Injectable Thermo-Responsive Dentin Matrix Hydrogel For Enhancing Dentin Regeneration

To develop a dentin biorepair material with superior biocompatibility, handling properties, and dentin-inductive capacity through polymer modification of dentin matrix-based materials. Fresh human dentin was enzymatically digested to obtain digested dentin matrix extract (DDME). An injectable thermosensitive PLGA-PEG-PLGA hydrogel served as the carrier for formulating PLGA-PEG-PLGA/DDME paste. Material characterization included the black bottle inversion method, rheological testing, SEM, EDS, and FTIR spectroscopy. In vitro assays (CCK-8, scratch assay, and Transwell assay) evaluated the material's effects on hDPC proliferation and migration. Cell viability within the PLGA-PEG-PLGA/DDME paste was assessed via a Live/Dead assay. Mineralization potential was evaluated using Alizarin Red staining, and dentinogenesis-related protein expression was analyzed via Western blotting. Degradation and biocompatibility were assessed via subcutaneous implantation in mice, and dentinogenic potential was validated in a rat maxillary first molar model. Label-free proteomics identified differentially expressed proteins and key signaling pathways involved in DDME paste-induced dentinogenesis. A thermosensitive, injectable PLGA-PEG-PLGA/DDME paste was successfully developed. In vitro and in vivo studies confirmed that PLGA-PEG-PLGA/DDME promoted odontogenic differentiation of dental mesenchymal stem cells and facilitated in situ dental tissue regeneration. The mTOR pathway was implicated in DDME-induced dentinogenesis. This study highlights the potential of an injectable dentin-derived paste, inspired by biomimetic mineralization, to promote dentin regeneration and repair dentin defects.