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The human heart regrows muscle cells after a heart attack, researchers find

Pioneering research by experts at the University of Sydney, the Baird Institute and the Royal Prince Alfred Hospital in Sydney has shown that heart muscle cells grow after a heart attack, opening up the possibility of new regenerative treatments for cardiovascular disease.

After the study was published in the journal Circulation Research, Dr. Robert Hume, a researcher at the School of Medicine and Health and the Charles Perkins Center for Biomedical Research, explained the significance of the discovery: "Until now, we knew that heart cells cannot pump blood around the body after a heart attack.

"Our research shows that after a heart attack, the scar remains, it produces new muscle cells, which opens up new possibilities.

"Although this new discovery of muscle cell regeneration is exciting, it is not enough to prevent the devastating effects of a heart attack. Therefore, over time, we hope to develop therapies that can strengthen the heart's natural ability to make new cells and regenerate the heart after an attack."

Although mitosis (a process by which cells divide and reproduce) increases in the heart muscle of mice after a heart attack, this is the first time this phenomenon has been demonstrated in humans.

Heart disease in Australia and the world

Cardiovascular disease is the leading cause of death worldwide and is responsible for almost a quarter (24%) of all deaths in Australia.

A heart attack can destroy up to a third of the cells in the human heart, and although survival rates have improved significantly over the past decade due to advances in treatment, many patients still develop heart failure that can only be cured by transplantation.There are approximately 144,000 people with heart failure in Australia, but only 115 heart transplants are performed each year, leaving huge differences in the treatments these patients need and can be provided.

Groundbreaking technology makes research possible

The study is also the first in the world to use tissue samples taken from living patients during bypass surgery.These "pre-mortem" tissue samples were obtained from consenting patients undergoing heart surgery at Sydney's Royal Prince Alfred Hospital.

Samples were collected from diseased and non-diseased parts of the heart using methods developed by Professors Paul Bannon and Sean Lal, who work together at the University of Sydney, the Royal Prince Alfred Hospital and the Baird Institute.

New treatments for cardiac regeneration

Advances in techniques for collecting live tissue samples mean that research teams now have a laboratory model that they hope will lead to new treatments for regenerating the human heart.

Professor Sean Lal, senior author of the study from the School of Medical Sciences and heart failure cardiologist at Royal Prince Alfred Hospital, said: "Ultimately the aim is to use this discovery to create new heart cells that can reverse heart failure.

"Using live human heart tissue models in our work means we will have more accurate and reliable data for developing new therapies for heart disease.

"Our research using these models has already identified several proteins that have already been shown to be involved in cardiac regeneration in mice, which is now a very interesting opportunity to translate to humans."

Robert D. Hume et al, The human heart increases cardiomyocyte mitosis after myocardial infarction, Circulation Research (2026).DOI: 10.1161/circresaha.125.327486

Newspaper information: circulation survey