“This demonstrates that you can go directly from stem cells to oocytes. I think that is exciting”, Petra Hajkova, a developmental epigeneticist at Imperial College London who was not involved in the study, tells The Scientist. The work, she notes, will help researchers explore the basic biology of oocyte development. In the future, says study coauthor Nobuhiko Hamazaki of Kyushu University, the research could aid in cloning endangered animals or helping women with mitochondrial diseases to have healthy children.
…“It’s believed that oocytes develop from germ cells, but we could make oocytes from non-germ cells”, he explains. “At first, I was so surprised that I could not believe my results, so I repeated the experiment again and again and when I got the same results, I was finally convinced.”…“I was initially in complete disbelief to see mouse stem cells so quickly and easily take the form of oocytes based on introducing just a handful of factors, but repeated experiments proved it was true”, said Nobuhiko Hamazaki, PhD, first author on the study reporting the results and assistant professor at Kyushu University at the time of the research. “To find that eight transcription factors could lead to such big changes was quite astonishing.”
…Richard Schultz, a cell biologist at the University of California, Davis, who was not involved in the study, says the work to identify the core set of transcription factors that can drive embryonic stem cells into a state where they look like oocytes is impressive. But the egglike cells don’t undergo meiosis, so they are not functional. “It’s a big step, but only 95% there. We haven’t gotten 100% there” to understanding the factors essential for maturation of germline egg cells to oocytes and then to viable eggs with half their chromosomes. Despite not working out the pathway to meiosis, the work “enabled us to produce a large number of oocytes. We believe that this technology can accelerate basic biological research on oocytes, which are still one of the most mysterious cell types”, Hamazaki says. He explains that the work could improve animal cloning because of the vast number of oocytes produced by the team’s technique…“Cytoplasm from oocytes is an invaluable resource in reproductive biology and medicine, and this method could provide a novel tool for producing large amounts of it without any invasive procedures”, commented Hayashi. “While the processes could still be much more complex for humans, these initial results in mice are very promising.”