Intravitreal delivery of human NgR-Fc decoy protein regenerates axons after optic nerve crush and protects ganglion cells in glaucoma models

Invest Ophthalmol Vis Sci. 2015 Feb 5;56(2):1357-66. doi: 10.1167/iovs.14-15472.


Purpose: Glaucoma is a major cause of vision loss due to retinal ganglion cell (RGC) degeneration. Therapeutic intervention controls increased IOP, but neuroprotection is unavailable. NogoReceptor1 (NgR1) limits adult central nervous system (CNS) axonal sprouting and regeneration. We examined NgR1 blocking decoy as a potential therapy by defining the pharmacokinetics of intravitreal NgR(310)-Fc, its promotion of RGC axonal regeneration following nerve crush, and its neuroprotective effect in a microbead glaucoma model.

Methods: Human NgR1(310)-Fc was administered intravitreally, and levels were monitored in rat vitreal humor and retina. Axonal regeneration after optic nerve crush was assessed by cholera toxin β anterograde labeling. In a microbead model of glaucoma with increased IOP, the number of surviving and actively transporting RGCs was determined after 4 weeks by retrograde tracing with Fluro-Gold (FG) from the superior colliculus.

Results: After intravitreal bolus administration, the terminal half-life of NgR1(310)-Fc between 1 and 7 days was approximately 24 hours. Injection of 5 μg protein once per week after optic nerve crush injury significantly increased RGCs with regenerating axons. Microbeads delivered to the anterior chamber increased pressure, and caused 15% reduction in FG-labeled RGCs of control rats, with a 40% reduction in large diameter RGCs. Intravitreal treatment with NgR1(310)-Fc did not reduce IOP, but maintained large diameter RGC density at control levels.

Conclusions: Human NgR1(310)-Fc has favorable pharmacokinetics in the vitreal space and rescues large diameter RGC counts from increased IOP. Thus, the NgR1 blocking decoy protein may have efficacy as a disease-modifying therapy for glaucoma.

Keywords: glaucoma; optic neuropathy; regeneration.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Axons / drug effects
  • Axons / pathology*
  • Cell Line
  • Disease Models, Animal
  • Female
  • GPI-Linked Proteins / administration & dosage
  • Glaucoma / etiology
  • Glaucoma / pathology
  • Glaucoma / prevention & control*
  • Humans
  • Intravitreal Injections
  • Male
  • Nerve Crush
  • Nerve Regeneration / drug effects*
  • Nogo Receptors
  • Optic Nerve / drug effects
  • Optic Nerve / metabolism
  • Optic Nerve / pathology*
  • Optic Nerve Injuries / complications
  • Optic Nerve Injuries / drug therapy*
  • Optic Nerve Injuries / pathology
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, Cell Surface / administration & dosage*
  • Retinal Ganglion Cells / drug effects*
  • Retinal Ganglion Cells / pathology


  • GPI-Linked Proteins
  • Nogo Receptors
  • RTN4RL1 protein, human
  • Receptors, Cell Surface