Adrenomedullin-loaded Gelatin Methacryloyl Hydrogel Promotes Endogenous Dental Pulp Regeneration: An In Vitro and In Vivo Study

INTRODUCTION: To prepare a gelatin methacryloyl (GelMA) hydrogel scaffold embedded with adrenomedullin (ADM) and investigate its impact and underlying mechanisms in endogenous pulp regeneration. METHODS: ADM was evenly distributed within the GelMA hydrogel through a simple and conventional physical mixing technique. The scaffold underwent characterization via scanning electron microscopy, alongside assessments of swelling, degradation, and release properties. Biocompatibility was evaluated using cytoskeletal and live-dead staining techniques. The hydrogel's influence on dental pulp stem cells' proliferation, migration, and differentiation was assessed with CCK-8 assays, Transwell assays, and alizarin red and alkaline phosphatase staining. Transcriptomics provided insights into potential mechanisms. The angiogenic effects on umbilical vein endothelial cells were examined using scratch and tube formation assays. In vivo, the composite hydrogel's regenerative capacity was tested in a rat model of pulp regeneration. Statistical analysis involved Student's t-test and one-way analysis of variance, with significance set at P < .05. RESULTS: The ADM-loaded GelMA (GelMA@ADM) hydrogel displayed a porous architecture under electron microscopy conducive to cell adhesion and demonstrated excellent biocompatibility. In vitro experiments showed that GelMA@ADM significantly boosted dental pulp stem cells' migration, proliferation, and differentiation, and enhanced the angiogenic activity of umbilical vein endothelial cells after one week of treatment. Corresponding in vivo experiments revealed that GelMA@ADM facilitated the formation of new vascularized pulp tissue after 2 weeks of treatment. CONCLUSIONS: The GelMA@ADM hydrogel effectively promotes dental pulp stem cells' proliferation and differentiation, augments vascularization by umbilical vein endothelial cells, and fosters the creation of new vascularized pulp tissue. These findings underscore the potential of GelMA@ADM hydrogel for endogenous pulp regeneration.