Stem-cell advance opens up the field
Pastor Dale Morgan
Stem-cell advance opens up the field*
By Peter N. Spotts
Nov 26, 3:00 AM ET
Colonies of tiny cells flourishing in petri dishes in the US and Japan
are reshaping the political and ethical landscape surrounding human
stem-cell research.
In the process, these diminutive colonies also may level the playing
field in stem-cell research – internationally and domestically.
These are some of the effects analysts say they see coming out of this
week's announcements that two teams have genetically reprogrammed skin
cells so that they take on the traits of embryonic stem cells.
Embryonic stem cells are the subject of intense medical interest because
of their ability to develop into any of the major cell types in the
human body. Over the long term, these stem cells could become the
foundation for therapies for a range of diseases, scientists say. This
week's announcement suggests it will be possible for scientists to study
these cells without the ethical and political difficulties of harvesting
them from unused human embryos.
For the emerging field of stem-cell research, "this is enormous," says
Jesse Reynolds, a policy analyst at the liberal Center for Genetics and
Society, based in Oakland, Calif. "I can't think of another development
"that has been this big,"
"This is a paradigm shift," agrees Rev. Tad Pacholczyk, director of
education at the National Catholic Bioethics Center in Philadelphia.
"This will have a huge impact on the ethical debate."
That debate has centered on the sources for human embryonic stem cells –
especially those that have the potential to be patient-specific. For
research purposes, scientists have turned to fertility clinics where
patients either have donated their nascent embryos to research or no
longer need them to start a family. But the process of extracting the
stem cells destroys these soon-to-be embryos, technically called
blastocysts. The destruction is abhorrent to those who hold that human
life begins at conception.
The ethical debate grows more heated when cloning – the most
controversial idea for generating patient-specific stem cells – enters
the picture. In 1997, a team in Scotland led by Ian Wilmut cloned Dolly
the sheep from adult tissue by extracting the DNA from nucleus of adult
cells and injecting it into the emptied nuclei of unfertilized sheep
eggs. The eggs were fertilized, then implanted into ewes.
The approach is banned in humans. Last week, however, scientists from
the Oregon National Primate Research Center in Beaverton, reported for
the first time that they had used the technique to generate embryonic
stem cells cloned from an adult primate – a macaque monkey. This
strongly hinted that eventually the approach could work with humans.
But the technique, which in principle could draw on a patient's own
cells to generate new tissue for treatments, is highly inefficient –
requiring many eggs to yield one successful clone from which stem cells
can be drawn and nurtured. It implies generating nascent embryos
exclusively as stem-cell factories. And it raises the concern among many
people that the approach will lead eventually to cloning humans as a
means of reproduction.
By contrast, the US and Japanese teams discovered genetic triggers that
could in effect turn back the clock on already-developed cells. Working
independently, each team found four genes that, when introduced into the
nucleus of skin cells, yielded cells indistinguishable from embryonic
stem cells. The Japanese team, led by Kazutoshi Takahashi at the
University of Kyoto, used the approach on mice last year. His lab, and
one led by the University of Wisconsin's James Thompson, essentially
tied for the race to test the approach using human cells.
For now, the two groups' work "changes everything and changes nothing;
and caution is warranted," says Dr. Thompson. "This changes everything
because these are not from embryos." But, he adds, it changes nothing
because scientists still don't know how embryonic stem cells morph into
the wide variety of cell types in the body. The caution comes because
without that information, it's unclear if the new cells can live up to
their promise. Thus, research on human embryonic stem cells is still
vital, he emphasizes.
Still, some labs appear to be doing that. In Scotland, Dr. Wilmut
announced earlier in the week that his lab is dropping the cloning
approach and focusing on the genetic reprogramming approach as well.
If this is any indication, a shift in stem-cell research could follow.
The new technique's relative ease, lower cost, higher output, and
scrubbed-up ethics are likely to draw more labs into the field, Thompson
suggests.
Moreover, such an expansion might further invigorate US research in the
face of aggressive competition from countries like Britain and Japan.
The advance could trigger some interesting political shifts, some
analysts suggest. For example, US restrictions on embryonic stem-cell
research could become harder to change in light of these discoveries,
according to Alta Charro, a University of Wisconsin law professor.
Already, the issue appears to be losing traction, Mr. Reynolds adds.
Earlier this month, for instance, New Jersey voters rejected a plan to
borrow $450 million for the state's stem-cell research program.
Indeed, the defeat, the discoveries, and the prospect that a new
administration might loosen the federal purse strings for human
embryonic stem research could add an element of uncertainty to existing
or planned state stem-cell programs.
"Right now, all of the activities on the pro-stem-cell front in the
states has been driven by the lack of federal funding for this
research," says Patrick Kelly of the Biotechnology Industry
Organization. "So if a new administration comes in and approves more
federal funding, the need in the states is going to be diminished." But
in states with existing programs "I don't think they'll ever be redundant."