Abstract: PURPOSE: To study the effect of exosomes derived from human dental pulp stem cells (hDPSCs) on recovery of peripheral nerve crush injury. METHODS: Thirty-six adult SD rats were randomly divided into two groups. Group A was treated with exosomes derived from hDPSCs after sciatic nerve injury, while group B was treated with PBS after sciatic nerve injury. The behavioral changes of rats were observed at 3, 7 and 14 d after injury. The nerve tracts were observed by H-E staining and immunohistochemical staining, and the changes of myelin sheath were observed by electron microscope. The data were analyzed by one-way ANOVA with SPSS 24.0 software package. RESULTS: Behavioral observation showed that the sciatic functional index(SFI) decreased in both groups after injury. With the time going on, the two groups basically recovered 2 weeks after injury, but the recovery in group A was faster than group B(P<0.05). H-E staining and immunohistochemical staining showed that after injury, nerve tract morphological damage and irregular perineurium appeared in both groups, but the degree of perineurium damage in group A was lighter than group B, and the recovery speed was faster. Electron microscopic observation showed that myelin disintegration, edema and degeneration occurred in both groups after injury, but the recovery speed of myelin in group A was faster than group B. CONCLUSIONS: Exosomes derived from hDPSCs can promote recovery of peripheral nerve injury, and its mechanism may be related to accelerating the regeneration of myelin sheath.

Key words: Dental pulp stem cells, Exosomes, Peripheral nerve injury, Myelin sheath