Three-Dimensional Printed Photo-Cross-Linked Gelatin Methacrylate Hydrogel Scaffold-Incorporated Mitochondria-Targeted Hydrogen Sulfide Donor-Loaded Liposomes for Spinal Cord Injury Repair

Spinal cord injury (SCI) results in severe mitochondrial dysfunction, oxidative stress, and excessive generation of reactive oxygen species at the lesion site. Hydrogen sulfide (H 2 S) has been shown to promote mitochondrial functional recovery. AP39, a mitochondria-targeted small-molecule H 2 S donor, holds therapeutic potential but suffers from a short half-life and rapid metabolism. To enhance its stability and cellular uptake, AP39 was encapsulated within liposomes (AP39@LIP). Furthermore, gelatin methacryloyl (GelMA) was employed to encapsulate AP39@LIP, and an AP39@LIP-GelMA hydrogel scaffold was fabricated via photo-cross-linked 3D printing. The AP39@LIP-GelMA hydrogel scaffold exhibited excellent biocompatibility and enabled the sustained release of AP39@LIP, effectively elevating spinal cord H 2 S levels and thereby alleviating mitochondrial damage, promoting motor function recovery, enhancing axonal regeneration, and reducing glial scar formation in SCI rats. Network pharmacology and molecular docking analyses predicted that AP39 engaged the PI3K/AKT signaling pathway, and Western blot analysis confirmed the activation of this pathway in AP39@LIP-GelMA–treated spinal cords. Collectively, these findings indicate that the AP39@LIP-GelMA hydrogel scaffold represents a promising therapeutic strategy for SCI repair.