Scientists have found that the human heart can regenerate muscle cells after a heart attack, a process previously confirmed only in mice. The finding challenges long-held assumptions that heart damage is permanent and opens a path toward regenerative treatments.
The study, led by researchers from the University of Sydney, the Baird Institute and the Royal Prince Alfred Hospital, shows that the heart produces new muscle cells even after being scarred by a heart attack.
A heart attack can destroy up to one-third of heart muscle cells. While survival rates have improved, many patients develop heart failure, which often requires a transplant. The new finding suggests the heart has some natural ability to repair itself.
Researchers say this regeneration is not enough to fully restore heart function but could be enhanced in the future to improve recovery.
Heart shows self-repair
Dr Robert Hume said, “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.”
The study confirms that cardiomyocyte mitosis, or cell division in heart muscle, occurs in humans after a heart attack. This had previously been observed only in animal models.
Researchers analyzed tissue samples collected from living patients undergoing bypass surgery. These samples, taken from both healthy and damaged areas of the heart, provided direct evidence of cell regeneration.
Living tissue unlocks insights
The ability to study living human heart tissue was key to the breakthrough. Scientists used a technique developed to collect samples during surgery, allowing them to examine cellular activity in real time.
Professor Sean Lal 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.”
\The team says this approach creates a reliable model to test new regenerative treatments. Early findings have already identified proteins linked to heart regeneration in animal studies, offering clues for future therapies in humans.
Cardiovascular disease remains the leading cause of death worldwide and accounts for about 24 percent of deaths in Australia. With around 144,000 people living with heart failure in the country and only about 115 transplants performed each year, the need for alternative treatments is urgent.
Researchers say the finding could reshape how heart damage is understood, shifting focus from permanent loss to limited biological repair. While the regenerative response is modest, it suggests the human heart retains a previously underestimated capacity for recovery.
The future work will focus on amplifying the heart’s natural ability to regenerate cells. If successful, this could reduce the need for transplants and improve long-term outcomes for heart attack patients, they added.
The study was published in Circulation Research.