Scientists have cloned a monkey -- the first non-human primate to be cloned -- in an experiment they hope will result in squads of genetically identical lab animals perfect for use in testing.
"Tetra," a bright-eyed rhesus macaque, was not made by the same method that made the world agog over Dolly the sheep.
While Dolly was cloned using nuclear transfer -- taking the nucleus out of an adult cell and using it to reprogram an unfertilized egg -- Tetra was made by splitting a very early embryo into four pieces.
"The birth of Tetra, a healthy female cloned from a quarter of an embryo, proves that this approach can result in live offspring," the researchers at the Oregon Regional Primate Research Center in Beaverton wrote in the journal Science.
The method is commonly used in animals such as cattle but had never before been used to create a monkey.
Gerald Schatten, who led the research, said the technique copied what nature does. "This is just artificial twinning," he said in an interview.
He said the purpose was to create laboratory animals.
"In order to move discoveries from the laboratory bench to a patient's bedside, we need to have genetically identical animals that would provide the information needed before these new therapies are tested on people," he said.
"Our contribution is to help provide the genetically identical models in which lifesaving cures can be perfected."
The method has been used to create clones of human embryos at least once. In 1993 Dr. Jerry Hall said he had cloned human embryos by splitting them, although he said he had destroyed them.
Very early on in development, an embryo can be split once or even twice and each piece will grow into a complete and separate embryo.
The method Schatten's team used is not very efficient yet. The researchers made 368 embryos by splitting 107 embryos into two or four pieces. They got four pregnancies in 13 tries. Only one survived -- Tetra, who came from one-fourth of an embryo.
They have four other pregnant monkeys which, if their babies make it, are due to start delivering in May.
Schatten said the embryo splitting method is better for many laboratory purposes than the cloning of an adult animal.
Scientists have learned that animals like Dolly cloned by nuclear transfer are not 100 percent clones, as they have genetic material both from the adult cell they were taken from, and from the egg that is hollowed out to make the clone.
"Now for the first time it is possible to have genetically identical monkeys," Schatten said. One thing they can be used to test is "nature versus nurture." "We could learn what the environmental effect is, separate from genetics," Schatten said.
"There are theories that maternal environment can result in an IQ drop of around 10 points. There are theories that influences in pregnancy have consequences very late in life."
For example, the children and even grandchildren of malnourished women may be prone to heart disease and diabetes.
"By taking say a set of triplets and putting them into three different moms ... you could have one mom listen to Mozart, another heavy metal, and maybe NPR (National Public Radio) for a third. And maybe you could have the very same baby born in the very same mom but in a sequential pregnancy. These are answers that we need today."
Schatten also intends to split the monkey embryos, letting one grow into a baby and keeping the other one frozen.
The frozen embryo could later be harvested for stem cells, the so-called master cells that can develop into any kind of cell in the body at all and which scientists hope one day to use as tissue transplants to treat diseases such as diabetes and Parkinson's.
Stem cells might also be used to grow entire organs for transplant. "The possibility of stem cell therapy could completely change the lives of children," Schatten said.
"No more diabetes, no more Alzheimer's, no more heart disease -- you could repair all these degenerative diseases."
