Behind the Headlines: Can lab-grown sperm restore fertility?

Sperm grown in vitro could lead to new treatments for infertile men, writes Emma Baines.

What is the story?

Men may soon be redundant, according to media reports claiming that a breakthrough in stem cell technology meant people would soon be able to 'grow their own sperm'.

The papers reported that seven baby mice had been born from eggs fertilised by artificial sperm grown from stem cells. Previous attempts to produce live animals using artificially grown sperm had all failed.

The technique offers the hope of a cure for male infertility, the reports said, because men who do not produce enough sperm may be able to grow it artificially.

What is the research?

The media reports are based on a study which showed for the first time that sperm grown in vitro from embryonic stem cells are capable of fertilising eggs and producing live offspring.

The researchers, led by Dr Karim Nayernia, of the Institute of Human Genetics at the University of Gottingen in Germany, genetically altered mouse embryonic stem cells so that they differentiated into male germline stem cells capable of developing into adult sperm.

When the researchers injected these lab-grown sperm cells into mouse eggs in vitro, the sperm fertilised the eggs and embryos started to form.

The researchers transferred 65 of these embryos at the two-cell stage into the oviducts of female mice to see how they would develop. In 12 cases, this transplantation resulted in a live birth. However, the pups born from the artificially-produced sperm were either smaller or larger than controls and died prematurely.

The researchers concluded that being able to grow viable sperm in the lab would be useful in research on the cellular mechanisms that can lead to male infertility.

What did the researchers say?

Professor John Burn, head of the Institute of Human Genetics at the University of Newcastle Upon Tyne, where the research was carried out, said that although the media had given the impression that a cure for male infertility was imminent, there were many problems that would need to be ironed out before the technique could be used safely in humans.

'This finding could lead to new ways of treating male infertility in the future, but stem cell fertility treatments are still a very long way down the line.'

He said that there were many safety issues that would have to be addressed before researchers could even think about using this technique in humans.

'These sperm did not produce normal offspring. They were either too small or too big, which means the foetal growth control mechanism was not working.

'Obviously, until we iron out these sorts of problems, this technique could not be used in humans,' he said.

'This is an important step forward in clarifying the mechanism of sperm production but, in terms of treating people, it is not going to make any difference.'

What do other experts say?

Dr Allan Pacey, senior lecturer in andrology at the University of Sheffield and secretary of the British Fertility Society, agreed that this technique was a good research tool.

'It offers a solution to the problem of how to study sperm production when it naturally occurs deep in the testicle, where it is very hard to observe.

'We are now going to be able to study lots of the critical events in producing sperm. This may shed light on why some men just do not produce sperm and why others do not produce enough.'

But he added that even if the safety problems were solved so that babies born using the artificially grown sperm were always healthy, it might still never be used as a fertility treatment.

'This technique relies on stem-cell technology and many people find this morally or ethically difficult,' he said.

The consultation on the government's review of the Human Fertilisation and Embryology Act, which closed last year, included a question on whether artificial gametes should be allowed in fertility treatment.

'It is possible that the government will say that they should not be used in this way, so it may well be that the use of this technology in the UK for treatment purposes will ultimately be banned,' said Dr Pacey.


- Researchers in Newcastle have used mouse sperm grown in a test tube to produce IVF offspring.

- Mice born using the technique were sick and died prematurely.

- The ability to grow sperm in vitro could help researchers find the causes of male infertility.

- The IVF process used in the experiment is not safe for use in humans.

- The stem-cell technology involved could soon be illegal for use in fertility treatment.

"First sperm from stem cells raises fertility hope" - The Guardian
"New hope for infertile men" - Daily Mail
"Is this the end of men?" - The Sun

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