A new treatment blocks a protein called 15‑PGDH. When the protein is stopped, old mice grow back the cartilage in their knees. The mice also avoid arthritis after a serious joint injury.
Why This Matters
Osteoarthritis is the most common type of arthritis. About one in five adults in the U.S. have it. The disease slowly wears away the smooth cartilage that cushions joints. This causes pain, stiffness, and swelling. Current medicines only ease pain. In severe cases doctors replace the joint.
There is no medicine that can slow, stop, or reverse the damage. The new drug could change that.
How the Treatment Works
Scientists call 15‑PGDH a “gerozyme.” Gerozymes increase as we age and make tissues weaker. By blocking this gerozyme, the drug lets cartilage cells, called chondrocytes, act like younger cells.
Unlike many tissues, cartilage does not rely on stem cells to repair itself. Instead, chondrocytes can change their gene activity. The drug helps them shift back to a youthful state.
Results in Mice
Older mice received the drug in two ways: an injection into the belly (which spreads through the whole body) and a direct injection into the knee joint. Both methods made the thin, worn cartilage grow thicker.
The new tissue was hyaline cartilage – the smooth kind that lets joints move freely. The growth was far greater than any other drug tested before.
Protection After Injury
Scientists also tested the drug on mice with an ACL‑like injury, a common sports knee tear. Mice given the drug twice a week for four weeks rarely developed arthritis. Untreated mice showed high 15‑PGDH levels and arthritis within weeks.
What Happens Inside the Cells
In old cartilage, many cells make inflammation signals and start breaking down collagen. After treatment, fewer of these harmful cells were seen. More cells that build healthy cartilage appeared.
Overall, the drug moved the cartilage toward a younger, healthier state without needing stem cells.
Early Human Findings
Samples taken from people undergoing knee‑replacement surgery were kept in the lab. After a week of exposure to the 15‑PGDH blocker, the tissue showed fewer breaking‑down signals and started forming new articular cartilage.
These early results suggest the approach might work in people, too.
Next Steps
An oral version of the drug is already being tested for age‑related muscle weakness. Researchers hope a similar trial for cartilage repair will start soon.
If successful, the treatment could cut the need for knee and hip replacements.