British researchers say they've used stem cells to create primitive forms of eggs and sperm, an accomplishment that could improve our understanding of both fertility problems and diseases related to aging.
Scientists at the University of Cambridge have reported using human embryonic stem cells to produce primordial germ cells, precursors of eggs and sperm.
Stem cells in a developing embryo can develop into any type of body cell.
"The creation of primordial germ cells is one of the earliest events during early mammalian development," says Naoko Irie, first author of the study published in the journal Cell. "It's a stage we've managed to recreate using stem cells from mice and rats, but until now few researches have done this systematically using human stem cells."
The same laboratory procedure can change adult skin tissue into egg and sperm precursors, raising the possibility of creating mature egg or sperm cells genetically matched to patients, the researchers say.
While using artificial egg or sperm cells to treat infertility in couples is currently prohibited in Britain by law, were the law to be revised skin cells could potentially be collected from patients and modified into genetically identical eggs or sperm to be used in IVF therapies, they point out.
"It's not impossible that we could take these cells on towards making gametes, but whether we could ever use them is another question for another time," research leader Axim Surani says.
Although use of the technique in humans remains hypothetical, there have already been successes in animal studies.
In 2002, U.S. researchers produced male and female baby mice from male stem cells, and 2012 Japanese scientists used stem cells to create mouse eggs and used them to make mouse pups.
In the Cambridge study, the researchers were able to turn about half the embryonic stem cells in their laboratory dishes into egg and sperm precursors, using natural chemical known as growth factors to push the stem cells in the desired developmental direction.
"It's remarkably fast," says Surani, who led the Cambridge team working in collaboration with the Weizmann Institute in Israel.
"We can now take any embryonic stem cell line and once we have them in the proper conditions, we can make these primordial cells in five to six days."
In addition, the likely ability to create immature eggs and sperm from skin cells means researchers might be able to see how sperm and eggs develop differently in healthy versus infertile people, Surani says.
"This is really the foundation for future work," he says.
Read more: EU Ruling Opens Doors for Stem Cell Patents
