Caution greets claim human sperm grown in lab

The Kallistem laboratory in Lyon said its finding paved the way for new methods of treating infertile men. Photo / Thinkstock

Human sperm cells have been grown in a laboratory in a breakthrough that could lead to a treatment for male infertility, scientists claim.

A French firm said it had produced "fully formed" sperm from basic reproduction cells.

The research has not yet been published in a peer-reviewed journal, and experts greeted the news with caution. However, if proven, the technique could offer hope to people who cannot have children.

The Kallistem laboratory in Lyon said its finding paved the way for new methods of treating infertile men.

Joyce Harper, professor of human genetics and embryology at University College London, said: "This is a great move forward - it is really exciting."

However, she added: "They have said that this is still early stages and we've got a long way to go, and that is absolutely correct. There are a number of studies that need to be done. The only way you can check if a sperm is really viable is if it fertilises an egg and goes on and develops into a baby."

Harper said most infertile men do produce sperm that can be extracted from their reproductive system as part of specialised treatment.

Kallistem's new treatment would be for those who do not produce any mature sperm at all, she added, although in these cases, the resulting cells would have to be checked to ensure they are "genetically normal".

Professor Allan Pacey, of the University of Sheffield, urged couples to treat the announcement with caution.

"This is a bold claim to make and we have had our fingers burned before.

"Until I see a peer-reviewed scientific publication showing unequivocally that this has been done, I have to remain sceptical."