The prospect of all-female conception By Steve Connor, Science Editor
Women might soon be able to produce sperm in a development that could allow lesbian couples to have their own biological daughters, according to a pioneering study published today.
Scientists are seeking ethical permission to produce synthetic sperm cells from a woman's bone marrow tissue after showing that it possible to produce rudimentary sperm cells from male bone-marrow tissue.
The researchers said they had already produced early sperm cells from bone-marrow tissue taken from men. They believe the findings show that it may be possible to restore fertility to men who cannot naturally produce their own sperm.
But the results also raise the prospect of being able to take bone-marrow tissue from women and coaxing the stem cells within the female tissue to develop into sperm cells, said Professor Karim Nayernia of the University of Newcastle upon Tyne.
Creating sperm from women would mean they would only be able to produce daughters because the Y chromosome of male sperm would still be needed to produce sons. The latest research brings the prospect of female-only conception a step closer.
"Theoretically is it possible," Professor Nayernia said. "The problem is whether the sperm cells are functional or not. I don't think there is an ethical barrier, so long as it's safe. We are in the process of applying for ethical approval. We are preparing now to apply to use the existing bone marrow stem cell bank here in Newcastle. We need permission from the patient who supplied the bone marrow, the ethics committee and the hospital itself."
If sperm cells can be developed from female bone-marrow tissue they will be matured in the laboratory and tested for their ability to penetrate the outer "shell" of a hamster's egg - a standard fertility test for sperm.
"We want to test the functionality of any male and female sperm that is made by this way," Professor Nayernia said. But he said there was no intention at this stage to produce female sperm that would be used to fertilise a human egg, a move that would require the approval of the Human Fertilisation and Embryology Authority.
The immediate aim is to see if female bone marrow can be lured into developing into the stem cells that can make sperm cells. The ultimate aim is to discover if these secondary stem cells can then be made into other useful tissues of the body, he said.
The latest findings, published in the journal Reproduction: Gamete Biology, show that male bone marrow can be used to make the early "spermatagonial" stem cells that normally mature into fully developed sperm cells.
"Our next goal is to see if we can get the spermatagonial stem cells to progress to mature sperm in the laboratory and this should take around three to five years of experiments," Professor Nayernia said.
Last year, Professor Nayernia led scientists at the University of Gottingen in Germany who became the first to produce viable artificial sperm from mouse embryonic stem cells, which were used to produce seven live offspring.
His latest work on stem cells derived from human bone marrow suggests that it could be possible to develop the techniques to help men who cannot produce their own sperm naturally.
"We're very excited about this discovery, particularly as our earlier work in mice suggests that we could develop this work even further," Professor Nayernia said.
Whether the scientists will ever be able to develop the techniques to help real patients - male or female - will depend on future legislation that the Government is preparing as a replacement to the existing Human Fertilisation and Embryology Act.
A White Paper on genetics suggested that artificial gametes produced from the ordinary "somatic" tissue of the body may be banned from being used to fertilise human eggs by in vitro fertilisation.
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