Hypoxia-conditioned BMSC exosomes improve short-term spinal cord injury outcomes via the miR-615-3p/PDE4C-mediated cAMP/PKA pathway

• Hypoxic preconditioning enriches miR-615-3p in BMSC-derived exosomes, enhancing their neuroprotective potential. • miR-615-3p directly targets PDE4C, activating the cAMP/PKA pathway and modulating calcium signaling to reduce ER stress and mitochondrial dysfunction. • In a mouse SCI model, hypoxic exosome treatment improves functional recovery within 14 days, reducing lesion volume and inflammation. • The miR-615-3p/PDE4C axis represents a novel neuron-specific therapeutic target for SCI, distinct from broad anti-inflammatory approaches.