News - Two Studies Cast Doubt on Stem Cells

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Two Studies Cast Doubt on Stem Cells

Wed Mar 13, 2:02 PM ET

By ALEX DOMINGUEZ, Associated Press Writer

Two new studies cast doubt on the tantalizing theory that adult stem cells can

serve as the body's all-around repairmen,

capable of converting into any type of cell to fight disease or replace faulty

organs.

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Stem Cell Research Debate

The findings, if confirmed, could force scientists to focus more on embryonic

stem cells — whose use is highly controversial

because they are taken from embryos that are killed in the process.

The studies could also influence the debate in Washington, where the Senate is

expected to take up the issue in the

next few weeks of whether to ban the use of cloning to create human embryos for

medical research.

Scientists have long known that stem cells from embryos are all-purpose cells

that can transform themselves into different

kinds of specialized tissue, such as muscle, bone, skin and organs. Researchers

hope someday to harness this ability to

treat various diseases and injuries.

In recent years, scientists have found surprising evidence that stem cells taken

from adult creatures have some of the

same transforming properties, or plasticity.

But the two new studies, conducted in separate laboratories in the United States

and England and published online

Wednesday by the journal Nature, cast doubt on that belief.

In the two studies, embryonic stem cells from mice were put in laboratory dishes

with mouse bone marrow and brain cells.

But instead of transforming into their neighboring cells, the stem cells simply

merged their genetic material with the marrow

and brain cells.

The researchers said the same phenomenon may have occurred in studies involving

adult stem cells, and may have

fooled scientists into thinking that the cells had transformed themselves.

The new findings " call into question almost all of the data generated using

adult stem cells, " said Lanza, medical

director of Advanced Cell Technology, a Worcester, Mass., company not involved

in the two studies.

He said the findings could influence the political debate.

" One of the main arguments that is being used to ban this research is the fact

that adult stem cells have been found that

can do the same thing — i.e., why kill human embryos if you don't have to? "

Lanza said.

" These two papers should send a message to lawmakers and to the public: It's

premature to conclude that adult stem

cells have the same potential as embryonic cells. In fact, it throws into

question which if any of these adult stem cells can

be harnessed to cure human diseases. "

President Bush (news - web sites) issued regulations last summer forbidding

federal funding of human embryonic stem cell

research except for experiments inolving cell colonies that already exist.

One of the Nature studies was led by stem cell researcher Austin of the

University of Edinburgh, the other by

Naohiro Terada, an associate professor of pathology at the University of

Florida.

" I think the major point of both papers is to call into question all of this

excitement that has been engendered by claims

that there is plasticity in tissue stem cells, " said Harinder Singh, a genetics

and biology professor at the University of

Chicago.

Verfaillie, director of the University of Minnesota Stem Cell

Institute, said the papers do not disprove adult stem

cell plasticity findings by other researchers, including herself.

However, she said it suggests stem-cell researchers should take a closer look at

the chromosomes in the cells they are

studying.