It's Alive!

Researchers in Japan have turned murine embryonic stem cells into fully functioning sperm, which they've also used to fertilize mouse eggs in vitro, says 80beats' Joseph Castro. When the researchers implanted the embryos via surrogate mothers, the pregnant mice produced healthy offspring. The researchers, who published their work in Cell, created epiblast-like cells from a mixture containing embryonic stem cells and several growth factors and proteins, and then turned the epiblast cells into primordial germ cells, Castro says. They then injected those germ cells into the testes of sterile mice, and found the cells had morphed into normal-looking sperm. "There is still a long way to go before the work can be translated to people — the main hurdle will be figuring out how to make human sperm cells from induced pluripotent stem cells, which are often taken from adult skin cells and other tissue," Castro says, adding that while the researchers were also able to generate functional sperm from murine iPSCs, "the process was a lot less successful than when they used embryonic stem cells." Eventually, however, the researchers hope this work will help solve the problem of human infertility, he adds.