Apoptotic extracellular vesicles derived from UC-MSCs promote spinal cord injury repair by inhibiting ferroptosis via OTUD1.

Spinal cord injury (SCI) is a severe central nervous system disorder. It often results in permanent sensory and motor deficits, with no effective therapeutic strategies available. Oxidative stress and ferroptosis are significant contributors to secondary neuronal damage following SCI. This study investigated the therapeutic potential and molecular mechanisms of apoptotic extracellular vesicles (ApoEVs) derived from human umbilical cord mesenchymal stem cells (UC-MSCs) in SCI repair. Our findings reveal that UC-MSC-ApoEVs significantly improve motor function, promote neuronal survival, and preserve tissue integrity in a murine SCI model. These results demonstrate their robust neuroprotective effects. Mechanistically, ApoEVs regulate ferroptosis-related molecules, including GPX4, TFR1, and ACSL4, reducing iron accumulation and lipid peroxidation. Additionally, ApoEVs maintain mitochondrial function, thereby inhibiting neuronal ferroptosis. Furthermore, proteomic analysis and functional validation identified OTUD1, a deubiquitinating enzyme enriched in ApoEVs, as a key regulator interacting directly with NRF2. OTUD1 stabilizes NRF2 via deubiquitination, enhancing its antioxidant response. Silencing OTUD1 in ApoEVs significantly diminished their anti-ferroptotic and neuroprotective effects, highlighting the pivotal role of OTUD1 in mediating therapeutic benefits. This study uncovers a novel OTUD1-NRF2 regulatory axis in ferroptosis inhibition, providing new insights into the development of ApoEV-based acellular therapies for SCI.