Bioactive adipose-derived ECM hydrogel loaded with cytokine-releasing microspheres promotes spinal cord repair by suppressing inflammation, apoptosis, oxidative stress, and ferroptosis.

Spinal cord injury (SCI) is a devastating neurological condition characterized by severe neuronal loss, inflammation, oxidative stress, and various forms of regulated cell death that collectively impair functional recovery. The present study aimed to develop a bioactive therapeutic platform based on an adipose-derived extracellular matrix (ECM) hydrogel incorporating cytokine-releasing PLGA microspheres to promote spinal cord repair. The hydrogel was fabricated from decellularized adipose tissue and combined with microspheres encapsulating interleukin-10 (IL-10), vascular endothelial growth factor (VEGF), and glial cell line-derived neurotrophic factor (GDNF) to achieve sustained cytokine delivery. Seventy-five male Sprague-Dawley rats were randomly allocated into five experimental groups, including control, SCI, hydrogel, microsphere, and Hydrogel + Mic groups. Tissue specimens were subsequently harvested from the lesion site for further analyses. In a rat model of SCI, treatment with the cytokine-releasing microsphere-loaded hydrogel significantly improved electrophysiological conduction and locomotor recovery compared with untreated SCI animals and groups receiving individual treatments. Molecular analyses demonstrated that the combined treatment markedly suppressed the expression of pro-inflammatory cytokines TNF-α and IL-1β. Additionally, apoptosis-related markers showed substantial modulation, characterized by decreased Caspase-3 and Bax expression and increased Bcl-2 levels. The therapy also improved the oxidative balance by increasing antioxidant markers including GSH, SOD, and CAT while reducing the lipid peroxidation marker MDA. Furthermore, ferroptosis-associated biomarkers were significantly regulated, with elevated levels of GSH, GPX4, and SLC7A11 and reduced ACSL4 expression. Histological analyses revealed significant preservation of spinal cord architecture, reduced cavity formation, enhanced neuronal survival, and decreased glial activation in animals treated with the composite hydrogel system. Collectively, these findings demonstrate that adipose-derived ECM hydrogel loaded with cytokine-releasing microspheres provides a multifunctional therapeutic strategy that attenuates inflammation, apoptosis, oxidative stress, and ferroptosis, ultimately promoting structural and functional recovery following spinal cord injury.