Scientists trial patch to mend failing hearts

Damaged hearts could be mended using small "patches" of heart muscle grown in the lab, say scientists writing in Nature.

The technology could give new hope to millions of people with advanced heart failure whose treatment options are currently limited, the German researchers say.

Based on early results of a small trial in humans and promising tests in monkeys, the patches appear to support the pumping of the heart safely.

However, the long-term potential of the treatment is as yet unknown, with a clinical trial in 15 patients still ongoing.

The patches are grown from another person's stem cells - special cells which can be turned into any number of different cell types - and made into heart muscle cells.

The lab-grown cardiac tissue can then be grafted on to beating hearts to help them repair.

It is like "implanting young muscle", says study author Ingo Kutschka, from University Medical Center Goettingen.

A small incision is made in the chest and the 3.5in (9cm) by 1.5in patch is stitched on to the surface of the heart.

"It's tricky because the tissues are floppy, and you have to take care to make it stay in shape," he says.

There have been encouraging results in trials of the patches on primates and on one human patient.

The 46-year-old woman had a heart attack in 2016, then developed heart failure which got steadily worse. In 2021, after all possible treatments had been tried, she chose to have a heart patch.

The researchers say her condition was stable and she experienced no side effects from the implant, before having a heart transplant three months later.

The patch was able to "adapt, grow, mature and start to support the failing heart," says lead author Prof Wolfram-Hubertus Zimmermann.

Her case shows that new muscle can be added to failing hearts "without safety concerns, such as tumours and arrhythmia [irregular heart rhythms]", he added.

The patches of engineered heart muscle have to survive in the patient and be nurtured over several months, so are not useful for people who need emergency care, the researchers say.

In trials on monkeys, the research team found the patches were good at contracting, enhancing and thickening the heart wall, which improved the pumping of the whole heart.

Heart failure is the leading cause of death worldwide, but there are few effective ways of fixing the organ once it is broken.

It is a condition that makes even simple daily tasks, like climbing the stairs or getting dressed, exhausting.

Heart devices can be costly and come with complications, and a heart transplant - although the best solution - is rarely an option.

Prof Zimmermann says: "99% of patients with heart failure won't receive a new heart."

The researchers have more to learn from the current human trial and plan a long-term follow-up of 15 patients to find out more about the health of those living with the patches for years.

Prof James Leiper, director of research at the British Heart Foundation charity, said the early results were "promising", but trials in a larger number of patients were needed "to determine the effectiveness of the heart patch in humans".

"If these are positive, it could help to usher in a new era of heart failure treatment," he said.

Previous attempts to inject heart muscle cells into people's failing hearts have had mixed results.

"Off the shelf" heart patches like the ones used in this study - made from millions of human stem cells and grown into working heart muscle - are seen to be a less dangerous option, although patients would need to take strong drugs to prevent their bodies rejecting them.

Using the patient's own stem cells to develop heart tissue has been attempted, but this process takes a very long time and previous trials using these grafts were not encouraging.