Scientists claim embryonic stem cell advance

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Scientists claim embryonic stem cell advance

Reprogrammed mouse cells avoid controversial destruction of embryos

The Associated Press

Updated: 4:34 p.m. PT June 6, 2007

NEW YORK - In a leap forward for stem cell research, three

independent teams of scientists reported Wednesday that they have

produced the equivalent of embryonic stem cells in mice using skin

cells without the controversial destruction of embryos.

If the same could be done with human skin cells — a big if — the

procedure could lead to breakthrough medical treatments without the

contentious ethical and political debates surrounding the use of

embryos.

Experts were impressed by the achievement.

" I think it's one of the most exciting things that has come out about

embryonic stem cells, period, " said researcher Dr. Asa Abeliovich of

Columbia University in New York, who didn't participate in the

work. " It's very convincing that it's real. "

'A long way to go'

But he and others cautioned that it will take further study to see

whether this scientific advance can be harnessed for creating new

human therapies. For one thing, the procedure used to get the mouse

skin cells to mimic embryonic stem cells wouldn't be suitable. And

it's simply not known whether the mouse results can be reproduced

with human cells.

" We have a long way to go, " said Gearhart of s Hopkins

University, a stem cell researcher who also wasn't involved in the

new work.

In any case, scientists said, the advance does not mean that research

that involves getting stem cells from human embryos should now be

abandoned. " We simply don't know which approach ... will work the

best, " said researcher Konrad Hochedlinger of the Harvard Stem Cell

Institute, who led one of the three teams.

Embryonic stem cells are prized because they can develop into all

types of tissue. So experts believe they might be used for transplant

therapies in people who are paralyzed or have illnesses ranging from

diabetes to Parkinson's disease.

To harvest human embryonic stem cells, embryos must be destroyed, an

action many people oppose.

Scientists have long hoped to find a way to reprogram ordinary body

cells to act like stem cells, avoiding the use of embryos altogether.

The new mouse studies seem to have accomplished that. Past

experiments seeking alternative routes to getting stem cells have

generally involved tampering with an embryo or egg.

At a press conference Wednesday, Hochedlinger and a member of a

second team said their work was not an attempt to evade the ethical

objections to embryo destruction. Instead, they said, the goal was to

learn how cell reprogramming works.

But in a telephone interview, a prominent critic of embryonic stem

cell research welcomed the new work on ethical terms.

" This is what we were looking for people to explore because it may

provide all the advantages of embryonic stem cells without the moral

problem, " said Doerflinger, deputy director of pro-life

activities for the U.S. Conference of Catholic Bishops. " So I'm very

encouraged. "

Hochedlinger and colleagues present their work in the inaugural issue

of the journal Cell Stem Cell. (The first word in the journal's name

refers to its publisher, Cell Press).

The other two teams reported their results Wednesday on the Web site

of the journal Nature. Rudolf Jaenisch of the Whitehead Institute in

Cambridge, Mass., is the senior author of one paper, and the work

behind the other paper was led by Shinya Yamanaka of Kyoto University

in Japan.

Will it work with human cells?

The new work builds on a landmark paper Yamanaka published last

August. He found that by slipping four genes into mouse skin cells

called fibroblasts, he could make the altered cells behave much like

embryonic stem cells in lab tests.

But these so-called " iPS " cells still showed significant differences

from embryonic stem cells. The three new papers report on creating

iPS cells that proved virtually identical to stem cells in a variety

of lab tests.

The technique used in the mouse studies could promote cancer in any

patients getting therapy based on iPS cells, so researchers

emphasized that a new approach that avoids that hazard would have to

be developed.

Gearhart called that a major issue to be resolved. In addition, he

said, scientists still must show that these cells can give rise to

many cell types in the lab, as embryonic stem cells can.

And all this must be accomplished in human cells — a difficult task,

he said, because introducing genes into human cells is a major

challenge.

If the technique can be harnessed for people, the iPS cells and the

tissue they develop into would provide a genetic match to the person

who donated the skin cells. That would make them suitable for

transplant to that person, theoretically without fear of rejection.

RL: http://www.msnbc.msn.com/id/19067616/