MDUK-funded researchers at the Royal Veterinary College, in collaboration with researchers at UT Southwestern Medical Center, have shown for the first time that gene editing can restore dystrophin production – a protein essential for good muscle health – in a large mammal with Duchenne muscular dystrophy. The results are promising, although much more work is needed before the technique can be trialled for people with the condition.
Duchenne muscular dystrophy is a serious and life-shortening muscle-wasting condition, which has no cure. It is caused by a genetic mutation which stops the production of the dystrophin protein, causing the body’s muscles to weaken and waste away.
Molecular scissors to edit genes
Researchers sought to fix the gene and restore dystrophin production. To do this, they used a gene editing technique called CRISPR/Cas9. This acts like a pair of molecular scissors, cutting the dystrophin gene and allowing it to be naturally repaired by the body.
The CRISPR/Cas9 tool was packaged into harmless viruses called adeno-associated viruses (AAV) and injected into the bloodstream of two dogs which naturally have a form of Duchenne. The animals were then monitored for eight weeks.
The researchers found that the CRISPR treatment had corrected the dystrophin gene and boosted dystrophin production in the dogs’ muscles, heart and diaphragm. While the muscles appeared to be healthier, the researchers didn’t assess how functional they were. The results were published in Science.
While the results of this study are promising, more research is needed before the technique can be tested in people with Duchenne. The study was too small and too short to know whether the CRISPR/Cas9 treatment was safe and effective. It’s important that larger, longer-term studies are carried out.
Hugely exciting, but more work to be done
Professor Richard Piercy from the Royal Veterinary College, who was part of the study, said:
This SingleCut gene editing approach, pioneered by Dr Eric Olson’s group, has the potential to be a one-time treatment that could restore dystrophin protein. It is hugely exciting that through a single intravenous injection we’ve been able successfully modify the dogs’ own DNA so they start generating dystrophin protein again. There is more work to be done, but with this exciting breakthrough, we feel we are a significant step closer to finding an effective treatment.
Dr Kate Adcock, Director of Research and Innovation at Muscular Dystrophy UK, said:
“It is exciting to see advances in how the technique can be applied to Duchenne muscular dystrophy, but as the authors recognise, there are limits to this study. The sample size was small and the study duration too short to know whether the gene editing was safe and effective. Although it seems to have largely boosted dystrophin production, which is key to tackling this condition, the team weren’t looking to record improvements in function.
“The next step will be to conduct larger, longer-term studies to see if the gene editing approach does help to slow the progression of the condition and improve muscle strength. This won’t be a cure, but that shouldn’t obscure that this is a key step forward in proving the CRISPR/Cas9 technology could work for Duchenne.”