Gene-editing technique could treat muscular dystrophy

A gene-editing technique has shown promise in treating Duchenne muscular dystrophy (DMD), the most common and severe form of muscular dystrophy among boys which is characterised by progressive muscle degeneration and weakness.

Although the genetic cause of DMD has been known for nearly 30 years, no effective treatments exist.

The disease breaks down muscle fibres and replaces them with fibrous or fatty tissue, causing the muscle to gradually weaken. This condition often results in heart muscle disease, or cardiomyopathy, the leading cause of death in these patients.

For the study, the researchers used a gene-editing approach to permanently correct the DMD mutation that causes the disease in young mice.

"This is different from other therapeutic approaches, because it eliminates the cause of the disease," said senior author Eric Olson from University of Texas Southwestern Medical Centre in the US.

In 2014, Olson's team first used this technique - called CRISPR/Cas9-mediated genome editing - to correct the mutation in the germ line of mice and prevent muscular dystrophy.

This paved the way for novel genome editing-based therapeutics in DMD. It also raised several challenges for clinical applications of gene editing.

Since germ line editing is not feasible in humans, strategies would need to be developed to deliver gene-editing components to postnatal tissues.

To test this out, researchers delivered gene-editing components to the mice via adeno-associated virus 9 (AAV9). DMD mice treated with this technique produced dystrophin protein and progressively showed improved structure and function of skeletal muscle and heart.

"This study represents a very important translational application of genome editing of DMD mutations in young mice. It is a solid step toward a practical cure for DMD," Rhonda Bassel-Duby, professor at University of Texas Southwestern Medical Centre, noted.

"Importantly, in principle, the same strategy can be applied to numerous types of mutations within the human DMD patients," Olson said.

The findings appeared in the journal Science.