Sheets of muscle grown in the lab can rebuild failing hearts ...Middle East

Sheets of lab-grown muscle are being tested as a radical new treatment for heart attacks and heart failure.

Promising results from two of the first patients to get the treatment suggest that the muscle ‘patches’ survive well and improve the heart’s function.

The patches of muscle, grown from cells in a dish, are sewn on to the outside of the patient’s heart, where they boost its ability to pump blood round the body.

“This exciting study is an outstanding example of how years of dedicated research is helping to mend broken hearts,” said Professor James Leiper, director of research at the British Heart Foundation. “These early results are promising.”

But other scientists have previously claimed to have developed similar cell therapies for heart disease – which later turned out to be false. So is there reason to think this time will be different?

Heart disease is one of the leading causes of death. While there are some effective treatments, many people who have heart attacks eventually experience the organ becoming weaker over the years, in a condition called heart failure.

In advanced heart failure the only option is a heart transplant, but there are far too few donated organs available.

The answer, some scientists have said, lies in stem cells, an unusual kind of cell with regenerative potential. The idea is to use them to rebuild cardiac muscle damaged by heart attacks, potentially reversing heart failure or even stop it from developing.

Why are stem cells so unique? Most of our body’s cells are “specialised” to do a particular job – like being a kidney or brain cell – and have little capacity to rebuild damaged tissues.

Stem cells, in contrast, are unspecialised, like the immature cells of early embryos. They can be turned into different tissues in the lab by manipulating them with biochemicals. The hope is that we could use stem cells to regrow damaged parts of the body – like heart muscle.

Since the early 2000s, several teams of scientists have claimed to have discovered in the body – in places like bone marrow – small numbers of stem cells that have potential for regrowing heart muscle.

Bone marrow stem cells have been turned into treatments for a few other conditions, such as leukaemia. Unfortunately, they don’t work for heart disease. Some of the papers describing the heart treatment experiments were found to contain faked data, in investigations by bodies including Harvard Medical School.

“There’s no evidence that any of those adult cells can generate cardiac muscle,” said Professor Patricia Murray, a stem cell expert at the University of Liverpool.

Embryo-like cells turned into heart muscle

But the new approach is different. Unlike in past work, the scientists have taken cells from an adult and “reprogrammed” them into an immature embryo-like state, before coaxing them to become heart muscle cells.

These are grown into patches, about 4cm in length and width, several of which are sewn together and then sewn on top of people’s heart muscle.

“We now have, for the first time, a laboratory grown biological transplant available which has the potential to stabilise and strengthen the heart muscle,” said Professor Wolfram-Hubertus Zimmermann, a heart surgeon at the University Medical Center Göttingen in Germany, who helped to develop the patches.

The downside is that the patient then needs to take immune-suppressing medicines to stop the patches from being rejected, as with organ transplants. Such medication has side effects like raising the risk of infections and cancer, but that is considered worth it, as advanced heart failure gives a life expectancy of only one year.

Although the full results from the trial have not yet been released, the doctors announced in March that the first patient to get 10 patches, a 66-year-old called Frank Teege, had better heart function two years after the operation.

“With the heart patch, my cardiac output [the heart’s pumping ability] has improved significantly. It is now at 35 per cent,” said Mr Teege. Before the operation, it was 10 per cent. “I was getting weaker and weaker and couldn’t walk 50m without getting short of breath.

He has continued to improve since then, Professor Zimmermann told The i Paper. “Our hypothesis is that the muscle contributes to the contractile performance of the heart,” he said.

A second patient has now been described in the journal Nature, because of unusual circumstances that meant her patched-up heart could be closely examined. The 46-year-old woman had a heart attack in 2016, then experienced worsening heart failure.

In 2021, she was put on a waiting list for a heart transplant as she was considered terminally ill. While on the list, she received the heart patch treatment, but after three months a suitable donated heart became available and she accepted.

This happened too soon to know if the patches had benefitted her, as they take at least three months to adapt to their new environment and start boosting the heart’s pumping ability.

But the transplant did mean the scientists could examine her original heart, to see how the patches had fared. They were found to be functioning well and blood vessels had grown into them. “This is one case report where we really could see that the patches survived, and we saw vital [heart muscle cells], and this was quite promising,” said Dr Ingo Kutschka, also at University Medical Center Göttingen.

Heart stem cells the ‘Wild West’ of research

While the results for the other people in the trial have not yet been made public, Professor Zimmermann said they showed a “favourable benefit-risk profile”.

The results from the team’s experiments on monkeys, which had been done before the human trial could begin, have also now been made available – but these are more equivocal.

The monkeys were made to have heart attacks by having one of their arteries blocked, then they were given the patch treatments. Three out of six who were given the highest number of patches had lasting improvements in their heart function, compared with untreated animals.

This means it is unclear how well the treatment works, said Professor Charles Murry, a stem cell researcher at the University of Southern California, who was not involved in the trial. “It is mysterious to me why some of the animals don’t respond,” he said. “We would like them all to respond.”

However, it is the results from human trials – with some early findings due out later this year – that everything now hinges on.

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“Further clinical trials in larger numbers of patients are needed to determine the effectiveness of the heart patch,” said Professor Leiper. “If these are positive, it could help to usher in a new era of heart failure treatment.”

Professor Murry said it was understandable if some people were still sceptical about stem cells for heart repair.

“This has been the Wild West of a field. People went to the clinic way too soon with crazy things like bone marrow cells that had no chance,” he added

“I get that people are frustrated, and they are like, ‘Haven’t we tried this already?’ And the answer is, ‘No, not for real. This field is just coming online.”

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