In a new study, researchers have used gene therapy to regenerate damaged nerve fibers in the eye, in a discovery that could aid the development of new treatments for glaucoma, one of the leading causes of blindness worldwide.
The research was conducted by a team at the University of Cambridge.
Axons—nerve fibers—in the adult central nervous system (CNS) do not normally regenerate after injury and disease, meaning that damage is often irreversible.
However, over the past decade, there have been a number of discoveries that suggest it may be possible to stimulate regeneration.
In the study, scientists tested whether the gene responsible for the production of a protein known as Protrudin could stimulate the regeneration of nerve cells and protect them from cell death after an injury.
The team used a cell culture system to grow brain cells in a dish. They then injured their axons using a laser and analyzed the response to this injury using live-cell microscopy.
The researchers found that increasing the amount or activity of Protrudin in these nerve cells vastly increased their ability to regenerate.
Nerve cells in the retina, known as retinal ganglion cells, extend their axons from the eye to the brain through the optic nerve in order to relay and process visual information.
To test whether Protrudin might stimulate repair in the injured CNS in an intact organism, the researchers used a gene therapy technique to increase the amount and activity of Protrudin in the eye and optic nerve.
When they measured the amount of regeneration a few weeks after a crush injury to the optic nerve, the team found that Protrudin had enabled the axons to regenerate over large distances.
They also found that the retinal ganglion cells were protected from cell death.
The researchers showed that this technique may help protect against glaucoma.
Glaucoma is one of the leading causes of blindness worldwide.
In glaucoma, the optic nerve that connects the eye to the brain is progressively damaged, often in association with elevated pressure inside the eye.
The causes of glaucoma are not completely understood, but there is currently a large focus on identifying new treatments by preventing nerve cells in the retina from dying, as well as trying to repair vision loss through the regeneration of diseased axons through the optic nerve.
To demonstrate this protective effect of Protrudin against glaucoma, the researchers used a whole retina from a mouse eye and grew it in a cell-culture dish.
Usually around half of retinal neurons die within three days of retinal removal, but the researchers found that increasing or activating Protrudin led to almost complete protection of retinal neurons.
The team says their strategy relies on using gene therapy—an approach already in clinical use—to deliver Protrudin into the eye.
It’s possible the treatment could be further developed as a way of protecting retinal neurons from death, as well as stimulating their axons to regrow.
It’s important to point out that these findings would need further research to see if they could be developed into effective treatments for humans.
One author of the study is Dr. Richard Eva.
The study is published in Nature Communications.
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