The cats recover within hours. Studies following the earliest feline surgeries, done on normal cats approximately five years ago by researchers in Atlanta, found the procedure caused no harm to the retina.
Narfstrom operates on one eye of each cat so that she can compare results to the other eye. She plans to study the Abyssinians for several years, putting them through mazes to see how well they can navigate and giving them functional MRI scans that will provide her with real-time data on how their brains are picking up visual signals.
"We are in the initial stages of this research. It will take years. But it's a start to a very exciting era," she says.
But electronics aren't the only technology that Narfstrom hopes to use. Eventually, after the gene responsible for causing the blindness in her Abyssinians is fully understood, she wants to try gene replacement therapy to restore their sight. Success with cats would pave the way for using this approach in people with RP.
Narfstrom already has had success using gene therapy to restore sight to French sheepdogs that suffer from another inherited retinal disorder. The dogs, called Briards, are born with night blindness and poor daylight vision that gets progressively worse with age.
It's a long-standing problem in this ancient breed. It was brought to Narfstrom's attention about 18 years ago when a breeder of show Briards came to her with five puppies out of a litter of nine that had obvious problems with night blindness.
The condition is very similar to Leber congenital amaurosis (LCA), a rare hereditary disorder in people. Infants with LCA may be blind at birth or lose their vision within a few years. When Narfstrom found the dogs, she recognized immediately that she might have another research model at hand. She helped organize an international effort to study the disorder.
A colleague in Germany identified the genetic defect responsible for the disorder in dogs. The gene is missing a protein that is essential to the production of rhodopsin, the pigment that triggers the retina's photoreceptors to respond to light.
The next step toward developing a gene therapy is finding a way to deliver the correct gene to the retina, where it can be incorporated into the photoreceptor cells. That delivery system often involves hitching the gene to a harmless virus that "infects" cells with the new genetic material.
With collaborators in Australia, Norway, Germany, Sweden and the United States, an innocuous adenovirus with the correct gene was constructed. The virus was then prepared at the University of North Carolina at Chapel Hill and shipped frozen in vials to Narfstrom in Columbia.
Published by the Office of Research.
©2007 Curators of the University of Missouri. Click here to contact the editor.