The Role of Small Extracellular Vesicles Derived from Lipopolysaccharide-preconditioned Human Dental Pulp Stem Cells in Dental Pulp Regeneration

Abstract Introduction Regenerative endodontics has created a desirable shift in the treatment paradigm despite current limitations of regenerative outcomes. Mesenchymal stem cells (MSCs) facilitate tissue regeneration and repair in a mild inflammatory environment. Small extracellular vesicles (sEVs) derived from MSCs play an imperative role in the paracrine modulation of regenerative responses modulated by MSCs. However, it remains unknown whether MSCs enhance dental pulp regeneration or whether this enhancement is mediated by sEVs in a mild inflammatory environment. The present study aimed to elucidate the effects of sEVs originated from lipopolysaccharide (LPS)-preconditioned human dental pulp stem cells (hDPSCs) on dental pulp regeneration. Methods All sEVs were isolated from hDPSCs cultured with or without LPS (ie, N-sEVs and L-sEVs, respectively). The effect of N-sEVs and L-sEVs on proliferation, migration, angiogenesis, and differentiation of rat bone marrow MSCs was identified in vitro. Moreover, N-sEVs or L-sEVs were implanted into rat pulpless root canal models, and the regenerated tissue in root canals was assessed via hematoxylin-eosin staining, Masson staining, and immunohistochemistry after 30 days of transplantation. Results Both N-sEVs and L-sEVs could modulate BMSC proliferation, migration, angiogenesis, and differentiation. Both kinds of sEVs enhanced the structure of the regenerated tissue closer to that of a normal dental pulp in vivo. L-sEVs had a more significant effect than N-sEVs. Conclusions sEVs released by hDPSCs in a mild inflammatory microenvironment are capable of facilitating the regeneration of dental pulp through functional healing instead of scar healing, which has potential applications in regenerative endodontics.