Hypoxic pretreatment ADSCs exosome treatment promote spinal cord repair after spinal cord injury by delivery circ-Astn1 and activation microglia autophagy

Background: Exosome (Exo) secretion by hypoxic pretreatment adipose-derived mesenchymal stem cells (ADSCs) promotes spinal cord repair after spinal cord injury (SCI). But the mechanism remains unclear. Methods: High-throughput sequencing was used to investigate abnormal expression of circRNA in hypoxic pretreatment ADSCs exosome (HExo) and ADSCs exosome (Exo). The abnormal expression of mRNA in spinal cord tissues after Exo or HExo treatment were also analysis using high-throughput sequencing. Bioinformatics analysis and luciferase reporting analysis were used to clarify the interacted relationship among circRNA, miRNA and mRNA. BV2 cells were employ to analysis the apoptosis, inflammatory cytokines expression under OGD condition by using immunofluorescence, ELISA detection. SCI mice model were constructed and the therapeutic effect of Exo were detected using immunohistochemistry, immunofluorescence. Results: The result show that HExo have more therapeutic effect on spinal cord repair after SCI by activation of autophagy. High-throughput sequencing detection show that circ-Astn1 play a role in HExo mediated spinal cord repair after SCI. Downregulation circ-Astn1 decreased the therapeutic effect of HExo to spinal cord repair after SCI. The study also found that Atg7 play a role in HExo mediated spinal cord repair after SCI. Luciferase reporting analysis confirmed that both miR-138-5p and Atg7 were downstream targets of circ-Astn1. Downregulation of Atg7 or overexpression of miR-138-5p reversed the protective effect of circ-Astn1 to BV2 after exposure to OGD condition. Upregulation circ-Astn1 increased the therapeutic effect of Exo to spinal cord repair after SCI by activation autophagy. Conclusions: In conclusion, ADSC-Exos containing circ-Astn1 promotes spinal cord repair after SCI by targeting miR-138-5p/Atg7 pathway mediated autophagy.