Monkey see, monkey two - researchers clone macaques
TWO monkeys are the first primates to be cloned using the technique that created Dolly the sheep.
The technique brings the prospect of cloned human beings closer, but scientists caution there may be no good reason to create such clones and that ethical and legal questions need to be addressed.
More immediately, the technique will allow researchers to create whole labs full of genetically identical monkeys.
That could prove tremendously useful in scientific and medical research - for instance, allowing doctors to watch how specific treatments affect the genetic make-up of animals that are otherwise exactly the same.
The two identical long- tailed macaques - Zhong Zhong and Hua Hua - were born eight and six weeks ago at a laboratory in China. They represent the furthest reaches of cloning technology, genetically resembling each other entirely.
They aren't the first primates cloned, but the first produced using the single cell nuclear transfer technique.
It involves transferring cell nucleus DNA to a donated egg cell that is then prompted to develop into an embryo - the same process used for Dolly in 1996.
Previous work has relied on splitting embryos - the phenomenon that happens when twins are born. It can produce only four offspring.
The macaques came from one of 79 transfer attempts using different techniques. Scientists had some luck cloning monkeys using adult cells, but those were able to survive for only a few days.
The genetic symmetry of these monkeys means scientists could create a whole experiment's worth of monkeys, identical except for specific genetic changes they wanted to study.
"You can produce cloned monkeys with the same genetic background except the gene you manipulated,” said Dr Qiang Sun, who led the team that produced the research that was published in the journal Cell.
"This will generate real models not just for genetically based brain diseases, but also cancer, immune or metabolic disorders, and allow us to test the efficacy of the drugs for these conditions before clinical use.”
But the research has exposed fears about where it could lead. The scientists stress they did the work under strict international codes and co-author Muming Poo said the team was aware "future research using non-human primates anywhere in the world depends on scientists following very strict ethical standards”.
The breakthrough means it would theoretically be easier to clone a human, since primates and humans share so much of their make-up.
"While they succeeded in obtaining cloned macaques, the numbers are too low to make many conclusions, except that it remains a very inefficient and hazardous procedure,” said Robin Lovell-Badge from the stem cell biology and developmental genetics laboratory at the Francis Crick Institute.
"Because they are non-human primates, macaques are obviously evolutionary much closer to humans than other animals typically used in research, and the aim of the work was to use the cloning methods to allow production of genetically identical macaques to use in biomedical research, where confounding factors of genetic variability could otherwise complicate experiments.
"However, with only two produced it would have been far simpler to just split a normal early embryo into two, to obtain identical twins. The work in this paper is not a stepping stone to establishing methods for obtaining live born human clones. This clearly remains a very foolish thing to attempt, it would be far too inefficient, far too unsafe, and it is also pointless. Clones may be genetically identical, but we are far from only being a product of our genes.”
Any cloned human would require a great deal of work and probably produce someone very different from the person being cloned - the effects of people's upbringing and environment is just too strong to mean that it would be a matter of creating another version of a person.
"We do need to think about not only is it not acceptable, but it is a bit pointless anyway,” said Darren Griffin, professor of genetics at the University of Kent. "What are people trying to achieve if they attempted to do that?”
"Because realistically a clone would only be somewhat similar to the individual they came from. They would be less similar than an identical twin: they would have a different upbringing, born from a different womb, and brought up in a different era.”
Jose Cibelli, a cloning expert at Michigan State University in the US, says technically speaking, cloning a human could be possible in a matter of years.
"The genie's out of the bottle now,” he told National Geographic.
Zhong Zhong and Hua Hua appear to be growing and developing like normal monkeys.
Scientists expect more clones in coming months.