Intravitreal delivery of NGF-chitosan hydrogel confers retinal ganglion cell protection and visual function recovery in experimental glaucoma

Glaucoma is one of the leading causes of irreversible blindness, and lowering intraocular pressure alone is insufficient to rescue lost retinal ganglion cells (RGCs) or restore visual function. In this study, we intravitreally injected a liquid chitosan gel loaded with nerve growth factor (NGF), previously developed by our group, into the vitreous body of rats with ocular hypertension-induced glaucoma. Using a combination of techniques--including multiplex immunofluorescence staining, TUNEL staining, CTB tracing, Western blotting, visual electrophysiology, and behavioral assessments--we demonstrated that, compared with the lesion control (LC) group, the NGF-chitosan hydrogel significantly enhanced RGC survival following glaucomatous injury (by approximately 27%), preserved dendritic architecture and long-distance axonal projections, and promoted recovery of visual function. Mechanistically, treatment with the NGF-chitosan hydrogel upregulated the expression of NGF and its high-affinity receptor, tropomyosin receptor kinase A (TrkA), in the retina. In addition, it suppressed retinal glial activation and enhanced mammalian target of rapamycin (mTOR) signaling, collectively contributing to RGC protection and repair. Notably, we further observed activation of Nestin + neural stem cells in the ciliary body region, along with their differentiation into BrdU + /Brn3a + neuron-like cells; the precise mechanisms underlying this phenomenon warrant further investigation. In conclusion, intravitreal delivery of NGF-chitosan hydrogel provides novel mechanistic insights and represents a promising therapeutic strategy for the treatment of glaucoma.