NYT -- Researchers Find a Type of Stem Cell May Have the Ability to Repair the Brain.
February 20, 2004
Researchers Find a Type of Stem Cell May Have the Ability to Repair the Brain
By SANDRA BLAKESLEE
A type of self-renewing cell found in the adult human brain
may have the potential to repair brain damage or disease,
scientists reported yesterday.
The cells, neural stem cells, have been known about for
some time. But their function has been a mystery.
Researchers theorized that the cells, as in rats and
monkeys, generated new neurons that migrated to olfactory
regions, helping maintain the sense of smell.
But the study, reported yesterday in Nature, indicates that
in humans, the stem cells behave differently. They form
ribbons that produce different types of brain cells,
including neurons. The new neurons do not migrate to
olfactory regions, and they are not involved in the human
capacity for smell, the study found.
Dr. Nader Sanai, a resident neurosurgeon at the University
of California at San Francisco School of Medicine and the
study's lead author, said much remained to be learned
before scientists knew whether the cells could be harnessed
to regenerate or replace tissue lost to disease or injury.
"First we need to understand the biology of these cells,"
Dr. Sanai said. "We don't know enough to predict their
usefulness."
One possibility, he said, is that the cells, found in the
lining of two fluid-filled pockets near the front of the
head, will turn out to serve no purpose. Or they may
migrate to other parts of the brain to carry out repairs.
Dr. Pasko Rakic of Yale, a leading expert on stem cells who
was not involved in the research, called the study
"important and interesting." The big challenge, Dr. Rakic
said, remains to find a way to induce the potential
neuronal stem cells to migrate into the right positions and
replace lost or damaged neurons.
Researchers are keenly interested in the cells because they
do not pose ethical questions raised by stem cells drawn
from embryos. Many tissues in the body produce localized
stem cells that presumably exist to replenish lost cells
throughout a person's lifetime.
The study was conducted in the laboratory of its senior
author, Dr. Arturo Alvarez-Buylla, a professor of
neurological surgery at San Francisco. To learn more about
human brain stem cells, the researchers collected target
tissue from 65 people who had brain surgery and from 45
autopsied brains.
The researchers were struck by the fact that the tissue,
when stained, contained ribbons of astrocytes, a kind of
brain cell known to support many aspects of brain function.
"We immediately knew we had to investigate them further,"
Dr. Sanai said.
When the researchers added growth factors to the ribbons in
a culture dish, tiny spherical balls appeared. Those balls
in turn gave rise to neurons, other astrocytes and a kind
of cell that insulates neurons.
In a second experiment, the scientists placed individual
ribbon astrocytes on a warm layer of ordinary astrocytes.
Again, the ribbon astrocytes produced new neurons and two
types of helper cells.
Copyright 2004 The New York Times Company. |
