The pigs had been dead in the lab for an hour—no blood circulating, their hearts still, their brain waves flattened. A group of Yale scientists then pumped a customized solution into the bodies of dead pigs with a heart-lung machine-like device.
What happened next raises questions about what science considers the wall between life and death. Although the pigs were by no means considered conscious, their apparently dead cells regenerated. Their hearts began to beat as the solution, which the scientists called OrganEx, circulated through the veins and arteries. The cells in their organs, including the heart, liver, kidneys, and brain, were functioning again, and the animals were never as stiff as a normal dead pig.
The other pigs, which had been dead for an hour, were treated with ECMO, a machine that pumps blood from their bodies. They stiffened, their limbs swelled and deformed, their blood vessels ruptured, and their backs developed purple spots where blood pooled.
The group reported its results Buddha in nature.
The researchers say their goal is to one day increase the supply of human organs for transplant to allow doctors to obtain viable organs long after death. And, they say, they hope their technology can also be used to prevent severe brain damage after a devastating heart attack or major stroke.
But the findings are just a first step, said Stephen Latham, a bioethicist at Yale University who worked with the group. He emphasized that the technology is “a long way from being used in humans.”
The group, led by Dr. Nenad Sistan, professor of neuroscience, comparative medicine, genetics and psychiatry at the Yale School of Medicine, was stunned by the ability to revive the cells.
“We didn’t know what to expect,” said Dr. David Andrejevic, a Yale neuroscientist and one of the paper’s authors. “What we recovered was incredible for us.”
Others who were not involved in the work were similarly surprised.
“It’s incredible, mind-blowing,” said Nita Farahani, a Duke Law professor who studies the ethical, legal and social implications of emerging technologies.
And, Dr. Farhani added, the work raises questions about the definition of death.
“We understand that death is a thing, it’s a condition,” he said. “Are there forms of death that can be reversed. Or not?”
This work started a few years ago when the group did Similar experience With the brains of dead pigs from the slaughterhouse. Four hours after the pigs died, the group added an OrganEx-like solution they called BrainEx and observed that Brain cells that should be dead can be revived..
Another Yale team member, Dr. Zunimir Varselja, said that this led them to ask if they could bring the whole body back to life.
The OrganEx solution contains nutrients, anti-inflammatory drugs, drugs to prevent cell death, neurodepressants – substances that slow down the activity of neurons and prevent any chance of the pigs regaining consciousness. – and a synthetic hemoglobin mixed with each animal’s own blood.
When they treated the dead pigs, the investigators took precautions to ensure the animals did not suffer. Pigs were anesthetized before killing by cardiac arrest and deep anesthesia was maintained throughout the experiment. In addition, the neurodepressants in the OrganEx solution stop the nerves from firing to ensure that the brain is not activated. The researchers also cooled the animals to slow the chemical reaction. Individual brain cells were alive, but there was no indication of any organized global neural activity in the brain.
There was a startling discovery: Pigs treated with OrganEx jerked their heads when researchers injected an iodine contrast solution for imaging. Dr. Latham emphasized that the cause of the movement was unknown, with no indication of brain involvement.
Yale has filed for a patent on the technology. The next step will be to see if the organs function properly and can be successfully transplanted, Dr Sistan said. After some time, the researchers hope to test whether the method can repair damaged hearts or brains.
The journal Nature asked two independent experts to write comments about the study. In oneDr. Robert Port, a transplant surgeon at the University of Groningen in the Netherlands, discussed the potential use of this system to expand the pool of organs available for transplant.
In a telephone interview, he explained that OrganEx could be used in the future in situations in which patients are not brain-dead but brain-injured to the point where life support is useless.
In most countries, Dr. Porte said, there is a five-minute “no touch” policy after breathing stops and before the transplant surgeon removes the organ. But, he said, “extra minutes will pass before you get to the OR,” and by then organs can be damaged enough to be unusable.
And sometimes patients don’t die immediately when life support is stopped, but their hearts beat too weakly for their organs to survive.
“In most countries, transplant teams wait two hours for patients to die,” said Dr Porte. After that, he said, if the patient isn’t dead yet, they don’t try to retrieve the organs.
As a result, 50 to 60 percent of patients who died after life support and whose families wanted to donate their organs could not be donors.
If OrganEx can regenerate those organs, Dr. Porte said, the impact would be “enormous” — greatly increasing the number of organs available for transplant.
gave Second comment Brandon Parent, a lawyer and ethicist who is director of transplant ethics and policy research at New York University’s Grossman School of Medicine.
In a telephone interview, he discussed what he called “difficult questions about life and death” that OrganEx raises.
“By the accepted medical and legal definition of death, these pigs were dead,” Mr Parent said. But, he added, “a key question is: What function and what kind of function will change things?”
Would the pigs still be dead if the group didn’t use nerve blockers to fix it and make their brains work again? This would raise ethical issues if the goal was to preserve organs for transplantation and the pigs become partially conscious during the process.
But restoring brain function may be the goal if the patient has suffered a severe stroke or drowning.
“If we’re going to get this technology to the point where it can help people, we have to see what happens in the brain without nerve blockers,” Mr. Parent said.
In his opinion, the method will eventually have to be tested on people who might benefit, such as stroke or drowning victims. But this will require a great deal of consideration by ethologists, neurologists and neuroscientists.
“How we get there is going to be an important question,” Mr. Parent said. “When does the data we have justify that leap?”
Another issue is the implications of OrganEx for the definition of death.
If OrganEx continues to show that the length of time after a lack of blood and oxygen before cells can recover is longer than previously thought, then the time it takes to determine that a person is dead may need to change. Is.
“It’s strange but not dissimilar to what we went through with ventilator development,” Mr. Parent said.
“There’s a whole population of people who might have been called dead in a different era,” he said.