Scientists discover the human heart can regrow muscle after a heart attack | University of Sydney Scientists discovered that the human heart can regrow muscle cells after a heart attack, raising hopes for future treatments that could help damaged hearts repair themselves. Summary: Researchers have shown for the first time that human heart muscle cells can regrow after a heart attack. The finding overturns the idea that damaged areas of the heart are completely incapable of regeneration. Scientists now hope to identify ways to dramatically boost this natural repair process, potentially opening a new path toward treatments for heart failure. --- Researchers from the University of Sydney, the Baird Institute and Royal Prince Alfred Hospital in Sydney have found that the human heart can produce new muscle cells after a heart attack. The discovery challenges the long-held assumption that heart muscle lost during an attack cannot regenerate and could eventually help scientists develop new treatments for cardiovascular disease. The findings were published in Circulation Research. First author Dr. Robert Hume, from the Faculty of Medicine and Health and Charles Perkins Centre, and Lead of Translational Research at the Baird Institute for Applied Heart and Lung Research, explained why the result could be important. Human Hearts Can Produce New Muscle Cells "Until now we've thought that, because heart cells die after a heart attack, those areas of the heart were irreparably damaged, leaving the heart less able to pump blood to the body's organs. "Our research shows that while the heart is left scarred after a heart attack, it produces new muscle cells, which opens up new possibilities. "Although this new discovery of regrowing muscle cells is exciting, it isn't enough to prevent the devastating effects of a heart attack. Therefore, in time, we hope to develop therapies that can amplify the heart's natural ability to produce new cells and regenerate the heart after an attack." Scientists had previously seen increased mitosis (a process in which cells divide and reproduce) in the heart muscles of mice following a heart attack. The new research is the first to demonstrate the same phenomenon in humans. The heart's natural regenerative response is not currently strong enough to replace all of the muscle destroyed during a heart attack. However, understanding how this process works could help researchers find ways to increase it. The Lasting Damage Caused by Heart Attacks Cardiovascular disease remains the leading cause of death worldwide. In Australia, it accounts for nearly a quarter (24 percent) of all deaths. A heart attack can destroy as many as one third of the cells in the human heart. Although advances in treatment have dramatically improved survival over the past decade, surviving the initial attack does not always prevent serious long-term consequences. Many patients eventually develop heart failure, a condition in which the heart can no longer pump blood effectively enough to meet the body's needs. A heart transplant is currently the only cure for heart failure. That option is available to only a small fraction of patients. Australia has approximately 144,000 people living with heart failure, while only about 115 heart transplants are performed each year. That leaves a major gap between the number of patients who could benefit from a new heart and the number of donor organs available. Living Heart Tissue Offers a New Research Tool The research also relied on a world-first approach involving heart tissue collected from living patients during bypass surgery. These "pre-mortem" tissue samples came from consenting patients undergoing heart bypass procedures at Royal Prince Alfred Hospital in Sydney. Researchers collected tissue from both diseased and non-diseased areas of the heart. The sampling technique was developed by Professor Paul Bannon and Professor Sean Lal, who work jointly at the University of Sydney, Royal Prince Alfred Hospital and The Baird Institute. Because the tissue comes from living human hearts, researchers can now study heart biology in a laboratory model that may more closely reflect what actually happens in patients. Toward Therapies That Regenerate the Heart The ability to collect and study living heart tissue could become an important tool in the search for regenerative treatments. The team hopes the model will help reveal how the heart produces new muscle cells and how that natural response might be strengthened. Professor Sean Lal, senior author of the study from the School of Medical Sciences and heart failure cardiologist at the Royal Prince Alfred Hospital, said: "Ultimately, the goal is to use this discovery to make new heart cells that can reverse heart failure. "Using living human heart tissue models in our work means that we will have more accurate and reliable data to develop new therapies for heart disease. "Already, our research using these samples has identified several proteins that have previously been shown to be involved in the regeneration of the heart in mice - which is a very exciting prospect to now translate to humans." Those proteins could provide researchers with clues about how to encourage damaged human hearts to generate more muscle cells. While such treatments remain a future goal, the discovery provides direct evidence that the adult human heart has at least some natural capacity to rebuild muscle after an attack. sciencedaily.com/releases/20…