Scientists Discover the Human Heart Can Regrow Muscle After a Heart Attack

Researchers from the University of Sydney, the Baird Institute and Royal Prince Alfred Hospital have found that the human heart can produce new muscle cells after a heart attack. The findings, published in the journal Circulation Research, challenge the long-held assumption that heart muscle lost during an attack cannot regenerate.

"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 the Baird Institute for Applied Heart and Lung Research. "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 cautioned that the effect is not yet strong enough to prevent the damage a heart attack causes.

Cardiovascular disease is the leading cause of death worldwide, accounting for nearly a quarter of all deaths in Australia. A heart attack can destroy as many as one third of the cells in the human heart, and many survivors go on to develop heart failure, a condition in which the heart can no longer pump blood effectively. A heart transplant is currently the only cure, but Australia performs only about 115 transplants a year for around 144,000 people living with heart failure.

The research relied on a world-first technique: collecting heart tissue from both diseased and healthy areas of living patients during bypass surgery, developed by Professor Paul Bannon and Professor Sean Lal. Scientists had previously observed increased cell division in the hearts of mice after a heart attack; this is the first study to demonstrate the same process in humans.

Senior author Professor Sean Lal, a heart failure cardiologist at Royal Prince Alfred Hospital, said the goal is to eventually make new heart cells that can reverse heart failure. Using the living tissue samples, the team has already identified several proteins previously linked to heart regeneration in mice, offering clues for how the process might one day be encouraged in human patients.