The CRISPR gene editing tool has stirred up a heated debate over whether it’s ethical to edit the genes of developing embryos, but now the technology has been used to treat a genetic disease in a fully developed living mammal for the first time.
With CRISPR, scientists can cut out and replace individual components of DNA in an organism, effectively rewriting its genetic code. In this breakthrough procedure at Duke University, researchers successfully used CRISPR to treat Duchenne muscular dystrophy (DMD) in a mouse.
Hundreds of children per year are born with DMD, a genetic disorder that leads to muscle weakness and atrophy, making it the most common fatal genetic disorder, according to Popular Science. The disease impairs the body’s ability to produce dystrophin, a protein chain that connects muscle fiber to surrounding tissue, and without the support of dystrophin, the muscles in the body start to deteriorate.
Sadly, there is no known cure for the disease. Better care for the heart and lungs only extends the average lifespan of a patient with DMD to age 27, so the potential to use CRISPR to treat the disease is an incredibly exciting possibility.
"Recent discussion about using CRISPR to correct genetic mutations in human embryos has rightfully generated considerable concern regarding the ethical implications of such an approach," Charles Gersbach, a biomedical engineer at Duke University, said in a press release. "But using CRISPR to correct genetic mutations in the affected tissues of sick patients is not under debate. These studies show a path where that's possible, but there's still a considerable amount of work to do."
Previously, researchers had used electrical jolts to deliver CRISPR in cultured cells, but this approach isn’t possible within a living patient. Instead, researchers are using viruses to deliver the treatments.
"A major hurdle for gene editing is delivery. We know what genes need to be fixed for certain diseases, but getting the gene editing tools where they need to go is a huge challenge," said Chris Nelson, one of the study’s researchers. "The best way we have to do it right now is to take advantage of viruses, because they have spent billions of years evolving to figure out how to get their own viral genes into cells."
In order to use viruses as the delivery vehicles for gene therapy, the researchers must take out all of the harmful genes in the virus and instead insert the therapeutic genes they want to deliver.
While using CRISPR to successfully treat DMD in a mouse is certainly an exciting advancement, there’s still a lot of work to be done before scientists will be able to use this approach to treat genetic diseases in living humans. Nonetheless, these findings will help researchers work toward the goal of applying this breakthrough science to the field of medicine.
“From here, we’ll be optimizing the delivery system, evaluating the approach in more severe models of DMD, and assessing efficiency and safety in larger animals with the eventual goal of getting into clinical trials,” said Gersbach.
So in the years to come, you might be able to go to the doctor and get a gene-edited virus unleashed in your body to treat a disease. What a time to be alive.