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Posted on Jun 23, 2005, 2 p.m.
By Bill Freeman
Belgian scientists said on Monday they have cloned the first human embryos from unripe eggs matured in the laboratory, an achievement that could help to overcome a stumbling block in stem cell research. Until now, scientists who have managed to clone human embryos have used donated mature eggs which are in short supply. But researchers at Ghent University Hospital in Belgium have demonstrated that immature eggs that are not suitable for fertility treatments can be grown in the laboratory and then be used to create embryos for stem cell research and therapeutic cloning to treat a range of diseases.
Belgian scientists said on Monday they have cloned the first human embryos from unripe eggs matured in the laboratory, an achievement that could help to overcome a stumbling block in stem cell research.
Until now, scientists who have managed to clone human embryos have used donated mature eggs which are in short supply.
But researchers at Ghent University Hospital in Belgium have demonstrated that immature eggs that are not suitable for fertility treatments can be grown in the laboratory and then be used to create embryos for stem cell research and therapeutic cloning to treat a range of diseases.
"We've created an alternative source for human eggs for cloning," Joisiane Van der Elst, one of the researchers, told a fertility meeting.
Stem cells are master cells that have the capability to grow into any type of cell in the body. Scientists believe stem cells could act as a type of repair system for the body.
Embryonic stem cells are currently derived from very early embryos left over from infertility treatments. Scientists are also trying to create very early human embryos to mine them for stem cells for therapeutic cloning.
In May, researchers at Seoul University in South Korea announced they had created batches of embryonic stem cells from nine patients. They used mature eggs harvested from human females to create the cloned embryos from which the stem cells were derived.
Van der Elst and her colleague Bjorn Heindryckx, who presented their research at a meeting of the European Society of Human Reproduction and Embryology, said about 10-15 percent of eggs retrieved during fertility treatments are too immature to be useful to patients. Most mature eggs are used for treatments.
"The availability of human oocytes (eggs) is a major obstacle at the moment for research into therapeutic cloning. Therefore, we consider this research important because it makes best use of more easily available biological material -- in this case, immature oocytes," said Heindryckx.
The Belgian scientists said the cloned embryos formed from the immature eggs grew to the 8-16 cell stage, which was too early to extract stem cells.
They are continuing their research to try to get the cloned embryos to the blastocyst stage when they can obtain the stem cells.
Although they still have a long way to go, the researchers said their ultimate goal is to develop treatments for patients who suffer from infertility.
"Our final goal is to use human therapeutic cloning for infertility treatment by creating artificial eggs and sperm for patients who are infertile because of absence or premature loss of eggs or sperm," Heindryckx said.
