“This is a significant achievement that I believe will have a sustained and long-lasting impact on the field of reproductive cell biology and genetics,” says Amander Clark, a stem cell biologist at University of California, Los Angeles.
The stem cells in both cases are embryonic stem (ES) cells and induced pluripotent stem (iPS) cells. The former are taken from embryos and the latter are adult tissue cells that are reprogrammed to act like stem cells. In theory, both can produce all of the body’s cell types, yet most researchers have been unable to turn them into germ cells, precursors of sperm and eggs.
The Kyoto group, led by stem cell biologist Mitinori Saitou, found a process that works. As with the sperm, the group started with ES and iPS cells and cultured them in a cocktail of proteins to produce primordial germ cell-like cells. To get oocytes, or precursor egg cells, they then mixed the primordial cells with fetal ovarian cells, forming reconstituted ovaries that they then grafted onto natural ovaries in living mice. Four weeks and 4 days later, the primordial germ cell-like cells had developed into oocytes. The team removed the ovaries, harvested the oocytes, fertilized them in vitro, and implanted the resulting embryos into surrogate mothers. About 3 weeks later, normal mouse pups were born, the researchers report online today in Science.
“It is remarkable that one can produce oocytes capable of sustaining complete development starting with embryonic stem cells,” says Davor Solter, a developmental biologist at Singapore’s Institute of Medical Biology. Clark adds that the immediate impact of the work will be on understanding the molecular mechanisms involved in forming germ cells. Saitou says that with a bit more progress in understanding the complex interactions at work, they may be able to coax the cells through the entire oocyte development process in a lab dish. If successful, “we may be able to skip the grafting,” he says.
Read more at Wired Science
No comments:
Post a Comment