THURSDAY, March 7 (HealthDay News) -- Implanting a type of human
brain cell into newborn mice makes them "smarter" as adults,
scientists have found -- an achievement experts say could aid in
understanding and treating human brain diseases.
It sounds a bit like science fiction, but many studies have
looked at the effects of implanting rodent brains with human cells,
said Paul Sanberg, a professor of neuroscience at the University of
South Florida, in Tampa.
What's new here is that researchers were able to implant mice
with human brain cells called glial cells, see those cells mature
and act like human ones, and see the effects on the mice's
learning, said Sanberg, who was not involved in the research.
"That's exciting," he said. "The cells were still functioning like human cells, and they actually enhanced aspects of learning."
The goal, though, is not to create brainy mice. The hope is to
open up new ways to understand human brain diseases and develop
therapies for them, said Dr. Steven Goldman, chairman of neurology
at the University of Rochester, in New York, and one of the
researchers on the study.
Human brains have different types of cells. Neurons are
considered the workhorses, sending electrical and chemical signals
to each other. Glial cells are seen as "support" cells that help
transfer information among neurons.
But the relative size of glial cells in the human brain is
bigger compared to non-primate animals. Humans also have more of
them, and greater diversity in them, Goldman said. It has been
thought that the evolution of glial cells may have been important
to allowing humans to become as smart as they are.
The new findings, which appear in the March 7 issue of the
Cell Stem Cell, support that theory.
Sanberg said there has already been a growing appreciation of
the importance of glial cells in degenerative brain diseases.
Multiple sclerosis is the "classic example of a glial disease," he
said. But research suggests impaired glial cells are involved in an
array of disorders, including Parkinson's disease and
Being able to study the function -- and dysfunction -- of human
glial cells in rodent brains could give researchers insight into
many diseases, Sanberg and Goldman said.
For the study, Goldman's team implanted human glial stem cells
into the brains of newborn mice. Stem cells are primitive cells
that give rise to mature, specialized cells.
The researchers found that over time, the human glial stem cells
matured and replaced the mouse glial cells -- in essence, "taking
over their brains," Goldman said.
His team then used mouse-appropriate learning tests -- like the
classic escape-from-the-maze challenge -- to compare the animals'
functioning with that of mice with no human glial cells.
"We thought these mice should be smarter. They should be able to learn faster," Goldman said. "And that's what we found."
"It's a remarkable finding," said James McGaugh, a research professor of neurobiology and behavior at the University of California, Irvine.
The results "elevate the role" of glial cells in human brain
functioning, said McGaugh, who was not involved in the research. As
for human health and disease, he added, "I don't see any immediate
implications. But clearly these are exciting findings that warrant
Goldman and his colleagues are already using this line of
research to study human disease. In a study published last month,
they reported that they have been able to take stem cells from the
skin of patients with certain brain diseases and use them to
generate glial stem cells. The cells can be implanted into mice to
gain a better understanding of those disorders, and to test new
therapies, Goldman said.
Right now, the researchers are experimenting with cells taken
from patients with schizophrenia and Huntington's disease.
Learn more about degenerative brain diseases from the
Institute of Neurological Disorders and Stroke.
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