Health & Medicine

Stanford Scientists Regrow Lost Cartilage and Reverse Arthritis in Breakthrough Study

A new treatment that blocks an aging-related protein restored lost cartilage in old mice and helped prevent arthritis after knee injuries. An oral version is already in clinical trials.

• Stanford researchers found that blocking a protein called 15-PGDH — a "gerozyme" that becomes more abundant with age — can restore cartilage and reverse osteoarthritis in mouse models.
• Human cartilage samples collected during knee replacement surgeries began producing new, functional cartilage when exposed to the treatment.
• An oral version of the drug is already being tested in clinical trials for age-related muscle weakness, potentially accelerating the path to human use.

Osteoarthritis is the most common form of arthritis, affecting roughly one in five adults in the United States. The disease gradually breaks down cartilage in the joints, causing pain, stiffness, and swelling. It generates an estimated $65 billion in direct health care costs each year. Current treatments focus mainly on pain relief and, in severe cases, joint replacement surgery. No approved medication can slow, stop, or reverse the underlying disease process — until now, perhaps.

Researchers at Stanford University have discovered that blocking a protein called 15-PGDH can restore lost cartilage and reverse the effects of osteoarthritis. The protein belongs to a class the team calls "gerozymes" — enzymes that become more abundant with age and contribute to declining tissue function throughout the body. The same research team first identified gerozymes in 2023.

Previous studies showed that 15-PGDH plays a major role in age-related muscle decline. When researchers block the protein, older mice gain muscle mass and endurance. When the protein is artificially increased in young mice, their muscles become weaker and smaller. The new study extends this finding to cartilage, showing that the same mechanism governs joint health.

What makes this discovery particularly striking is that cartilage regeneration appears to work differently from other tissues. In many tissues, regeneration occurs because stem cells multiply and develop into new specialized cells. Cartilage-producing cells called chondrocytes, however, seem able to shift their gene activity and return to a more youthful state — a form of cellular rejuvenation rather than stem-cell-driven replacement.

Researchers also found encouraging results in human tissue. Samples collected during knee replacement surgeries began producing new, functional cartilage when exposed to the treatment. This raises the possibility that damaged cartilage caused by aging or osteoarthritis could one day be repaired with either a local injection or an oral medication. If successful in people, the approach could reduce the need for knee and hip replacement surgeries.

An oral version of the treatment is already being tested in clinical trials for age-related muscle weakness. This means the drug's safety profile is already being established in humans, which could significantly shorten the timeline for osteoarthritis applications. The convergence of a well-understood molecular target, positive human tissue data, and an existing clinical trial pipeline makes this one of the more promising osteoarthritis research developments in recent years.