Patching up a broken heart

Scientists have found a novel way of repairing the hearts of patients who have suffered cardiac arrest by creating “patches” of stem cells which could be affixed to damaged hearts to repair heart muscle tissue.

The research team, based at the University of Cambridge’s Stem Cell Institute, used human induced pluripotent stem cells to generate patches of living heart muscle. The 2.5 square centimetre patches could be grown on demand and could potentially save hundreds of thousands of lives in the UK alone, where heart disease remains the leading cause of all deaths.

Pluripotent stem cells are cells which can transform into any cell type. Pluripotency is a characteristic found naturally in embryonic stem cells but can also be artificially induced by reprogramming adult cells. Once the stem cells have adopted this characteristic, they can be programmed into any cell type, including cardiomyocytes, the cells that make up the heart.

The 2.5 square centimetre patches could potentially save hundreds of thousands of lives in the UK alone

A constant supply of oxygen from the coronary arteries is what the heart relies on to function. When this supply of oxygen is blocked, heart muscle cells begin to die within minutes. During a heart attack, surgeons must act quickly to treat the blockage as over one billion cells can die within an hour.

The problem with heart muscle is that, unlike other organs (such as the skin), it is not very good at repairing itself; heart muscle cells replicate at a rate of just 0.5% per year. As a result, when the heart is damaged, tough scar tissue forms in place of dead cells so regions of the heart simple cease to function.

Heart muscle cells replicate at a rate of just 0.5% per year

The research is particularly exciting because the only way to treat a patient with a heart condition currently is by transplant. Transplants require donor hearts coming from those who have died young in accidents or due to other conditions. With an organ shortage in the NHS already, only 200 of these transplant operations happen in the UK each year. Cardiologist at Addenbrooke’s Hospital in Cambridge, Sanjay Sinha, explains that transplant will never be a feasible option to repair damaged cardiac muscle because “you don’t get thousands of young people dying with healthy hearts” since “there’s only a very small pool of people who’ve died, in traffic accidents or through head injuries, where the heart is still strong and can be used for a transplant.”

With research teams from around the world collaborating on this venture, scientists hope that one day, a simple “patch” could repair damaged cardiac muscle, in a method as simple as using a plaster. Regenerative Biology Professor at the University of Wisconsin, Tim Kamp, who is a part of the collaboration explains that these heart “patches” would revolutionise cardiac care, with their advantage being that “they’re personalised to the patient, so the heart is unlikely to reject them.” However, one obstacle in the implementation of these “patches” lies in ensuring the new “patch” beats in synchrony with the heart muscle. Kamp anticipates this can be achieved, “the electrical signals which pass through the heart muscle like a wave and tell it to contract will drive the new patch to contract at the same rate.”

With an organ shortage in the NHS already, only 200 of these transplant operations happen in the UK each year

With Sinha’s team at Cambridge hoping to progress the “patches” through to human clinical trials as soon as five years from now, we could soon be seeing a new dawn in regenerative medicine and cardiac care as transplants could be eliminated altogether in favour of harnessing the power of stem cells.