Gene editing technique CRISPR/Cas9 showed, for the first time, the ability to treat retinitis pigmentosa, a type of inheritable blindness, in test mice.

Scientists from the Los Angeles-based Cedars-Sinai Board of Governors Regenerative Medicine Institute conducted the experiment. Retinitis pigmentosa is a degenerative eye condition that eventually leads to blindness.

In early states of the eye disease, patients experience night blindness, pigment changes and weakening of the retina, and visual field contraction. To date, the eye illness has no known treatment.

Clustered Regularly Interspaced Short Palindromic Repeat/Cas9 or CRISPR/Cas9 is a gene editing technique that has the ability to tweak out genetic mutations that cause illness. The research team used CRISPR/Cas9 to remove the gene mutation that causes retinitis pigmentosa in test mice. The research is deemed a milestone in the medical and scientific communities.

"Our data show that with further development, it may be possible to use this gene-editing technique to treat inherited retinitis pigmentosa in patients," said senior author Shaomei Wang.

The milestone research was published in the Molecular Therapy journal.
CRISPR/Cas9 Treats Retinitis Pigmentosa

For the study, test mice were genetically engineered to mimic inherited retinitis pigmentosa. The test mice were injected with the CRISPR/Cas9 system designed to remove the mutated gene causing the degenerative blindness.

A technique called optomotor reflex involves head turns in response to moving stripes in varying brightness levels. This technique was used to measure the effect of the CRISPR/Cas9 system single shot in the test mice. A single shot enabled the mice to see better compared to the mice in the control group.

"It is a truly remarkable result and paves the way for more exciting studies and translation to the clinic in the future," said Board of Governors Regenerative Medicine Institute's director Clive Svendsen.

CRISPR/Cas9 Technology

Genetic researchers have been using the CRISPR/Cas9 technology for nearly five years. Despite the social and ethical issues surrounding CRISPR/Cas9, the technology made gene editing easier, less expensive and more precise.

The CRISPR/Cas9 is based on a system used by bacteria to terminate invasive viruses. First, the bacteria copies a piece of the invasive virus' genetic code. The code is copied into a special structure ribonucleic acid (RNA) that transmits the code's instructions.

When the invasive virus comes back, RNA attaches itself to the Cas9 protein. The RNA guides the Cas9 protein to the similar gene in the invasive virus so the protein can deactivate the matching gene.

Photo: National Institute of Health Image Gallery | Flickr

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