Scientists Turn Stem Cells Into Brain Cells
Two separate teams of international researchers said on Friday they had found reliable ways to coax human embryonic stem cells into becoming brain cells.
Nov 30 2:14 PM ET
Posted on: 12/01/2001
Scientists Turn Stem Cells Into Brain Cells
By Maggie Fox, Health and Science Correspondent
WASHINGTON (Reuters) - Two separate teams of international
researchers said on Friday they had found reliable ways to coax
human embryonic stem cells into becoming brain cells.
Their work is a step forward in the busy but controversial
field of stem cell research, which scientists say holds the
promise of treating a range of diseases from brain damage to
diabetes, but which critics say kills human embryos.
Stem cells are a kind of master cell that can develop into
a variety of tissues. When taken from very small embryos they
seem to be even more flexible, with the ability to become any
kind of cell in the body at all.
They also seem to live and grow forever in lab dishes,
unlike "differentiated" cells that have become skin cells,
muscle cells and so on, providing a potentially endless source
of tissue, and perhaps someday even organs, for transplant.
Both teams, writing in the journal Nature Biotechnology,
said they coaxed the stem cells into becoming the three types
of brain cells -- astrocytes, oligodendrocytes and mature
They transplanted the cells into the brains of newborn mice
and saw them spread throughout the brains, take up residence
and, evidently, start working.
They took stem cells from human embryos -- typically tiny
balls of cells left over from IVF or test-tube baby fertility
treatments -- grew them in special cultures in the laboratory
and then injected them into the brains of the mice.
"These are the cells that will be used, ultimately, to
treat Parkinson's and other central nervous system disorders,"
Su-Chun Zhang of the University of Wisconsin, who led one of
the studies, said in a statement.
They looked at the mouse brains after a few weeks.
"The neuron that we're seeing after transplant is almost
identical to what the neuron should be in the healthy brain,"
"These transplanted cells had no experience in the brain,
and we wanted to see if they would mirror the development of
the mouse brain," Zhang says. "And they do."
STEM CELLS DIFFICULT TO ISOLATE
Benjamin Reubinoff and colleagues at Hadassah University
Hospital in Jerusalem and Monash University in Melbourne,
Australia, reported similar results.
Stem cells are difficult to isolate and identify but it is
even trickier to direct their development. The particular mix
of nurturing chemicals is vital.
Zhang, James Thomson and colleagues at Wisconsin, working
with a team at the University of Bonn in Germany, said one step
involved starving tumors of a protein called FGF-2.
Sometimes transplanted embryonic stem cells can form
tumors, but they did not in these mice, the researchers said.
"We put a lot of cells, in one instance half a million, in
a mouse," says Zhang. "The more cells you put in, the more
likely you are to have a tumor. The absence of tumors shows our
methods for purifying the precursor cells are pretty good."
Stem cell researcher Lorenz Studer of Memorial
Sloan-Kettering Cancer Center in New York said both papers
offered insight into how stem cells might be harnessed.
"The list of diseases that may be treatable with human
embryonic stem cell research is vast and includes neurological
disorders (such as) Parkinson's disease (news - web sites), white-matter loss or
spinal cord injury, and many non-central nervous system
disorders (such as) juvenile diabetes, muscular dystrophy or
cardiac dysfunction," Studer wrote in a commentary for Nature
In a recent interview Curt Freed of the University of
Colorado, who experiments with brain cell transplants on
Parkinson's patients, said he was looking for such results.
"As soon as a cell comes along that can be mass-produced it
will make brain cell repair much more predictable and
reliable," Freed said.
But he warned that federal approval was a long way off.
President Bush (news - web sites) also limited avenues for such research in August
when he said federally funded researchers could only work with
currently existing supplies of embryonic stem cells.
"It will still be some years before we can even try this in
people," Zhang said.
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