In a paper he recently co-authored, University of Chicago researcher, Jeffrey Loeb found that after simulated death, glial cell gene expression increased considerably. These so-called “zombie genes” may prove fruitful in the treatment and prevention of certain diseases, such as autism and Alzheimer’s.
Wanting to understand discrepancies between living and dead brain tissue samples from patients with neuropsychiatric disorders, Loeb and his team decided to run a death simulation. The team acquired brain tissues harvested during surgeries conducted on epileptic patients, who consented to having their tissue used in research. Removing brain tissue helps eliminate epileptic seizures, and it provides research materials for scientists like Loeb. For 24 hours, the brain tissue sat at room temperature, thereby replicating a postmortem period during which time they found that approximately 80% of the genes they analyzed remained relatively stable the entire time, while those present in neurons and associated with thinking, memory, and seizures degraded within just a few hours. The third set — the zombie genes — increased expression until peaking at about 12 hours after death. So, as the neuronal genes degraded, the glial cell activity increased.
That the glial cells enlarged postmortem did not surprise Dr. Loeb. They are, he says “inflammatory, and their job is to clean things up after brain injuries like oxygen deprivation or stroke.” Moreover, scientists already know that brain death is not simultaneous across gene transcriptions. What was significant about the findings was the “time-dependent changes in gene expression in post-mortem brain samples,” which “is critical for the interpretation of research studies on human brain disorders.” But why are time-dependent changes in gene expression critical to understanding human brain disorders?
Dr. Loeb’s results reveal that treatments based on gene expression should take into account time-dependent dynamics. Most research into brain disorders that use post-mortem brain tissue do not account for genetic and cellular changes. With the results of Loeb’s recent study, researchers working with postmortem brain tissue can factor in which types of cells and genes remain stable, which rapidly degrade, and which increase.