Bone Marrow Mesenchymal Stem Cell-Derived Exosomes Promote the Recovery of Spinal Cord Injury and Inhibit Ferroptosis by Inactivating IL-17 Pathway

Mesenchymal stem cell (MSC)-derived exosomes are considered as alternative to cell therapy in various diseases. This study aimed to understand the effect of bone marrow MSC-derived exosomes (BMMSC-exos) on spinal cord injury (SCI) and to unveil its regulatory mechanism on ferroptosis. Exosomes were isolated from BMMSCs and the uptake of BMMSCs-exos by PC12 cells was determined using PKH67 staining. The effect of BMMSC-exos on SCI in rats was studied by evaluating pathological changes of spinal cord tissues, inflammatory cytokines, and ferroptosis-related proteins. Transcriptome sequencing was used to discover the differential expressed genes (DEGs) between SCI rats and BMMSC-exos-treated rats followed by functional enrichment analyses. The effect of BMMSC-exos on ferroptosis and interleukin 17 (IL-17) pathway was evaluated in SCI rats and oxygen–glucose deprivation (OGD)-treated PC12 cells. The results showed that particles extracted from BMMSCs were exosomes that could be taken up by PC12 cells. BMMSC-exos treatment ameliorated injuries of spinal cord, suppressed the accumulation of Fe²⁺, malondialdehyde (MDA), and reactive oxygen species (ROS), with the elevated glutathione (GSH). Also, BMMSC-exos downregulated the expression of acyl-CoA synthetase long chain family member 4 (ACSL4) and upregulated glutathione peroxidase 4 (GPX4) and cysteine/glutamate antiporter xCT. A total of 110 DEGs were discovered and they were mainly enriched in IL-17 signaling pathway. Further in vitro and in vivo experiments showed that BMMSC-exos inactivated IL-17 pathway. BMMSC-exos promote the recovery of SCI and inhibit ferroptosis by inhibiting the IL-17 pathway, which provides BMMSC-exos as an alternative to the management of SCI.