Mitochondrial Homeostasis Mediates the Sustained Neuroprotection of CNTF-Chitosan Hydrogel Against NMDA-Induced Retinal Ganglion Cell Excitotoxicity.

N-methyl-D-aspartate (NMDA) excitotoxicity drives mitochondrial dysfunction and retinal ganglion cell (RGC) loss in blinding retinal disorders. Ciliary neurotrophic factor (CNTF) is neuroprotective, but its short half-life limits long-term therapy. Here, we investigated whether mitochondrial homeostasis mediates the sustained protection of a CNTF-loaded chitosan hydrogel. In vitro, free CNTF and the hydrogel equally protected RGCs against NMDA, effects completely abolished by the mitochondrial uncoupler carbonyl cyanide m-chlorophenyl hydrazone (CCCP). In vivo, free CNTF provided only transient rescue, whereas the hydrogel sustained RGC survival, mitochondrial integrity, and visual function for 28 days, with persistent upregulation of mitochondrial biogenesis genes. Adeno-associated virus-mediated DRP1 overexpression-induced mitochondrial fission fully reversed the hydrogel's benefits, mirroring CCCP inhibition. Collectively, intact mitochondrial homeostasis is essential for the long-term neuroprotection of the CNTF-chitosan hydrogel, which extends CNTF retention without altering its mitochondrial-dependent mechanism. This hydrogel represents a promising long-acting treatment for retinal excitotoxicity.