British scientists have made a major breakthrough with the discovery that both sperm and eggs can be grown from stem cells.
They say the discovery may in future solve the shortage of donated eggs and sperm needed for fertility treatment.
Some experts are claiming the technique comes too close to human cloning and are already cautioning that the discovery raises serious ethical questions.
They say that 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.
Researchers from the Centre for Stem Cell Biology at the University of Sheffield deny these claims.
The team studied six human embryonic stem cell (HESCs) lines taken from very early embryos that had been donated by couples undergoing IVF treatment.
These cell lines are the building blocks of human development and turn into any type of cell, such as organs or tissue. But scientists have been unclear about when HESCs begin to differentiate into primordial germ cells (PGCs), which are the ancestral cells that eventually form sperm and eggs.
In their study 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.
They found that a very small proportion of cells in the embryoid bodies, had within two weeks of development, begun to "express" some of the genes found in PGCs, and some had also begun to express proteins that are only found in maturing sperm, which suggested that human stem cells can develop into PGCs, and eventually eggs and sperm.
Lead researcher,Dr Behrouz Aflatoonian, says that it might in the future, be possible to produce sperm and eggs for use in assisted conception treatments. He says before that can happen the the culture process would have to be proven to be safe because, for example, the process may cause genetic changes.
Aflatoonian says that for some men and women, this could be the only way to produce sperm and eggs.He says 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.
In Britain one in seven couples has fertility problems, and about 7,000 a year are treated using donated eggs or sperm, while some couples are able to use their own eggs or sperm, for others with particular problems, are reliant on donated samples.
As only 250 men and 1,100 women donate their sperm or eggs each year, there is a drastic shortage.
Many experts are concerned that when the rules governing anonymity changed, making it possible for children born as a result of fertility treatment to obtain details about their biological parents, fewer people were prepared to become donors.
http://www.shef.ac.uk/
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