Interventions resulting in optic nerve regeneration restored some components of vision, according to the results of a mouse model study published online May 21 issue of the Proceedings of the National Academy of Sciences. If these findings are confirmed and extended to other models, they may ultimately offer promise to patients with glaucoma or optic nerve damage.
This study used an optic nerve crush model in mice treated with 3 interventions shown to act synergistically to stimulate growth of optic nerve fibers. These were a conditional deletion of the phosphatase and tensin homolog (PTEN) gene, combined intraocular injections of zymosan (a microglia activator stimulating a growth-promoting compound called oncomodulin), and using a cyclic adenosine monophosphate (cAMP) analog (4-chlorophenylthio) adenosine, CPT) to increase cAMP levels.Adequate stimulation of retinal ganglion cells with these interventions enabled them to partially regenerate myelinated axons over the full length of the visual pathway and to navigate into the lateral geniculate nucleus, superior colliculus, and other visual centers. By forming synapses with other neurons in these regions, the regenerated axons allowed partial restoration of visual circuits.
Leber’s hereditary neuropathy, a rare genetic disease condition causing vision loss, has been shown to be amenable to gene therapy. An advantage of using gene therapy in the eye is that virus vectors used to introduce genes into nerve cells can easily reach retinal ganglion cells and mostly remain in the eye.