Once it’s been injured, the protective cartilage in our knees and other joints heals very slowly – if at all. A new injectable gel, however, could both reinforce the tissue after it’s been damaged, and encourage new cartilage to grow over top of it.

Currently being developed by scientists at the University of Pennsylvania, the hydrogel contains a modified form of a gooey substance known as hyaluronic acid, which is produced naturally by the body’s connective tissue. In recent years, the acid has also been experimentally used to ward off glaucoma, heal damaged cardiac tissue, and refill herniated spinal discs.