Scientists have for the first time used gene-editing to treat Duchenne muscular dystrophy in a large mammal, a significant step towards effective treatment for people with the disorder.
The condition, which has no cure, leads to loss of muscle function and strength and ultimately an early death.
But in a study on dogs, scientists were able to partially restore the key protein people with DMD cannot make.
Within several weeks of the edit made in the dogs, the missing protein was restored in muscle tissue throughout the body, including a 92% correction in the heart and 58% in the diaphragm, the main muscle needed for breathing, according to the study in the journal Science.
Scientists have estimated that a 15% or greater improvement is needed to significantly help patients.
The study was a collaboration between the Royal Veterinary College, in London, and the UT Southwestern Medical Center, in the US.
Dr Eric Olson, one of the authors, from UT Southwestern, said: “Children with DMD often die either because their heart loses the strength to pump or their diaphragm becomes too weak to breathe.
“This encouraging level of dystrophin expression would hopefully prevent that from happening.”
Richard Piercy, professor of comparative neuromuscular disease at the Royal Veterinary College, said: “The ambition is to show that this is safe and effective in dogs and then move into humans trials.
“If that works, then the treatment could also apply to pet dogs that we see in our clinics – and that’s what we hope for here at the college, as it’s our goal to make animals better.”
‘Key step forward’
Independent experts said the study was “promising” and might one day be seen as “ground-breaking” but pointed out that there were some limitations, including the small group of dogs used.
And while dystrophin production was increased, what impact this might have had on improvements in muscle function was not measured.
Nevertheless, experts said the findings were an important step towards the use of gene editing for DMD.
Darren Griffin, professor of genetics at the University of Kent, said: “This work represents a small, but very significant step towards the use of gene editing for DMD.
“Any steps towards significant treatment regimes can only be good news. In the fullness of time, this paper may well be seen as one of the ground-breaking studies that led the way to effective treatment.”
Dr Kate Adcock, director of research and innovation at the charity Muscular Dystrophy UK, said: “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 technology could work for Duchenne.”
