A team of Japanese researchers has created mouse eggs from stem cells and has fertilised them using IVF to produce baby mice. It is the first time scientists have reported producing properly functioning eggs using this type of stem cell.
Dr Katsuhiko Hayashi and his team from Kyoto University used both embryonic stem cells and induced pluripotent stem cells developed from skin cells to produce germ cell-like cells in the laboratory. These cells were then grown with ovary cells and turned into eggs capable of fertilisation, which were transplanted back into adult mice to mature.
The researchers, who already created viable mouse sperm from embryonic mouse stem cells in an earlier study, then fertilised the eggs using IVF and in vitro maturation and implanted the embryos into a surrogate mouse, leading to healthy mouse pups. Not all of the embryos developed normally and of the eight mouse pups born, one reportedly died - but some of the others have gone on to produce offspring of their own.
'Combined with a previous study, our system serves as a robust foundation to investigate and further reconstitute female germline development in vitro, not only in mice, but also in other mammals, including humans', wrote the researchers.
If scientists are in future able to turn adult cells into sperm or egg cells in humans, then this could lead to fertility treatments being developed.
Robert Norman, professor for reproductive and periconceptual medicine at the University of Adelaide, Australia, who was not involved in the study, said: 'For many infertile couples, finding they have no sperm or eggs is a devastating blow. This paper offers light to those who want a child, who is genetically related to them, by using personalised stem cells to create eggs that can produce an offspring that appears to be healthy'.
'It also offers the potential for women to have their own children well past menopause raising even more ethical issues', he said.
Dr Hayashi warned that such technology is not likely to be used in humans for several years, however. 'I must say that it is impossible to adapt immediately this system to human stem cells, due to a number of not only scientific reasons, but also ethical reasons', he said.
this, the research has been welcomed by other members of the scientific
community. Dr Evelyn Telfer from the Institute of Cell Biology at the
University of Edinburgh, who was not involved in the study, told BBC News: 'It's an
absolutely brilliant paper - they made oocytes from scratch and got live
offspring. The science is quite brilliant. If you can show it works in human
cells it is like the Holy Grail of reproductive biology'. Dr Telfer admitted, however, that the work had 'no clinical relevance' until such work had been done.
The study was published in the journal Science.