The researchers, from Penn's School of Veterinary Medicine and Perelman School of Medicine, in collaboration with University of Florida scientists, developed a therapy that effectively eliminates the abnormal copy of rhodopsin, a light-sensing molecule, and then restores it with a healthy copy of the protein. This knockdown and replacement approach preserved the retina's light-sensing photoreceptor cells in affected dogs, which can develop a very similar disease to affected humans.
What's more, they accomplished this using a single viral vector to co-deliver the genetic material needed to achieve both the knockdown and replacement. Though more than 150 different mutations in rhodopsin have been identified to cause retinitis pigmentosa, this approach is intended to work regardless of the mutation or the mechanism by which rod photoreceptor cells, those responsible for vision in dim light, die. That means that a large percentage of patients with rhodopsin autosomal dominant retinitis pigmentosa could benefit if the therapy is found to be safe and effective in people.
Treatment - William - A - Beltran - Professor
"It's a one treatment fits all," says William A. Beltran, professor of ophthalmology and director of the Division of Experimental Retinal Therapies at Penn Vet and co-lead author of the study, which appears in this week's Proceedings of the National Academy of Sciences. "The treatment targets a region of the rhodopsin gene that is homologous in humans and dogs and is separate from where the mutations are located. That gives us great hope about making this a translational treatment."
"We've known for decades that this specific molecule causes a specific form of retinitis pigmentosa, but developing a treatment has not been straightforward," says Artur V. Cideciyan, research professor of ophthalmology at Penn Medicine and co-lead author. "Now, with these elegant results based on years of study in dogs we can start working toward treating these mutations and prevent deterioration of photoreceptor cells...
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