An American biotech company has claimed that it has created the firsthum an embryos ever produced by cloning，provoking a storm of criticism and reigniting the ethical debate about the promises and dangers of biology's most controversial new technology．
ADVANCED CELL TECHNOLOGY may be a small，privately financed company that few outside the rarefied① world of biotechnology， and not many within it，have ever heard of．But whatever else that can be said about the firm，its managers certainly know how to make asplash． On November 25th，the company claimed to have created the first cloned human embryos， and made the announcement with all the skill of a Hollywood publicist②．It published its results not in a major scientific journal such as Nature or Science，but in an obscure online journal called e-biomed：The Journal of Regenerative Medicine，which many leading medical scientists don't read．To make sure that the wider world paid attention，the three scientists behind the experiments wrote a dramatic first-person account of their research for Scientific American，a popular journal for lay readers，and they seem to have given a thorough advanced briefing to US News ＆ World Report，a mass-market news magazine，which portrayed the three as intrepid③ pioneers，and even described one of them，Robert Lanza，“as the living embodiment of the character played by Matt Damonin the movie Good Will Hunting．
Despite all this，the announcement immediately provoked a storm of protest．President George Bush declared that“the use of embryos to clone is wrong．We should not as a society grow life to destroy it．And that's exactly what'staking place．The Vatican④ joined in，saying that the firm 's announcement“called for unequivocal⑤condem nation．The European Com m ission said that it would never finance any similar projects．“Not everything scientifically possible and technologicallyfeasible is necessarily desirable or adm issible，observed Philippe Busquin，the commissionerfor re- search．The firm 's experiments，declared Jorg-Dietrich Hoppe，the president of the Asso ciation of German Doctors，were“unethical and testify to a horrifyingly low estimation of human life．Michael West，Advanced Cell Technology's chief executive，denied this：“We are not talking about a human life．Weare talking about cellular life．There is a fundamental distinction．
Ironically，all this fuss was causedby what many rival resear-chers prom ptly announced was a scientific“failure．That may be a little harsh，but what the firm 's scientists have actually managed to do does not quite match their sweeping claim s either．The com pany，based in Worcester，Massachusetts，used twodifferent m ethods to create human“em bryos，but all died within days，failing to live long enough to produce the kind of material that would yield“stem cells”⑥in the laboratory，which was the purpose of the experim ent．Stem cells are special cells which can，theoretically，grow into almost any kind of human cell type．Many believe that if a way can be found to growand harvest these cells，they can be usedas replacement tissue to combat a variety of human diseases and ailments，from diabetes⑦ to organ failure．Tissue cloned in this way from the patient's own cells would not，it is thought，be rejected by the body's immune system ，which is currently a major obstacle to organ transplants and many other treatments．
Advanced Cell Technology，according to its paper，adopted the same method asthat used to clone Dolly，the first cloned sheep，a few years ago，inserting genetic material from an adult cell into a human egg．But of the 19eggs used，16 died before they could divide even once．Only three divided once or twice before dying．None of the eggs lived long enough to produce stem cells．“It's a complete failure， Dr George Seidel，a cloning expert atColorado State University，told the New York Times． Moreover，the company is not really the first to claim human cloning—a group of South Korean researchers said they had managed to do the same in 1998，but their claim was never verified．
Nevertheless，the firm 's scientists claimed that their paper“provides the first proof that reprogrammed human cells can supply tissue for transplantation．Declared Dr Lanza：“These are exciting preliminary results．
In fact，the results published by the Advanced Cell team seem to confirm that big technical hurdles still stand in theway，despite what seems like the dizzying pace of recent proGREss．Deriving human embryonic stem cells is not an easy matter，even from embryos created in the well-established technique of in vitro⑧ fertilisation⑨．Proving that cells are truly stem cells—with the capacity to renew themselves and become virtually any tissue in the body—is tricky．Controlling the fate of these cells—driving them to become，say，nerve or heart-muscle cells—is nearly impossible at the moment．
As for deriving stem cells from cloned embryos，there is only one published example of this having been done successfully，by a group of researchers at Monash University in Melbourne，who have managed it in mice．This established the theoretical possibility that it could be done in humans as well．But extrap- olating⑩ from mice to man，biologists have learned，is fraught⑾ with peril．
Despite the remaining obstacles，most scientists believe that human cloning is now on the horizon．This prospect has rovoked intense controversy．The Catholic church，other religious groups and many people concerned about the use of humans for medical experiments have condemned cloning．Many of the scientists in- volved in the research have countered by pointing out the huge potential gains from cloning and other new genetic techniques．
The debate has tended to distinguishbe- tween two kinds of cloning．So-called“reproductivecloning would use the technique to create a human being，much as Dolly the sheep was created．Although a few mavericks ⑿ have insisted that they will do this as soon as possible，most responsible scientists argue that repro-ductive cloning is still far too dangerous to be tried on humans．When done with animals， it produces many foetuses⒀ with abnorma-lities． Most die at birth．
So-called“therapeutic⒁ cloning would use the technique to create embryos to produce stem cells，which could then be used to produce material for the treatment of diseases．In this instance，the embryos are not allowed to develop beyond a very early stage．Advanced Cell Technology insists that it is only interested in the latter．“Our intention is not to create cloned human beings，but rather to make life-saving therapies for a wide range of human disease conditions，including diabetes，strokes，cancer， AIDS，and neurodegenerative⒂ disorders such as Parkinson's and Alzheimer's disease⒃ declared Dr Lanza．
Governments have struggled to navigate these conflicts，and to pass new lawsto control research in this area．So far，few have managed to arrive at enough of a consensus to pass new regulations．America，where the debate has been the most strident⒄，is typical．In August， Mr．Bush decided to deny the use of federal funds for any research using human embryos， and to allow it only for research on stem cells that had already been harvested fromembryos which had been killed and discarded．America's ConGREss has so far been unable to agree to a law controlling the research．The House of Representatives has already passedlegislation banning all hum an cloning，both therapeutic and reproductive，but the Senate has notyet acted on the law．In the wake of the company's announcement，Mr．Bush's spokesman urged it to do so．
Many believe that the only way to regulate hum an cloning，and to outlaw any possible excesses，will be to draw up international rules to govern it．In June France and Germany launched an initiative to win approval for a international convention banning human cloning． The United Nations is due to begin negotiations on the subject next year．And yet，even with the remaining technical obstacles，cloning research now seems to be moving too fastto becontrolledby the grindingly⒅ slow processes of international diplomacy．
注释：①rarefied 只限于小圈子内的；②publicist 宣传人员，时事评论员；③intrepid 勇猛无畏的；④Vatican 梵蒂冈，罗马教廷；⑤unequi-vocal 明确的，不含糊的；⑥stem cells 干细胞；⑦diabetes 糖尿病；⑧in vitro 在生物体外；⑨fertilisation 受精；⑩extrapolating 推断，推测；⑾fraught 充满……的；⑿mavericks 独行其是者；⒀foetuses 胎儿； ⒁therapeutic治疗的； ⒂neurodegenerative；神经退行性（疾病）⒃Parkinson's and Alzheimer's disease 帕金森氏疾病和阿尔滋海默 氏疾病；⒄strident 刺耳的，尖锐的；⒅grindingly 费事地，难挨地
