Researchers at the Sanford Burnham Prebys Medical Discovery Institute (SBP) reported new findings this week that may lead to new therapeutic strategies for Duchenne muscular dystrophy (DMD).

Muscle Repair

DMD is a muscle‑wasting disease affecting about 1 in 7250 males aged 5 to 24 in the United States. It is caused by a genetic mutation that prevents the body from producing dystrophin. The dystrophin protein protects muscle cells. Without dystrophin, muscle fibers become fragile. Instead of repairing themselves, scar tissue replaces the muscle in a process called fibrosis. This leads to progressive muscle degeneration and weakness.

Boys with DMD typically show muscle weakness between ages 3 and 5 and often lose the ability to walk by their early teens. Over time, the muscles needed for breathing and heart function also fail. The disease has no cure, and average life expectancy is about 26 years.

SBP scientists aim to treat DMD by enhancing muscle repair, but first needed a deeper understanding of how muscle regeneration works. Their study focused on fibro/adipogenic precursor (FAP) cells, which help activate muscle stem cells after acute injury in healthy individuals. However, FAPs are also involved in the fibrosis and muscle wasting characteristic of DMD.

Gene Activity

The researchers analyzed gene activity in single FAP cells from mouse models of acute injury and DMD. They identified a distinct subpopulation of FAPs, called sub‑FAPs. During early muscle repair, these cells activate muscle stem cells. Later, they drive fibrosis. In healthy injury responses, immune cells quickly clear Vcam1‑positive sub‑FAPs, which prevents scarring. In DMD, this clearance fails, allowing these cells to persist and trigger collagen buildup and fibrosis—key drivers of muscle degeneration.

Barbora Malecova, Ph.D., first author of the study, explained the significance in a press release::

“This study elucidates the cellular and molecular pathogenesis of muscular dystrophy. These results indicate that removing or modulating the activity of Vcam1-positive sub-FAPs, which promote fibrosis, could be an effective treatment for DMD.”

The lab, led by Pier Lorenzo Puri, M.D., will next search for drugs that target Vcam1‑positive sub‑FAPs and potentially prevent fibrosis in DMD.

The study, funded in part by CIRM, appears in Nature Communications. CIRM is also supporting a Phase 2 clinical trial testing a stem‑cell–based therapy aimed at improving the life‑threatening heart muscle degeneration seen in DMD.

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