In retinal degenerative diseases, once light and color-sensing photoreceptor cells degrade and die, they cannot self-regenerate in mammals. As a result, gene therapy is a popular potential therapeutic approach for maintaining and/or regenerating retinal cell function.
Optogenetic gene therapy is a technique that allows control of target cells through the expression and activation of light-sensitive molecules in those cells. For retinitis pigmentosa and other retinal diseases, optogenetic molecules are delivered to ganglion cells which are outer retinal cells, via adeno-associated virus (AAV)-mediated gene therapy. Success in restoring partial visual function was noted with optogenetic gene therapy in earlier studies using mouse models.
Here, researchers conducted similar experiments with larger animal models such as dogs, primates, and human-derived retinal models. They found similar success, noting the ganglion cells were still functional after 16 months, along with evidence confirming partial vision restoration. This success has further led to three human optogenetic Phase I/II clinical trials, one active and two under recruitment.
What this means for Usher syndrome: Initial trial results confirm one patient with end-stage retinitis pigmentosa experienced partial restoration of vision. If these trials continue to demonstrate successful restoration of vision, USH patients and others afflicted with retinal degenerative diseases may be able to gain back some sight.
