Revolutionary Treatment for Arthritis

A groundbreaking study led by Stanford Medicine has made a significant breakthrough in the treatment of arthritis. Researchers have discovered a way to regrow lost cartilage and reverse arthritis, potentially making joint replacements far less common.

The treatment targets a protein called 15-PGDH, which is linked to aging and contributes to declining tissue function throughout the body. By blocking this protein, researchers were able to restore lost knee cartilage in older mice and prevent arthritis from developing after serious joint injuries.

Human tissue samples collected during knee replacement surgeries also showed promising results, producing new, functional cartilage when exposed to the treatment. This breakthrough has the potential to reduce the need for knee and hip replacement surgeries.

Osteoarthritis is the most common form of arthritis, affecting approximately one in five adults in the United States. The disease gradually breaks down cartilage in the joints, causing pain, stiffness, and swelling. 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.

The researchers first identified the gerozyme 15-PGDH in 2023. Previous studies showed that this protein plays a major role in age-related muscle decline in mice. When researchers block the protein, older animals gain muscle mass and endurance. When the protein is artificially increased in young mice, their muscles become weaker and smaller.

The team wondered whether the same mechanism might influence cartilage aging. They compared cartilage from young and old mice, finding that levels of 15-PGDH approximately doubled with age. To test the idea, researchers treated older mice with a small molecule drug that blocks 15-PGDH activity. Some animals received injections into the abdomen, exposing the whole body to the treatment. Others received injections directly into the knee joint.

Both approaches produced striking results. Cartilage that had become thinner and less functional with age grew thicker across the joint surface. Additional testing showed the regenerated tissue was hyaline cartilage, the type needed for healthy joint function, rather than the less effective fibrocartilage.

The researchers also investigated whether the treatment could protect joints after injury. They used a mouse model that mimics ACL tears, a common sports injury seen in activities such as soccer, basketball, and skiing that involve sudden stopping, pivoting, or jumping.

Although ACL injuries can be surgically repaired, roughly half of affected people develop osteoarthritis in the injured joint within about 15 years. Mice that received the gerozyme inhibitor twice weekly for four weeks after injury were far less likely to develop osteoarthritis. In contrast, untreated animals showed 15-PGDH levels that were about twice as high as those of uninjured mice and developed osteoarthritis within four weeks.

Treated mice also walked more normally and placed more weight on the injured limb.

A closer look at cartilage cells revealed important differences between young and old joints. Older chondrocytes were more likely to activate genes linked to inflammation and unwanted conversion of cartilage into bone. They were less likely to express genes associated with healthy cartilage formation.

The treatment appeared to reverse many of these age-related changes. One group of chondrocytes that produced 15-PGDH and expressed genes involved in cartilage breakdown dropped from 8% of cells to 3% after treatment. Another group associated with fibrocartilage production fell from 16% to 8%.

Meanwhile, a population of cells involved in building hyaline cartilage and maintaining the extracellular matrix increased from 22% to 42%.

The results suggest the treatment shifts cartilage toward a younger, healthier state without requiring stem or progenitor cells.