Researchers discover muscles' "control center" – could help elderly with better muscle healing
Researchers from Aarhus University have found the cells that function as "construction managers" during muscle injuries. The result could lead to new treatments for elderly and sick people and may be the key to combating muscle mass loss.
When a house is hit by a hurricane, you must first remove the damaged parts before reconstruction can begin.
The same applies to our muscles after injuries – and now researchers from Aarhus University and Steno Diabetes Center Aarhus have discovered who functions as the coordinator of this repair process.
In a study just published in the scientific journal Nature Communications, the researchers have identified a completely new form of cellular communication that is crucial for muscles' ability to heal after injuries.
The discovery could have great significance for treating age-related muscle mass loss and other conditions where muscle mass is lost.
"Our primary finding is the pronounced inter-cellular communication between fibro-adipogenic progenitors (FAPs) and immune cells, which helps ensure the function of immune cells and thereby support muscle regeneration," explains Associate Professor Jean Farup from the Department of Biomedicine at Aarhus University, who leads the project.
The study shows that FAPs – specialized cells located locally in muscle tissue – function as a kind of coordinator that communicates with the body's "repair team" of macrophages.
These immune cells are responsible for removing damaged tissue and helping with the healing process.
"FAPs are thus a kind of coordinator that lives in the house and knows how it should be rebuilt and communicates with the various craftsmen necessary for the reconstruction," explains Jean Farup.
Surprising local production of signaling substances
One of the most surprising findings was that FAPs produce the signaling substance complement C3 directly in muscle tissue.
Until now, researchers' theory has been that complement C3 was produced in the liver and then released into circulation.
The local production turns out to be crucial for regulating the inflammation necessary for effective muscle reconstruction.
Hope for elderly and sick
The researchers' discovery provides new opportunities to help patient groups struggling with muscle mass loss.
"We know that inflammation plays a significant role both in relation to muscle regeneration and in connection with muscle mass loss in patients and elderly people. Our new insight therefore provides new opportunities to regulate inflammation with, for example, medicine that affects FAPs," explains Jean Farup.
The next step is to investigate what role the mechanism plays under other circumstances, particularly when chronic inflammation in muscle tissue leads to muscle mass loss.
"We have long known that chronic inflammation is associated with a range of diseases such as type 2 diabetes, cardiovascular diseases and cancer, where muscle mass, muscle quality and muscle function are lost. Here we believe that our new understanding of the interaction between FAPs and the immune system can be important," says Jean Farup.
About the research result
Study type: Randomized controlled trial
Partners: Steno Diabetes Center Aarhus and Aarhus University Hospital
External funding: Novo Nordisk Foundation, Independent Research Fund Denmark and Lundbeck Foundation
Potential conflicts of interest: None
Link to scientific article: https://www.nature.com/articles/s41467-025-60627-2
Contact
Associate Professor Jean Farup
Aarhus University, Department of Biomedicine & Steno Diabetes Center Aarhus
Phone: 22927972
Email: jean@biomed.au.dk