Blind World

Retinitis Pigmentosa.
Vision conference told treatment could halt retinitis pigmentosa.

November 08, 2004.

By Michele Oberoi,
Ottawa Citizen (Canada).

A promising new gene therapy that could potentially halt the progression of an inherited eye disease should be ready for human trials in as soon as three years, says a respected Ottawa researcher.

Robert Korneluk, director of the Solange Gauthier Karsh Laboratory, made the announcement yesterday at the Foundation Fighting Blindness Canada's Vision Quest 2004 conference during a workshop on the future of gene therapy.

Retinitis pigmentosa (RP) is a group of related eye diseases that cause progressive vision loss. Estimated to affect 1.5 million people worldwide, it has no treatment or cure.

The disease is caused when genetic defects lead the cells in the retina to die prematurely. Mr. Korneluk and his coworkers, who are conducting research on XIAP, the X-linked inhibitor of apoptosis (cell death), believe that XIAP therapy can make the retina's photoreceptor cells more resistant to dying, and therefore preserve sight.

XIAP "is the most potent inhibitor of cell death," Mr. Korneluk said, adding that it makes cells "bulletproof."

Although some in the scientific community believe his sight-saving hypothesis is too simplistic, Mr. Korneluk disagrees. He said there have been several successful examples of XIAP gene therapy done on animals with a variety of acute conditions including RP, Parkinson's disease, and stroke. In each case, "the cell that received the XIAP cell therapy not only looks good, but it functions."Researcher touts 'potent' gene therapy

Preliminary data from rats bred specifically with a genetic mutation causing RP that are injected with XIAP at birth "is fantastic," said Mr. Korneluk. "XIAP has rescued a genetic defect."

But, because XIAP therapy seems to work only at the area of injection, surrounding cells are probably not rescued.

"When you inject XIAP in the eye, you only cover 20 per cent of the retina at most," Mr. Korneluk said.

Also, XIAP only works on living cells. Once the eye's photoreceptor cells are dead, XIAP will not bring them back to life.

Still, "the eye is a particularly good place to do gene therapy," Mr. Korneluk said. The retina is accessible, monitoring the therapy's effects is easy, and "there are a lot of gene therapy vectors."

Along with Mr. Korneluk's sessions on gene therapy, the Vision Quest conference also ran workshops on other topical issues for the visually impaired. They included stem-cell research, current and upcoming treatments for age-related macular degeneration, and fitness and self-esteem.

Close to 300 ophthalmologists, researchers, people living with degenerative eye diseases, and their family members attended the one-day conference, which was held for the first time in Ottawa.

Canada's largest supporter of innovative eye research, the Foundation Fighting Blindness, was founded in 1974 and is the only Canadian organization dedicated to finding cures for retinal degenerative diseases, including RP, and adult-onset macular degeneration.

Retinal degenerative diseases are the leading cause of blindness in the western world. In Canadians 50 years of age and older, adult-onset macular degeneration is the most prevalent form of blindness, with close to 10 per cent of adults affected by the age of 65, and 25 per cent affected by the age of 75.

"AMD is the big one," says FFB president Donna Green, adding that in Canada, adult-onset macular degeneration diagnoses outnumber breast cancer diagnoses three-to-one. "The numbers are staggering.

"Some of these diseases have been compared to living with a major stroke," she says of retinal degenerative diseases.

Ms. Green has personal experience. Having lived the past 27 years with RP, which, unlike AMD, usually strikes children and young adults, the 50-year-old business entrepreneur has had to make many adjustments over the years to accommodate her constantly narrowing field of vision.

"It's a lot of work to keep converting the outside world into a visually impaired translation," she says. "It's always a game of substitution and management."

The Ottawa Citizen 2004.

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