Tendon stem cells can transform injury recovery
The recovery from torn rotator cuffs and other injuries to the tendon is difficult due to an accumulation of scar tissue. Chen-Ming Fan from Carnegie published research in Nature Cell Biology about the existence of tendon stem cells. These cells may be developed to enhance healing tendons and avoiding 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.”
Furthermore, tendons seldom recover completely upon injury. Consequently, the patient’s ability to move is impaired and therapy can be a lifelong ordeal. Fibrous scars are a cause of this challenge and they impact the tissue of the tendons.
The researchers Tyler Harvey, Sara Flamenco, and Fan discovered cell types in the Patellar tendon, the tendon below the kneecap. They were able to see tendon stem cells that had not yet been identified.
“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.”
The team discovered that tendon stem cells and fibrous scar tissue develop from the same source: the cells around the tendon protecting it. They also found that both groups of cells are activated by a protein called platelet-derived growth factor-A. If the growth factor is not activated, scar tissue results rather than new cells for the tendon to heal injury.
“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.
This work was supported by the U.S. National Institutes of Health.