BMSCs-derived small extracellular vesicles promote periodontal regeneration.

Liu, Li; Guo, Shujuan; Shi, Weiwei; Liu, Qian; Huo, Fangjun; Wu, Yafei; Tian, Weidong

Bone marrow mesenchymal stem cells-derived small extracellular vesicles (BMSC-sEV) can be used as a potential cell-free strategy for periodontal tissue regeneration, and we aim to investigate the effect and possible mechanism of BMSC-sEV in periodontal tissue regeneration in this study. The BMSC-sEV was isolated by Exosome Isolation™ reagent and identified by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and western blotting (WB). The human periodontal stem cells (hPDLCs) were co-cultured with BMSC-sEV in vitro to detect the effects of BMSC-sEV on hPDLCs migration, proliferation and differentiation. The BMSC-sEV loaded by hydrogel was injected into experimental periodontitis rats to verify the therapeutic effect and possible mechanism. The results showed that BMSC-sEV was 30-150 nm vesicles and expressed the exosomes protein CD63 and tumor susceptibility 101 (TSG101), which could promote the migration, proliferation, osteogenic differentiation of hPDLCs. The BMSC-sEV-hydrogel had a therapeutic effect on periodontitis rats. After administration for four to eight weeks, micro-CT and histological analysis showed the alveolar bone loss (ABL), inflammatory infiltration and collagen destruction in BMSC-sEV-hydrogel group were less than that in PBS-hydrogel group and periodontitis group. The further immunohistochemical and immunofluorescent staining revealed that the number of Trap positive cells and the expression ratio of osteoprotegerin (OPG) and receptor-activator of nuclear factor kappa beta ligand (RANKL) in BMSC-sEV-hydrogel group were lower than that in PBS-hydrogel group and periodontitis group, while the expression of transforming growth factor-beta 1 (TGF-β1) and the ratio of macrophages type 2 and macrophages type 1(M2/M1) were opposite. Therefore, BMSC-sEV can promote the regeneration of periodontal tissues, and that may be partly due to BMSC-sEV involve in the OPG-RANKL-RANK signaling pathway to regulate the function of osteoclasts and affect the macrophages polarization and TGF-β1 expression to modulate the inflammatory immune response, thereby inhibiting the development of periodontitis and immune damage of periodontal tissue.