Abstract: Objective:To explore the effect of exosomes on the osteogenic differentiation of dental pulp stem cells (DPSCs) induced by lipopolysaccharide (LPS). Methods:Stem cells from human exfoliated deciduous teeth (SHED) from deciduous teeth of healthy adults and children were collected. DPSCs and SHED were isolated, cultured and identified by flow cytometry. Exosomes were collected from the supernatant of SHED and identified by transmission electron microscopy, Western blot and nanoparticle tracking analysis. The extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) levels of the control group (10 mg/L PBS), LPS group (10 mg/L LPS) and LPS + exosomes group (10 mg/L LPS+10 mg/L exosomes) were examined; The osteogenic differentiation ability of each group was detected by real-time fluorescent quantitative PCR (RT-PCR) and Alizarin Red staining after addition of mitochondrial respiratory enzyme inhibitor AA. Results: DPSCs and exosomes derived from SHED were successfully obtained. LPS could increase the ECAR level of DPSCs and decrease the OCR/ECAR ratio. After adding exosomes, the level of OCR increased and the decreased OCR/ECAR ratio was restored; RT-PCR and Alizarin Red staining results showed that exosomes can restore the decreased osteogenic differentiation induced by LPS, and AA can inhibit the enhanced osteogenic differentiation ability of exosomes. Conclusions: SHED-derived exosomes can increase the OCR/ECAR ratio of DPSCs to promote osteogenic differentiation in the inflammatory microenvironment.

Key words: exosome, ?dental pulp stem cells, ?inflammatory microenvironment, ?osteogenesis differentiation, ?metabolism