Scientists in Newcastle claim to have created artificial sperm in a laboratory for the first time, sparking major ethical concerns.
The research, carried out at the North East England Stem Cell Institute, involved the destruction of human embryos.
Although producing babies using artificial sperm or eggs is illegal, critics have warned the process could be “used and abused” to conceive children who did not know who their father was.
Professor Karim Nayernia, who led the team, said: “This is an important development as it will allow researchers to study in detail how sperm forms”.
He said the research aims to better understand the causes of infertility in men, and will not be used in fertility treatment to conceive children.
However, Sarah Norcross, Director of the Progress Educational Trust, an assisted conception and genetics charity, said the discovery “gives hope to males whose fertility is compromised and who wish to have a child who shares their genes”.
She added: “This would be a novel way to solve the shortage of donor sperm in the UK.”
Evan Harris MP, who tabled amendments on creating artificial sperm and eggs during the passage of the Human Fertilisation Embryology Act 2008, said: “While the Newcastle team is not seeking at present to use stem cell derived sperm as a treatment for infertility, it is clearly a possible future application.”
GP and lecturer in ethics Dr Trevor Stammers warned that the technology could be “used and abused” to create children who did not know who their father was.
Doubt has been cast on the validity of the research by other scientists.
Dr Allan Pacey, from the University of Sheffield, said he was unconvinced about the team’s claim to have produced spermatozoa – early-stage sperm cells.
He said there were characteristics of human sperm not described in the team’s report, and that their video of the cells “did not have sufficient resolution” for him to properly assess them.
Professor Azim Surani, a specialist in physiology and reproduction at the University of Cambridge, said: “These sperm-like cells made in a dish from embryonic stem cells are a long way from being authentic sperm cells.”