A research team led by U.T Southwestern Medical Center edited muscle cells in young dogs with Duchenne to remove a short, problematic segment of protein-coding DNA that occurs in both canine and human patients. Within about two months, the dogs were producing a greater amount of dystrophin.
To get this gene-editing technology into the dog’s muscles, the research team created viruses to transport the gene-editing machinery. To do so, the scientists had to extract some of the virus’s own DNA in order to fit the gene-editing machines. The viruses were assigned either of two tasks. Some viruses carried Cas9-molecular “scissors” to cut out the DNA sequence that blocks the production of dystrophin in muscle cells. The other viruses carried a guide molecule to help the Cas9 to identify where it should make those cuts.
Using viruses as a means to transport the gene-editing technology is very helpful because viruses are very small, even smaller than bacteria. When a virus enters your body, it invades some of the cells and takes control of the cell’s functions by injecting its genetic materials into the cell.
For now, the research team has already demonstrated that CRISPR can treat Duchenne in human cells in the lab, but this test was the first success with a large mammal. Adding on, for this study, the research team focused on the protein level, not on how this treatment may have affected the dog’s behavior.
To conclude, one question that remains in the air after this demonstration is how long one injection with CRISPR will last in human Duchenne patients versus dogs. The research team is hoping once, but there is still so much to discover!