Duchenne muscular dystrophy (DMD), a rare genetic disease usually diagnosed in young boys, gradually weakens muscles across the body until the heart or lungs fail. Symptoms often show up by age 5; as the disease progresses, patients lose the ability to walk around age 12. Today, the average life expectancy for DMD patients hovers around 26.
It was big news, then, when Cambridge, Massachusetts-based Sarepta Therapeutics announced in 2019 a breakthrough drug that directly targets the mutated gene responsible for DMD. The therapy uses antisense phosphorodiamidate morpholino oligomers (PMO), a large synthetic molecule that permeates the cell nucleus in order to modify the dystrophin gene, allowing for production of a key protein that is normally missing in DMD patients. “But there’s a problem with PMO by itself. It’s not very good at entering cells,” says Carly Schissel, a PhD candidate in MIT’s Department of Chemistry.
