The human heart has the ability to repair itself, scientists have found, in a breakthrough that could provide a lifeline for hundreds of thousands of patients.
When someone has a heart attack or heart failure, crucial muscle cells are lost and the heart cannot replace them.
There is no current way to grow new heart cells after damage, meaning patients must rely on medication, implanted devices, surgery or a transplant.
But now, experts have discovered a gene which turns off after birth can be ‘reactivated’ to make new, functioning heart cells.
Scientists from the Icahn School of Medicine at Mount Sinai, in New York, realised that injecting the gene back into damaged middle–aged donor hearts can kickstart cell renewal.
The team first proved the technique worked in pigs over a decade ago, but this is the first time they have shown it to work in humans.
‘Heart disease is the leading cause of death worldwide, yet adult human heart muscle cells stop dividing after birth,’ Dr Hina Chaudhry, director of cardiovascular regenerative medicine at Mount Sinai, said.
‘Our work was the first to show that we can regenerate the porcine heart after injury, and now we’ve advanced the field by demonstrating that even middle–aged adult human heart cells—long believed incapable of division—can be coaxed back into making new, functional cells. This shifts the paradigm from managing symptoms to actually repairing the human heart.’
Still images from live microscopy. Froom left to right – the cell in the initial frame is from a 55–year–old donor heart. The next image shows the cell rounding up after receiving Cyclin A2 and the cell division takes place shortly after. The third image represents the same heart muscle about to split apart into two daughter cells. The last image is the end result of that division where the cell in image one has now fully divided into two cells.
In the UK, more than 100,000 people are admitted to hospital each year after a heart attack – the equivalent of roughly one every five minutes.
Meanwhile, more than one million people are living with heart failure, with around 200,000 new cases diagnosed each year.
The technique harnesses the power of a naturally–occurring gene called Cyclin A2 (CCNA2) which is essential for heart cell division and growth during development in the womb.
However, the gene switches off soon after birth – meaning adult heart cells are unable to divide or repair themselves when damaged.
Following their earlier success in pigs, the team used a harmless virus to deliver an active version of the CCNA2 gene into heart muscle cells taken from donor organs aged 21, 41 and 55.
In the two older patients, they witnessed the human heart cells dividing – with the resulting cells behaving like normal, healthy heart cells.
Further analysis showed that CCNA2 helped heart cells briefly ‘turn back the clock’ by reactivating certain growth genes so they can divide and repair the heart.
‘This is the culmination of nearly two decades of work,’ Dr. Chaudhry said.
The breakthrough could provide a lifeline for hundreds of thousands of heart attack and heart disease patients (file image)
‘We pioneered the concept that the heart could be regenerated by reawakening dormant cell division genes, and now we’ve brought that vision one step closer to patients.
‘Our goal is to deliver a therapy that allows the heart to heal itself after a heart attack or in heart failure—reducing the need for transplants or mechanical devices.’
The next step will be to seek approval from America’s Food and Drug Administration (FDA) to test the treatment in people with heart disease.
The findings were published in the journal Regenerative Medicine.
