Scar tissue build up makes recovery from torn rotator cuffs, jumper’s knee, and other tendon injuries a painful, challenging process. And secondary tendon ruptures often result. New research, however, suggests the existence of tendon stem cells that could potentially be harnessed to improve tendon healing and even to avoid surgery.
The results are very promising to stem cell doctors and the patients we treat.
The research was recently published in Nature Cell Biology.
“Tendons are connective tissue that tether our muscles to our bones,” explained Chen-Ming Fan, lead researcher for the project at the Carnegie Institution for Science. “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.”
A New Treatment with Improved Mobility Possible
Once these tendons are injured, recovery is rare, and results are mixed. Mobility is limited and long term pain management is often necessary. Often, patients require surgery.
But Fran discovered previously undefined tendon stem cells just below the kneecap. He conducted his research alongside Carnegie’s Tyler Harvey and Sara Flamenco.
“Because tendon injuries rarely heal completely, it was thought that tendon stem cells might not exist,” said lead author Harvey. “Many searched for them to no avail, but our work defined them for the first time.”
“Surprisingly, the team’s research showed that both fibrous scar tissue cells and tendon stem cells originate in the same space — the protective cells that surround a tendon. What’s more, these tendon stem cells are part of a competitive system with precursors of fibrous scars, which explains why tendon healing is such a challenge.”
Both tendon stem cells and scar tissue precursor cells are stimulated into action by a protein called platelet-derived growth factor-A.
“Tendon stem cells exist, but they must outcompete the scar tissue precursors in order to prevent the formation of difficult, fibrous scars,” Fan explained. “Finding a therapeutic way to block the scar-forming cells and enhance the tendon stem cells could be a game-changer when it comes to treating tendon injuries.