New research by the Carnegie Institution of Washington reveals the existence of tendon stem cells
that could potentially be harnessed to improve tendon
healing and even to avoid surgery.
The buildup of scar tissue often makes recovery from torn rotator cuffs, jumper’s knee, and other tendon injuries a painful, challenging process, often leading to secondary tendon
Carnegie’s Dr Chen-Ming Fan told Thailand Medical
are connective tissue that tether our muscles to our bones. 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.”
Sadly, 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
The recent study was published in the medical journal, Nature Cell Biology.
Along with Carnegie’s Dr Tyler Harvey and Dr Sara Flamenco,Dr Fan revealed all of the cell types present in the Patellar tendon
, found below the kneecap, including previously undefined tendon stem cells
Dr Tyler Harvey , lead author of the study commented, “Because tendon injuries rarely heal completely, it was thought that tendon stem cells
might not exist. Many searched for them to no avail, but our work defined them for the first time.”
Typically, stem cells
are “blank” cells associated with nearly every type of tissue, which have not fully differentiated into a specific functionality. They can also self-renew, creating a pool from which newly differentiated cell types can form to support a specific tissue’s function. For example, muscle stem cells
can differentiate into muscle cells. But until now, stem cells
for the tendon
The team’s research surprisingly 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.
The researchers demonstrated that both tendon stem cells
and scar tissue precursor cells are stimulated into action by a protein called platelet-derived growth factor-A. When tendon stem cells
are altered so that they don’t respond to this growth factor, then only scar tissue and no new tendon
cells form after an injury.
Dr Chen-Ming Fan added, “Tendon stem cells
exist, but the
y must outcompete the scar tissue precursors in order to prevent the formation of difficult, fibrous scars. 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
The team is seeking regulatory approvals to use the tendon stem cells
for treatments in the medical industry.
Reference: Harvey, Flamenco and Fan. 2019. A Tppp3+Pdgfra+ tendon stem cell population contributes to regeneration and reveals a shared role for PDGF signalling in regeneration and fibrosis. Nature Cell Biology. DOI: https://doi.org/10.1038/s41556-019-0417-z