Stem cells created without destroying embryos

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Stem cells created without destroying embryos

http://www.latimes.com/features/health/la-sci-

stemcells11jan11,1,7350682.story

A government official says the technique would make such research

eligible for federal funding.

By Kaplan, Los Angeles Times Staff Writer

Scientists reported Thursday that for the first time they have made

human embryonic stem cells without destroying embryos, a development

that the government's top stem cell official said would make the

controversial research eligible for federal funding.

Story Landis, who chairs the National Institute of Health's stem

cell task force, said that with certain safeguards, the new method

appeared to comply with federal restrictions that have largely cut

scientists off from the $28 billion the government spends on medical

research each year.

In the latest study, the researchers used 41 embryos that were

frozen by fertility clinics. They thawed them and prompted them to

grow to the eight-cell stage, then used a tiny glass pipette to

remove one or two blastomeres. Most of the donor embryos continued

to develop normally for two more days before they were refrozen.

The individual cells were grown in dishes and surrounded by human

embryonic stem cells and other compounds that induced them to

develop into embryonic stem cells.

The scientists created four cell lines that were able to grow into

all the main tissue types in the body, including neurons and beating

heart cells.

Colleagues at UC San Francisco repeated the experiment with two more

embryos, but they did not use established stem cells to help the

blastomeres grow. They produced a stem cell line that didn't involve

any materials derived from dismantled embryos.

There is a potential flaw with the technique: Even the delicate

removal of one cell could place an embryo's health at risk.

" How do you demonstrate that the embryo was not harmed? " Landis

said. " Right there, you have a significant problem. "

Protecting embryo health

The ideal experiment -- in which embryos that have been biopsied to

make stem cells are implanted in surrogates so that the babies can

be studied for medical problems -- is impossible to conduct for

health and ethical reasons.

But Lanza said there is a straightforward solution.

To avoid potential risk to embryos, scientists could piggyback on

PGD biopsies that clinics are performing anyway, he said. After the

blastomere is removed, it could be nurtured in a dish for about 12

hours until it divides. Then one cell could be used for genetic

screening and the other would be available for research.

Landis agreed that stem cells derived in this manner would appear to

meet the federal standards.

Lanza said he believed that the method was safe enough to use on

spare embryos from fertility clinics and still qualify for federal

funding. In his experiments, 80% to 85% of the donor embryos

developed to the stage where they could be implanted in a uterus --

a higher rate than at fertility clinics.

" Any clinic would be thrilled with 85%, " said Dr. Mark ,

director of the Genesis Genetics Institute in Detroit. " Many clinics

would be happy with 60%. "

Landis said there was no way to know whether the embryos that didn't

survive were lost because of the initial thawing or the subsequent

biopsy.

Researchers could get some idea by comparing the pregnancy rates of

couples that used PGD to those of couples that opted for standard in

vitro fertilization.

A study published last year in the New England Journal of Medicine

found that among older women who had IVF, those who also used PGD

were about 30% less likely to have a baby. But specialists who

perform the diagnostic procedure said that the study was flawed and

that an alternative reading of the data showed that genetic

screening slightly boosted the odds of having a baby.

The entire exercise of trying to satisfy the Bush policy could

become moot after the presidential election if a new administration

scraps the restrictions. But Lanza said the researchers couldn't

wait.

" We need more lines to study, " he said. " We can't afford to waste

time. "

Graphic

Technique for developing stem cells

click to enlarge

Graphic

Stem cell therapy

click to enlarge

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Federal law prohibits the National Institutes of Health from paying

for experiments that place human embryos at risk of injury or death,

and spending on human embryonic stem cell research is restricted to

projects involving a handful of cell lines that were created before

August 2001.

Researchers at Advanced Cell Technology in Worcester, Mass., created

four stem cell lines out of individual cells plucked from 3-day-old

embryos, which continued to develop normally after the procedure.

The method was described in the online edition of the journal Cell

Stem Cell.

The removal of a single cell from a young embryo is done thousands

of times a year in the U.S. by fertility laboratories to screen

embryos for genetic diseases.

Dr. Lanza, Advanced Cell Technology's chief scientific

officer, said researchers could piggyback on the procedure by

allowing the removed cell to divide in a laboratory dish. Then, with

the consent of patients, one copy could be used for genetic

screening and the other to make stem cells.

Under those circumstances, the research " should be permissible under

the Bush policy, " said Korobkin, a stem cell expert at the

UCLA School of Law. " The NIH should not decline to fund this. "

Though the technique spares embryos, it still raises ethical

concerns.

The Rev. Tadeusz Pacholczyk, an ethicist at the National Catholic

Bioethics Center in Philadelphia, said that removing a single cell

from an embryo turns it into " a starting source for harvestable raw

materials, in a gesture that reduces young humans to commodities. "

And because the single embryonic cell can be grown into stem cells,

some scientists and ethicists wondered whether the cell itself has

the potential to become a whole new embryo.

" It would be hard to rule out, " said Pera, director of the

Center for Stem Cell and Regenerative Medicine at USC.

New optimism

But for scientists who have struggled under federal restrictions,

the technique has injected a sense of optimism that there may soon

be a break in the political logjam that scientists blame for

stalling progress in the field.

After all, the idea of producing stem cells by taking a single cell

from an embryo was suggested by the President's Council on Bioethics

in a 2005 white paper that examined ways to make the valued cell

lines without creating, harming or destroying embryos.

" The president's own bioethics advisory council suggested this

approach, " said on, director of the University of

Michigan Center for Stem Cell Biology, who was not involved in the

study. " The administration has a responsibility to now support it. "

Michigan is one of at least nine states where it is illegal to

derive new human embryonic stem cell lines using traditional

methods, even with private funding. on said the new method

appears to comply with Michigan law.

The study puts the finishing touches on a highly touted experiment

19 months ago that demonstrated the feasibility of the process but

did not actually preserve any embryos, largely for practical reasons.

The approach relies on culling individual embryonic cells using a

biopsy technique known as pre-implantation genetic diagnosis, or

PGD. About 5,000 couples in the U.S. opt for PGD each year,

according to the Society for Assisted Reproductive Technology.

In late 2005, Lanza demonstrated that the technique was possible in

mice. The donor embryos were implanted into surrogate mothers and

resulted in live births 49% of the time, virtually the same as for

intact embryos.

The following year, Lanza's team showed that a single cell taken

from an early-stage human embryo could be grown into a stem cell

line. To maximize their chances of success, they used all of the

cells, called blastomeres, from the donor embryos and therefore

couldn't track whether their development would have been hampered by

the biopsy.