A team of scientists say they’ve found a way to better preserve and even partially restore the function of cells throughout a pig’s body an hour after death. The technology, described in a paper published in Nature, is still far off from being tested with humans, but it could possibly help increase the supply of viable donated organs for transplantation in the future.
In April 2019, a group of researchers at Yale University made big waves with the their experiments. Using a cocktail of synthetic blood and other compounds, they showed that it was possible to restore some circulatory and cellular activity in a pig’s brain four hours after the animal had died, for up to six hours. These “zombie” brain cells—as many outside observers were quick to coin them—were able to perform functions that normally cease within minutes of clinical death. Importantly, though, the researchers weren’t trying to, nor did they, restore the kind of electrical activity associated with consciousness or awareness.
That same team has now broadened their work. Previously, the brains of deceased pigs were removed from the skull and hooked up to their system, which they called BrainEx. This time around, they connected the pigs’ entire body via the circulatory system to a scaled-up version called OrganEx.
The mechanical half of OrganEx resembles existing machines meant to support a person’s heart and lungs. But the system’s unique aspect comes from a synthetic fluid developed by the team that’s pumped through a pig’s circulation. Some of the fluid’s ingredients are proprietary, while others are existing drugs, but overall, it was meant to promote cellular health, decrease the rate of cell death, and suppress inflammation.
In these new experiments, the attempted resuscitation began an hour after the pigs were killed via cardiac arrest. For comparison’s sake, pigs on OrganEx were matched against pigs placed on an extracorporeal membrane oxygenation, or ECMO, device, a form of life support that can temporarily take over for the heart and lungs’ function in circulating blood.
As with the pigs’ brains in the earlier research, parts of the OrganEx pigs seemed to flicker back to a semblance of life. Compared to ECMO pigs, the organs of pigs on OrganEx showed fewer signs of bleeding or tissue inflammation. And on a more individual level, there were signs that their cells were once again carrying out some standard processes, including self-repair.
“Similar to the previous study in this work, we actually show that we can restore certain cell functions sometime after death,” said study author Zvonimir Vrselja, an associate research scientist in neuroscience at the Yale School of Medicine, in a press conference announcing the findings.
Though the work is far from creating ‘zombie’ pigs, the researchers once again took care to prevent anything like consciousness from being possible in the dead pigs. All of the experiments took place in temperatures that would inhibit any kind of brain activity from occurring, and the pigs were anesthetized prior to their induced heart attack. And just like before, there was no evidence that the pigs’ brains were restored back to the point of consciousness.
While it’s theoretically feasible that this technology could be used with living humans, the clearest possible benefit currently is for organ preservation, the team says. The system might be able to lengthen the survival period of healthy body parts from people who have recently died from stroke or other conditions that interrupt blood flow, for instance.
The study is still only a proof of concept for this technology, though. They’ve shown that it’s possible to restore some function across a wide range of organs post-death, but not to the same degree everywhere. And it will take more research in animals to figure out whether any of these organs can truly be viable for transplantation. The researchers, while excited about the potential of their technology, were also quick to dismiss the idea that these pigs were revived in any sort of conventional meaning.
“We’re nowhere near being able to say, ‘Oh, my goodness, we’ve restored life not only to this pig, but to any individual organs.’ We can’t say that yet. It’s still very much too early,” said study author Steven Lantham, director of the Interdisciplinary Center for Bioethics at Yale.
Even assuming that further animal studies do show that the system can restore viable organs, it will take longer before scientists can perform similar research in humans, much less have the technology available in the real world. “I think we’re quite far away from a human application of this whole body kind of experiment. There’s going to need to be a lot more work to be done, a lot more precision to be had, before we would launch anything in that direction,” Lantham said.
Zombies likely aren’t in our near future, but this kind of research could raise important ethical questions about the often-debated boundaries of life and death. It’s not impossible, for instance, that scientists might one day be able to resurrect someone’s organs long after that person has actually shuffled off the mortal coil. But that possibility, some ethicists have argued, could challenge our current definitions of clinical or brain death. And this current research may already warrant new guidelines for working with partially revived animals.