A Failing Heart Can Still Heal Itself: Study
New research shows how mechanical heart support can trigger unprecedented heart muscle cell regeneration in heart failure patients.
December 16, 2024
In a recent discovery that challenges long-held beliefs about heart regeneration, researchers have found a hidden healing mechanism in the human heart.
A healthy heart has a heart cell regeneration rate of about 0.5 percent annually, but this percentage drastically decreases after a heart attack or other injuries.
However, researchers found that a failing heart equipped with a device that helps it pump blood could regenerate at a rate of 3.1 percent per year—approximately six times higher than the renewal rate of healthy hearts.
“For decades, the prevailing belief has been that adult hearts cannot regenerate significant numbers of heart muscle cells, making recovery of heart function after a heart attack seem impossible,” Dr. Marschall Runge, executive vice president of medical affairs at the University of Michigan, who wasn’t part of the study, told The Epoch Times via email.
As a result, much of the research on heart regeneration has focused on stem cell transplants, gene therapy, and tissue engineering methods. Still, these techniques have yet to achieve significant success in human therapy.
“The study brings surprising new hope for patients with heart failure,” Runge said.
Heart Pump Kickstarts Heart’s Repair Mechanism
The study, published in Circulation in late November, analyzed heart tissue from advanced heart failure patients and healthy people.
Researchers at Karolinska Institutet, a leading medical research university in Sweden, found that the heart renewal rate drops 18- to 50-fold after a heart-related injury.
It declines to 0.01 percent in people who experience heart failure from hardened arteries and reduced blood flow.
The renewal rate declines to 0.03 percent in patients with nonischemic cardiomyopathy, which occurs when people experience a heart injury that is not due to reduced blood flow.
On its own, a heart is unable to renew itself sufficiently. By default, it will try to repair itself by producing more DNA, but this can actually make the cells less efficient, as cells with more DNA and nuclei need more energy and are thus more vulnerable to damage.
However, researchers found that patients whose hearts had a left ventricular assist device (LVAD), a surgically implanted mechanical pump that helps the heart circulate blood and alleviate strain on a failing heart, had six times the regeneration capacity of healthy people.
The authors found that this intervention leads to a process known as reverse remodeling, where the failing heart undergoes structural, cellular, and molecular improvements.
“Some patients with an LVAD have been known to recover enough heart function to no longer require a transplant—and in rare cases, even have the LVAD removed,” Runge said.
“Despite many theories, the mechanism behind this phenomenon has remained unclear.”
Researchers theorize that mechanical unloading, or the assistance the LVAD provides, reverses harmful chains of chemical reactions in damaged cells.
This prevents processes that damage DNA and stop new cell formation. Mechanical unloading thus creates a more favorable environment for heart muscle cell regeneration.
In the study, this resulted in smaller, less-stressed heart cells with fewer mitochondria, indicating reduced energy demands and lower cell stress.
The authors also found that patients with an LVAD had more cells that were younger, measured through carbon-14 (14C) birth dating.
Carbon-14 in the body comes from radioactive 14C inhaled from the atmosphere. Radioactive 14C was released into the air during the Cold War because of nuclear bomb tests and has been in gradual decline since.
Therefore, older cells in the heart would have been made when the atmosphere had a higher 14C concentration and would, thus, have more 14C. Younger cells have less of it in their DNA.
Each year, newly formed cells contain less of this carbon, allowing researchers to distinguish between old, long-lived cells and new ones, providing insight into how often cells are replaced.
Future Therapeutic Possibilities
The discovery of the heart’s latent ability to regenerate under certain conditions, such as mechanical unloading, paves the way for targeted therapies designed to enhance this intrinsic repair mechanism.
This finding is “monumental” for two reasons, according to Runge.
“First, it helps explain how heart function can improve during LVAD support; and second, it opens the door to understanding what makes these regenerating cells different,” he wrote in an email.
“With advances in genetic medicine and AI (artificial intelligence), this discovery offers exciting possibilities for developing better, long-term treatments for heart failure. These therapies could save lives, reduce reliance on donor hearts, and address the challenges of complex, expensive transplants.”
The researchers hope their findings will inspire further studies to uncover the molecular mechanisms behind myocardial recovery and identify strategies to promote it.
