Targeting of Deciduous Tooth Pulp Stem Cell-Derived Extracellular Vesicles on Telomerase-Mediated Stem Cell Niche and Immune Regulation in Systemic Lupus Erythematosus.

Systemic transplantation of stem cells from human exfoliated deciduous teeth (SHED) is used to treat systemic lupus erythematosus (SLE)-like disorders in MRL/ mice. However, the mechanisms underlying the SHED-based therapy remain unclear. In this study, we hypothesized that trophic factors within SHED-releasing extracellular vesicles (SHED-EVs) ameliorate the SLE-like phenotypes in MRL/ mice. SHED-EVs were isolated from the culture supernatant of SHED. SHED-EVs were treated with or without RNase and systemically administered to MRL/ mice. Subsequently, recipient bone marrow mesenchymal stem cells (BMMSCs) isolated from SHED-EV-administered MRL/ mice were examined for the in vitro and in vivo activity of hematopoietic niche formation and immunoregulation. Furthermore, the recipient BMMSCs were secondarily transplanted into MRL/ mice. The systemic SHED-EV infusion ameliorated the SLE-like phenotypes in MRL/ mice and improved the functions of recipient BMMSCs by rescuing mRNA-associated telomerase activity, hematopoietic niche formation, and immunoregulation. The secondary transplantation of recipient BMMSCs recovered the immune condition and renal functions of MRL/ mice. The RNase treatment depleted RNAs, such as microRNAs, within SHED-EVs, and the RNA-depleted SHED-EVs attenuated the benefits of SHED-EVs in MRL/ mice. Collectively, our findings suggest that SHED-secreted RNAs, such as microRNAs, play a crucial role in treating SLE by targeting the telomerase activity of recipient BMMSCs.