IT isn’t every week that a scientific breakthrough shifts the goalposts for death.

But researchers at the Yale School of Medicine in the US have done exactly that with a paper showing that they were able to revive cell function in pigs an hour after fatal cardiac arrests.

The implications are huge.

First and foremost, it could lead to thousands more lives being saved every year through organ transplants.

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On the other hand, it could also lead to organ function being restored to bring people back to life hours after they have died from drownings, car accidents, strokes, or heart defects; instances where the cause of death was sudden but fixable, if only doctors had extra time. This, of course, would reduce the number of organs available for transplant.

It could also throw up ethical dilemmas about when we should, and shouldn’t, keep people alive.

The study, published this week in the journal Nature, is still a long way from being replicated in humans.

However, it follows on from previous work by the same team in 2019, which challenged the idea that brain death is final when they partially restored metabolic activity in pigs’ brains hours after slaughter.

HeraldScotland: Overview of the OrganEx technology (Soure: Nature)Overview of the OrganEx technology (Soure: Nature)

The result was achieved by pumping a special fluid containing Hemopure - a synthetic form of the protein haemoglobin, which carries oxygen in red blood cells - through the brains’ blood vessels.

The latest experiment scaled the technique up to the whole body.

The scientists induced cardiac arrest in the pigs and waited an hour before hooking them up to a machine - OrganEx - which pumped an optimised form of this fluid, known as perfusate, around their bodies for six hours.

HeraldScotland: Images show organ repair post-mortem using OrganEx versus ECMO, an existing form of perfusion technology (Source: Nature)Images show organ repair post-mortem using OrganEx versus ECMO, an existing form of perfusion technology (Source: Nature)

Normally, when the heart stops, cells begin to die due to lack of oxygen and chemical changes begin that harm tissues and organ function. At normal temperature, irreversible changes set in after a few minutes.

OrganEx appeared to reverse the cellular damage caused after death. The pigs’ hearts emitted electrical activity. Cells in their kidneys, livers, and lungs were functioning again and showed signs of repairing themselves.

The discovery is important for transplants because it could preserve organs better, for longer.

Martin Monti, a professor of cognitive psychology at the University of California Los Angeles (UCLA), said:”This technology is not about magically reviving dead tissue.

"It is about expanding the window for restoring organ function by interrupting the death cascade.”

In essence, it would “buy time”.

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As far as organ donation is concerned, there are two forms of death: brain stem death (where blood circulation is intact), and circulatory death, where the patient has suffered a severe and irreversible brain injury which means their lungs and heart can only operate artificially.

Organs retrieved from individuals following circulatory death - which is much more common - are associated with poorer outcomes in transplant patients because of the damage they sustain once support systems are shut off.

OrganEx, if adapted to humans, has the potential to prevent that damage.

Dr Sam Parnia, director of critical care and resuscitation research at New York University, described the findings as “incredibly significant”, adding that it was “entirely feasible” OrganEx will be used by doctors “in the near provide novel treatments to preserve the organs post-mortem [enabling] access to many more organs for transplantation, which will lead to thousands of lives saved every year”.

HeraldScotland: Most organs for transplant come from donors who have experienced circulatory, rather than brain stem, death. These organs are damaged when life support is switched offMost organs for transplant come from donors who have experienced circulatory, rather than brain stem, death. These organs are damaged when life support is switched off

Even more groundbreaking, he added, is the potential further down the line for it “to preserve organs in people who have died, but in whom the underlying cause of death remains treatable”.

This might include athletes who die suddenly from a heart defect.

Dr Parnia said: “The OrganEx system can preserve such people’s organs and prevent brain damage for hours in people after death.

“This will provide time for doctors to fix the underlying condition (such as a blocked blood vessel in the heart that had led to a massive heart attack and death, or a torn blood vessel that had led to death from massive bleeding after trauma), restore organ function and bring such people back to life many hours after death.”

Dr Anders Sandberg, a senior research fellow at Oxford University’s Future of Humanity Institute, cautioned that, on the downside, there was a risk that “it mainly prevents people from dying rather than making them recover” - for example following a massive stroke.

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It could also make it harder to determine “medical futility” in cases where a patient would normally be a donor candidate.

For example, extracorporeal membrane oxygenation (ECMO) - an existing perfusion technology - is already used in hospital settings to support patients whose heart or lungs have stopped working. It can also slow deterioration of organs for transplant.

If OrganEx replaced ECMO for this purpose, however, there are concerns that “there might be few cases where it could restore organs without also restoring some important level of brain and heart function” as well, according to Brendan Parent, an assistant professor of transplant ethics at New York University’s school of medicine.

By the time medical futility could be determined, so much organ damage might have occurred from prolonged lack of blood flow “that the patient’s organs would no longer be transplantable”.

For now though, the findings reframe death as a biological process which is potentially reversible for hours, rather than a black and white moment in time.

As Dr Sandberg put it: “Once, lack of breathing was regarded as a sign of permanent death, until artificial breathing merely made it a dangerous state to be in.

"Later, other technologies have pushed back the point of no return, first to cardiac arrest, and later to brain death.

“OrganEx shows that there is more medical wiggle room in cases with no circulation to fix things than previously looked possible.”