Researchers Turn Stem Cells Into Human Eggs

Researchers in China say they have managed to generate new eggs using stem cells from the ovaries of young and adult female mice, taking a step toward addressing problems of female infertility.

It is presently accepted in scientific circles that the production of eggs, known as oocytes, stops before birth for most species of mammals, including humans.

In an article published in the journal Nature Cell Biology, scientists in China said they found a way to generate new eggs using stem cells harvested from the ovaries of juvenile and adult female mice.

"The finding may have important implications in regenerative and reproductive medicine," they wrote.

Two other scientists, unrelated to the study, said the results were interesting but needed independent confirmation.

Led by Ji Wu from the School of Life Science and Biotechnology at Shanghai Jiao Tong University, the researchers said they isolated female germline stem cells (FGSC) from the ovaries of five-day-old and adult mice.

The cells were cultured for more than six months and then transplanted into the ovaries of infertile female mice, they said, adding that eighty percent of these mice went on to produce offspring after natural mating.

"These results suggest that oocytes can be regenerated in sterile recipient females by transplantation of FGSCs," they wrote.

Azim Surani, professor of physiology and reproduction at Gurdon Institute, University of Cambridge, who was not connected to the study said: "Sperm are produced continuously in men but the number of eggs in women is fixed at birth."

"This new study in mice now suggests that there are also stem cells present in ovaries that can be cultured in a dish, which upon transfer to ovaries can develop into viable eggs and give rise to offspring. This finding, if confirmed independently, could advance understanding of these ovarian stem cells and advance research on female infertility."

Another researcher who was also unrelated to the study, called for caution.

"A lot more work is needed to understand what these new cells really are, and to verify the findings and the claims," said Robin Lovell-Badge at the MRC National Institute for Medical Research in Britain.