Regeneration of the optic nerve

For the first time, it was possible to restore vision to mice whose connection between the optic nerve and the brain was disrupted

Marina Astvatsaturyan, Echo of Moscow

Restoration of severed nerve pathways is an important achievement in the search for treatment of glaucoma and other eye diseases associated with damage to the optic nerve. Article by Lim et al. Neural activity promotes long-distance, target-specific regeneration of adult retinal axons, which a group of authors led by Andrew Huberman from the Stanford University School of Medicine published in the journal Nature Neuroscience, reports unprecedented success in restoring connections between retinal ganglion cells that are capable of generating nerve signals. impulses, and various parts of the brain of mice.

Scientists described the process of regeneration of nerve fibers, axons that carry visual information, but also found that these self–healing fibers begin to transmit impulses along the same visual tracts - pathways that they used earlier. As explained in the press release of the First-ever restoration of vision achieved in mice, before scientists fused the severed axons, the state of mouse vision was similar to glaucoma. In humans, this disease is the main cause of blindness due to the fact that the function of the optic nerve is impaired due to increased eye pressure.

According to Professor Huberman, while the restoration of vision in people with cataracts is possible by removing and replacing the clouded lens, it is not yet possible to regain the vision lost as a result of glaucoma. There are about 70 million people with glaucoma in the world. Damage to the optic nerve is also caused by injuries, retinal detachment, pituitary tumors and brain cancer. To restore the severed connections coming from the optic nerve, the authors of the study restarted one of the signaling pathways. Their results are recognized as an important milestone in the field of regeneration of nervous tissue.

To start regeneration, Huberman's group acted in two directions. Usually, when the cells of the mammalian central nervous system reach a mature state, the growth mechanism is turned off, but the authors turned it on by genetic manipulation by activating a protein called rapamycin target in mammals (mTOR), which is part of complexes that provide a cascade of biochemical reactions regulating cell growth.

This genetically engineered approach was supplemented with visual stimulation: rodents were shown videos with moving contrasting black-and-white lines. Three weeks later, the authors found that the neurons had grown to an unprecedented length – they became 500 times longer than they were originally, But the restoration of vision was incomplete. The authors suggest that not all ganglion cells have reached the large hemispheres. 

Portal "Eternal youth" http://vechnayamolodost.ru  23.09.2016