SPERM have for the first time been created in a laboratory, using stem cells. Experts said that the breakthrough – by British scientists – could have "monumental" consequences for infertile men.
Researchers saw the cells, which were treated with acid, begin to split and divide, then eventually push out a tail and begin to move.
The scientists behind the research said that, theoretically, the sperm could be used to fertilise eggs to produc
e human babies.
They emphasised, however, that this was not their intention, and highlighted that it was illegal in the UK.
Instead, they said, it would enable crucial research into infertility and could in the future lead to new treatments.
Professor Karim Nayernia, of Newcastle University, who led the research, said: "This understanding could help us develop new ways to help couples who suffer infertility, so they can have a child which is genetically their own.
"It will also allow scientists to study how cells involved in reproduction are affected by toxins; for example, why young boys with leukaemia who undergo chemotherapy can become infertile for life – and possibly lead us to a solution."
He called for the introduction of laws "sooner rather than later" to control how the research is used.
Prof Nayernia added that the artificial sperm would not mean "an end to men".
He explained that only male stem cells were successfully turned into fully mature, functioning sperm. Female stem cells only formed early-stage sperm.
The team also believe that studying the process of forming sperm could lead to a better understanding of how genetic diseases are passed on.
Dr Allan Pacey, senior lecturer in andrology at the University of Sheffield, was among scientists who were not convinced that fully formed sperm had been created by the team at Newcastle University.
He said that, while the cells possessed some of the features of sperm, he thought that they did not portray all the characteristics of "fully differentiated human spermatozoa".
However, if fully functioning sperm had been created, he said that the breakthrough would be "monumental".
And he said other countries did not have such strict legislation as the UK – meaning that, potentially, the sperm could be used overseas to create babies.
He said many would be "horrified" by the idea, but he would not be concerned if the procedure could be shown to be safe.
Prof Nayernia said they had no intention of producing humans "in a dish". He added: "This work is a way of investigating why some people are infertile and the reasons behind it. If we have a better understanding of what's going on it could lead to new ways of treating infertility."
One in seven couples has fertility problems.
Prof Nayernia believed the research could lead to new treatments, which could be on offer within about a decade to people such as young boys who had received chemotherapy that can leave them infertile.
The work is published in the academic journal Stem Cells and Development.
Big possibilities for research and human fertility – but I have yet to be convincedIF SPERM has been created from stem cells it would be monumental, opening up all kinds of research possibilities writes Dr Allan Pacey.
If sperm can be created in a dish you could do many experiments that you would never be able to do otherwise. You would be able to look at what happens as the sperm are being formed, which you could never do with sperm being created in a testicle, because once you take them out, the sperm production process cannot be maintained.
Creating sperm in the lab could theoretically be used to treat men with fertility problems. You could take cells from his testicles, grow them in the lab and maybe overcome whatever block is preventing them reaching maturity. The mature sperm could theoretically then be used in an infertility procedure.
You may never be able to cure someone, although if you discovered the reason why his sperm weren't forming properly, you might be able to add whatever factor was missing and his testicles might start producing sperm again.
But, as a sperm biologist of 20 years' experience, I am unconvinced from the data presented in this paper that the cells produced by Professor Nayernia's group from embryonic stem cells can be accurately called "spermatozoa".
While the cells they have produced may possess some of the distinctive genetic features and molecular markers seen in sperm, fully differentiated human spermatozoa have specific cellular morphology, behaviour and function that are not described in their paper.
Furthermore, because the structural elements of spermatozoa are very distinctive, I would need to see thin sections of their putative sperm taken with an electron microscope. If I could see that data, I might be more convinced.
• Dr Allan Pacey, senior lecturer in andrology at the University of Sheffield
