New method generates stem cells safely from mice New method generates stem cells

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New method generates stem cells safely from miceNew method generates

stem cells safely from mice

Thu Oct 9, 5:14 PM

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WASHINGTON (Reuters) - Japanese researchers who invented a way to make

powerful stem cells out of ordinary cells say they have now found a

safer way to do it.

Shinya Yamanaka of Kyoto University in Japan and colleagues invented a

new way to transform ordinary cells into embryonic-like stem cells

called iPS cells, using a ring of genetic material called a plasmid.

Working in mice, they generated induced pluripotent stem cells, or iPS

cells, and said they believe the method can work in people, too, and is

an important step toward a new field called regenerative medicine.

Stem cells are the body's master cells, giving rise to all the tissues,

organs and blood. Embryonic stem cells are considered the most powerful

kinds of stem cells, as they have the potential to give rise to any type

of tissue.

But they are difficult to make, requiring the use of an embryo or

cloning technology. Many people also object to their use, and several

countries, including the United States, limit funding for such

experiments.

In the past year, several teams of scientists have reported finding a

handful of genes that can transform ordinary skin cells into iPS cells,

which look and act like embryonic stem cells.

To get these genes into the cells, they have had to use retroviruses,

which integrate their own genetic material into the cells they infect.

This can be dangerous and can cause tumors and perhaps other effects.

Last month U.S. researchers did the same thing using a harmless virus

called an adenovirus, but the method was not efficient -- and

introducing any virus into the body can pose risks.

Yamanaka's team tried several different methods but eventually looped

three of the genes needed into one plasmid and the fourth into another,

and transplanted these into cells from a mouse embryo.

The mouse embryonic cells reverted to a stem-like state and began

behaving like embryonic stem cells.

Yamanaka's team said the method was also not as efficient as using

retroviruses but said they plan to try their method using human cells.

If it works, some day doctors may be able to make tailor-made

transplants to treat diseases in people by removing a few cells,

transforming them in the lab and transplanting the new tissue or organs

back in.

(Reporting by Maggie Fox; Editing by Beech)