X-Message-Number: 18744
Subject: SF Gate: Big hurdles overcome in stem cell research
From: "Peter Christiansen" <>
Date: Sun, 10 Mar 2002 08:24 -0800

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This article was sent to you by someone who found it on SF Gate.
The original article can be found on SFGate.com here:
http://www.sfgate.com/cgi-bin/article.cgi?file=/c/a/2002/03/10/MN9865.DTL
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Sunday, March 10, 2002 (SF Chronicle)
Big hurdles overcome in stem cell research
Nicholas Wade, New York Times


   Scientists say they have jumped a double hurdle in the race to cure
disease with embryonic stem cells, the all-purpose clay from which the
body is sculptured.
   Working with mice, one team at the Whitehead Institute at the
Massachusetts Institute of Technology has mastered making embryonic stem
cells metamorphose into the cells that generate the blood and immune
systems.
   Another team converted skin cells from the tip of a mouse's tail back into
the embryonic state and then, with the first team's technique, used them
to cure a mouse whose blood and immune system had been destroyed. The
experiments were published electronically on Friday in the journal Cell.
   The second experiment is among the first claimed instances of therapeutic
cloning, a technique strongly opposed by those who fear it may be used
instead to clone a person. By providing proof of its possible benefits,
the experiment "hopefully should influence the debate," said Dr. Rudolf
Jaenisch of the institute in Cambridge, Mass.
   Therapeutic cloning is based on the idea of taking a mature cell, like a
skin cell, from a patient, walking it back in biological time to its
embryonic state, then growing new mature cells of the type necessary to
repair a diseased organ.
   The controversy arises because the nucleus of the skin cell, containing
the patient's genome or genetic information, would be injected into an
unfertilized human egg whose own nucleus had been removed. The injected
human egg would be kept in laboratory glassware and allowed to divide a
few times into an early embryo, from which embryonic stem cells can be
harvested. If the embryo were placed into a woman's uterus, it might
successfully develop, creating a clone or almost identical twin of the
patient who provided the skin cell nucleus.
   Jaenisch and his colleagues have created mouse embryos by this method and
converted them into blood-forming stem cells, first correcting an inborn
genetic defect of the donor mouse by a standard genetic method.
   The blood-forming cells were then injected back into the mice that donated
the nuclei. These mice had been irradiated to destroy their bone marrow
cells and would have died without the new cells.
   Jaenisch's team had to inject 202 unfertilized mouse egg cells with skin
cell nuclei to get a single working embryo. Acquiring such a number of
human egg cells would be difficult and expensive.
    
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Copyright 2002 SF Chronicle

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