Blocking an age-linked enzyme regrew knee cartilage in old mice and in tissue from knee replacements

What the research found

Study (old mice, plus human cartilage taken during knee replacement). ScienceDaily carried the Stanford Medicine account on 6 October 2026. Mamta Singla, Yu Xin Wang, Helen Blau, Nidhi Bhutani, and colleagues report in Science (2026; 391(6789):1053; doi 10.1126/science.adx6649). The enzyme 15-PGDH, which they call a gerozyme, was about twice as abundant in knee cartilage from old mice as from young mice. A small-molecule inhibitor, given into the abdomen or into the knee, thickened hyaline cartilage across the joint in older mice. After an ACL-like injury, twice-weekly inhibitor for four weeks lowered the chance of osteoarthritis; mice given a control drug had about twice the 15-PGDH of uninjured knees and developed osteoarthritis within four weeks. The release says about half of people with these ligament injuries develop osteoarthritis in that joint within about 15 years, and that osteoarthritis affects about one in five U.S. adults. In cartilage from people undergoing total knee replacement, one week of the inhibitor reduced degradation-related gene activity and the tissue began making articular cartilage. The release does not give the number of mice or the ages of the people whose tissue was studied. An oral 15-PGDH inhibitor has phase 1 data for muscle weakness in healthy volunteers, not for joints. Some authors are inventors on Stanford patents licensed to Epirium Bio, and Blau is a cofounder. This is not a drug available for arthritis. Educational notes. This is not medical advice.

Evidence level: Clinical trial. This is among the stronger kinds of evidence, but one study rarely settles a question.

Read the original at Stanford Medicine / Science