Mums could be dads soon

London: Women could one day grow their own sperm, says a scientist who yesterday claims to have turned bone marrow into early-stage sperm cells.

His team is now studying how to grow fully fledged sperm from bone marrow as a means to restore fertility in young men who have undergone cancer treatments. It could be five years before trials start.

Prof Karim Nayernia and his colleagues have completed similar experiments with female mice. Within a few months, they expect to see if the method can be extended so that early-stage sperm can in principle be made from women, too. Along with cloning, this could mark the second technique that makes men redundant.

The derivation of "putative" early-stage sperm from four male volunteers was published yesterday in the journal Reproduction: Gamete Biology by Prof Nayernia of the Northeast England Stem Cell Institute, Centre for Life, Newcastle upon Tyne.

Some experts urged caution about his claims, questioning the safety of using sperm derived from stem cells, and one was sceptical about the idea of women making sperm. For the experiment, which was undertaken at Göttingen University in Germany, Prof Nayernia's team took bone marrow from male volunteers and isolated a "parent cell". These stem cells have been found to grow into other tissues such as muscle.

In laboratory tests, they persuaded the stem cells to develop. The resulting cells look ordinary but genetic markers suggested that they were partly-developed sperm cells.

Prof Nayernia said: "We're very excited about this discovery. Our next goal is to see if we can get the spermatogonial stem cells to progress to mature sperm." He is to ask for permission to carry out similar experiments with human bone marrow in Newcastle, where the Centre for Life unveiled the world's first cloned human embryos.

Genetic concerns

As for growing sperm from females, "we have evidence that it is possible, in the mouse at least".

Prof Nayernia is concerned that Britain could outlaw such treatments. A White Paper argued that the use of artificial eggs and sperm would "raise profound possibilities such as the creation of a child by combining the genetic material of two women".

Prof Harry Moore at the University of Sheffield said: "These manipulations can lead to permanent genetic changes, which would make them unsafe to use."