Starting with skin cells rather than egg cells, Japanese researchers say they have generated eggs that led to healthy mouse pups capable of living normal lives and reproducing.
Leading stem cell researchers said the research, by Kyushu University in Japan, represented a huge landmark with potentially enormous human implications further down the road.
“This study represents a major accomplishment; it is very impressive indeed,” said Professor Azim Surani, of the University of Cambridge.
“It provides a substantial advance in our understanding of how artificial eggs might be made. One day this approach might be useful for women who have lost their fertility at an early age, as well as for improvements in more conventional infertility treatments,” added Professor Richard Anderson, of the University of Edinburgh.
For Dr Dusko, of King’s College London, the breakthrough was almost as significant as Dolly the sheep, the first mammal to be cloned from an adult cell, in 1996.
“This is not a Dolly the sheep moment yet, but it is close,” he said.
Professor Katsuhiko Hayashi and colleagues at Kyushu University created 11 healthy mice pups using tissue cells from the tail of a mouse. These were turned into stem cells which were then transformed into eggs in the lab and fertilised.
“We need to now carefully look at the quality of mouse artificial eggs. This kind of quality check will contribute to an application to humans in future,” said Prof Katsuhiko.
Brand new eggs
Because women are born with all their eggs they can struggle to conceive as they get older and their eggs age. But if eggs could be produced from human stem cells this problem should disappear because they would be brand new – while women born with a low number of eggs could also be helped, experts said.
But Prof Hayashi’s research is hugely significant, scientists said it could be many years before the technique is safe and reliable enough for humans – and cautioning it may never be applicable to humans.
The main stumbling block is that eggs take more than 10 years to fully develop after birth.
“There is a long way to go before these methods could be adapted and used in humans. It usually takes longer than a decade to have fully grown eggs in humans. Will it take this long to recapitulate the process in vitro, which would pose immense practical challenges?” said Prof Robin Lovell-Badge of the Francis Crick Institute.