Human eggs grown in lab for first time by scientists in UK

Scientists at the University of Edinburgh have said they have succeeded in growing human eggs in the laboratory for the first time, offering new hope for fertility treatments.

Experts believe the latest development could not only help the understanding of how human eggs develop but open the door to a new approach to fertility preservation for women at risk of premature fertility loss such as those undergoing chemotherapy or radiotherapy.

While the process has previously been achieved with mice, it has proved difficult with human eggs.

"It's very exciting to obtain proof of principle that it's possible to reach this stage in human tissue. But that has to be tempered by the whole lot of work needed to improve the culture conditions and test the quality of the oocytes [eggs]," said Prof Evelyn Telfer, one of the researchers on the project.

"But apart from any clinical applications, this is a big breakthrough in improving understanding of human egg development," she said.

In the journal 'Molecular Human Reproduction', the researchers describe how they took ovarian tissue from 10 women in their late twenties and thirties and, over four steps involving different cocktails of nutrients, encouraged the eggs to develop from their earliest form to maturity. Of the 48 eggs that reached the penultimate step of the process, nine reached full maturity.

The process is still very inefficient with only 10 percent of eggs completing their journey to maturity. And the eggs have not been fertilised, so it is uncertain how viable they would be.

Work on mouse eggs, which was achieved 20 years ago, showed the technology could be used to produce live animals. Matching this achievement in human tissue could eventually be used to help children having cancer treatment.

Chemotherapy and radiotherapy can lead to making patients sterile. Women can freeze matured eggs, or even embryos if they are fertilised with a partner's sperm, before starting treatment but this is not possible for girls with childhood cancers.

It would be legal to fertilise one of the lab-made eggs to create an embryo for research purposes in the UK.

But the team in Edinburgh do not have a licence to carry out the experiment. They are discussing whether to apply to the UK's embryo authority or collaborate with a centre that already has one.