Scientists grow test-tube sperm capable of fertilising eggs

Researchers at Yokohama City University in Japan who used stem cells from mice and cultured sperm in the laboratory said their research is a "small but important step" towards curing male infertility.

The research also raised hopes that young boys who are left sterile by treatment for cancer will still be able to father their own children when they grow up, the Daily Mail reported.

For the research, the Japanese team led by Dr Takehiko Ogawa took slivers of testicular tissue from mice and added the right combination of proteins and other foods to trigger the production of sperm and nourish its growth.

The sperms were then used to fertilise eggs using IVF techniques which resulted in the birth of 12 baby mice. The pups -- which were both male and female -- went on to have families themselves.

Ogawa and colleagues, who detailed their work in journal Nature, said: "The obtained sperm resulted in healthy and reproductively competent offspring."

Although many scientists have tried to make sperm from testicular tissue in the test-tube, none has hit upon the right recipe until now.

The key to Dr Ogawa's success was patience: he kept mixing the chemicals in the lab until he found exactly the right recipe.

He also showed that the technique works on tissue that has been frozen. Now, he plans to test the technique on samples taken from men.

If successful, young boys could one day freeze samples ahead of chemotherapy or radiotherapy for cancer. Defrosted years later, the tissue could be used to generate sperm, allowing them to father children who are genetically their own, the researchers said.

In an accompanying article, US fertility and cancer experts welcomed the advance, saying: "Anti-cancer therapies can impair male fertility. Whereas men can opt to freeze their sperm before treatment, young boys don't produce mature sperm, so lack this choice. Work in mice offers hope for such patients."

However, they cautioned that the research is still at an early stage -- and while it is clear the baby mice produced from the test-tube sperm were fertile, it is unclear if they were healthy in other ways.

Dr Allan Pacey, a fertility expert at Sheffield University, also stressed that techniques that work in mice do not always work in people.

But, he added, "This is a very interesting study. To be able to 'grow' sperm in this way would be useful so that we could study the process of sperm production."