Dr. Michael West, of Advanced Cell Technology in Worcester, Massachusetts and his team have created a monkey embryo without the use of sperm that can be used to create stem cells. Through a process called parthenogenesis, stem cells were extracted from the embryo to make specialized tissues such as heart and brain material. ?These were fully developed cells that could have been used medically,? he says.
He and his colleagues used chemicals to cause a monkey egg to turn into an embryo that was allowed to grow to six cells. West says it may be possible to make human embryonic stem cells this way. Other experts say that this technique would work only with women of reproductive age who could provide the eggs and thus would not benefit males.
West says he making embryos through parthenogenesis may avoid ethical objections. However, George Bush and some members of Congress are opposed to all forms of human cloning. A bill to ban all human cloning has passed the United States House of Representatives, and the Senate is expected to take up the issue this year.
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Robert Lanza, also of Advanced Cell Technology, has grown functional kidneys using stem cells taken from cloned cow embryos. His team, working in collaboration with a group at Harvard University, turned the stem cells into kidney cells, and then grew them into a kidney shape. The two-inch-long mini-kidneys were then transplanted back into genetically identical cows, where they started functioning.
This raises the possibility of using stem cells taken from human patients with kidney failure to create new organs for transplant.
It?s not known whether these miniature kidneys are actually complete, functional organs. The kidney is a very complex organ, with an intricate supply of blood vessels that are key to its ability to filter blood.
British kidney experts are skeptical that ACT has re-created the kidney in its entirety. ?I?d be very surprised if they could recreate an organ with a very complex vascular [blood] system,? says one scientist. It is possible that the company made a simpler structure that could still produce urine, he says.
Lanza admits that his work is still in the early stages. ?It?s just a proof of principle that demonstrates that you can use therapeutic cloning to create a functional organ,? he says. ?There is obviously a considerable amount of work to be done before that could be applicable clinically.?
ACT attracted publicity in November, 2001 for its announcement that it had created the first human clones. These claims have been disputed by other scientists.
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