For the first time in the world, the researchers were able to get mouse sperm from embryonic and induced pluripotent stem cells. The sperm was used for in vitro fertilization of the mice eggs, which, having been transplanted into mouse, gave rise to normal baby mice. The finding published in a special online release in the journal Cell can cast light on reproductive mechanisms and help find new ways of infertility treatment.
The researchers from Kyoto University created mouse sperm form stem cells in a number of stages. First, they used special proteins to turn stem cells into epiblast-like cells (cells similar to pregasrulating epiblasts at the early stage of embryo development). Then, having added another protein to these cells, they received primordial germ cells (PGCs), or sperm precursors. These PGCs were transplanted into the testicles of a sterile male mouse.
Ten weeks later, the researchers found that PGCs gave rise to normal sperm. The sperm was used for in vitro fertilization of mice eggs which were implanted into a female mouse. The latter gave birth to healthy baby mice. The offspring grew into fertile male and female mice.
In the experiment, the team used both embryonic and induced pluripotent stem cells to produce sperm. Both stem cell types were successfully turned into primordial germ cells. Now the team is aiming at producing sperm and egg cells in experiments on monkeys and other animals.
The researchers hope that creating primordial germ cells in numerous quantities could serve studying reproductive mechanisms and infertility causes. Still, given the differences in mouse and human organisms, the scientists are cautious as regards the possibility of creating sperm from induced pluripotent stem cells to treat infertility in humans.