Gene therapy of macular degeneration of Best
New gene therapy cured hereditary retinal dystrophy in dogs
Marina Astvatsaturyan, Echo of Moscow
In the study, the results of which scientists from The University of Pennsylvania (University of Pennsylvania) published in the Proceedings of the National Academy of Sciences, presents the results of gene therapy of macular degeneration of Best, or yolk-shaped macular degeneration, on a canine model of the disease. This form of retinal degeneration manifests itself in the gradual loss of central vision, or visual acuity, the purpose of which is to perceive small objects and their details. The disease is caused by a mutation of a gene called BEST1.
Before starting experiments on gene therapy, scientists have figured out the subtle mechanism underlying Best's disease. "There are two layers of retinal cells in our eye that join together to form a zipper-like connection where the visual cells converge with the supporting cells," says Artur V. Cideciyan, one of the authors of the study, from Penn's Perelman School of Medicine at Penn's Perelman School of Medicine. The disease actually consists in "unbuttoning" this zipper, and we fastened it," he explains.
On the left is a section of the retina of an untreated dog's eye with macular degeneration of Best, on the right, the protein expressed by the BEST1 gene is highlighted in red after gene therapy. Drawings from the press release of New Gene Therapy Corrects a Form of Inherited Macular Degeneration in Canine Model – VM.
A group of The University of Pennsylvania has revealed in dogs the exact similarity of human Best's disease. Earlier, ophthalmologist William Beltran (William Beltran) found that in dogs, as in humans, there is a small area in the center of the retina, densely packed with photosensitive cells cones. This area is called the central fossa, and it is important for visual acuity. But the BEST1 mutation in both humans and dogs eventually causes the destruction of this fossa, which leads to loss of vision. As shown by co–author Karina Sidesyan Guziewicz (Karina E. Guziewicz), associate professor of the Veterinary Faculty of the same university (Penn's School of Veterinary Medicine), this is due to the underdevelopment of the supporting cellular layer - retinal pigment epithelium, which is in close contact with photosensitive cells.
A snapshot of the dog's fundus before and 5 years after treatment.
This discovery pointed the way for a new gene therapy and changed the perception of the disease as a lesion of the entire retina. Using a harmless viral carrier, the authors of the publication injected a normal copy of the BEST1 gene – either human or canine – into dogs with a model of Best's disease at an early or middle stage of development. Subsequent studies have shown that in dogs that underwent the gene therapy procedure, the "zipper" between the retinal pigment epithelium and photosensitive cells was restored.
This effect has persisted for the past five years. Testing of the method for human safety should begin in the next two years," says Gutsievich.
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