Self-healing hydrogel reduces inflammation through ANT1/OPTN axis mediated mitophagy for spinal cord injury repair

Spinal cord injury is hard to repair due to the aggregated injury to neighbor cells caused by neuro-inflammation, which always results in severe outcomes. In this work, Tc peptide, which served as the antagonist of CXCR4 and the agonist of CXCR7, was loaded in a self-healing hydrogel. The hydrogel containing Tc was found to possess superior spinal cord injury repair abilities, including motor neuron regeneration, axon bridging repair and motor functions recovery, due to the inflammation inhibition. The mechanism analysis by RNA-sequencing and in vitro experiments found that the elevated ANT1 accelerates OPTN recruitment, which subsequently recognized by LC3 to form phagophore around dysfunctional mitochondria, resulting in a regressive NLRP3 expression. However, this regression was abolished after inhibiting OPTN. Beneficial from the mitophagy process, ROS was reduced and type 1 microglia activation was diminished. This positive feedback loop accelerated spinal cord injury repair. In summary, the hydrogel containing Tc could promote spinal cord injury repair through reducing neuro-inflammation via enhanced ANT1/OPTN axis mediated mitophagy, which may provide a new peptide containing hydrogel for repairing spinal cord injury.