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Stem Cells Extracted from Cloned Human Embryo |
Posted:
02.17.04 | |
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Scientists in South Korea have extracted stem cells from a cloned human embryo
- a breakthrough that has potential for treating various diseases but also ignites
fears that rogue scientists will use the technology to clone humans. Printer-friendly
versions: HTML / PDF | |
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Other scientists have cloned small numbers of human embryos that lived for
a short time, but the South Koreans who announced their work last week in the
journal Science, apparently succeeded on a scale that far outstripped earlier
human cloning efforts. | |
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| South
Korean researchers make medical history | |
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The researchers began with a group of 16 women who were given hormone treatments
to produce large numbers of reproductive egg cells. They eventually obtained 242
eggs from  the
women. Then the scientists used innovative techniques to strip out the
nucleus from each of these egg cells. The nucleus is the portion of the cell containing
many of the cell's genetic instructions.
The scientists next took
body cells from the same women who had donated the egg cells. The body cells have
two sets of chromosomes, the full genetic blueprint needed to create a human being.
The scientists removed these body cells' nuclear material and placed it into the
egg cells. The result was 66 cloned eggs, in effect, human embryos, with
the exact genetic makeup of the original females. The researchers grew 30 of the
embryos for a week to the so-called blastocyst stage, when stem cells could be
extracted. | |
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| Stem
cell technology could help cure diseases | |
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Embryonic stem cells are unique because they have the potential to develop
into any type of tissue or cell in the body. The research, called therapeutic
cloning, could allow scientists to take a plug of skin or blood sample from a
patient and use it to grow tissue, organs or batches of cells. The new cells would
 have
the same genetic makeup as the donor and would therefore lower the risk that the
injured or sick person's body would reject the new tissue. "Our approach
opens the door for the use of these specially developed cells in transplantation
medicine," said Woo Suk Hwang, who led the government-funded study. Researchers
also hope the stem cell research will lead to treatments for a range of diseases
from Alzheimer's to Parkinson's to diabetes. | |
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| Ethical
questions | |
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But embryonic stem cell research is controversial because harvesting the cells
destroys an embryo that could have grown into a baby if implanted in a woman's
uterus.  President
Bush is against making and destroying human embryos.
"The use of embryos
to clone is wrong. We should not as a society, grow life to destroy it,"
he said in 2001. The Bush administration policy does not allow the government
to fund any research on stem cells taken from embryos destroyed after Aug. 9,
2001. Since the research is expensive, the ban has limited the amount of work
being done in the United States. | |
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| Reproductive
vs. therapeutic cloning | |
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Some fear that the South Korean scientific advance will encourage people to create
human clones, called reproductive cloning.
In reproductive cloning, which
has been performed with animals but not people, the embryos are implanted in the
womb and allowed to develop into a fetus. In therapeutic cloning, the  embryos
are never implanted, but are grown for a few days in the laboratory so that the
stem cells can be extracted.
The first mammal was cloned in 1996 when
Scottish researchers made Dolly the sheep. Dolly died a year ago of what scientists
said was premature aging and complications from cloning. Most scientists
believe human reproductive cloning is unethical because any baby created by this
method would be prone to severe deformities. | |
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| Scientific
research in the United States | |
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many U.S. lawmakers would like to ban human reproductive cloning, the debate is
complicated by the question of whether to allow therapeutic cloning. Conservative
lawmakers have attached bans on embryonic stem cell research to all bills regarding
reproductive and therapeutic cloning, preventing Congress from coming up with
a clear policy. Some U.S. scientists worry that the lack of government support
for all cloning related to humans is already harming the future of American medical
research. "We will be sitting here with the best scientists in the
world watching things on television," Dr. Jose Cibelli, professor of animal
biotechnology at Michigan State University told the New York Times. Cibelli collaborated
with the South Korean scientists and is an author of their paper. Several
countries in Europe ban all human cloning, including therapeutic cloning. --
Online NewsHour | |
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