Japan — Researchers at Kyoto University reported for the first time the ability to efficiently create primordial mouse germ cell-like cells in a dish that had the capacity to go on to form viable sperm. They started from embryonic stem cells.

While other groups have generated primordial germ cells from both embryonic and induced pluripotent (iPS) cells, their processes were inefficient, generating few of the desired cells. These cells generally were not good at generating sperm.

The Kyoto team, led by Mitinori Saitou, used a three-step process. First they developed a very specific cocktail of three factors that were able to differentiate the stem cells into epiblast-like cells, a cell type that appears very transiently around Day 8 of embryo formation in mice. They next used a protocol they developed a couple years ago to mature those cells into primordial germ-like cells, then used molecular markers to select those cells in the culture that were most likely to have the ability to form sperm. Those cells were used for artificial insemination and resulted in the healthy births of 60 mice that were then able to produce their own offspring.

The study was published in the August 4 issue of Cell.

— Compiled from CIRM President's Science Update