San Diego scientists have restored partial vision to rats carrying a gene that causes blindness, and they say their new approach to gene editing holds promise for one day targeting genetic diseases in humans.
To show that genes can be inserted into the fully developed, non-dividing cells of an adult rat, Salk Institute researchers devised an extension of the existing gene editing tool CRISPR. It allowed them to insert a gene that corrects a mutation associated with retinitis pigmentosa, an inherited disease that causes progressive loss of vision.
Salk Institute scientist Jun Wu, one of the first authors on the study published Wednesday in Nature, said "this is the first time" scientists have proven DNA sequences can be inserted into adult tissue, "especially in cells that are not dividing, such as the brain or the eye or muscle."
The rats didn't regain crystal-clear vision, but they did perform four times better on vision tests compared to rats that did not receive gene replacement injections.
Wu said this technique is still in early stages, but he thinks its effect in non-dividing cells holds promise for one day treating genetic diseases in adult humans, not just their unborn children.
"In gene therapy, we want to target as many cells as possible. If we only target stem cells, then existing cells cannot be repaired. This technology has the potential to increase efficiency and the range of tissues that can be targeted," Wu said.
However, the idea of using gene editing in humans attracts significant controversy. Wu said more studies to test the safety of this technique are needed before trying to tackle genetic forms of blindness in people.
Scientists not involved with the study told KPBS via email that they were impressed with the work. Cedars-Sinai scientist Shaomei Wang called the new technique "novel," and UC San Diego's Gene Yeo said its potential is "very exciting."
But the scientists said the technique, as with other gene editing approaches, could potentially lead to "off-target effects," or unintended impacts on the genome. With those caveats in mind, Scripps Research Institute scientist Marc Weinberg said the technique "opens up the opportunity to develop novel therapies for many difficult-to-treat diseases."
"For example," he said, "neurological diseases such as Huntington’s and and muscular diseases such as Duchenne’s muscular dystrophy, both of which have no cure, are now potentially amenable to therapy where the precise genetic mutations can be removed or replaced."
