Adult human neurons donated from patients who had
undergone brain surgery have been successfully grown in a first-of-its-kind study published in Cell Reports. From these cell cultures, they identified more than
five brain cell types and the potential proteins each cell could make.
The research team from the Perelman School of Medicine at the
University of Pennsylvania is led by James Eberwine, a professor of
Pharmacology, Sean Grady, chair of Neurosurgery, and Junhyong Kim, a professor of Biology in Penn's School of Arts & Sciences.
"We were surprised that we could grow these neurons at all,"
Eberwine said. "The oldest tissue came from a donor who was in their
mid-sixties. This is even more surprising because neurons don't divide,
so they need to last a lifetime. We are finally able to characterize
adult aged cells from the most enigmatic organ of the body - the seat of
learning and memory, as well as consciousness."
‘First cell culture of live adult human neurons has enabled identification of more than five brain cell types and the potential proteins each cell could make.’
This avenue of research is in line with the goals of the national
BRAIN Initiative - including a cell census of neurons in the brain. In
these terms, the characterizing feature is the cell's transcriptome:
those genes that are transcribed into RNA to make working proteins,
which differ from cell to cell. "This tells us the potential of each
cell to function and respond," Eberwine said.
The team used tumor-free tissue from seven patients: three who
underwent a temporal lobectomy, in which a portion of the temporal lobe
is removed to stop epileptic seizures, and four who had glioblastoma
tumors removed. (MRIs and other tests did not show any evidence of tumor
or other abnormal cells in the non-tumor tissues used for the study.)
"Our findings may help us understand how cells change in response to
the anti-convulsants the epilepsy patients were getting and how that
might impact seizure treatment in the future," said Grady. "We may also
be able to tell basic up- and down-regulation of certain genes that
could affect how neurons connect with each other. This might play a role
in 'reconstructive neurosurgery,' where we could use cellular
replacements to mend damaged brain tissue, but this is not in human
Eberwine's lab received the tissue sample from each patient and
immediately treated it with papain, a pineapple-derived enzyme that
breaks up proteins. This procedure dissociates the neurons, and from
this mixture, the team cultured the live neurons.
Single cell analyses were performed on over 300 living cells. From
this the team identified five known brain cell types after three weeks
in culture: oligodendrocytes, microglia, neurons, endothelial cells, and
Using deep RNA sequencing, they found over 12,000 expressed genes in
the cells, including hundreds of different types of RNAs specific to
the different cell types. They also identified long noncoding RNAs
involved in regulation of many other genes that correlated with cell
type. They found that each patient's neurons had a specific
gene-expression profile that was consistent between cells. "We don't
know how important such transcriptional hierarchies are as of yet, but
it does lend support to the importance of taking a personalized medical
approach for evaluating and treating each patient," Eberwine said.
The neurons used in this study came from subjects ranging in age
from their twenties to their sixties, showing that this system will
permit human aging studies that have previously only been possible in
rodents. "We are now testing to see how aged live neurons differ from
those of a younger person so that we might investigate molecular
signatures of aging," Eberwine said.