Stem Cell Debate Drives Alternatives

Scientists Search for Way Around Ethical Controversy

Medically Reviewed by Louise Chang, MD on November 07, 2006
From the WebMD Archives

Nov. 7, 2006 - Researchers in the U.S. and elsewhere are finding ways to getaround the ethical roadblocks to embryonic stem cell research.

And at a forum in Washington this week, experts are discussing some of themost promising strategies.

Congress -- with the backing of a majority of Americans -- passed a billearlier this year removing the strict limits on federal funding for embryonicstem cell research. That bill would have cleared the way forgovernment-sponsored research on the stem cells plucked from embryos left overat fertility treatments.

But President Bush blocked the measure, citing a belief -- shared by manyreligious conservatives -- that the government should not promote research thatdestroys human embryos for the sake of harvesting their stem cells.

However, such research remains a hot topic in Washington and is sure toresurface after Tuesday's elections.

In the meantime, scientists are busy looking for ways to harvest or createstem cells without harming human embryos or asking women to donate theireggs.

"We don't need any eggs or embryos at all," says Shinya Yamanaka,MD, a professor at the Institute for Frontier Medical Sciences in Kyoto,Japan.

Yamanaka describes his lab's early successes in mice creating stem cellsfrom adult cells. His research involves isolating two dozen chemicals that giveembryonic stem cells their ability to grow into nearly any tissue in thebody.

That property, called "pleuripotency," is what makes scientiststhink stem cells can be coaxed to form new tissues that could help cureParkinson's and other diseases.

The Japanese researchers found that four of the chemicals, in the rightmixture, transformed connective tissue cells from adult cells into pleuripotentcells Yamanaka says are "indistinguishable" from embryonic stemcells.

Still, significant problems remain.

"I have to point out, the efficiency … is very low," Yamanaka todaytold the scientific conference hosted by the Institute of Medicine. Only one in1,000 attempts to transform adult cells into stem cells was successful.

Also, the cells formed tumors when implanted in mouse tissue -- asignificant roadblock to using such cells for human treatments.

Plucking Grapes

Meanwhile, researchers at a Massachusetts biotech firm called Advanced CellTechnologies (ACT) have shown they can extract stem cells from early embryoswithout killing them. The technique has been used for a decade to perform earlygenetic testing during fertility treatments.

The extraction takes place when a fertilized embryo is about two-and-a-halfdays old and consists of just eight cells.

"You are able to pluck out one of those cells just as you would pluckout a grape from a bunch of grapes," Robert Lanza, ACT's vice president ofresearch, told the Washington forum.

Lanza's company showed that an extracted cell can be grown into pleuripotentstem cell line, and that the remaining embryo is just as viable as a normal one-- at least in mice.

This method was promoted by conservatives in Congress who opposed a repealof the federal limits on embryonic stem cell research.

It also provides a way around the narrow supply of fertility clinic embryosthat prospective parents would clear for use in research.

The method is essentially a hedge for Lanza, who favors still-controversialcloning methods to create a supply of stem cells from early embryos.

Preventing Implantation

Last year in the journal Nature, scientists at the WhiteheadInstitute for Biomedical Research in Cambridge, Mass., published results froman experiment in which they removed a gene in mice that allows an embryo toimplant in the mother's uterus.

Without that gene, any embryos produced through cloning (in this case, mousecloning) could not implant and hence could not be born.

That created a buzz in religious circles but did not settle thecontroversy.

Some Catholic authorities, including William Levada, the Archbishop of SanFrancisco, endorsed the procedure by stating that embryos without the abilityto implant in a womb are not "true embryos."

But some anti-abortion groups, including the American Life League, rejectedthe method, saying it would "create and then kill human embryos."

The controversy around the procedure is unlikely to end any time soon, Lanzasays.

Show Sources

SOURCES: Shinya Yamanaka, MD, PhD, professor, Institute for Frontier Medical Sciences, Kyoto, Japan. Robert Lanza, MD, vice president, Advanced Cell Technologies. Meissner, A. Nature, Jan. 12, 2006; vol 439: pp 212-215. News release, American Life League.

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