| Researchers isolate human stem cells in the lab Breakthrough could lead to treatments for paralysis, diabetes |
WASHINGTON (CNN) -- Researchers have announced that they
have successfully grown human stem cells in a laboratory, a
major advance that could one day help in organ
transplantation, gene therapy and treatment of such maladies
as paralysis, diabetes and AIDS.
Stem cells are blank cells that can develop into virtually
any kind of cell in the human body. Most cells have a
specific function -- liver cells, skin cells, brain cells
and so forth -- and once they have taken on this function,
in a process called differentiation, they can't be adapted
for any other function. Stem cells, however, have not gone
through the differentiation process.
By isolating stem cells in a laboratory, scientists
theoretically could grow new heart cells to repair damage
from heart attacks, new liver cells to treat hepatitis and
new red blood cells for cancer patients.
However, any such use of stem cells is at least a decade in
the future because scientists still don't know how to
customize these blank stem cells and turn them into cells
with a specific function.
According to the lead researchers, James Thomson of the
University of Wisconsin and John Gearhart of Johns Hopkins
University, stem cells could potentially be used for such
things as:
· Growing nerve cells to repair spinal injuries and restore
function to paralyzed limbs.
· Growing heart muscle cells to replace useless scar tissue
after a heart attack.
· Making brain cells that would secrete dopamine for the
treatment and control of Parkinson's disease.
· Growing cells that make insulin, creating a lifelong
treatment for diabetes.
· Growing bone marrow to replace blood-forming organs
damaged by disease or radiation.
· Making blood cells genetically altered to resist specific
disease, such as HIV, to replace diseased blood cells.
Thomson cautioned that this doesn't mean that scientists
will be able to grow a liver in a lab dish any time soon.
"We are not taking about making whole organs, but we are
talking about repairing organs," he said. According to
researchers, many diseases such as Parkinson's disease and
juvenile diabetes result from the death or dysfunction of
just one or a few cells. Replacement cells, then,
could offer "lifelong treatment," they wrote in an article
to be published in the journal Science.
Thomson says huge banks of frozen stem cells could be
established one day, each tissue-typed in the same way that
organ donations now are. Such a bank of cells could be used
not only to repair organs
but to test new drugs.
The cells could also be used for basic scientific research
in human development. to isolate the stem cells, researchers
took sperm from a man and an egg from a woman and fertilized
them in a petri
dish for several days until they became a ball of cells
called a blastocyst. They then took special cells within the
blastocyst and cultured them to produce the stem cells.
The research, however, may raise a number of ethical
considerations. In one experiment, couples were asked for
permission to use eggs and sperm they had donated. But in
another experiment, researchers used cells from aborted
fetuses.
Indeed, while scientists long ago isolated stem cells from
mice and other laboratory animals, work on human stem cells
has been slowed by opposition from anti-abortion groups who
consider blastocysts
to be human life. Medical Correspondent
Elizabeth Cohen and Reuters contributed to this report.
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