Sperm and eggs grown from stem cells

The shortage of donated eggs and sperm for fertility treatment could be solved after British scientists found they can both be grown from laboratory stem cells.

The shortage of donated eggs and sperm for fertility treatment could be solved after British scientists found they can both be grown from laboratory stem cells.

But some specialists warned the discovery raised serious ethical questions, saying it could mean that a single man could provide both the sperm and egg for fertility treatment, making him genetically father and mother of his child.

They also claimed the technique came close to human cloning, although scientists who conducted the study denied that.

Researchers from the Centre for Stem Cell Biology at the University of Sheffield studied six human embryonic stem cell (HESCs) lines taken from very early embryos that had been donated by couples undergoing IVF treatment.

HESCs are the building blocks of human development and turn into any type of cell, such as organs or tissue. But scientists have not been clear about when HESCs begin to differentiate into primordial germ cells (PGCs), which are the ancestral cells that eventually form sperm and eggs.

The Sheffield researchers allowed the human stem cells to develop into collections of cells called embryoid bodies, and then tested them to see which genes were active in them.

Within two weeks of development, a very small proportion of cells in the embryoid bodies had begun to "express" some of the genes found in PGCs.

Some also began to express proteins that are only found in maturing sperm, suggesting that human stem cells can develop into PGCs, and eventually eggs and sperm.

Dr Behrouz Aflatoonian, who led the research, said: "Ultimately, it might be possible to produce sperm and eggs for use in assisted conception treatments. This is a long way off, and we would have to prove that it was safe because, for example, the culture process may cause genetic changes.

"For some men and women, this would be the only route for producing sperm and eggs. It would not be reproductive cloning as fertilisation would involve only one set of gametes produced in this way, and a unique embryo would form."

One in seven couples in Britain experiences fertility problems, and about 7,000 a year are treated using donated eggs or sperm. Some couples are able to use their own eggs or sperm, but others with particular problems are reliant on donated samples.

Only 250 men and 1,100 women donate their sperm or eggs each year, meaning there is a drastic shortage.

There are also concerns that fewer people may be prepared to become donors after the rules governing anonymity changed, making it possible for children born as a result of fertility treatment to obtain details about their biological parents.