Restoration of pig organs after cardiac arrest raises hopes for transplants

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Once the heart stops pumping blood, death quickly follows. Or not?

Scientists have developed a way to restore pigs’ organ function an hour after their hearts have stopped beating, raising new questions about the nature of death and pointing to ways to improve organ transplant rates.

For decades, scientists have assumed that a flattened heart, and the deficit of oxygen and nutrients it brings, sets off a cascade of events that lead to irreparable cell death and damage to vital organs.

But in 2019, professor Nenad Sestan of Yale University and his colleagues announced a technique to restore some degree of cell function in pig brains up to six hours after death by pumping a form of synthetic blood called cryoprotectant perfusate through their vessels. blood.

In addition to providing oxygen and nutrients, it contained drugs and other substances to protect cells from injury and prevent blood clots. Even though the pigs’ brains showed no signs of consciousness, the study provided key proof that irreparable cell damage caused by death may not be so irreparable.

Now, the same team has achieved a similar feat in other organs. His updated device, OrganEx, restored circulation and improved cell function in the hearts, brains, livers and kidneys of pigs that had died of heart attacks an hour earlier. It also activated programs involved in cell repair.

The research, published in Nature, highlights a previously unappreciated ability of the body to partially recover after blood flow has stopped, the researchers said.

“These cells are working hours later than they should be. which [this] tells us is that cell death can be stopped and their functionality restored in many vital organs, even an hour after death,” said Sestan.

“These results open the door to future transplant studies and possible treatments for ischemic damage. [where blood flow to vital organs is disrupted].”

Currently, the best way to restore the supply of oxygen and nutrients to deprived organs and tissues is extracorporeal membrane oxygenation (ECMO), where blood is pumped through a machine that removes carbon dioxide and sends oxygen-filled blood back. to the body.

However, when Sestan’s team examined organs from pigs that had undergone ECMO treatment an hour after their hearts had stopped beating, they found that many of the smaller vessels supplying oxygen to these tissues had collapsed. Organs that underwent OrganEx treatment appeared to be less damaged and there were even signs of kidney repair.

“This is a truly remarkable and incredibly significant study. This demonstrates that, after death, cells in mammalian (including human) organs, such as the brain, don’t die for many hours — well into the postmortem period,” said Sam Parnia, associate professor of critical care medicine at the Grossman School. from New York University. Medicine, who did not participate in the research.

“By developing this organ preservation system, in the near future, doctors will be able to provide new treatments to preserve organs post-mortem. This will allow access to many more organs for transplantation, which will result in thousands of lives saved every year.”

In the future, it may even be possible to support organ function in people who have died, for example, as a result of drowning, heart attacks or massive bleeding after a car accident, and bring them back to life hours later, as soon as doctors repaired the damage, he added.

Sestan’s team warned that more animal experiments would be needed before tests on human organs could begin. Even so, it would likely take many years for a deceased person to be connected to the device.

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