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Stem cell breakthrough leaves embryos unharmed
17:00 10 January 2008
NewScientist.com news service
Andy Coghlan


For the first time, human embryonic stem cells have been obtained without having to destroy the embryos they came from.

The breakthrough sidesteps the primary ethical objection to human embryonic stem cell (hESC) research – that embryos must perish to yield up hESCs.

The new technique generates stem cells by extracting and culturing a single embryonic cell, leaving the remaining embryo to develop normally.

The US researchers involved demonstrated that the procedure worked a year ago, but without proving that embryos could survive the process. Now, they have shown unequivocally that the embryos survive and could develop to full term.

"These are the first hESCs created without destroying embryos," says Robert Lanza, chief scientific officer at Advanced Cell Technology, the company that pioneered the breakthrough in Worcester, Massachusetts.

Ethical approval
The hope now is that President George W Bush will now lift heavy restrictions on federally funded hESC research that he imposed in 2001 because of his own objections to embryo research.

"It's here and now, and could increase massively the number of stem cells available," says Lanza, who wants Bush to give immediate ethical approval for new cell lines to be produced using the ACT approach. "We could triple the number of hESC lines available within a few months," says Lanza.

Since Bush's clampdown in 2001, only 22 cell lines have been available for use by US government-funded researchers, but most are of such poor quality they are useless, so fresh supplies are desperately needed.

"Hopefully the president will do the right thing," says Lanza. "We've been in dialogue with the White House, and it's our understanding that they would wait until a peer-reviewed paper appeared before approving our approach."

That paper has now appeared, in the journal Cell Stem Cell (DOI: 10.1016/j.xtem.2007.12013). In it, Lanza and his colleagues describe how they produced four new lines of hESCs from blastomeres – single undifferentiated cells that make up very early embryos.

Efficient process
By nourishing each blastomere with special blends of nutrients or growth factors, ACT produced new colonies of embryonic stem cells and demonstrated that these could be converted into all tissues of the body.

By introducing a new nutrient, a protein called laminin found in the base layer of skin tissue, they massively improved the efficiency with which they converted blastomeres stably into hESCs.

Importantly, a fifth line has been produced using ACT's method by Olga Genbacev's team at the University of California at San Francisco, proving the procedure is replicable.

Despite praising the breakthrough, some researchers claim that it panders to people whose objections to current methods of extracting hESCs are morally groundless.

"It's designed to appease people who oppose embryo research despite the fact that thousands of IVF embryos are discarded each year," says Stephen Minger, director of the Stem Cell Biology Laboratory at King's College London, UK.

Limited lines
Lanza accepts this to an extent, but says the objections have to be overcome to kick-start US stem cell research. "The clock is ticking, and it keeps getting held up and held up," he says.

Evan Snyder of the Burnham Institute for Medical Research in La Jolla, California, applauds the breakthrough, but says that moral opponents might still not be satisfied.

"Can one prove that the biopsied embryos, if implanted, would yield normal individuals?" he asks. "Opponents might claim even sillier arguments: that the embryos are donating cells without 'informed consent'," Snyder adds.

The other shortcoming of the technique is that it cannot provide stem cells matched to each individual patient, whereas two other technologies have the potential to do using the patient's own skin or other cells – although each has its own limitations.

Lanza accepts that ACT's procedure cannot be tailored to each patient, but estimates that around 100 different lines grown in stem cell banks would be enough to tissue-match and treat most individuals.

Journal reference: Cell Stem Cell (DOI: 10.1016/j.xtem.2007.12013)