited slow degradation and sustained drug release for over 55 days. After implantation of Gel/UFN-filled dentin discs into nude mice, H&E staining demonstrated the formation of vascular structures, dentin-like mineralized tissue and cell-rich pulp-like tissue. Western blot analysis further revealed increased expression of the odontogenesis-related proteins RUNX2, DSPP, DMP1, and COL1A1 in the Gel/UFN group, providing additional protein-level evidence of its pro-odontogenic effects in vivo. These newly formed tissues were observed to cover exposed dentinal tubules on the surface of dentin disc using scanning electron microscopy (SEM). Micro-CT further confirmed that dental tissue induced by Gel/UFN exhibited a higher remineralization density at the defect site, supporting enhanced dentin remineralization. Overall, Gel/UFN may serve as a promising bioactive hydrogel platform for dentin repair and vascularized pulp-dentin-like tissue formation through antibacterial, anti-inflammatory, pro-angiogenic and pro-differentiation effects.