Doctors believed that once the human heart was badly damaged, it could never truly heal. When heart muscle cells died after a heart attack, the loss was considered permanent. However, a new study from Australia is now challenging that long-held belief, suggesting that the human heart can slowly repair itself.
It shows that the human heart may have a natural ability to regenerate muscle cells after a heart attack. The findings are raising fresh hope for future treatments. They have also drawn global attention in the medical community.
A heart attack happens when blood flow to the heart is blocked, usually by a clot. This blockage cuts off oxygen, causing heart muscle cells to die. To protect itself, the body forms scar tissue in the damaged area.
While this scar tissue helps keep the heart intact, it does not beat or contract like healthy heart muscle. As a result, the heart becomes weaker and less efficient at pumping blood. Over time, this can lead to heart failure or increase the risk of another heart attack.
Scientists believed that human heart muscle cells could not divide or replace themselves after such damage. This belief shaped modern heart treatment, focusing on preventing further damage rather than attempting to repair what was lost. However, the new Australian research shows that this view may not be completely correct.
The study was published in the journal Circulation Research and was led by cardiologist Robert Hume from the University of Sydney. According to Hume, the discovery changes how scientists understand the heart’s ability to respond to injury.
“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,” he said. He explained that “Our research shows that while the heart is left scarred after a heart attack, it produces new muscle cells, which opens up new possibilities,” Hume said.
This is the first time that increased mitosis, the process in which cells divide and reproduce, has been clearly shown in human heart muscle after a heart attack. In the past, this process had only been observed in animals such as mice. For example, mice are known to have hearts that can partially regenerate after injury, as their heart muscle cells are able to divide. By contrast, human heart cells were believed to lack this ability. This makes the new findings especially important.
Researchers examined living human heart tissue using advanced laboratory techniques. They studied a full human heart from a donor who had been declared brain-dead. Moreover, they examined tissue samples collected from patients during bypass surgery. The team closely analyzed RNA, proteins, and metabolism in the heart cells. This helped them understand how these cells behave after being deprived of oxygen.
The researchers also identified specific biological signals in the damaged heart tissue that appear to encourage cell division. These signals had previously been linked to heart regeneration in animal studies. “We also characterized the blood-deprived environment that promoted this intrinsic cardiomyocyte cell division, identifying transcripts, proteins, and metabolites previously shown to induce cell division in rodent studies,” the scientists wrote in their paper.
Experts stress that the heart’s natural ability to regenerate is very limited. A severe heart attack can destroy up to one-third of the cells in the human heart. Although survival rates have improved greatly over the past decade due to better emergency care and treatments, many patients still go on to develop heart failure.
In Australia, around 144,000 people live with heart failure, yet only about 115 heart transplants are performed each year. This gap highlights the urgent need for new medical solutions. At present, heart failure can only be cured with a transplant, making donor shortages a serious problem.
Hume said the findings should be seen as a starting point rather than a cure. “Although this new discovery of regrowing muscle cells is exciting, it isn’t enough to prevent the devastating effects of a heart attack,” he said. “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 believe that if this natural repair process can be boosted through future treatments, it could change how heart disease is managed worldwide. As a result, such therapies could help patients recover better after a heart attack. They may also reduce the risk of heart failure and improve long-term survival.
