Astrocyte Membrane-Engineered Extracellular Vesicles with Hypoxia-Remodeled Cargo Attenuate Reactive Astrocyte Programs and Promote Spinal Cord Repair

Abstract Small extracellular vesicles (sEVs) represent promising cell-free therapeutics for spinal cord injury (SCI). However, their therapeutic efficacy remains limited by variable cargo potency and insufficient cell-selective delivery. Here, we developed a modular biomimetic vesicle platform integrating hypoxic remodeling of mesenchymal stem cell-derived sEV (MSC-sEV) cargo with astrocyte membrane engineering. In a rat model of SCI, hypoxia-preconditioned MSC-sEVs (Hyp-sEVs) attenuated C3-positive astrocyte reactivity and improved functional outcomes. Proteomic profiling and functional analyses identified ERBIN as a key therapeutic cargo enriched in Hyp-sEVs that contributed to suppression of the NOD2/IRF3/GBP1 signaling axis. To enhance astrocyte-directed delivery, Hyp-sEVs were fused with astrocyte-derived membranes to generate astrocyte membrane-engineered vesicles (A-EVs). A-EVs were preferentially taken up by astrocytes, and blocking and knockdown experiments implicated MERTK and the ligands PROS1/GAS6 in this uptake. A-EVs outperformed Hyp-sEVs in preserving spinal cord tissue and promoting functional recovery. Together, these findings indicate that coupling hypoxia-remodeled sEV cargo with astrocyte membrane engineering promotes preferential vesicle uptake by astrocytes, attenuates C3-positive astrocyte reactivity, and improves functional recovery after SCI in rats.