For decades, scientists believed that the human heart was incapable of repairing itself after a major injury. Once heart muscle cells were damaged during a heart attack, the loss was thought to be permanent. However, new research from Australia is overturning that assumption, revealing that the human heart can, in fact, regenerate muscle cells following a heart attack.
The study, published in the prestigious journal Circulation Research, provides the first direct evidence that human heart muscle cells are capable of dividing and forming new cells after injury—a phenomenon previously observed only in animals.
Why Heart Attacks Cause Lasting Damage
A heart attack occurs when blood flow to the heart is blocked, depriving heart tissue of oxygen. This leads to the death of heart muscle cells. The body responds by forming scar tissue, which helps maintain the heart’s structure but cannot contract like healthy muscle.
Because scar tissue does not beat, the heart’s pumping ability weakens over time. This often increases the risk of heart failure, repeat heart attacks, and long-term disability, even among patients who survive the initial event.
New Evidence of Heart Cell Regeneration in Humans
Earlier studies had shown that animals such as mice possess an ability to regenerate heart tissue, as their heart muscle cells can re-enter the cell cycle and divide after injury. Human heart cells were long thought to lack this capability.
The new Australian study changes that understanding. Researchers observed increased mitosis, the process by which cells divide and reproduce, in human heart muscle cells following a heart attack. This marks the first time such regeneration has been conclusively demonstrated in humans.
What the Researchers Say
“Until now, we believed that when heart cells died after a heart attack, those regions were irreparably damaged,” said Dr Robert Hume, cardiologist at the University of Sydney and first author of the study.
“Our research shows that while the heart remains scarred after a heart attack, it also produces new muscle cells. This opens up entirely new possibilities for treatment.”
However, Dr Hume cautioned that this natural regeneration is currently not sufficient to fully repair the heart.
“Although this discovery is exciting, the amount of new muscle produced is not enough to prevent the devastating long-term effects of a heart attack. Our goal is to develop therapies that can amplify the heart’s natural ability to regenerate and significantly improve recovery,” he said.
Hope for Future Heart Failure Treatments
Heart attacks can destroy up to one-third of the cells in the human heart. While advances in medical care have dramatically improved survival rates, many patients eventually develop heart failure, a condition that currently can only be cured through a heart transplant.
In Australia alone, there are an estimated 144,000 heart failure patients, yet only about 115 heart transplants are performed each year. This stark gap highlights the urgent need for alternative treatments.
Scientists believe that therapies designed to stimulate or enhance heart cell regeneration could one day reduce dependence on transplants and transform care for millions of heart attack survivors worldwide.
Why This Discovery Matters
The findings suggest that the human heart is not as biologically limited as once believed. Understanding and harnessing this regenerative potential could pave the way for revolutionary treatments that help hearts heal themselves—something once thought impossible.