On Wednesday, a group of scientists announced they had partially revived the brains of dead pigs, which they'd retrieved from a slaughterhouse four hours earlier. By injecting a solution into the brains, they restored some of their cellular function, creating something not quite dead and not quite alive.
Like its subject, the groundbreaking experiment is also in a gray area. The researchers' success has sweeping implications for brain research in humans, but it's also raised serious questions: Could we do this with human brain tissue? Should we?
While bioethicists will be debating the latter for quite some time, it's clear that researchers have a lot of leeway on what they can do with tissue from dead people, brains or otherwise. The United States has an elaborate system of protections for living human research subjects, but tissue from the deceased gets less oversight—aside from guidance on how you obtain, store, and identify it. "Once a human dies and their tissue is in a laboratory, there are many fewer restrictions on what can be done," Christine Grady, chief of the department of bioethics at the National Institutes of Health Clinical Center, told NPR.
Although the deceased are not considered "human subjects" under the U.S. regulatory framework, some bioethicists have suggested they should be, considering that genetic studies on human tissue may reveal information about surviving family members. In some cases, this regulatory vacuum has led to controversial and even criminal uses of research tissue. As Peter Andrey Smith wrote about the black market for human remains in Pacific Standard:
Unlike organs for transplants, which are closely regulated by the federal government's Health Resources & Services Administration, cadavers are regulated in a more patchwork manner. But there is no simple fix, Charo says; it's not simply a matter of extending the rights of live research subjects. "In general," Charo told me in an email, "it is probably wise that we do not treat cadavers or tissues of dead people as subjects of research regulations that have been developed to protect living people who are in experiments."
All of that, of course, is prefaced on the assumption that the dead stay dead. This experiment suggests otherwise. The Yale University team writes that their "findings demonstrate that under appropriate conditions the isolated, intact large mammalian brain possesses an under-appreciated capacity for restoration of microcirculation and molecular and cellular activity" after death.
Would current regulations allow researchers to do the same thing with human brains? "As far as I know researchers could try this with humans, though it would have to be humans who had consented (before their deaths) for such a use," Stanford University bioethicist Henry Greely writes in an email. The consent issue, he added, would be "very very tricky."
In a comment published alongside the study in Nature on Wednesday, Greely and Duke University law professor Nita Farahany argue that the experiment raises a "slew of ethical quandaries," particularly around organ donation: "Most fundamentally, patients or donors will need to understand what kinds of brain activity could result and what that activity could mean. They will also need to know the chances of recovery [are] only partial, and the implications that will have."
Hundreds of people have paid to have their brains frozen in hopes that they will one day be revived, the bioethicists note, but many more donate their brains to help researchers study disorders like dementia.
As scientists experiment with brain surrogates in the lab, or conduct experiments retrieving memories from dreams, the possibility of researchers summoning sentience from beyond the grave seems more likely. Crucially, the Yale research team was careful to avoid restoring the kind of electrical activity that signifies consciousness. That's a line they weren't willing to cross.