A procedure that repairs damage to cells after the heart stops pumping blood could lead to more organ transplants. Not only that, but also the best treatments for heart attacks and strokes. One day it could even save the lives of people who, today, would be considered dead.
The method team tested the method on pigs only. It consists of connecting an animal to a pump that perfuses its body with an artificial blood substitute, containing oxygen and a mixture of other chemicals to prevent cell death and promote repair processes.
“We have shown that cells do not die as quickly as we thought, which opens up new possibilities for intervention. We can convince cells not to die,” he says Zvonimir Vrselja of the Yale School of Medicine.
Currently, people whose heart is collapsing can be linked to heart-lung machines, which oxygenate the blood, remove carbon dioxide and pump it back into the body.
But if a person's heart stops while they are outside a hospital, their cells and organs deteriorate rapidly from lack of oxygen. His chances of survival plummet. The blood becomes more acidic due to the accumulation of CO2 and many harmful substances are released.
Artificial blood, a new perspective
The new system, called OrganEx (we introduced it briefly in this post), dilutes the animal's blood in a 1-to-1 ratio with an artificial blood substitute that carries oxygen, has the right acidity, and the right levels of electrolytes and other biochemicals. 13 drugs are also added to the compound.
These are existing or experimental drugs. These include compounds that thin the blood to prevent small blood vessels from being blocked by clots, drugs that block a cell death process called necroptosis, and others that have anti-inflammatory effects.
The blood substitute is also an unusual compound because it does not contain red blood cells, which normally carry oxygen bound to a protein called hemoglobin. The fluid instead contains a compound called Hemopure, a form of hemoglobin obtained from cow blood.
In 2019, Vrselja and her team reported that their system was capable of reverse signs of cell death when connected to pig brains, four hours after their beheading. In the latest study, they wanted to see whether the fluid could help reverse damage that occurs in other organs after death. For this reason it was tested on whole bodies.
The procedure
The pigs were put to sleep with a general anesthetic and given ventilators to control breathing. Then their hearts were electrically stopped and the fans were turned off, at which point they would be considered normally dead.
After an hour, treatments began to try to restore cellular function. Six pigs were connected to the OrganEx system and another six were connected to a standard heart-lung machine as a comparison, with both groups' body temperatures reduced to 28°C to help reduce damage. There were then three other control groups, in which the animals were not given any treatment.
After 6 hours, the amount of blood flow was measured by injecting a dye and scanning the animals. Pigs given the OrganEx treatment had better blood flow to their organs than animals given the heart-lung machine, in which many of the smaller blood vessels had collapsed.
Tests on animal cells and tissue samples showed that those treated with OrganEx had lower cell mortality. Again: they had restored the functioning of the cells, based on measures such as the amount of glucose they could metabolize.
Artificial blood: will it be used for human transplants?
According to the team, the system's first practical use could be to keep organs destined for transplants healthier for longer. In this way they can be transported for longer times between deceased donors and the people who need them.
Peter Friend from the University of Oxford says the initial results are promising. The best way to evaluate the health of animal organs, however, would be to transplant them into another animal. “Only in this way can you see if they work,” he says.
The system could also be used to help people who have had a heart attack or stroke – when blood supply to the heart or brain is reduced – by perfusing one of these organs with the healing fluid. “If it can resuscitate an organ that has suffered a normally fatal injury, then potentially it will be very exciting,” says Friend.
Hunt for a way to escape death
Stephen Latham, a Yale University ethicist who was part of the research team, argues that the prospect of “reversing death” – for example, treating someone some time after their heart stops due to drowning – is still far in the future.
“Much further experimentation would be necessary,” says the expert. “The perfusate should be adapted to a human body. And one would have to think about what state a human being would be brought back to. If you gave them a perfusate that reversed some, but not all, of the damage, that could be a terrible thing.”
