NYT article - researchers turn bone marrow cells into nerve cells.
August 15, 2000
Researchers Turn Bone Marrow Cells Into Nerve
Cells
By GINA KOLATA
Scientists have spurred bone marrow
cells to turn into nerve cells, raising the
tantalizing possibility of an easily
accessible source of replacement cells to treat
brain and nerve injuries and diseases.
But the work is just beginning, experts say,
and it remains to be seen whether the newly
created nerve cells can correct spinal cord
injuries or brain diseases like Alzheimer's and
Parkinson's, even in animals.
The research is described in the current issue of the Journal of Neuroscience
Research. The lead author of the article, Dr. Ira Black, who is a professor
and the chairman of the neuroscience and cell biology department at the
Robert Wood Johnson Medical School in Piscataway, N.J., said he began the
research with the thought of studying how the body's cells, each of which
has the same set of genes, determine whether they would become blood
cells, brain cells, liver cells and so on.
Like many other researchers, he wondered what signaled a cell to become
one type or another. And he wanted to know how easy it was to redirect
cells to develop into the type needed. The research is a new field with
potentially revolutionary implications, including the possibility of correcting
even the most intractable health problems with cell replacements.
"The exciting thing is the idea that the adult body has cells in it that can divide
and differentiate and can potentially be used for cellular replacement," said
Dr. Fred Gage, a neurobiologist at the Salk Institute for Biological Studies in
La Jolla, Calif.
In Dr. Black's study, the investigators removed cells from the bone marrow
of rats -- and of humans -- that normally would develop into tendon,
cartilage, bone, muscle and fat, and grew them in the laboratory in shallow
dishes. Then they added an antioxidant, beta mercaptoethanol, which, Dr.
Black had discovered in his previous work, seemed to be a sort of biological
double negative. It appeared to block chemicals that prevented cells from
becoming nerve cells.
"Over the course literally of minutes, the cells converted from rather
pedestrian, flat, undistinguished stem cells into absolutely typical
neuron-looking cells," Dr. Black said, explaining that they looked like bright
spheres surrounded by halos. Then the cells began growing long fibrous
extensions, just like nerve cells. "We were disbelieving," Dr. Black said.
As the cells continued to change their type, they matured into cells that
appeared, by all the chemical tests that Dr. Black applied, to be nerve cells.
By tinkering with the chemical signals he used to stimulate the conversion,
Dr. Black and his colleagues were able to turn 80 percent of the bone
marrow cells into nerve cells. He said he transplanted the rat nerve cells to
the brains and spinal cords of rats and found that they survived, for months
so far.
Other neurobiolgists said they were impressed.
"It's really beautiful," said Dr. William Greenough, a neuroscientist at the
Beckman Institute for Advance Science and Technology of the University of
Illinois in Urbana-Champaign. While many researchers are working with
tissue from embryos or with animal cells to develop replacement cells for the
human body, and others are trying to redirect mature cells from other body
organs to become replacement cells, Dr. Black's approach has some potential
advantages: bone marrow cells are easy to obtain, and they could theoretically
be obtained from the very patient to be treated, obviating the problem of
adding foreign tissue that the immune system might attack.
"I see this as a truly significant step along the way toward developing new
technologies for the repair of the damaged brain," Dr. Greenough said.
But experts emphasized the huge amount of work that needs to be done. Dr.
Evan Y. Snyder, a neurobiologist at Harvard Medical School, said that it
remained to be seen whether cells that looked and acted like nerve cells when
they were grown in a dish in a laboratory would look and act like nerve cells
when they were transplanted into the body. "The level of proof is going to be
incredibly high," Dr. Snyder said.
Dr. J. William Langston, who is president of The Parkinson's Institute in
Sunnyvale, Calif., said that while he was excited by the possibility of creating
brain cells from bone marrow, he wondered if the new cells would be
specific enough to treat a disease like Parkinson's. With that disease, Dr.
Langston said, patients need not only nerve cells but brain cells that will make
the nerve chemical dopamine. They also need cells that will remain brain cells
and not revert to fat cells or bone cells, he added. And, he said, it is important
that the transplanted cells not overproduce dopamine. "If those cells make too
much dopamine, you could throw the patient into overdrive," he said. "How
do you make sure that they make the right amount?"
At this point, Dr. Greenough said, "the important thing to realize is that going
from basic science to effective clinical treatment is a pathway that invariably
has many steps."
"This is a really big step along this pathway," he added, but there is still a long
way to go.
Copyright 2000 The New York Times Company |
