Experiment With CRISPR Gene-Editing Proves Successful By Restoring Vision In Legally Blind Patients


CRISPR gene-editing, also known as Cas9, is short for Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR associated protein 9. It is described by The Conversation as an ‘easier, cheaper and more efficient than previous strategies for modifying DNA.’

Recently, this ground-breaking therapy was also used to partly help restore vision in patients suffering from a rare genetic disorder.

For 55-year old patient, Carlene Knight, because of CRISPR, she has been able to circumnavigate her call center office without needing her walking stick, as well as see more colors vividly, and locate objects easier too.

Meanwhile, another patient, 43-year old Michael Kalberer, also found that during his cousin’s wedding, he could see more colors while on the dancefloor, as well as getting back some of his peripheral vision.

Carlene and Michael were only two of seven patients that were given CRISPR that was directly injected into their eye, which was a procedural method that had never been done with CRISPR before. This normally entails ‘removing cells, editing them in vitro, and injecting them back where they were found.’

Although both of these patients, who suffer from a rare mutation in the retina called Leber congenital amaurosis or LCA, are still far from being cured of their disease. But they are no longer considered legally blind. And although their treatment hasn’t been successful for some patients within their three and nine-month follow up checkups, there were no negative side effects that were reported either.

As for Ms. Knight, she shared, “I’ve always loved colors,” as she lives near Portland. She went on to say, “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.”

According to a report in NPR, professor of ophthalmology, Mark Pennesi, who also has an MD and a Ph.D. from the Baylor College of Medicine, he called the results “a really amazing technology and very powerful,” during a recent symposium.

But like most other scientists and medical professionals, he also says that they should err on the side of caution, since there still need to be many more follow-up research requirements to be done before they can fully understand the value of the CRISPR trial on patients.

Of course, early success stories of cases like Knight’s and Kalberer’s were so clear and substantial that it has caused researchers to move on to their next group of patients to see if they will also garner positive results.

How CRSIPR works is by taking harmless viruses that have been taught to carry edited genes and injecting them into the retina where the cells cannot be taken out, which is considered the in vitro approach. To make sure that the patients didn’t lose their already limited vision fully, the very experimental treatment was only done to one eye of each patient, while the injection doses were also varied.

For some patients, they didn’t regain any of their vision, which could be due to the injection dose or because it was limited to just one retina. Dr. Pennesi chooses to believe that some of the patients that received the experimental treatment could have improved vision even nine months after they received the treatment, after the brain starts to eventually figure out how to manage any of the extra images.

The treatment CRISPR has been used to treat other medical health issues such as sickle-cell disease, hypertrophic cardiomyopathy, and even to create an antidote to the deadly Australian box jellyfish sting. If the CRISPR shows that it’s safe to apply in vivo, then it could be huge in terms of helping ‘genetic disorders inherent to organs that are difficult to draw samples from, such as the brain.’

Professor of ophthalmology at Harvard Medical School, Dr. Eric Pierce, who been assisting with the trails says, “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.”