Scientists have discovered brain cells that continue to grow even after death

Within hours of death, some human brain cells are still active. Some even increase their activity and reach gigantic proportions, according to new research from the University of Illinois at Chicago (UIC).

In the study, recently published in the journal Scientific Reports, UIC researchers analyzed the gene expression of fresh brain tissue taken during routine brain surgery several times after extraction to simulate death and post-mortem period. Yes found that gene expression in some cells actually increased after death.

It is a specific type of cells glial calls. The researchers observed that these develop and generate long appendages in the form of arms for many hours after death.

“That glial cells enlarge after death is not too surprising given that they are inflammatory and their job is to clean things up after brain damage like oxygen deprivation or a stroke.” said Dr Jeffrey Loeb, director of neurology and rehabilitation at UIC School of Medicine and one of the authors of the article.

What’s important, Loeb said, are the implications of this finding: Most research studies using post-mortem human brain tissue to find potential treatments and cures for disorders like autism, schizophrenia and Alzheimer’s disease, do they not take into account post-mortem gene expression or cellular activity.

“Most studies assume that everything in the brain shuts down when the heart stops beating, but it doesn’t.” Loeb said. “Our results will be needed to interpret research on human brain tissue. We just haven’t quantified these changes so far. “

Loeb and his team noted that the general pattern of gene expression in fresh human brain tissue does not match any of the published reports of postmortem brain gene expression in people without neurological disorders or in people with a wide variety. neurological disorders, ranging from autism to autism Alzheimer’s disease.

“We decided to conduct a mock death experiment by observing the expression of all human genes, at 0 to 24 hours, from a large block of newly collected brain tissue, which was left to rest. at room temperature to reproduce the autopsy interval “, Loeb said.

The scientist and his colleagues have a particular advantage when it comes to studying brain tissue. Loeb is the director of UI NeuroRepository, a human brain tissue bank of patients with neurological disorders who have consented to the collection and storage of tissue for research purposes after death or during standard care surgery for treat conditions such as epilepsy.

For example, in some surgeries to treat epilepsy, epileptic brain tissue is removed to help rule out seizures. Not all tissues are required for pathological diagnosis, so some can be used for research. This is the fabric that Loeb and his colleagues analyzed in their research.

The researchers determined that about 80% of the genes analyzed remained relatively stable for 24 hours; his expression hasn’t changed much. These included genes often called housekeeping genes that provide basic cellular functions and are commonly used in research studies to show tissue quality. Another group of genes, which are known to be present in neurons and which have been shown to be closely involved in human brain activity, such as memory, thinking, and epileptic activity, were rapidly degraded within hours. followed death. These genes are important to researchers studying disorders such as schizophrenia and Alzheimer’s disease.

A third group of genes, the “ zombie genes ”, increased their activity at the same time as the neural genes decreased. The pattern of postmortem changes peaked around 12 noon.

“Our results do not mean that we should abandon research programs on human tissues”, it just means that researchers need to be aware of these genetic and cellular changes and reduce the postmortem interval as much as possible to reduce the magnitude of these changes.Loeb said.

“The good news of our findings is that we now know which genes and cell types are stable, which are degraded and which increase over time, so that the results of postmortem brain studies can be better understood.», He concluded.

KEEP READING