The research team has previously successfully applied a similar approach to two other heritable vision disorders that occur in both humans and dogs: Leber congenital amaurosis and achromatopsia. The present study was more challenging, as it was necessary to target both main classes of photoreceptor cells.
While the exact disease mechanism of the RPGR form of XLRP is still unknown, the researchers were able to successfully treat dogs with two different RPGR mutations. The mutations disrupt photoreceptors in different ways, but both ultimately cause them to become useless for vision. While this form of blindness is rare in dogs, it is common in humans. Patients with XLRP usually begin to lose night vision as children and become almost totally blind by middle age.
This is the first proof that this condition is treatable in an animal model; a single subretinal injection administered to the diseased dogs led to functional and structural recovery. The dogs' recovery was assessed using a variety of methods that are used clinically in patients, such as electroretinography and optical coherence tomography.
The researchers feel the results are promising and relevant for translation to the clinic.
"We are intervening to treat both classes of photoreceptor cells, rods and cones, and that has never been done before in a large animal model," Beltran said. "And not only can we prevent the disease onset but also restore the remaining photoreceptors cells to normal once the disease is ongoing."
While the ability to repair both rods and cones was itself a first, the research team went further, showing that its treatment also repaired the photoreceptor connections to other retinal neurons that eventually send visual signals to the brain, another first.
"This not only provides hope fo
|Contact: Evan Lerner|
University of Pennsylvania