Vision restored in mice thanks to refined CRISPR system
It's been about seven years since researchers used the CRISPER gene-editing system to reverse a blindness-inducing condition called retinitis pigmentosa in stem cells outside the body. Now, using a more refined version of CRISPR, a different research team has restored vision in a live animal model afflicted with the condition. The results may open the door for treatment for the one in 5,000 humans afflicted with the condition.
The CRISPR process allows scientists to precisely cut genes from strands of DNA using an enzyme called Cas9. Once the cutting is done, the genes can be altered, replaced or deleted. The technology has been used for everything from reducing the flowering time of trees to fighting cancer. It's also been previously used to treat retinitis pigmentosa in rats, by switching off mutated genes that cause a loss of photoreceptors in the eye.
Now, researchers at the Wuhan University of Science and Technology in China have refined the CRISPR tool into a system they call PESpRY. They used it to fix a mutated gene responsible for encoding an enzyme called PDE6β.
Once the mutation was repaired, the gene went back to encoding the enzyme – this action prevented the death of rod and cone cells, which is the process by which retinitis pigmentosa causes blindness. After the enzyme was being properly produced again, the mice regained their sight as verified through head-turning tests as well as successful completion of a visually guided water maze puzzle. The research team verified that the restored vision remained even into the animals' old age.
Kai Yao, who led the research, says that more research needs to be conducted to ensure that PESpRY remains effective in other tests and that it is a safe technique for future use, in the same way CRISPR was recently verified.
"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," he added.
While it only affects about 1 in 5,000 people worldwide, retinitis pigmentosa is the most commonly inherited disease of the retina, so research seeking a cure across a variety of modalities is ongoing.
The current study has been reported in the Journal of Experimental Medicine, a peer-reviewed publication.