Steve Connor of the The Independent, from Britain, tells us the history of cloning.
But first, the “good news:”
A technical breakthrough has enabled scientists to create for the first time dozens of cloned embryos from adult monkeys, raising the prospect of the same procedure being used to make cloned human embryos.
Attempts to clone human embryos for research have been dogged by technical problems and controversies over fraudulent research and questionable ethics. But the new technique promises to revolutionise the efficiency by which scientists can turn human eggs into cloned embryos.
It is the first time that scientists have been able to create viable cloned embryos from an adult primate – in this case a 10-year-old male rhesus macaque monkey – and they are scheduled to report their findings later this month.
The scientists will also demonstrate that they have been able to extract stem cells from some of the cloned embryos and that they have managed to encourage these embryonic cells to develop in the laboratory into mature heart cells and brain neurons.
Scientists who know of the research said it was the breakthrough that they had all been waiting for because, until now, there was a growing feeling that there might be some insuperable barrier to creating cloned embryos from adult primates – including humans.
The Oregon team, working with a group in China, has so far produced about 100 cloned embryos that have been transferred into around 50 female macaques, but none has resulted in a full-term pregnancy, he said.
“It’s possible that we’re still just having bad luck. We’re producing may be one in 20 or one in 30 cloned blastocysts that are ‘normal’ and capable of producing a pregnancy and we just haven’t got them into the animal recipient at the right time to allow implantation and pregnancy to occur,” Professor Wolf said.
“The focus now is going to be on therapeutic cloning and using the non-human primate as a paradigm for therapeutic cloning for what you might be able to do clinically,” he said.
“We’re the first to do it, although it’s a tainted subject because of the fraudulent research that came out of South Korea. One can never be sure but there may be some validity to what the South Koreans did. But this would now be the first documented therapeutic cloning in a primate,” he added.
A brief history of cloning
The monkey-cloning technique is the same basic procedure that resulted in Dolly the sheep. The nucleus of a healthy, unfertilised egg is removed and another nucleus from the mature skin cell of an adult animal is placed inside the egg. With careful timing and the use of electrical pulses, an embryo can be created which is a genetic clone of the skin tissue donor. It is possible to implant embryos created in this way into the womb to produce cloned animals. This so-called ‘reproductive cloning’ of humans is illegal in Britain and many other countries. However it has been applied to a range of animal species, including:
* Cow: Many domestic cattle have been successfully cloned. First attempt to clone an endangered species was Noah, a rare gaur ox, which was cloned in the US in 2001 but died 48 hours after birth
* Mouse: Cumulina was a common brown house mouse, cloned from adult cells at the University of Hawaii in 1997. She survived to adulthood and produced two litters, before dying in May 2000
* Horse: Called Prometea, the first cloned horse, born in Italy in May 2003
* Cat: A kitten called CopyCat was born in 2002 in Texas, and gave birth to three kittens by a natural father in September 2006
* Dog: Snuppy, born in South Korea. Doubts about its authenticity were dispelled by DNA tests. The group has also cloned two wolf cubs, called Snuwolf and Snuwolffy using the same procedure. Cloned Afghan hounds named Bona, Peace and Hope have also been born.