Abstract
Regenerative endodontic therapy that is based on the use of stem cells or their derivatives to induce dentin-pulp complex regeneration has recently gained substantial interest. This study aimed to compare the effect of preconditioning through odontogenesis (OD) and/or low-level laser therapy photobiostimulation (LLLT) of human dental pulp stem cells (hDPSCs) on the regenerative potentials of their derived small extracellular vesicles (sEVs) aiming to develop a novel pulp capping therapy. In the current study, hDPSCs were subjected to OD, LLLT, or dual preconditioning protocols before the isolation of sEVs, then the derived sEVs were co-cultured with naïve hDPSCs. Cell viability and wound healing capacity were evaluated using MTT and scratch assays, respectively. RT-qPCR was performed for odontogenic gene expression (DSPP, DMP1, and COL1A1), followed by immunocytochemical staining. Matrix mineralization was also assessed, and relevant statistical analyses were performed. All sEVs-treated groups revealed enhanced cellular and odontogenic activities. OD-sEVs enhanced wound healing and mineralization, while LLLT-sEVs showed relatively higher viability, odontogenic gene and protein expression levels. However, no significant differences were detected between both groups. The novel dual preconditioning protocol surpassed either treatment alone representing a promising approach for odontogenic induction of mesenchymal stem cells. The results highlighted the regenerative potential of preconditioned sEVs as a biological, promising pulp capping material that could open new avenues in the field of regenerative endodontic treatment after being tested in-vivo in experimental animals.