CRISPR Gene-Editing Experiment Partly Restores Vision In Legally Blind Patients

CRISPR Gene-Editing Experiment Partly Restores Vision In Legally Blind Patients

A lot of work is being done in the fields of CRISPR gene-editing, and recently the revolutionary therapy was used to partially restore the vision in patients with a rare genetic disorder.

55-year-old Carlene Knight is now able to move around her call center office without the aid of her walking stick, easily locate objects, and can see colors much more vividly now.

43-year-old Michael Kalberer also learned he could see colors again while on the dancefloor of his cousin’s wedding, and he has gradually regained some of the peripheral field of vision.

They were two of seven patients who received CRISPR injected directly into their eye, a procedural method never before done with CRISPIR, which normally involves removing cells, editing them in vitro, and injecting them back where they were found.

Both patients are far from cured of their Leber congenital amaurosis, or LCA, a rare mutation in the retina, but they’re no longer legally blind, and while the treatment failed to work for some patients during the three- and nine-month followups, no side effects were reported.

“I’ve always loved colors,” said Knight, who lives near Portland. “Since I was a kid it’s one of those things I could enjoy with just a small amount of vision. But now I realize how much brighter they were as a kid because I can see them a lot more brilliantly now; it’s just amazing.”

Mark Pennesi, a professor of ophthalmology holding an MD and a Ph.D. from the Baylor College of Medicine, presented the results at a recent symposium, calling it “a really amazing technology and very powerful,” according to NPR.

Like all scientists, Pennesi urges caution, as a lot more follow-up research needs to be conducted before the true value of the CRISPR trial can be measured.

However, the early success was so significant and clear for people like Knight and Kalberer, the researchers are already moving on to the next group of patients.

CRISPR works by injecting harmless viruses taught to carry edited genes into the retina, where cells cannot be removed, thus facilitating the in vivo approach. To ensure the highly-experimental treatment wouldn’t ruin what limited vision the patients did have, only one eye received the injection, and doses were varied.

The fact that some patients didn’t regain any vision could have been the dose size, or the limit to the single retina. Pennesi believes some may continue to improve even after nine months as a matter of course, while the brain begins to gradually figure out what to do with all these extra images.

CRISPR has been used to treat sickle-cell disease, hypertrophic cardiomyopathy, and even to create an antidote to the Australian box jellyfish sting, and the number of potential uses for CRISPR could be huge if it’s shown safe to apply in vivo, as genetic disorders inherent to organs that are difficult to draw samples from, such as the brain, could be approached.

“We’re thrilled to see early signs of efficacy because that means gene editing is working. This is the first time we’re having evidence that gene editing is functioning inside somebody and it’s improving—in this case—their visual function,” said Dr. Eric Pierce, another professor of ophthalmology at Harvard Medical School who’s assisting with the trials.

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