Good article summarizing research results for  ESC vs. adult stem cells
Currently available online at:
http://msnbc.msn.com/id/5251749/site/newsweek/

The Life in a Cell
Stem-cell researchers find fresh hope for curing deadly diseases—along
with new controversies
By Claudia Kalb

Newsweek June 28 issue

Under the microscope, they look like luminous stars in a black-and-white
galaxy. They are dazzling, mysterious, magical. They are human embryonic
stem cells.


Hailed by some as a cure for deadly disease, derided by others as the
destruction of human life, embryonic stem cells are at the center of a
heated debate over science, religion and politics around the globe. These
microscopic flecks have the extraordinary capacity to become any one of
the more than 200 cell types that make up the human body, but to those
who consider the fusion of sperm and egg sacred life—whether it takes
place in the womb or a lab dish—they are morally off-limits for research.


There are, however, less-controversial molecular building blocks: adult
stem cells, derived from mature human beings. Several years ago research
suggested that these cells were far more "plastic" than anyone dreamed,
and embryonic opponents began praising them as the ethical answer to
stem-cell science. But new studies are now challenging earlier data and
raising questions about just how malleable and powerful adult stem cells
really are. "People are starting to realize that the science of
plasticity is not all there," says Harvard researcher Dr. Leonard Zon,
president of the International Society for Stem Cell Research. In the
minds of many scientists, embryonic stem cells are pulling ahead in the
race toward a medical revolution.

Unlike embryonic stem cells, adult stem cells are wired to become a
particular kind of tissue. Much like theatrical understudies, they stand
quietly in the wings, rushing in only when cells need replenishment after
injury or disease. Scientists know the most about adult stem cells of the
blood, which have been used for decades in bone-marrow transplants for
patients with cancer or blood diseases. That success prompted researchers
to wonder: could adult blood stem cells have the same acrobatic ability
as their embryonic counterparts? Initially Dr. Markus Grompe, of Oregon
Health & Science University, thought yes. In 2000, he reported that adult
blood stem cells were able to turn into liver cells in mice. Other
studies reported that the cells could become neurons and heart muscle.
But in 2002, several scientists put forth a new theory: adult bone-marrow
cells weren't actually becoming new tissue types, they were fusing with
existing cells. Those findings persuaded Grompe, a Roman Catholic who
does not study embryonic stem cells on religious grounds, to reassess his
data and revise his conclusion: the blood cells were indeed merging with
liver cells—a case of biological identity theft rather than
transformation.

New studies are now challenging earlier work on heart disease, as well.
In 2001, news that bone-marrow stem cells turned into heart muscle after
being injected into the damaged hearts of mice spurred great hope, even
leading to human trials. Dr. Piero Anversa, of New York Medical College,
worked on one of the original studies and stands by the research "1,000
percent." "What we're offering is a novel approach to the treatment of
cardiac disease," he says. But other scientists were skeptical, and this
spring, two groups reported that they could not reproduce the earlier
findings, a critical step in the validation of science. "Our paper says
it doesn't work," says Stanford University's Dr. Irv Weissman.

Scientists believe the greatest potential of adult stem cells may be in
regenerating the organs they come from, and they are actively searching
for stockpiles of the cells in different parts of the body. For years
researchers hoped that adult stem cells in the pancreas —could be coaxed
into becoming insulin-producing beta cells, which people with type 1
diabetes lack. But last month Harvard biologist Doug Melton dashed the
hopes of many when he reported that he could find no adult stem cells in
the pancreas at all. While the study doesn't rule out their existence,
the conclusion is clear to Melton: "If you want to make more beta cells,
the place to look is embryonic stem cells."

Embryonic opponents are looking elsewhere—to a unique group of adult stem
cells isolated by Dr. Catherine Verfaillie at the University of
Minnesota. Verfaillie reports that the cells appear to have some of the
transformative capacity of embryonic stem cells, converting into other
tissue types, like muscle or liver. Scientists are watching closely. But
the cells are exceedingly sensitive and difficult to grow, a challenge
Verfaillie hopes to resolve as she continues to study their development.
And the data need to be replicated by other labs before the cells' true
powers can be confirmed. Even Verfaillie, clearly enthusiastic, says the
cells' transformative ability as compared with embryonic stem cells
remains to be seen. "It's way too early to tell," she says.

Too early, certainly, to make absolute statements about what works and
what doesn't. Stem-cell science is constantly evolving: even with all the
recent challenges to plasticity, new studies of adult stem cells continue
to report intriguing successes. As a result, scientists say research must
proceed down both pathways: adult and embryonic alike. The politicians,
meanwhile, are still battling it out. Last week a spokesman for George W.
Bush said the president would not relax his restrictions on embryonic
research, but Massachusetts Sen. John Kerry, the Democratic presidential
candidate, says he would overturn the current policy if elected in
November. Other countries, like Ireland and Austria, have even stricter
regulations. But elsewhere, in nations like South Korea, where scientists
recently announced that they had extracted stem cells from cloned human
embryos, and the United Kingdom, which last month opened the world's
first stem-cell bank, more-liberal policies may lead to progress. And
that, says Dr. Octavi Quintana, director of health research for the
European Commission, will be all it takes to galvanize support for
embryonic research around the globe. "The day the first clinical trial
shows therapeutic benefits for a patient," he says, "the whole opposition
will disappear." Just what the scientists—and millions of patients—want
to hear.

With Liat Radcliffe in London

http://msnbc.msn.com/id/5251749/site/newsweek/

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