Circulation and cellular activity were restored in a pig’s brain four hours after its death, a finding that challenges long-held assumptions about the timing and irreversible nature of the cessation of some brain functions after death, Yale scientists report April 17 in the journal Nature [nature.com].
The brain of a postmortem pig obtained from a meatpacking plant was isolated and circulated with a specially designed chemical solution. Many basic cellular functions, once thought to cease seconds or minutes after oxygen and blood flow cease, were observed, the scientists report.
“The intact brain of a large mammal retains a previously underappreciated capacity for restoration of circulation and certain molecular and cellular activities multiple hours after circulatory arrest,” said senior author Nenad Sestan [yale.edu], professor of neuroscience, comparative medicine, genetics, and psychiatry.
However, researchers also stressed that the treated brain lacked any recognizable global electrical signals associated with normal brain function.
“At no point did we observe the kind of organized electrical activity associated with perception, awareness, or consciousness,” said co-first author Zvonimir Vrselja [yale.edu], associate research scientist in neuroscience. “Clinically defined, this is not a living brain, but it is a cellularly active brain.”
[...]researchers in Sestan’s lab, whose research focuses on brain development and evolution, observed that the small tissue samples they worked with routinely showed signs of cellular viability, even when the tissue was harvested multiple hours postmortem. Intrigued, they obtained the brains of pigs processed for food production to study how widespread this postmortem viability might be in the intact brain. Four hours after the pig’s death, they connected the vasculature of the brain to circulate a uniquely formulated solution they developed to preserve brain tissue, utilizing a system they call BrainEx. They found neural cell integrity was preserved, and certain neuronal, glial, and vascular cell functionality was restored.
Vrselja, Z. et al. Restoration of brain circulation and cellular functions hours post-mortem. Nature, 2019 DOI: 10.1038/s41586-019-1099-1 [doi.org]
The article in The New York Times explores some of the medical ethics of this experimentation and what it may hold down the line. Consider, for example, current policies and practices concerning organ donations from "dead" people.