Stanford Scientists Regrow Cartilage, Reverse Arthritis

Millions of people living with painful, creaky knees might one day skip surgery altogether thanks to a stunning breakthrough from Stanford Medicine.

Researchers found that blocking a single aging-related protein can reverse cartilage loss in older joints and stop arthritis from developing after knee injuries. The treatment worked in mice and also triggered regeneration in human cartilage samples taken from knee replacement surgeries.

The protein at the center of this discovery is called 15-PGDH, a so-called "gerozyme" that increases as we age. Higher levels of this enzyme are linked to the gradual breakdown of tissue function throughout the body. When researchers blocked 15-PGDH in older mice, their worn-down knee cartilage grew back.

The same treatment also prevented arthritis in mice with ACL-like tears, the kind of injury that sidelines athletes and weekend warriors alike. Even more promising, human cartilage tissue responded by forming new, functional cartilage when exposed to the therapy.

Osteoarthritis affects one in five American adults and costs the healthcare system $65 billion annually. Current treatments only manage pain or replace damaged joints surgically. No approved drugs can actually reverse the underlying cartilage damage until now.

What makes this discovery especially exciting is how cartilage regenerates. The research team, led by professors Helen Blau and Nidhi Bhutani, expected to find stem cells driving the repair. Instead, they discovered that existing cartilage cells simply shift into a more youthful state, producing fresh tissue without needing stem cells at all.

"This is a new way of regenerating adult tissue," said Blau, who holds the Donald E. and Delia B. Baxter Foundation Professorship. "We were looking for stem cells, but they are clearly not involved. It's very exciting."

Bhutani emphasized the dramatic nature of the results. "This gerozyme inhibitor causes a dramatic regeneration of cartilage beyond that reported in response to any other drug or intervention," she said.

Why This Inspires

This research targets the root cause of joint degeneration rather than just treating symptoms. For the first time, scientists have found a way to actually turn back the clock on aging joints instead of simply managing the consequences.

An oral version of the treatment is already being tested in clinical trials for age-related muscle weakness, which means the pathway to human trials for joint health could move faster than typical drug development timelines. The fact that human tissue samples responded so positively adds weight to the possibility that this could work in real patients.

If successful in people, this approach could transform how we think about aging and joint health, potentially making knee and hip replacements far less common.

A future where aging joints can heal themselves might be closer than we think.