A treatment that blocks an age-related protein restored cartilage in aging and injured joints by reprogramming existing cells rather than using stem cells.

Researchers at Stanford Medicine report that blocking a protein linked to aging can restore cartilage that naturally wears away in the knees of older mice.

In the study, the injectable treatment not only rebuilt cartilage but also stopped arthritis from developing after knee injuries similar to ACL tears, which are common among athletes and active adults.

A pill-based version of the same therapy is already being tested in clinical trials aimed at treating muscle weakness associated with aging.