BEIJING: Scientists in China have created the
First monkeys cloned by the same
process that produced
Dolly the sheep more than 20 years ago, a breakthrough
that could boost medical research into human diseases.
The two long-tailed macaques (Macaca fascicularis) named Hua Hua and Zhong Zhong were born at the Chinese Academy of Sciences (CAS) Institute of Neuroscience in Shanghai, and are the fruits of years of research into a cloning technique called somatic cell nuclear transfer.
?The barrier has been broken by this work,? co-author Muming Poo, director of the Institute of Neuroscience of CAS Center for Excellence in Brain Science and Intelligence Technology, told AFP.
Until now, the technique has been used to clone more than 20 different animal species, including dogs, pigs and cats, but primates have proven particularly difficult.The birth of the now six and eight-week old macaque babies also raises ethical questions about how close scientists have come to one day cloning humans.
Humans could be
cloned by this technique, in principle, said Poo, though this team?s focus was on cloning for medical research.One day, the approach might be used to create large populations of genetically identical
monkeys that could be used for medical research ? and avoid taking
monkeys from the wild.
?In the United States alone they are importing 30,000 to 40,000
monkeys each year by drug companies,? said Poo. ?Their genetic backgrounds are all variable, they are not identical, so you need a large number of monkeys. For ethical reasons I think having
cloned monkey will greatly reduce the (number of)
monkeys used for drug tests.?
Monkeys are commonly used in medical research on brain diseases like Parkinson?s, cancer, immune and metabolic disorders.?The method used for these experiments is similar to
that used to clone Dolly,? in 1996 but
With several ?updates,? said William Ritchie, an embryologist on the team
that cloned Dolly the sheep at the Roslin Institute of the University of Edinburgh.
The
process involves removing the nucleus from a healthy egg, and replacing it
With another nucleus from another type of body cell. The clone becomes the same as the creature
that donated the replacement nucleus.
?We tried several different methods, but only one worked,? said senior author Qiang Sun, Director of the Nonhuman Primate Research Facility at the Chinese Academy of Sciences Institute of Neurosciences.
?There was much failure before we found a way to successfully clone a monkey.?Adult donor cells were attempted, but those clones died within hours of birth.What worked as replacement nuclei were cells
that came from fetal connective tissue.
Poo said it took
First author Zhen Liu, a postdoctoral fellow, three years to perfect the procedure. ?The SCNT procedure is rather delicate, so the faster you do it, the less damage to the egg you have, and Dr Liu has a green thumb for doing this.?
Other
monkeys have been
cloned in the past, by a different and simpler technique called embryo splitting, which mimics how twins arise naturally.The
First primate ever
cloned this way was Tetra, a rhesus monkey born in 1999.
Embryo splitting can produce a maximum of four at a time, while the new technique could in theory clone far more.Still, the
process that produced Hua Hua and Zhong Zhong remains ?very inefficient and hazardous,? because the two babies were the only born from a group of 79
cloned embryos, said British scientists Robin Lovell-Badge, group leader of The Francis Crick Institute.
?While they succeeded in obtaining
cloned macaques, the numbers are too low to make many conclusions,? said Lovell-Badge, who was not involved in the study.?With only two produced it would have been far simpler to just split a normal early embryo into two, to obtain identical twins.? Nor do the findings, published in the US journal Cell, bring scientists any closer to human cloning, Lovell-Badge argued.
?This clearly remains a very foolish thing to attempt, it would be far too inefficient, far too unsafe, and it is also pointless.? Darren Griffin, professor of genetics at the University of Kent, greeted the paper
With ?cautious optimism? and called it ?very impressive? from a technical standpoint.
?The
First report of cloning of a non-human primate will undoubtedly raise a series of ethical concerns,
With critics evoking the slippery slope argument of this being one step closer to human cloning,? he added.?The benefits of this approach however are clear. A primate model
that can be generated
With a known and uniform genetic background would undoubtedly be very useful in the study, understanding and ultimately treatment, of human diseases, especially those
With a genetic element.?
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