Summary: Using highly versatile CRISPR gene editing, researchers were able to restore vision in mice with retinitis pigmentosa.
Source: Rockefeller University Press
Chinese researchers have successfully restored sight to mice with retinitis pigmentosa, one of the leading causes of blindness in humans.
The study will be published on the 17 March Journal of Experimental Medicineuses a new, highly versatile form of CRISPR-based genome editing that can correct a wide range of disease-causing genetic mutations.
Researchers have previously used genome editing to restore sight to mice with genetic diseases such as Leber’s congenital amaurosis that affect the retinal pigment epithelium, the non-neuronal layer in the eye that supports light-sensing rod and cone photoreceptor cells. . However, most inherited forms of blindness, including retinitis pigmentosa, are caused by genetic damage to the photoreceptors in the neurons themselves.
“The ability to edit the genome of retinal neurons, especially unhealthy or dying photoreceptors, would provide much more compelling evidence for the potential applications of these genome editing tools in the treatment of diseases such as retinitis pigmentosa,” says Professor Kai Yao. Wuhan University of Science and Technology.
Retinitis pigmentosa can be caused by mutations in more than 100 different genes, and is estimated to affect vision in 1 in 4,000 people. It begins with the dysfunction and death of rod cells that detect dim light, before spreading to the cone cells required for color vision, eventually leading to severe, irreversible vision loss.
Yao and colleagues tried to rescue vision in mice with retinitis pigmentosa, which was caused by a mutation in the gene encoding a critical enzyme called PDE6β. To do this, Yao’s team developed a new, more versatile CRISPR system called PESprywhich can be programmed to correct many different genetic mutations regardless of where in the genome they occur.
When programmed to target the mutant PDE6β gene, PESpry system was able to effectively correct the mutation and restore enzyme activity in the retina of mice. This prevented the rod and cone photoreceptors from dying and restored their normal electrical responses to light.
Yao and colleagues performed various behavioral experiments to confirm that the genetically engineered mice retained their vision even into old age. For example, the animals were able to find their way out of a visually guided water maze almost as well as normal, healthy mice and showed typical head movements in response to visual stimuli.
Yao cautions that much work remains to be done to determine the safety and effectiveness of PESpry system in humans.
“However, our study provides significant evidence for the in vivo applicability of this new genome editing strategy and its potential in various research and therapeutic contexts, particularly in inherited retinal diseases such as retinitis pigmentosa,” says Yao.
This is about gene editing and visual neuroscience research news
Factor: Press office
Source: Rockefeller University Press
Contact: Press Office – Rockefeller University Press
Picture: Image credit to Qin et al / JEM
Original research: Open access.
“Vision rescue through unrestricted in vivo prime editing in degenerating neural retinas” Huan Qin et al. Journal of Experimental Medicine
Rescue of vision by unrestricted in vivo prime editing in degenerating neuroretinas
Retinitis pigmentosa (RP) is an inherited retinal dystrophy that causes progressive and irreversible loss of retinal photoreceptors.
Here, we developed a genome editing tool characterized by the versatility of prime editors (PEs) and the unrestricted PAM requirement of a SpCas9 variant (SpRY) called PE.Spry.
Diseased retinas Pde6b-associated RP mouse model was transformed via dual AAV system packaging PESpry for in vivo genome editing via non-NGG PAM (GTG).
The progressive cell loss was reversed when the mutation was corrected, leading to a marked rescue of photoreceptors and the production of functional PDE6β. Treated mice showed significant responses in the electroretinogram and showed good performance in both passive and active avoidance tests.
In addition, they showed an obvious improvement in optomotor responses guided by visual stimuli and efficiently performed visually guided water maze tasks.
Taken together, our study provides compelling evidence for the prevention of vision loss caused by RP-associated gene mutations by unrestricted in vivo prime editing in degenerative retinas.