Study: Stem Cells Could Develop Into Eggs By EMMA ROSS, AP Medical Writer
2 hours, 50 minutes ago
Scientists in Britain have shown that stem cells extracted from human
embryos can develop in the laboratory into the early forms of cells that
become eggs or sperm. The research raises the possibility that one day eggs
and sperm needed for infertility treatment could be grown in a dish.
Preliminary experiments also suggest that scientists may eventually be able
to use the technique to create a supply of eggs for cloning.
But the more immediate benefit of the work could be a better understanding
of why some men and women do not create their own sperm or eggs and whether
toxic chemicals in the environment play a role, one of the researchers said
before the start of the annual conference of the European Society of Human
Reproduction and Embryology. The findings were scheduled to be presented
Monday in Copenhagen.
"It may allow us to investigate the very earliest processes of how a human
(ovary and testis) develops," said Harry Moore, a professor of reproductive
and developmental medicine at Sheffield University in England.
Many scientists believe that chemical pollutants, such as pesticides, that
mimic the action of hormones, might interfere with human development at the
stage where eggs and sperm ? called germ cells ? are forming and that this
disruption may cause birth abnormalities, infertility and possibly cancer.
"By developing suitable tests with embryonic stem cells as they
differentiate into germ cells, we can investigate the action of these
chemicals in the laboratory," Moore said.
Stem cells are the master cells of the body, appearing when embryos are
just a few days old and developing into every type of cell and tissue in
the body, including sperm and eggs.
Scientists can study the stem cells by extracting them from the embryo. If
the researchers create the embryo by cloning a cell from a patient, any
resulting cells would be a genetic match to the patient.
The cloning technique, called cell nuclear replacement, involves emptying
out the genetic material in an egg and replacing it with the genetic
material of another cell, for example a skin cell from an adult. Instead of
being fertilized by sperm, the newly reconstituted egg is bathed in
chemical nutrients and electrocuted to shock it into dividing. It then
evolves into an embryo, from which stem cells can be extracted.
For infertile couples, that approach would eliminate the need for donor
sperm or eggs.
But any treatment using eggs and sperm grown from stem cells, let alone
from stem cells extracted from a cloned embryo, may be many years away,
Moore said.
"We would need to prove that sperm or eggs produced in this way were safe
before we could contemplate using them to treat patients," he said.
Other experts said the advance from the University of Sheffield could also
raise some ethical issues.
"It opens new and challenging possibilities: because the technique can be
used to generate eggs from a man's (adult) cells, gay couples could have
children genetically related to both," said Anna Smajdor, a medical
ethicist at Imperial College in London.
"These possibilities raise new questions about how we define parenthood and
about how we decide who has access to these new technologies," she said.
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