Damaged Hearts May Have Hidden Self-Healing Powers, Study Finds

The right therapy can dramatically boost the self-healing capabilities of the human heart after heart failure, a new study has found – giving the vital organ regenerative powers even beyond those of a healthy heart.

It means we may be able to develop treatments that improve recovery rates for damaged hearts, according to the international team of researchers behind the study – though for now it's not clear exactly why this repair rate boost happens.

"The results suggest that there might be a hidden key to kickstart the heart's own repair mechanism," says molecular biologist Olaf Bergmann, from the Karolinska Institute in Sweden.

Recovery rates were monitored in 52 patients who had suffered heart failure, 28 of whom were treated using a left ventricular assist device (LVAD), a surgically implanted device that helps to pump blood around the body.

Advanced heart failure patients normally receive this implant for life or until they can get a heart transplant. Some patients' hearts improve so dramatically that LVAD removal becomes an option.

However, the mechanisms underlying LVAD-supported recovery are not clear, and it was previously unknown whether new heart muscle cells, known as cardiomyocytes, are generated during this process.

To track cardiomyocyte renewal, the team looked at the levels of radioactive carbon (14C) inside heart cells. Since nuclear testing was banned in 1963, the levels of 14C in the atmosphere are steadily falling over time, so its presence in cells gives a good idea of how old those cells are.

Mathematical models were then applied to calculate regeneration levels. In hearts damaged by heart failure, the regeneration rate of cardiomyocytes was found to be 18–50 times lower than in a typical healthy heart.

However, the researchers found that when a LVAD was implanted, the cells were able to regenerate with impressive speed – at least six times faster than in a healthy heart. This benefit was in addition to the improved heart function and structure that a LVAD brings.

That LVAD-supported hearts seem to have supercharged repair abilities is encouraging, but more research will be needed to understand why it's happening, before any drugs or treatment methods can be explored.

"In the existing data we cannot find an explanation for the effect, but we will now continue to study this process at a cellular and molecular level," says Bergmann.

Supporting the heart's own self-healing processes would be a more natural and straightforward therapy than other options that are currently being investigated, such as transplanting cells from elsewhere in the body.

Working out how to get a damaged heart back up to something close to full speed again is a huge challenge for scientists, but progress is being made: researchers are continually improving approaches to growing heart tissue in the lab, for example.

Recent studies have also taken a closer look at the biological processes involved when the heart attempts to repair itself, and at techniques for getting heart cells to act more like stem cells when damage needs fixing. Now we have another promising route to explore.

"This offers some hope that the recovery after a heart incident can somehow be boosted," says Bergmann.

The research has been published in Circulation.