Japanese scientists use genes in ES cells to improve sperm generation for the first time
A Japanese research team led by Mitinori Saitou, a professor specializing in germ cell biology at the Kyoto University Graduate School of Medicine has found a new method of transforming embryonic stem cells to generate sperm faster and more efficiently. This finding that could lead to a clearer understanding of how sperm and ova are created. The new method follows the team’s announcement in 2011 that it had produced sperm from induced pluripotent stem (iPS) cells and ES cells for the first time. Under the original method using mice, ES cells were first transformed into cells called epiblasts (extraembryonic ectoderm). These, in turn, became primordial germ cells, which lead to the creation of sperm and ova.
When creating the primordial germ cells, the team added growth-factor messengers to the ES cells. The researchers’ latest study involved placing three newly discovered genes in the ES cells of the mice. This raised the efficiency in producing primordial germ cells to about 80 percent from the previous 10 percent.The new method also halved the period of creating primordial germ cells to about three days.The growth factors are considered a trigger that activates the three genes, they said. The team said it was the first time that so-called master cells, such as the ES cells, could be transformed into germ cells with the use of specific