Irreversible vision loss may no longer be a major problem soon after scientists found a way to alter the genes affecting different cells needed by the eyes to see. They managed to reverse vision loss in mice in a new study.
Published in the Journal of Experimental Medicine on Friday, the study detailed how a team of researchers used a new and highly versatile form of CRISPR-based gene editing to restore the vision of mice with retinitis pigmentosa.
Retinitis pigmentosa refers to a group of rare eye diseases affecting the retina, particularly the light-sensitive photoreceptor cells. The rod and cone cells are responsible for sensing dim light and colors, respectively.
The genetic disease causes the breakdown of the retina cells, leading to vision loss over time. Symptoms typically start to surface in childhood, and people lose their vision later in life. While there is no cure for retinitis pigmentosa, vision aids and rehabilitation programs help patients make the most of their remaining vision before irreversible vision loss takes place, according to the National Eye Institute.
As one of the most common inherited diseases of the retina, retinitis pigmentosa affects 1 in 3,500 to 1 in 4,000 people in the United States and Europe, according to data presented by MedlinePlus.
Previous research allowed scientists to restore vision in mice with other genetic diseases affecting the non-neuronal cells in the eye that support the rod and cone photoreceptor cells. The new study is different since it tackles the most commonly inherited form of blindness affecting the neural photoreceptor themselves.
The team developed a versatile CRISPR system called PESpRY, which can be programmed to correct different genetic mutations occurring within the genome. Retinitis pigmentosa is mainly caused by a mutation in the gene encoding a critical enzyme called PDE6β. By targeting the mutant gene, the system was able to restore the enzyme’s activity in the retinas of mice.
The researchers subjected the mice to behavioral tests to know if the technology saved the rod and cone photoreceptors in their eyes. The test animals found their way out of a visually guided maze water similar to healthy mice. They also responded well to visual stimuli.
“The ability to edit the genome of neural retinal cells, particularly unhealthy or dying photoreceptors, would provide much more convincing evidence for the potential applications of these genome-editing tools in treating diseases such as retinitis pigmentosa,” study author Kai Yao, a professor at the Wuhan University of Science and Technology, said, as quoted by Neuroscience News.
Though the findings are very promising, Yao and colleagues admitted that much work is still needed to establish the safety and efficacy of the gene-editing tool in humans.
“However, our study provides substantial evidence for the in vivo applicability of this new genome-editing strategy and its potential in diverse research and therapeutic contexts, in particular for inherited retinal diseases such as retinitis pigmentosa,” Yao added.