For many years, scientists believed the human heart could not repair itself after serious damage. A new study from Australia is now challenging this view, showing that heart muscle cells in humans can regenerate after a heart attack.
A heart attack occurs when blood flow to the heart is blocked, cutting off oxygen and causing heart cells to die. The body usually repairs this damage by forming scar tissue. However, scar tissue does not beat like healthy heart muscle, which reduces the heart's ability to pump blood efficiently. Over time, this can increase the risk of heart failure and repeat heart attacks.
Earlier research showed that animals such as mice can regenerate heart tissue, as their heart muscle cells can divide after injury. Human heart cells were thought to lack this ability. The new findings suggest humans also have a limited capacity for heart repair, offering hope for future treatments that could improve recovery after heart attacks.
The research was published in the journal Circulation Research.
"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," says Robert Hume, first author of the study and cardiologist at the University of Sydney.
"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."
Though increased mitosis (a process in which cells divide and reproduce) after a heart attack has been observed in the heart muscles of mice, this is the first time the phenomenon has been demonstrated in humans.
Heart attacks can eliminate a third of the cells in the human heart and, though survival rates have improved dramatically over the last decade thanks to therapeutic advancements, many patients still go on to develop heart failure, which can only be cured with a transplant. With approximately 144,000 heart failure patients in Australia and only 115 heart transplants per year, there is a huge disparity in what these patients need and the treatment that can be offered.
