BEIJING – For the first time, researchers have used the cloning techniquethat produced Dolly the sheep to create healthy monkeys, bringing sciencean important step closer to being able to do the same with humans.
Since Dolly’s birth in 1996, scientists have cloned nearly two dozen kindsof mammals, including dogs, cats, pigs, cows and polo ponies, and have alsocreated human embryos with this method. But until now, they have beenunable to make babies this way in primates, the category that includesmonkeys, apes and people.
“The barrier of cloning primate species is now overcome,” declared MumingPoo of the Chinese Academy of Sciences in Shanghai.
In a paper released Wednesday by the journal Cell, he and his colleaguesannounced that they successfully created two macaques. The female babymonkeys, about 7 and 8 weeks old, are named Zhong Zhong and Hua Hua.
“It’s been a long road,” said one scientist who tried and failed to makemonkeys and was not involved in the new research, Shoukhrat Mitalipov ofOregon Health & Science University. “Finally, they did it.”
Poo said the feat shows that the cloning of humans is theoreticallypossible. But he said his team has no intention of doing that. Mainstreamscientists generally oppose making human babies by cloning, and Poo saidsociety would ban it for ethical reasons.——————————
In this undated photo provided by the Chinese Academy of Sciences, clonedmonkey Zhong Zhong sits with a fabric toy. Photo: AP——————————
Instead, he said, the goal is to create lots of genetically identicalmonkeys for use in medical research, where they would be particularlyvaluable because they are more like humans than other lab animals such asmice or rats.
The process is still very inefficient – it took 127 eggs to get the twobabies – and so far it has succeeded only by starting with a monkey fetus.The scientists failed to produce healthy babies from an adult monkey,though they are still trying and are awaiting the outcome of somepregnancies. Dolly caused a sensation because she was the first mammalcloned from an adult.
The procedure was technically challenging. Essentially, the Chinesescientists removed the DNA-containing nucleus from monkey eggs and replacedit with DNA from the monkey fetus. These reconstituted eggs grew anddivided, finally becoming an early embryo, which was then placed intofemale monkeys to grow to birth.
The scientists implanted 79 embryos to produce the two babies. Still, theapproach succeeded where others had failed. Poo said that was because ofimprovements in lab techniques and because researchers added two substancesthat helped reprogram the DNA from the fetus. That let the DNA abandon itsjob in the fetus, which involves things like helping to make collagen, andtake on the new task of creating an entire monkey.
The Chinese researchers said cloning of fetal cells could be combined withgene editing techniques to produce large numbers of monkeys with certaingenetic defects that cause disease in people. The animals could then beused to study such diseases and test treatments. The researchers said theirinitial targets will be Alzheimer’s and Parkinson’s.
Mitalipov, noting the Chinese failed to produce healthy babies from adultcells, said he suspects attempts to clone babies from a human adult wouldalso fail. “I don’t think it would be advisable to anyone to even thinkabout it,” he said.
Jose Cibelli, a scientist at Michigan State University, said it might betechnically possible someday, but “criminal” to try now because of thesuffering caused by the many lost pregnancies the process entails.
If the procedure became efficient enough in monkeys, he said, society couldface “a big ethical dilemma” over whether to adapt it for humans. The keystep of transferring DNA might be combined with gene editing to correctgenetic disorders in embryos, allowing healthy babies to be born, he said.
Of course, the familiar image of human cloning involves making a copy ofsomeone already born. That might be possible someday, but “I don’t think itshould be pursued,” said researcher Dieter Egli of Columbia University. “Ican’t think of a strong benefit.”
Henry Greely, a Stanford University law professor who specialises in theimplications of biomedical technologies, said the strongest argument he canthink of would be the desire of grieving parents to produce a geneticduplicate of a dead child. But he doubts that’s a compelling enough reasonto undertake the extensive and costly effort needed to get such a procedureapproved, at least for “decades and decades.”
Marcy Darnovsky, executive director of the Center for Genetics and Societyin Berkeley, California, called it unethical to subject that new child to“the psychological and emotional risks of living under the shadow of itsgenetic predecessor.” Human cloning could also require many women to donateeggs and to serve as surrogates, she said.
At the moment, because of safety concerns, federal regulators in the U.S.would not allow making a human baby by cloning, and internationalscientific groups also oppose it, said biomedical ethics expert Insoo Hyunof Case Western Reserve University in Cleveland.
People for the Ethical Treatment of Animals condemned the monkey-cloningexperiments.
“Cloning is a horror show: a waste of lives, time and money and thesuffering that such experiments cause is unimaginable,” PETA Senior VicePresident Kathy Guillermo said in a statement. – Agencies