Hopes for blindness breakthrough

Hopes have increased that a way may be found to treat blindness by replacing lost light-sensitive cells in the back of the eye.

Scientists have successfully injected cells — immature photoreceptors— into the retinas of genetically engineered mice that could not see in the dark.

The injected cells grew nerve connections and generated visual signals that were sent to the brain.

Scientists found the treated mice were better able to perform a water maze task in low light conditions.

However, the British and American scientists, led by Prof Robin Ali from University College London (UCL) say more work is needed before the technique can be attempted on human patients.

The scientists also plan to experiment with photoreceptors derived from embryonic stem cells.

Photoreceptors are lost in a number of common degenerative diseases, such as retinitis pigmentosa, age-related macular degeneration (AMD) and diabetic retinopathy.

In a separate development, researchers at Trinity College Dublin announced this week they have found a way of slowing sight loss caused by age-related macular degeneration.

One of the TCD scientists, Dr Matthew Campbell said two to three years of research may be enough to allow human trials to begin, with proven new therapies expected within a decade.

The researchers believe they have identified an inflammatory protein that prevents the AMD progressing to the ‘wet’ form, where blood vessels underneath the retina begin to grow, leading to central blindness.

The main treatment currently used to block the change involves regular injections of anti-bodies into the eyeball that will target a component that will stop the blood vessels growing.

The treatment is only effective in the end stage of the disease when the vessels have started growing.

The TCD scientists, whose research work was published in Nature Medicine, are all familiar with the work of Prof Ali, who anticipates the first clinical trial may be five to ten years away.

Director of Trinity College’s Ocular Genetics Unit, Prof Pete Humphries said the British study, published in Nature, was very exciting.

“It holds great potential for human therapy,” he said.

“Most of us know people with AMD that affects one in 10 over 55s and a quarter of people over the age of 75,” said Prof Humphries.

“If you hold two coins immediately in front of your eyes, you will see a single large black circle blocking your central vision.

“This is a very realistic simulation of what it is like to live with advanced disease,” he said.

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