Major leap towards reanimation after death as mammal’s brain preserved

A full mammalian brain has been successfully preserved using a new technique that will soon be available to terminally ill individuals. The goal is to preserve essential neural information for potentially reconstructing the person’s mind in the future.

“They would need to donate their brain and body for scientific research,” explains Borys Wróbel of Nectome in San Francisco, a company dedicated to memory preservation. “As a company, we’re offering to indefinitely maintain their body and brain, with the hope that one day it might be possible to extract information from the brain and reconstruct the person, allowing them to effectively continue their life.”

Timing is crucial when preserving the intricate structure of the brain. Within a few minutes of blood circulation stopping, enzymes start breaking down neurons and cells begin to self-digest.

Cryonics typically involves preserving individuals’ bodies at sub-zero temperatures, aiming for future revival if a treatment or cure becomes available. This traditional approach focuses on preserving the brain quickly after natural death by cooling and adding fixatives. However, if the cryonics team isn’t present at the time of death, deterioration begins before preservation can occur.

To address this challenge, Wróbel and his team have developed a protocol compatible with physician-assisted death, allowing terminally ill individuals to choose the timing of their death. This approach aims to preserve the brain in a state that closely resembles its living condition.

Wróbel’s team tested this protocol on pigs, whose brain and cardiovascular anatomy are similar to humans. They inserted a cannula into the heart about one minute after cardiac arrest, then flushed out the blood and introduced preservation solutions into the brain. These solutions, containing aldehyde chemicals, create molecular bridges between cells, effectively locking cellular activity in place.

Next, they introduced cryoprotectants to replace water within tissue, preventing ice crystal formation during cooling, which could otherwise damage cells. The brain was then cooled to approximately -32°C, where cryoprotectants form a glass-like state, allowing indefinite preservation of the brain’s structure.

To evaluate the success of this method, the team examined samples from the brain’s outer layer using microscopy. Initial attempts with perfusion starting around 18 minutes after death showed significant cellular damage. However, reducing the delay to just under 14 minutes resulted in excellent preservation of fine structures, including neurons, synapses, and their molecular components.

Wróbel suggests that, in theory, this protocol could be used to reconstruct the three-dimensional structure of neurons and their connections, known as the connectome. By mapping the connectome, it might be possible to gain insights into how the brain produces thoughts, feelings, and perceptions. To date, only a small portion of the mouse brain has been mapped in this way, a process that took seven years to complete.

Despite progress in cryopreservation and computing, “reanimation” remains unattainable. “The approach is essentially a form of fixation using toxic chemicals that preserves the structure of the brain and neurons, but without expectation of biological viability,” says Joao Pedro de Magalhaes at the University of Birmingham, UK. “There is currently no way to revive an organ preserved in this way, as it is a sort of embalming.”

De Magalhaes is also skeptical about the possibility of a person “living on” through connectome reconstruction. “Even a perfect copy of my mind would still be a different entity, although I appreciate that some people see this as a potential path to a sort of ‘virtual immortality,’” he says.

Nonetheless, Wróbel’s team believes the human mind might eventually be recreated, digitally or biologically. “Although we’re agnostic towards the type of revival methods, we think we may be able to preserve all the information needed for revival,” Wróbel states.

He mentions that Nectome plans to invite terminally ill individuals to Oregon, where they can spend time with their family before participating in the new protocol. “They would come to us, take the medication – which would have to be prescribed by an independent doctor, not us – and then, after it is legal to do so, we would start the surgery,” says Wróbel.

Beyond potential future scenarios, this work provokes deep philosophical questions about the definition of death. “It’s long been known that declaration of death based on stopped blood circulation is a formalised prognosis of futility, not a metaphysical event,” says Brian Wowk from biotechnology company 21st Century Medicine in Fontana, California.

“The ability to preserve the detailed structural and molecular composition of a brain, perhaps even preserve what makes a person who they are at the most fundamental level – even after considerable periods of stopped blood circulation, as this study does – underscores that the difference between life and death is more complicated than just cessation of vital functions,” he concludes.