Research team breeds mice from sperm derived from stem cells

A world first - Kyoto University research team led by researchers Mitinori Saitou and Katsuhiko Hayashi has succeeded in producing normal baby mice from eggs fertilized with sperm created from induced stem cells (iPS cells) --
The accomplishment, published recently in the U.S. journal Cell, could help cast light on the mechanisms of reproduction, as well as open new avenues of treatment for infertility.
Led by professor Michinori Saito, they created the sperm from iPS cells produced from mouse embryonic cells in a multi-stage process. The iPS cells were first treated with two types of protein and a special reagent to turn them into ones very similar internally to those of 4 to 6-day-old embryonic cells. The addition of another protein then transformed these cells into ones very close to sperm or ovum precursors called primordial germ cells.
Ten weeks after transferring these cells into the testicles of a sterile male mouse, the researchers confirmed they had become sperm. The sperm were used to artificially fertilize eggs then implanted in the womb of a female mouse, which gave birth to a normal litter.
(The team also successfully performed the experiment with embryonic stem cells, with both the embryonic cells and iPS cells producing sperm that led to healthy adult mice with normal reproductive capacities).
The first generation of mice to be born using the stem cell-derived sperm now has grandchildren, leading the researchers to state that the new technology to a success. The team will now focus on creating sperm and egg stem cells from other animals.
"If we can create a lot of these primordial germ cells in a test tube, we can make progress on research into reproductive mechanisms, and that relates directly to discovering the causes of human infertility," Saito said. "However, mice and humans are very different. Considerable amount of basic research is probably necessary before it becomes clear whether our latest result are directly applicable to humans….Application to humans and other primates still has a lot of technical and ethical challenges, but I hope research will be accelerated dramatically."


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