The smile that shows there’s a transplant revolution ALREADY saving lives
Pioneering pig-to-human heart op ended tragically. But now a ray of hope...
AS MEDICAL breakthroughs go, it was as astonishing as it was innovative. In early January, David Bennett became the first patient in history to receive a heart transplant from a pig. At the time of the operation, the 57-yearold American had been given just days to live, having suffered heart disease for several years. Just a month after the surgery, doctors said his heart was now ‘as efficient as a Ferrari engine’.
Experts around the world hailed the event as a turning point in transplant care.
Every year, more than 300 Britons die while waiting for a new heart. But thanks to Bennett’s pioneering operation – which involved a pig that had been genetically altered so it’s heart would be compatible with a human – desperate patients would soon be spared the agony of lengthy waits for a human donor heart, it was claimed. Then, on Tuesday March 8, he died.
It is unknown whether his body rejected the pig’s heart. He never left hospital, and the cause of his death has still not been
established, but experts say that is the most likely explanation. Speaking to The Mail on Sunday, leading NHS transplant surgeons claim that, while there is still hope for animal-to-human transplants – so-called xenotransplantation – these operations carry a mass of potential complications. This means that while the surgery is possible, it is unlikely to be offered routinely any time soon.
However, there are advances closer to home that are already transforming lives. And unlike animal transplants, these innovations could be commonly available on the NHS in just a few years, doubling the number of organs available.
One of the most exciting, already in use, is a technique that allows children to receive a donor organ that doesn’t match their blood type. About 50 children are waiting for a heart transplant in the UK, and because the donor has to be roughly the same size as the recipient, the wait to find a match is twice as long for children and babies as it is for adults.
Another stumbling block, as in the case of all transplants, is finding a donor of the same blood group.
Each blood type corresponds to a different make-up of antibodies and other proteins on the surface of red blood cells. Transplanting an organ from a donor with an incompatible blood group normally triggers the recipient’s immune system to attack it, leading to life-threatening organ rejection.
BUT transplant experts have come up with a workaround. The procedure, developed by surgeons at Newcastle’s Freeman Hospital and Great Ormond Street Hospital, London, involves a young patient having some of their blood removed and replaced, via a transfusion, with blood of the same type as the donor. They are also hooked up to a machine that filters their blood, taking out antibodies that might attack the donor organ before it is put in. Although the treatment doesn’t change the patient’s blood type permanently, the body becomes accustomed to the mismatching organ, and the immune system doesn’t attack it. At present they have not made the same technique work in adults, due to the amount of blood that would need to be transfused, and because more mature immune systems don’t seem to ever accommodate the new organ.
One of the first people in the UK to benefit, a ten-year-old called Lucy, got her new heart in April 2020. Born with a heart defect, Lucy, from Basingstoke in Hampshire, suffered seizures and was unable to walk even short distances. She had been on the transplant waiting list for threeand-a-half years.
Now, two years on from her operation, she’s taken to trampolining.
Her mum Jenny said: ‘Since the operation, she’s been so eager to try everything and catch up with her big sister Freya. She’s missed out on a normal childhood.
‘It’s the simple things that make me well up. The other day she just ran ahead of me like any child would, and she’d never done that. She told me, “I don’t feel left out any more.” And that’s all you really want as a parent, isn’t it?’
Another exciting development already in use is a machine that lets doctors bring ‘dead’ hearts back to life. Normally, surgeons take donor hearts from brain-dead patients – a person whose heart is still beating, but is unable to survive without medical life support. This ensures the organ is in the best condition prior to transplantation.
But if the heart stops, it quickly deteriorates and becomes too risky to use in a transplant. ‘The longer a heart has stopped pumping, the more likely it is that it could malfunction,’ says John Dark, professor of cardiothoracic surgery at Newcastle University.
But a high-tech machine is now allowing surgeons to revive hearts that have stopped, increasing the number of possible donors.
The Organ Care System – dubbed ‘the heart in a box’ – mimics the human body. Once placed in the sterile chamber, the heart is fed with warm oxygenated blood via tubes. The portable device starts the heart beating again and flushes it with nutrients until it is ready to be transplanted. In February 2020, 15year-old Anna Hadley became one of the first British children to receive a transplant using the technique. She had waited almost two years after she was diagnosed with restrictive cardiomyopathy, a rare condition that means the muscles in the lower chambers of the heart become stiff. The talented hockey player first became aware of her lifethreatening condition after she collapsed during PE class.
Her father Andrew said: ‘Five days after the transplant, she was walking up and down the corridors chatting away and high-fiving staff. It was incredible.’ There is one downside, however. The Organ Care System remains expensive, with each use costing the NHS up to £32,000 – part of the reason that it’s deployed only about 30 times a year.
Once a heart is taken out of the body, it is put on ice – quite literally, in a box similar to a cool box you’d take on a picnic. By reducing the temperature, the organ can be preserved for up to four hours before it either needs to be transplanted or is thrown away.
The Organ Care System supports the heart for a maximum of 12 hours, but the organ will begin to degrade after six to eight hours. A trial due to begin in the next few months will see doctors in Newcastle and Birmingham attempt to extend this window further.
They will place newly stopped hearts into a cutting-edge machine which, like the Organ Care System, will pump blood through the organ, but also cool it to 8C. By chilling the heart, the machine, called Xvivo, stops it beating while still keeping it ‘alive’.
This means the mechanics of the device are far simpler, and it will cost considerably less to operate.
‘It will be much more accessible to NHS hospitals, as currently most are reluctant to use the Organ Care System because of the price,’ says Prof Dark. The cooling process also protects the heart from swelling and inflammation which can occur in the transition, particularly in organs from older donors.
Crucially, experts believe the chilling technology could extend the time the organ spends outside the body to up to 24 hours, massively increasing the window in which patients can receive their transplant. It could even mean a heart could travel internationally, widening the potential network of
donors and recipients. ‘You could take a heart from Belgium to London via the Channel Tunnel, with the extra time this buys you,’ says Prof Dark.
Xvivo has already been put to use in some European hospitals, and was used to transport the pig’s heart given to David Bennett, but this will be the first time it will be used as part of a clinical trial.
And it’s not just heart transplants which are facing ground-breaking changes. New research is under way to overhaul kidney, liver and lung transplants too.
One world-first trial, which could begin as early as next year, will involve damaged kidneys receiving stem-cell therapy outside of the body before being transplanted into a recipient. The treatment uses cells taken from the bone marrow of the donor to repair damaged tissue.
Dr Emily Thompson, a transplant specialist at Newcastle University, says the development could reduce the number of donated kidneys which never end up in a patient.
‘We can’t regrow a brand new kidney, but we can use treatments to improve blood flow or reduce inflammation in the organ,’ she says.
‘If we can turn these kidneys back into working organs then we could increase the number of transplants that happen every year, and save lives.’
Studies have already shown treating damaged kidneys with stem cells improves their function, though these organs have yet to be transplanted into people.
Similar studies have also shown stem cells can improve the function of livers and lungs, potentially paving the way for UK trials for these organs too.
There are also trials under way to give organ donors certain drugs before they die.
Last year, NHS Blood And Transplant, the special health authority which oversees transplant care in England, announced the world’s largest randomised controlled organ donation trial. The study will explore the benefits of giving brain-dead patients statins – the cholesterollowering agents which also reduce inflammation before a heart transplant. It follows a small-scale study in Finland that showed lung donors who were given the drug had, on average, 50 per cent less organ damage.
So do all these incredible feats mean we will never see a pig’s heart transplant on the NHS?
According to Prof Dark, the xenotransplantation dream is not over, but it has been put on ice.
He says: ‘The developments we’ve seen recently are a sign that the technology is accelerating. The same team behind David Bennett’s transplant initially transplanted a pig’s heart into a baboon which lived for more than two-and-a-half years. Even just a few years ago, the monkey might have lived for weeks or months.’
He believes that, once scientists successfully keep one patient alive on a pig’s heart, more will quickly follow.
‘Breeding a pig is very inexpensive, so once you’ve bred one genetically altered pig with a heart that can be given to people, you can breed it again and again in huge numbers. I think there is a future where xenotransplantation becomes common practice, it’s on the horizon, but I think before then we’ll see some other amazing advances.’
The donor heart is placed in the sterile chamber of the Organ Care System and kept at 34C, just below the average human body temperature.
The organ is fed via a loop of tubes with oxygenated blood, which starts it beating again. The device also monitors and displays the heart’s health.
The blood, which is enriched with nutrients, flows through the heart on a cycle. It can remain in the machine for up to six hours, until the organ is ready to be transplanted.