The attempts, using embryonic stem cells, however, did not yield viable germ cells until now. A research team at Kyoto University has succeeded in turning mouse embryonic stem cells into viable sperm precursor cells. Previous attempts focused on the creation of epiblast stem cells from regular epiblast cells in a mouse embryo. The epiblast stem cells were further cultured in a dish, in the hope that they could give rise to primordial germ cells and, eventually, sperm cells. The Kyoto group cultured embryonic stem cells in cocktails of growth-factors and proteins, which led to epiblast-like cells that could be used to generate primordial germ cells.
A team at Kyoto University first turned mouse embryonic cells into sperm, according to a study in the journal Cell. This had the effect of turning the embryonic cells into epiblast-like cells in a lab dish. For starters, the recipe used to transform the mouse stem cells into sperm will need to be modified to work with human embryonic stem cells.