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Monday, January 21, 2008

US company claims ,cloned humans



US company claims cloned humans, made stem cells
A California company said on Thursday it used cloning technology to make five human embryos, with the eventual hope of making matched stem cells for patients. Stemagen Corp. in La Jolla, California, destroyed the embryos while testing to make sure they were true clones. But the researchers, based at a fertility center, said they believed their ready source of new human eggs would make their venture a success.


Other experts were skeptical about the claims, published in the journal Stem Cells. If verified, the team would be the first to prove they have cloned human beings as a source of stem cells, the master cells of the body.


There are several types of stem cells. Embryonic stem cells, made from days-old embryos, are considered the most powerful because they can give rise to all the cell types in the body.


The Stemagen team said they got five human embryos using skin cells from two adult men who work at the IVF center. They said they had painstakingly verified that the embryos were clones of the two men.


"We hope it is a bit of a turning point for many more studies," Andrew French, who led the research, said in a telephone interview.


They used a technique called somatic cell nuclear transfer, or SCNT, which involves hollowing out an egg cell and injecting the nucleus of a cell from the donor to be copied -- in this case, the skin cells from the men. It is the same technique used to make Dolly the sheep in 1996, the first mammal to be cloned from an adult. Researchers hope to use the technique to create tailor-made transplants of cells, tissue or organs for patients, treating injuries and diseases like juvenile diabetes.


"Since a significant percentage of couples undergoing fertility treatments appear willing to participate in this type of research, we believe the method described to obtain donated oocytes is a viable and ethically acceptable strategy," the researchers wrote.
MOST SUCCESSFUL SO FAR


Some cloning experts said the work appeared to be genuine.


"This is the most successful description so far of the use of the cloning techniques with purely human material. However, it is still a long way from achieving the goal of obtaining embryonic stem cells," said Robin Lovell-Badge of Britain's Medical Research Council's division of stem cell biology.


"I hope that the authors have the opportunity to continue their work and derive embryo stem cell lines," Ian Wilmut, who led the team that cloned Dolly and who is now at the University of Edinburgh, said in an e-mail.


The field is controversial for several reasons.


President George W. Bush opposes the use of human embryos to make stem cells and has vetoed bills from Congress that would expand federal funding of this research.


South Korean scientist Hwang Woo-suk made headlines when he was found to have faked key parts of a report that his team had used cloning technology to make human embryos in 2004.


"We need to be ultra-cautious after the Hwang scandal and not make the same mistake all over again," said Dr. Robert Lanza of Advanced Cell Technology, a Massachusetts company that is also trying to make human embryonic stem cells. "I'd really like to believe it, but I'm not sold yet," Lanza said.


Other teams have made stem cells they believe are similar to embryonic cells using a variety of techniques, including reprogramming a human egg cell alone, reprogramming ordinary skin cells into what are called induced pluripotent stem cells, or by taking one cell from a human embryo without harming the embryo
But most stem cell experts agree it is important to continue trying to make stem cells from embryos too.


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Human cloning
Human cloning is the creation of a genetically identical copy of an human being, human cell, or human tissue. The term is generally used to refer to artificial human cloning; human clones in the form of identical twins are commonplace, with their cloning occurring during the natural process of reproduction.


Although genes are recognized as influencing behavior and cognition, "genetically identical" does not mean altogether identical; identical twins, despite being natural human clones with near identical DNA, are separate people, with separate experiences and not altogether overlapping personalities. The relationship between an "original" and a clone is rather like that between identical triplets raised apart; they share nearly all of the same DNA, but little of the same environment. A lively scientific debate on this topic occurred in the journal Nature in 1997.[1] Ultimately, the question of how similar an original and a clone would be boils down to how much of personality is determined by genetics, an area still under active scientific investigation.
Techniques
There are no documented cases of successful human cloning. However, the most successful common cloning technique in non-human mammals is the process by which Dolly the sheep was produced. Dolly was one of 276 attempts, It is also the technique used by Advanced Cell Technology (ACT), the first company to successfully[2] clone early human embryos that stopped at the six cell stage. The process is as follows: an egg cell taken from a donor has its cytoplasm removed. Another cell with the genetic material to be cloned is fused with the original egg cell. In theory, this process, known as somatic cell nuclear transfer, could be applied to human beings.


ACT also reported its attempts to clone stem cell lines by parthenogenesis, where an unfertilized egg cell is induced to divide and grow as if it were fertilized, but only incomplete blastocysts resulted. Even if it were practical with mammals, this technique could work only with females. Discussion of human cloning generally assumes the use of somatic cell nuclear transfer, rather than parthenogenesis.


On January , 2008, Wood and Andrew French, Stemagen's chief scientific officer in California, announced that they successfully created the first 5 mature human embryos using DNA from adult skin cells, aiming to provide a less-controversial source of viable embryonic stem cells. Dr. Samuel Wood and a colleague donated skin cells, and DNA from those cells was transferred to human eggs. It is not clear if the embryos produced would have been capable of further development, but Dr. Wood stated that if that were possible, using the technology for reproductive cloning would be both unethical and illegal. The 5 cloned embryos, created in Stemagen Corporation lab, in La Jolla, were later destroyed
Claims of success in human cloning beyond the embryo stage
In 1978 David Rorvik claimed in his book In His Image: The Cloning of a Man that he had personal knowledge of the creation of a human clone. A court case followed. He failed to produce corroborating evidence to back up his claims; now regarded as a hoax.


Severino Antinori made claims in November, 2002 that a project to clone human beings had succeeded, with the first human clone due to be born [in January 2003.] His claims were received with skepticism from many observers.


In December 2002, Clonaid, the medical arm of a religion called Raëlism, who believe that aliens introduced human life on Earth, claimed to have successfully cloned a human being. They claim that aliens taught them how to perform cloning, even though the company has no record of having successfully cloned any previous animal. A spokesperson said an independent agency would prove that the baby, named Evá, is in fact an exact copy of her mother. Shortly thereafter, the testing was cancelled, with the spokesperson claiming the decision would ultimately be left up to Evá's parents.






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