Altering eye cells may one day restore vision

January 25, 2013 by Michael C. Purdy in Ophthalmology

Altering eye cells may one day restore vision

Enlarge

The light-sensing cells of the eye are the top purple and pink layers in these images. The cells on the left have been reprogrammed to make them less vulnerable to the degenerative effects of retinitis pigmentosa. As a result, more have survived compared to the untreated cells in the right image. Credit: Joseph Corbo, MD, PhD

(Medical Xpress)—Doctors may one day treat some forms of blindness by altering the genetic program of the light-sensing cells of the eye, according to scientists at Washington University School of Medicine in St. Louis.

Working in mice with , a disease that causes gradual blindness, the researchers reprogrammed the cells in the eye that enable night vision. The change made the cells more similar to other cells that provide sight during daylight hours and prevented degeneration of the retina, the light-sensing structure in the back of the eye. The scientists now are conducting additional tests to confirm that the mice can still see.

"We think it may be significantly easier to preserve vision by modifying existing cells in the eye than it would be to introduce new ," says senior author Joseph Corbo, MD, PhD, assistant professor of pathology and immunology. "A diseased retina is not a hospitable environment for transplanting stem cells."

The study is available in the early online edition of .

Mutations in more than 200 genes have been linked to various forms of blindness. Efforts are underway to develop for some of these conditions.

This video is not supported by your browser at this time.

Rather than seek treatments tailored to individual mutations, Corbo hopes to develop therapies that can alleviate many forms of . To make that possible, he studies the that allow cells in the developing eye to take on the specialized roles necessary for vision.

The retina has two types of light-sensing cells or photoreceptors. The rods provide night vision, and the cones sense light in the daytime and detect fine visual details.

In retinitis pigmentosa, the rods die first, leaving patients unable to see at night. Daytime vision often remains intact for some time until the cones also die.

Corbo and others have identified several genes that are active in rods or in cones but not in both types of photoreceptors. He wondered whether turning off a key gene that is activated only in rods could protect the cells from the loss of vision characteristic of retinitis pigmentosa.

'"The question was, when retinitis pigmentosa is caused by a mutation in a protein only active in rods, can we reduce or stop vision loss by making the cells less rod-like?" he explains.

The new study focuses on a protein known as Nrl, which influences development of photoreceptors. Cells that make Nrl become rods, while cells that lack the protein become cones. Turning off the Nrl gene in developing mice leads to a retina packed with cone cells.

To see if this rod-to-cone change was possible in adult mice, Corbo created a mouse model of retinitis pigmentosa with an Nrl gene that could be switched on and off by scientists.

"In adult mice, switching off Nrl partially converts the rod cells into cone cells," he says. "Several months later, when the mutant mice normally had very little left, we tested the function of their retina."

The test showed a healthier level of electrical activity in the retinas of mice that lacked Nrl, suggesting that the could still see.

Corbo now is looking for other critical development factors that can help scientists more fully transform adult rods into cones. He notes that if complete conversion of rods to cones were possible, this therapy could also be helpful for conditions where cone die first, such as macular degeneration.

More information: Montana CL, Kolesnikov AV, Shen SQ, Myers CA, Kefalov VJ, Corbo JC. Reprogramming of adult rod photoreceptors prevents retinal degeneration. Proceedings of the National Academy of Sciences, online January 14, 2013.

Journal reference: Proceedings of the National Academy of Sciences search and more info website

Provided by Washington University School of Medicine in St. Louis search and more info website

5 /5 (3 votes)  

Rank 5 /5 (3 votes)
Relevant PhysicsForums posts

More news stories

Glaucoma drug can cause droopy eyelids

Prostaglandin analogues (PGAs), drugs which lower intraocular pressure, are often the first line of treatment for people with glaucoma, but their use is not without risks. PGAs have long been associated with blurred vision, ...

Ophthalmology created 11 hours ago | popularity not rated yet | comments 0

Eyes on the sun: Child sunshine exposure and eye development

(Medical Xpress)—Exposure to sunshine as a small child is crucial to the development of a healthy eye according to results of long-term myopia study conducted by University of Sydney researchers.

Ophthalmology created 16 hours ago | popularity 5 / 5 (1) | comments 0

New study pinpoints biochemical mechanism underlying fibrosis following glaucoma surgery

The most common cause of failure after glaucoma surgery is scarring at the surgical site, so researchers are actively looking for ways to minimize or prevent scar formation. Previous work had suggested that vascular endothelial ...

Ophthalmology created May 17, 2013 | popularity not rated yet | comments 0 | with audio podcast

Early screenings key to diagnosing glaucoma

New research is emphasizing the importance of regular screenings for glaucoma, a disease that deteriorates the optic nerve over time and is a leading cause of irreversible blindness worldwide. The onset of glaucoma is associated ...

Ophthalmology created May 17, 2013 | popularity not rated yet | comments 0 | with audio podcast

University partners with Sony to find cure for 'lazy eye'

The University of Nottingham and Nottingham University Hospitals NHS Trust, have been working with Sony Computer Entertainment Europe (SCEE) to develop special 3-D glasses and games to help treat children ...

Ophthalmology created May 08, 2013 | popularity not rated yet | comments 0


If you can remember it, you can remember it wrong

(Medical Xpress)—Native peoples in regions where cameras are uncommon sometimes react with caution when their picture is taken. The fear that something must have been stolen from them to create the photo ...

B vitamins could delay dementia

(Medical Xpress)—Despite spending billions of dollars on research and development, drug companies have been unable to come up with effective treatments for dementia and Alzheimer's Disease (AD). Now, A. ...

Reducing caloric intake delays nerve cell loss

Activating an enzyme known to play a role in the anti-aging benefits of calorie restriction delays the loss of brain cells and preserves cognitive function in mice, according to a study published in the May ...

New sleeping pill poised to hit US markets

An experimental sleeping pill from US drug company Merck is effective at helping people fall and stay asleep, according to reviewers at the US Food and Drug Administration, which could soon approve the new drug.

Insight into the dazzling impact of insulin in cells

Australian scientists have charted the path of insulin action in cells in precise detail like never before. This provides a comprehensive blueprint for understanding what goes wrong in diabetes.

Antidepressant reduces stress-induced heart condition

A drug commonly used to treat depression and anxiety may improve a stress-related heart condition in people with stable coronary heart disease, according to researchers at Duke Medicine.