By Katie Clary

Sarcopenia is a common but debilitating condition that causes progressive loss of muscle mass and strength as people age, affecting around one in five people over 60 and up to half of people over 80. It starts with muscle weakness that makes daily tasks such as going up the stairs or carrying heavy grocery bags increasingly difficult and can cascade into falls, injuries and frailty, hospitalization, the need for assisted living and increased mortality risk. There are currently no FDA-approved treatments for sarcopenia, which drives billions in U.S. health care expenses, including hospitalization and caregiving.

Helen Blau is working to change that.

A renowned stem cell biologist and professor of microbiology and immunology at Stanford Medicine, Blau received the prestigious National Medal of Science earlier this year for her pioneering research in cellular biology and regenerative medicine. One of the first women scientists to receive tenure at Stanford, Blau and her research team at the Baxter Laboratory for Stem Cell Biology have been at the forefront of stem-cell science for decades, and her work explores how they can slow the decline of muscle strength due to injury, illness, and perhaps most consequentially, aging.

“Our lifespan is increasing but not our health span,” says Blau. “It would be a dream come true if something that was discovered in my lab could actually help people with quality of life.”

Blau’s most recent research, published in the July issue of Cell Stem Cell, found that injecting a single dose of the molecule prostaglandin E2 (PGE2) can restore muscle strength in old mice. The hormone-like molecule nudges muscle stem cells into action to repair torn muscle fibers after injury, and it now appears that they can also counteract weakness due to aging. Blau and her team found that after a month of treatment, the muscle fibers of the injected mice resembled young muscle and had grown 15% to 20% stronger.

While Blau cautions that “mice are not humans,” the findings may signal a potential breakthrough in interrupting the muscle-aging pathway that leads to sarcopenia in humans, who, she says, typically lose about 10% of muscle strength each decade after the age of 50.

Weakening nerve connections are partly to blame — as is a specific enzyme identified in her lab that Blau named “gerozyme” for its pivotal role in aging, by slowing the muscle’s ability to regenerate.

Blau holds 16 patents and has launched two biotech companies with colleagues to advance drug discovery, and says she is cautiously optimistic that human therapies can be developed using PGE2. “It’s an easily delivered molecule, it’s an easily delivered drug,” she says. “It would be straightforward to translate it to people.”

One of the companies that Blau co-founded began a Phase 1 clinical safety trial early in 2025, with hopes of having initial results by December. Should human applications emerge from the research, Blau says not to expect a muscle-loss vaccine or vitality jab, but rather “a short-term treatment to get people back on their feet again,” in conjunction with exercise.

It remains to be seen whether PGE2 injections will be effective for a more fragile patient population, older people recovering from hospitalization or injury who often have multiple chronic conditions, says William Evans, adjunct professor of medicine at Duke University and adjunct professor of human nutrition at the University of California, Berkeley.

In an interview, Evans described Blau’s study as “elegant” and says it “suggests an important potential way to overcome the aging effects on muscle repair by the use of PGE2.”

At 77, Blau remains committed to educating the public and inspiring the next generation of stem-cell scientists. Last year, she teamed up with a grad school friend to author a children’s picture book, Stem Cells to the Rescue, in part to help her grandkids understand her work. Her lab at Stanford is a hub for engineers, chemists, biologists and AI experts from around the world. “New discoveries are forged by bringing these diverse people together,” Blau says. “I really love launching their careers, and I’m hoping that our discovery will help people broadly after losing muscle strength due to disuse or disease or aging.”

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