Effect of hUCMSC-sEV-Loaded GelMA Microspheres on Pulp/Dentin Repair and Regeneration.

BACKGROUND: This study evaluated the biocompatibility of small extracellular vesicles (sEVs) derived from human umbilical cord mesenchymal stem cells (hUCMSC) loaded in gelatin methacryloyl hydrogel microspheres (sEVs@GM-MS), and examined their effects on the proliferation and migration of human dental pulp stem cells (hDPSCs)/human umbilical vein endothelial cells (HUVECs), as well as their capacity to promote endothelial cell tube formation. Pulpotomy in a rat molar model was used to assess sEVs@GM-MS as a potential pulp-capping agent. METHODS: sEVs@GM-MS were prepared and physicochemically characterized. In vitro assessments included live/dead staining, Cell Counting Kit-8 (CCK-8), migration assay and tube formation assay. In vivo, 7 and 14 days after pulpotomized with sEVs@GM-MS, GM-MS, iroot BP or without any pulp capping material, rat molars were evaluated using hematoxylin and eosin (H&E), Masson's trichrome, and immunohistochemical (IHC) staining. RESULTS: GM-MS exhibited a porous surface via scanning electron microscopy. PKH67-labeled sEVs@GM-MS showed sustained release of sEVs. The cell proliferation, migration, tube formation in the sEVs@GM-MS group were significantly enhanced compared with those of the NC and GM-MS groups (p < 0.05). In rat pulpotomy model, sEVs@GM-MS group exhibited significant cell proliferation, angiogenesis, and reparative dentinogenesis with immunocytochemical localization of PCNA, CD31 and DMP-1 compared to NC and GM-MS groups (p < 0.05). Compared with the BP group, the sEVs@GM-MS group showed no significant difference in DMP-1 positive expression (p > 0.05). CONCLUSION: sEVs@GM-MS demonstrated excellent biocompatibility, sustained hUCMSC-sEV release, and enhanced pulp/dentin repair and regenaration, highlighting their potential as a pulp-capping agent.