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cyst from which ES cells can be derived, but thedeactivated gene means that the ball lacks theability to implant in a uterus and so developinto a baby (A. Meissner and R. JaenischNature doi:10.1038/nature04257; 2005).

In the other paper, a team led by RobertLanza of Advanced Cell Technology inWorcester, Massachusetts, plucked single cellscalled blastomeres from eight-cell embryos.They derived new ES cell lines from the blastomere, while the embryos went on toform apparently healthy mice (Y. Chung et al. Nature doi:10.1038/nature04277; 2005).

This method is similar to a technique usedin in vitro fertilization (IVF) called preimplanta-tion genetic diagnosis(PGD), in which a blasto-mere is removed from theeight-cell embryo for genetictests before it is implanted.The work by Lanza’s teamraises the possibility that fresh stem-cell linescould be derived from human embryos beingused in IVF before they are transferred to the uterus.

Although the quality of the work is impres-sive, there is much disagreement over the eth-ical benefits of each strategy. Some scientistsseem more convinced by the PGD method.

In the balance“In my mind, this takes away the ethicaldilemma of destroying embryos,” says AlanTrounson, a reproductive biologist at MonashUniversity in Melbourne, Australia. There is currently a moratorium on therapeuticcloning in Australia, due for review at the endof this year, and Trounson has applied to thecountry’s major medical funding agency to dosimilar work with human PGD embryos.

But there is the practical disadvantage thatthe resulting cell lines can come only from the embryos of couples undergoing IVF, sowouldn’t be genetically matched to patients.And ethicists are troubled by the question ofwhether the extracted blastomere itself has thepotential for life. “If you grow it in certain con-ditions, it could divide and differentiate tohave the same properties as embryos,” explainsYuri Verlinsky, chief executive of the Repro-ductive Genetics Institute in Chicago.

Although the number of successful birthsfrom PGD embryos indicates that removing asingle cell early on doesn’t compromise thebaby, it is still possible that it might have subtlelong-term consequences (see page 1075). “Youare getting a live birth, but are you getting thesame child you would otherwise get?” asksWilliam Hurlbut, a consulting professor atStanford University and a prominent advocate

of ANT. “It is uncomfortable to me to endorsesuch a strategy.”

Because of this, Hurlbut says that the PGDmethod is unlikely to get past the DickeyAmendment, which is passed by the US Con-gress every year and forbids federal funds beingspent on experiments that endanger or destroyan embryo. And President George W. Bush’sCouncil on Bioethics, on which Hurlbut sits,dismissed the idea earlier this year in a whitepaper on alternative means for deriving ES cells.

The ANT method of altering the geneticmake-up of an embryo troubles some scien-tists, but seems more acceptable to conserva-

tive ethicists and religiousfigures. “I think this is anartificial concept and I’m notcomfortable with it,” saysTrounson. “You do an engi-neering step to essentiallydestroy the embryo so thatyou can then use it.” Because

of this, some argue that ANT might itself fallfoul of the Dickey Amendment.

George Daley of Harvard Medical School inBoston is also unconvinced, partly because theeffects of the genetic modification don’t kick inuntil the eight-cell stage. “A normal embryoand the embryo created by this method areindistinguishable until that stage,” he says.

But Hurlbut maintains that the alteredembryo has no moral status. “You have theembryonic equivalent of brain death,” he says.“This changes the dynamic of the politicaldebate,” agrees analyst Eric Cohen of the Ethicsand Public Policy Center in Washington DC.

Hurlbut is doing all he can to push ANT, andhas compiled a public letter supporting it signedby scientists, ethicists and religious figures. Andin August 2004, he persuaded William Levada,one of the most prominent Catholics in theUnited States, to write to President Bushencouraging him to consider the method. Thepresident’s bioethics council also gave the ideatentative support in its white paper.

Some observers warn against overreactingto the work. “If science gets us to the pointwhere we don’t need embryos any more that’sfine, but right now policy-makers are makinga huge mistake if they say ‘we’ve got one paperand we’ll make policy based on that’,” says SeanTipton of the Coalition for the Advancementof Medical Research in Washington DC.

And either way, the ethical debate over whatconstitutes life — or the potential for life —looks set to dog the field. “The challenge is todefine what an embryo is,” says Hurlbut. “Weneed to sort that out or we’ll be having thisargument all the way along.” ■

Carina Dennis and Erika CheckSee also News & Views doi:10.1038/nature04305

“I'm not comfortable withit. You do an engineeringstep to essentiallydestroy the embryo so you can use it.”

STEM CELLS IN FOCUSCatch up on all of Nature’sstem-cell coverage at:www.nature.com/news/infocus/stemcells.html

NATURE|Vol 437|20 October 2005 NEWS

The World Stem Cell Hub, an internationalnetwork for exchanging embryonic stem-cell lines and cloning technology, has beenlaunched by the South Korean government.

Unveiled on 19 October, the hub will beheaded by Woo Suk Hwang, who shot tointernational fame last year for successfullyderiving human embryonic stem-cell linesby therapeutic cloning.

The hub’s headquarters will be at SeoulNational University Hospital, but it willhave branches around the world that willtrain researchers in the technique, provide a bank of cell lines and, where local lawspermit, create patient-specific lines. Thefirst branches will be in Britain andCalifornia, but Hwang told Nature that he is also talking to researchers in Spain,Sweden and France.

Organizers hope that the first regionalbranch will be open by January. Each branch will need to find its own funding,but South Korea will establish a non-profitfoundation to support the hub’sheadquarters and the travel of Koreantechnicians to foreign sites. GeraldSchatten, a reproductive biologist at theUniversity of Pittsburgh, Philadelphia, who will chair the hub’s international board of directors, says that the SouthKorean government is providing aboutUS$50 million.

Western scientists have cautiouslywelcomed the development. “I’m pleasedthat the Koreans have been as willing as theyhave to share their technology,” says ArnoldKriegstein, director of the Institute for StemCell and Tissue Biology in San Francisco,whose staff have visited Hwang’s lab.

“The Koreans are the experts — no one approaches their efficiency,” addsStephen Kennedy, a clinical researcher inreproductive medicine at the University of Oxford, UK.

But Kriegstein has ethical concerns aboutegg donations, and the associated issues ofinformed consent and record-keeping. Hesays he is also worried about the technologybecoming centralized at such an early stage.Michael German, a diabetes researcher atKriegstein’s institute, agrees: “I would notlike to see it become a specialized clubwhere only a limited number of scientistshave access to the technology.” ■

Carina Dennis

Korea launchesnetwork to sharecloning information

20.10 News 1076-1077 am 18/10/05 10:33 AM Page 1077

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