For decades, the working assumption in cardiology has been simple and grim: once heart muscle dies during a heart attack, it’s gone for good. A new study from the University of Sydney, the Baird Institute, and Royal Prince Alfred Hospital challenges that assumption directly, with evidence, for the first time, that human heart muscle cells can regrow after a heart attack.
Not as Irreparable as Once Thought
A heart attack
can destroy as much as a third of the cells in the human heart. Scientists had
already observed increased mitosis, the process by which cells divide and
multiply, in the hearts of mice after a heart attack, but nobody had shown the
same thing happening in humans. This study is the first to do it.
“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 first author Dr. Robert Hume, from the
Faculty of Medicine and Health and Charles Perkins Centre at the University of
Sydney, 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.”
That said, the researchers are careful to temper expectations. The heart’s natural regenerative response isn’t currently strong enough to replace all of the muscle lost during an attack. As Hume put it, the discovery “isn’t enough to prevent the devastating effects of a heart attack” on its own, the hope is to eventually find ways to amplify this natural repair process.
A New Research Tool: Living Heart Tissue
Part of what
makes this study notable is how the researchers got their data. Rather than
relying solely on animal models or post-mortem tissue, the team collected
“pre-mortem” heart tissue samples from consenting patients undergoing bypass
surgery at Royal Prince Alfred Hospital, sampling both diseased and
non-diseased areas of the heart. The technique was developed by Professor Paul
Bannon and Professor Sean Lal, who work jointly across the University of
Sydney, RPA Hospital, and the Baird Institute.
Because the tissue comes from living human hearts rather than animal models or cadavers, it gives researchers a laboratory model that may track much more closely with what’s actually happening inside patients, a potentially significant tool for future cardiac research.
Why This Matters: The Heart Failure Gap
Cardiovascular disease remains the world’s leading cause of death, accounting for roughly a quarter of all deaths in Australia. Many people who survive a heart attack go on to develop heart failure, where the heart can no longer pump blood effectively. Right now, a heart transplant is the only cure, but transplants are scarce. Australia has an estimated 144,000 people living with heart failure, yet only around 115 heart transplants are performed there each year. That gap is exactly what makes a regenerative approach so appealing: a therapy that helps the heart repair itself wouldn’t depend on a matching donor organ.
What Comes Next
Professor Sean
Lal, the study’s senior author and a heart failure cardiologist at RPA
Hospital, framed the long-term goal plainly: “Ultimately, the goal is to use
this discovery to make new heart cells that can reverse heart failure.” Using
the living tissue model, the team says it has already identified several
proteins previously linked to heart regeneration in mice, raising the exciting
possibility that some of the same biological pathways could be at work in
humans, and could eventually be targeted with new therapies.
The study was published in Circulation Research.
Sources
·
University of Sydney press release:
Human heart regrows
muscle cells after heart attack, world-first study shows
· Original paper: Hume et al., “Human Hearts Intrinsically Increase Cardiomyocyte Mitosis After Myocardial Infarction,” Circulation Research, 2026
Source: Human Hearts Can Regrow Muscle After a Heart Attack, World-First Study Finds
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