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Researchers in Australia have found evidence that the adult human heart can produce new muscle cells after a heart attack, challenging the long-held belief that damaged heart muscle is permanently lost. The discovery could eventually lead to treatments designed to strengthen the heart’s natural ability to repair itself.
The study was led by researchers from the University of Sydney, the Baird Institute and Royal Prince Alfred Hospital in Sydney. Published in Circulation Research, the research provides the first evidence that increased cell division, previously observed in the hearts of mice after a heart attack, also occurs in humans.
“Until now we’ve thought that, because heart cells die after a heart attack, those areas of the heart were irreparably damaged,” said Dr. Robert Hume, the study’s first author and a researcher at the University of Sydney and Baird Institute.
The findings suggest that the heart is not completely incapable of regeneration. After an attack, researchers found evidence that surviving heart muscle cells can undergo mitosis, the process through which cells divide and produce new cells.
However, the regenerative response is currently far too limited to replace all the muscle lost during a heart attack. An attack can destroy as much as one-third of the heart’s muscle cells, leaving permanent scar tissue and reducing the organ’s ability to pump blood.
That damage can have consequences years after a patient survives the initial event. Many people eventually develop heart failure, in which the heart cannot pump enough blood to meet the body’s needs. A heart transplant remains the only definitive cure for advanced heart failure, but donor organs are extremely limited.
Australia has an estimated 144,000 people living with heart failure, while only around 115 heart transplants are performed each year, highlighting the need for alternative treatments.
The researchers also developed a new way to study living human heart tissue. With consent from patients undergoing bypass surgery at Royal Prince Alfred Hospital, the team collected small samples from both diseased and healthy areas of the heart.
The approach, developed by Professors Paul Bannon and Sean Lal, gives scientists access to living human heart tissue that can be studied in laboratory models. The researchers say this could provide more reliable insight into human heart regeneration than relying solely on animal studies.
The team is now investigating the biological mechanisms behind the regenerative response. Researchers have already identified several proteins in the human tissue that have previously been linked to heart regeneration in mice.
Dr. Hume said the long-term goal is to develop therapies that can amplify the heart’s existing ability to produce new muscle. Such treatments remain experimental, but the discovery suggests the adult human heart may possess a limited regenerative capacity that scientists could eventually learn to harness.
