Blocking one enzyme restored strength to old muscle

Researchers at Stanford University looked for what changes inside old muscle tissue itself. They found rising levels of an enzyme called 15-PGDH, which breaks down a signaling molecule muscle needs to stay strong.

When the team forced young mouse muscle to overproduce the enzyme, it withered the way old muscle does. When they blocked the same enzyme in old mice, either by deleting its gene or with a small-molecule drug, aged muscle gained back mass, strength and exercise endurance on a treadmill.

The enzyme works by breaking down prostaglandin E2, a molecule that normally supports mitochondrial function and muscle repair, and restoring PGE2 levels appeared to be the key step behind the recovery. Several authors hold patents on blocking the enzyme and have financial ties to a company pursuing it as a drug, a conflict of interest the paper discloses. The experiments were run entirely in mice; an inhibitor has since entered early safety testing in healthy volunteers.

One enzyme, blocked, and old muscle came back.