Debilitating tendon injuries may soon be a thing of the past now that researchers have discovered the existence of "tendon stem cells" for the first time.

The buildup of scar tissue makes recovery from torn rotator cuffs, jumper's knee, and other tendon injuries a painful, challenging process, often leading to secondary tendon ruptures.

New research led by Carnegie's Chen-Ming Fan and published in Nature Cell Biology reveals the existence of tendon stem cells that could potentially be harnessed to improve tendon healing and even to avoid surgery.

"Tendons are connective tissue that tether our muscles to our bones," Fan explained. "They improve our stability and facilitate the transfer of force that allows us to move. But they are also particularly susceptible to injury and damage."

Unfortunately, once tendons are injured, they rarely fully recover, which can result in limited mobility and require long-term pain management or even surgery. The culprit is fibrous scars, which disrupt the tissue structure of the tendon.

Working with Carnegie's Tyler Harvey and Sara Flamenco, Fan revealed all of the cell types present in the Patellar tendon, found below the kneecap, including previously undefined tendon stem cells.