(AFP) – Nov 14, 2007
PARIS (AFP) — Scientists said Wednesday they had created the world's first cloned embryo from a monkey, in work that could spur cloning of human cells for use in medical research.
In a paper published online by the British journal Nature, a team in the US said they had created cloned embryos of rhesus macaques, using the same method that famously led to Dolly the Sheep and other genetically duplicated animals.
It is the first time that this technique has been successfully used to create cloned primate embryos.
The group generated two lines of embryonic stemcells from the embryos, according to the research headed by Shoukhrat Mitalipov of the Oregon Health and Science University in Beaverton, Oregon.
Dolly, the world's first cloned animal, was created in 1996, by using so-called somatic cell nuclear transfer (SCNT) in which the genetic core of an egg is removed and replaced with the nucleus of an adult cell.
The egg is then stimulated with chemicals or a jolt of electricity to prompt its division.
The list of other cloned creatures using SCNT includes mice, pigs, cats, cows and dogs.
Until now, though, there has been no cloned primate, for researchers have encountered obstacles that cause cell development to be catastrophically flawed.
Work on primate cloning has also stirred controversy among ethicists, who say it could open the door to cloning human beings, not just cells. In an exceptional move, Nature said it moved forward the release of the paper because of "continuing speculation."
Researchers distinguish between "reproductive cloning" of humans, in which a putative cloned baby would be born and "therapeutic cloning," in which only cloned cells would be used for medical reasons and no baby would result.
Helen Wallace of Genewatch UK, a British group that monitors cloning and other activities in biotechnology, said the breakthrough announced on Wednesday would cause "a real worry" in some quarters that it would tempt a renegade scientist to create a cloned baby.
"The clear risk of an experiment [in human reproductive cloning] is of a deformed baby and maternal suffering," she told AFP in a phone interview.
"In Britain, we don't think that the technology is going to go that far because there are laws against reproductive cloning," she said. "However, in most countries around the world, there are no legal safeguards."
Stemcells are immature cells that develop into the specific tissues of the body.
Embryonic stemcells have the highest capability of all, because they can differentiate into any tissue. Scientists hope to be able to coax these cells into one day becoming replacement tissue for organs that are damaged or diseased.
Transplanted cells from a donor, though, run the risk of being attacked as intruders by the patient's immune system. By creating stemcells that are programmed with the patient's own DNA the risk of rejection would be skirted.
Mitalipov's team said they collected 304 eggs, also known as oocytes, from 14 female rhesus macaques.
The donor nucleus came from skin cells taken from an adult male monkey housed at the Oregon National Primate Research Center.
The claim that the stemcells were an exact DNA copy of the donor monkey's genetic code was validated independently by a team led by David Cram of Monash University in Melbourne, Australia.
That confirmation comes on the heels of a scandal surrounding earlier claims on cloning. In 2004, South Korean scientist Hwang Woo-suk announced he had created 30 cloned human embryos from which he derived stemcells, but his data turned out to be fake.
In a commentary published in Nature, British scientist Ian Wilmut -- Dolly's "father" -- and colleague Jane Taylor of the Centre for Regenerative Medicine in Edinburgh, Scotland, said the new advance's brightest benefits may lie not in creating replacement tissue from stemcells but in unlocking basic knowledge about inherited disorders.
By making patient-specific cells, doctors could obtain cells whose genome would provide a telltale of a disease. These cells could be compared with healthy counterparts to see what is wrong, and a library of drugs could then be screened to see if a treatment is available.
"Ultimately, this approach might lead to treatments for neurodegenerative diseases, some cancers and psychiatric disorders," the pair said.
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