On the left, fluorescent photographs of collagen strands show increasing levels of damage revealed in tendons that are progressively stretched (from top to bottom: 7.5%, 10.5%, 13.5% elongation). The fluorescent signals match the computer simulation on the right of the damage to the collagen molecule under tension. (Photo courtesy of Jeffrey Weiss and Michael Yu)
A team of researchers from the University of Utah suggests that collagen damage can occur at the molecular level as the result of too much physical stress, and therefore may act as an alert that tissue damage and pain could be forthcoming.
“When we are talking about this mechanical damage, we’re talking about cartilage and tendons and even heart valves that move all the time,” says University of Utah bioengineering professor Michael Yu, in a media release from the University of Utah.
“There are so many tissues which involve collagen that can go bad mechanically. This issue is important for understanding many injuries and diseases,” adds Yu, who led the research team along with bioengineering professor Jeffrey Weiss.
Their research, funded by the National Institutes of Health, is published in Nature Communications.
Prior to this study, the scientists believed that strands of collagen stretched and slid past each other during repeated stress, and they didn’t know if the collagen actually got damaged.
As a result, those who put repeated stress on their bodies wouldn’t know if their physical activity could make their bodies susceptible to tissue damage.
However, the research team discovered that the collagen molecule does in fact get unraveled at a molecular level before complete failure of the tissue occurs.
This type of minor damage, called “subfailure damage,” is associated with common injuries to connective tissues such as ligament and meniscus tears and various types of tendinitis such as tennis elbow and rotator cuff tendinopathy, the release explains.
“Accumulation of subfailure damage can go on for a long time with no catastrophic failure, but repeated damage results in inflammation,” Weiss says in the release. “So this vicious cycle continues, the inflammation breaks down the tissue, making it more susceptible to damage, which then can result in a massive tear.”
As part of their research, the team used a new probe called collagen hybridizing peptide (CHP), a tiny version of collagen that binds to unraveled strands of damaged collage, to figure out where and how much damage has occurred in overloaded tendons.
The team believes that the use of CHP probes could be used in the future to diagnose whether a person has damaged collagen, and if so, how much and where, before a tear occurs; to deliver treatment straight to the damaged tissue because the CHP targets only the damaged collagen; and to educate physicians even more about what happens to one’s body during repeated physical activity.
“A fundamental understanding of the loads and strain that cause molecular damage has eluded us until now,” Weiss states in the release. “Our findings can translate into recommendations for athletes on how to train or what rehabilitation protocols people who are injured can use.”
[Source(s): University of Utah, Newswise]
