In a finding that could transform the future of cardiac care, scientists in Australia have shown for the first time that human heart muscle cells can regrow after a heart attack, a phenomenon previously observed only in mice.
The groundbreaking study, led by researchers from the University of Sydney, the Baird Institute for Applied Heart and Lung Research, and Royal Prince Alfred Hospital, has raised hopes for regenerative therapies that may one day help repair damaged hearts and even reverse heart failure.
The findings were recently published in Circulation Research. For decades, doctors believed that once heart muscle cells died during a heart attack, the damage was permanent. Unlike skin or liver cells, heart muscle cells or cardiomyocytes were considered largely incapable of meaningful regeneration in adults.
'New study challenges long-held belief'
“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,” said Dr Robert Hume, first author of the study and Lead of Translational Research at the Baird Institute.
“Our research shows that while the heart is left scarred after a heart attack, it produces new muscle cells, which opens up new possibilities,” he added.
A heart attack occurs when blood flow to part of the heart is blocked, depriving heart tissue of oxygen. The resulting cell death weakens the heart’s pumping ability and can eventually lead to chronic heart failure.
Globally, cardiovascular disease remains the leading cause of death, accounting for nearly 18 million deaths every year, according to the World Health Organization.
In India too, heart disease is a growing public health challenge, with experts warning about rising cases among younger adults. According to estimates published in medical journals and by global health agencies, cardiovascular diseases account for more than a quarter of all deaths in the country. Doctors have repeatedly flagged lifestyle changes, stress, diabetes, hypertension, smoking, obesity and delayed diagnosis as major contributors to the crisis.
India is also often referred to as the 'diabetes capital' of the world, further increasing the risk of cardiac disease. Heart failure, a condition in which the heart cannot pump blood efficiently, has emerged as a major long-term consequence of heart attacks. Experts say discoveries that improve the heart’s ability to repair itself could eventually have significant implications for countries like India with a massive cardiovascular burden.
“For decades, we believed that once heart muscle cells die after a heart attack, the damage is permanent. This research suggests the human heart may possess a limited but real regenerative capacity,” said Dr Ramesh Shah, practicing in Central Mumbai. “While this is still early-stage science, it opens the door to future therapies that may help repair damaged heart tissue. That could fundamentally change how we treat heart failure in the future.”
Until now, evidence of heart cell regeneration after injury had largely come from animal studies, especially in mice. Scientists had observed increased mitosis, the process through which cells divide and reproduce, in mouse heart tissue after cardiac injury.
But confirming the same process in humans has proven difficult because obtaining and studying living human heart tissue is extremely challenging.
The Australian team overcame this hurdle by establishing a reliable method to collect and study living human heart tissue samples.
According to the researchers, this has enabled them to build laboratory models that more accurately mimic how the human heart responds after injury.
Professor Sean Lal, senior author of the study and heart failure cardiologist at Royal Prince Alfred Hospital, said the work could pave the way for future regenerative treatments.
“Ultimately, the goal is to use this discovery to make new heart cells that can reverse heart failure,” Lal said.
“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,” he added.
Researchers also said they have already identified several proteins in human heart tissue that were previously linked to cardiac regeneration in mice.
This, scientists say, is particularly exciting because it suggests that some of the biological pathways involved in repair may be shared across species.
Despite the excitement, researchers caution that the natural regrowth observed is still limited and nowhere near enough to fully heal the heart after a major attack.
“The discovery itself is important, but the regeneration we see is not sufficient to prevent the long-term effects of heart attacks,” said Hume.
Possible future therapies could include drugs, gene therapies, or stem-cell-based approaches designed to stimulate heart muscle regeneration and reduce scarring.
The findings come amid a broader global push toward regenerative medicine, an emerging field focused on repairing or replacing damaged tissues and organs.
Experts say the use of living human heart tissue models could accelerate that process by giving researchers a more realistic platform for testing potential treatments.
For patients living with heart failure, a condition in which the heart cannot pump blood effectively, the implications could eventually be enormous.
For a long time, the heart was seen as an organ incapable of self-repair. This study suggests that it may not entirely be the case.