After a heart attack, the shock of the event leaves behind a trail of damaged heart muscle, which becomes a scar over time. However, the scar tissue doesn't have the elasticity and flexibility of healthy heart muscle, meaning there can be complications with pumping and transporting blood.
For the first time, an international team of researchers has developed a method to reverse the loss of elasticity of damaged heart tissue following heart attacks.
Heart disease is currently the largest cause of death globally.
Preclinical studies in rats found a single injection of tropoelastin into the wall of the heart in the days following a heart attack could 'turn back the clock' on muscle damage, making the scars 'stretchier' and help improve the heart's ability to contract.
Tropoelastin is the protein building block that gives human tissue its elasticity and ability to stretch.
The results are published in Circulation Research and is the first time this potential of tropoelastin in treating heart disease has been investigated.
"This research showcases the potential of tropoelastin in heart repair and suggest further work will show exciting possibilities of its role in future treatments and therapies," says lead researcher Dr Robert Hume who conducted the research at the Westmead Institute for Medical Research. Dr Hume is currently based at the University of Sydney's Charles Perkins Centre.
Repairing tissue damage from heart attacks
Ultrasound showing tropoelastin being introduced into the wall of the heart.Source. Hume et al. 2022
Four days after a heart attack, purified tropoelastin was injected into the heart.
Co-author Professor Anthony Weiss from the Charles Perkins Centre and Faculty of Science explained:
"Tropoelastin can repair the heart because it is a precise replica of the body's natural elastic protein,"
For this injection, the researchers used a new surgical method utilising ultrasound to guide the needle into the heart wall, which is less invasive than previous methods.
Echocardiography of the heart wall in rats. LVAW is the section after a heart attack and shows scarring damage compared to LVPW which is healthy. Tropoelastin was given 4 days after a heart attack, then the heart recovered as shown by the wave-like patterns. Credit: Hume et al. 2022
After 28 days the researchers found the heart muscle, originally damaged and scarred at the beginning, regained its elasticity and resembled muscle function similar to before the heart attack.
Further tests found tropoelastin reduced scar size and essentially stabilises it by increasing its elastin content and therefore decreasing the stiffness of the scar.
Additional experiments on human cardiac fibroblasts (a subset of human heart cells responsible for maintaining the structure of a normal heart), in a petri dish showed after the cells were treated with tropoelastin, they were able to generate elastin.
Elastin is a crucial protein that gives human tissue elasticity and the ability to stretch.
"What we have found is highly encouraging," says senior author Associate Professor James Chong.
"We hope to continue developing the method so it can eventually be used in a clinical setting and used to treat and improve the lives of the millions of heart failure patients worldwide."
Declaration: Ethics approval was obtained from the Animal Ethics Committee, University of Sydney. Professor Anthony Weiss is the scientific founder of Elastagen Pty Ltd, which was sold to Allergan, an AbbVie company. The other authors declare no competing interests.
