THANKS to research on “mighty mice”, the lives of people suffering from muscle-wasting diseases such as muscular dystrophy could be transformed. Two treatments that block a protein called myostatin, which slows muscle growth, are now in the pipeline.The first approach, announced this week, aims to use a drug to mop up myostatin. Meanwhile a second method, which is already in clinical trials in people with muscular dystrophy, uses antibodies to disable the protein.In 1997, researchers led by Se-Jin Lee of Johns Hopkins University School of Medicine in Baltimore, Maryland, engineered mice in which the gene for myostatin had been “knocked out”. The animals grew muscles twice as big as normal. A defect in the myostatin gene was what caused a German toddler, whose story was widely publicised last year, to develop prodigious muscles.Now Lee has produced a soluble molecule called activin type IIB receptor (ACVR2B) that binds to myostatin in normal mice, causing their muscles to bulk up. He hopes ACVR2B can be used to treat conditions such as Duchenne muscular dystrophy, a genetic disease that affects 1 in 3000 boys. Their muscles waste away because of a defect in the gene for the protein dystrophin, which is important in organising muscle structure.
