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Health, Scientific progress

15 - 07 - 2016

Could the optic nerve be one day repaired?

For the first time, researchers have shown that following a lesion of the optic nerve, strong visual stimulation and a treatment could regenerate the neural axons to recreate and restore some of the lost vision. The study was conducted in mice. 

 

 

American researchers have shown in mice that visual stimulation by high contrast images helped the regrowth of axons ( fibers composing the optic nerve) from the retinal neurons and that a drug accelerated the process. They found new axons were connecting to the right place in the brain, partly restoring vision in blind mice.

 

 

What is the optic nerve ?

The optic nerve (see below) is composed of about one million axons, each of which is the extension of a neuron in the retina. It transmits visual information captured by the retina to the brain. If it is damaged, vision is affected or impaired. For example, Glaucomas, a common visual condition, cause blindness by destroying the optic nerve. However, there is currently no treatment for optic nerve damage. 

 

 

Schéma de l’œil humain. © Totophe64/Wikimedia Commons

 

 

How to fix it ?

 Researchers caused optic nerve injuries in mice and then placed them several hours a day for three weeks in an environment with marked visual contrasts (black and white bands). They found that a small but significant regrowth of the axons of the optic nerve compared to the mouse that were not subjected to high visual contrasts. 

 

  

 

Voici une chambre dans laquelle les chercheurs ont placé les souris, dont un nerf optique a été lésé. © Andrew D. Huberman & al/NIH/Nature neuroscience

 

 

   

The researchers then applied this method to mice subjected to gene therapy to increase the production of a protein which promotes the regeneration of the optic nerve. They were then able to see a total regrowth of the nerve in just three weeks, all the way to the visual centers in the brain. Finally, and most importantly, several tests have shown that this method allowed mice to recover some of their lost vision. 

 

 

What next ?

Thanks to this study, scientists know more about the mechanisms involved in the repair of the optic nerve: stimulating the regrowth of axons from the retinal neurons is possible and is comes with connections all the way through to the visual centers of the brain and may help partially recover vision. To better model the human disease, this new method will be applied to mice with glaucoma. 

  

 

 

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Marie-Anaïs Lien