CAMBRIDGE, United Kingdom — A new discovery may give patients dealing with one of the leading causes of blindness new hope. Scientists from the University of Cambridge are using gene therapy to regenerate damaged nerve fibers in the eyes. The study is proving that injuries that were once thought to be irreparable may be preventable in humans.
Researchers say axons, the nerve fibers leading to the brain, don’t normally regenerate when affected by disease or injury. This study tested if the gene responsible for producing a protein called Protrudin stimulates the regeneration of nerve cells.
Protrudin typically resides inside the tiny structures within the cells, known as endoplasmic reticulum. The study finds these structures inside axons also provide materials which are vital to growth and survival. This makes them important to the regeneration process following an injury. Researchers reveal Protrudin stimulates the transportation of these materials to injured areas.
Protrudin sparks regeneration
The study experimented on brain cells grown from cell cultures which then had their axons damaged using a laser. Researchers observed as the cells responded to the injuries using live-cell microscopy. The results reveal increasing the amount of Protrudin active in these nerve cells significantly raised their ability to regenerate.
For nerve cells in the retina (retinal ganglion cells), their axons extend from the eye to the brain via the optic nerve. This allows it to relay and process visual information, giving you eyesight. To check how Protrudin stimulates repair processes in the central nervous system of a living being, researchers used a gene therapy technique which increases Protrudin activity in the eye.
After measuring regeneration a few weeks after crush injuries, the British team discovered Protrudin allowed the axons to regenerate over large distances. The retinal ganglion cells also gained protection from cell death. The study finds this technique may help defend against glaucoma, which is characterized by progressive damage to the optic nerve. Much of this damage is often linked to rising pressure inside the eye. If glaucoma is not diagnosed early, it can lead to vision loss.
Stopping glaucoma in mice
The study specifically targeted the symptoms of glaucoma, using a whole retina from a mouse eye. Normally, around half of retinal neurons will die within three days of being removed, but researchers discovered that increasing Protrudin leads to nearly complete protection of retinal neurons.
“Glaucoma is one of leading causes of blindness worldwide. 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,” Dr. Veselina Petrova says in a university release.
“Our strategy relies on using gene therapy – an approach already in clinical use – to deliver Protrudin into the eye. It’s possible our 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.”
Dr. Petrova adds nerve cells in the central nervous system eventually lose the ability to regenerate as they age. For injuries to the brain, spinal cord, and optic nerve, a new therapy can provide relief after potentially life-changing accidents.
“The optic nerve injury model is often used to investigate new treatments for stimulating CNS axon regeneration, and treatments identified this way often show promise in the injured spinal cord. It’s possible that increased or activated Protrudin might be used to boost regeneration in the injured spinal cord,” Petrova concludes.
The study appears in the journal Nature Communications.