Stem cell defect behind muscular dystrophy: study

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TORONTO – Canadian researchers have made a discovery about muscle stem cells that may pave the way for more effective treatments for Duchenne muscular dystrophy.

The genetic disease that affects only boys causes muscles to deteriorate over time and typically leads to death in the second or third decade of life.

Researchers at the University of Ottawa have found that muscles in Duchenne patients are unable to repair themselves due to a defect in muscle stem cells.

Normally, muscle stem cells generate precursor cells that become muscle fibres, which repair damage after injury and exercise.

But in Duchenne muscular dystrophy, the stem cells are missing a protein called dystrophin, which allows them to induce the development of new muscle fibres.

Duchenne muscular dystrophy affects about one in 3,600 boys. It is the most common form of muscular dystrophy.

“For nearly 20 years, we’ve thought that the muscle weakness observed in patients with Duchenne muscular dystrophy is primarily due to problems in their muscle fibres, but our research shows that it is also due to intrinsic defects in the function of their muscle stem cells,” said senior author Dr. Michael Rudnicki, director of the regenerative medicine program at the Ottawa Hospital.

“This completely changes our understanding of Duchenne muscular dystrophy and could eventually lead to far more effective treatments.”

The study, published Monday in Nature Medicine, was conducted in mouse cells, but the findings are expected to be the same in humans, Rudnicki said.