Scientists at Stanford University have successfully managed to reprogram human skin cells and turn them into sperm cell precursors. Their findings, published in the journal Cell Reports, show that skin cells of infertile men can be changed into stem cells and take on the characteristics of primordial germ cells when implanted in mice. While the development falls just short of creating viable sperm cells that can fertilize an egg, the news gives hope to the roughly 9 percent of men in the US suffering from infertility.

The scientists harvested skin cells from three infertile donors and engineered them into induced pluripotent stem cells (iPSCs). Those cells were then placed inside the testes of lab mice, where they became germ-cell-like-cells (GCLCs). Skin cells from mice have already been coaxed into functioning sperm and eggs cells in the past, resulting in normal fertilization. However, as the researchers assert in their paper, the requirements for human gamete production are not perfectly understood. Now, even though the GCLCs are unable to support conception, the scientists are confident that the same technique can one day be used to create fertile cells.

The findings show the first time that cells from men with fertility problems could be used to create sperm precursors. Similar work at the University of Pittsburgh showed that germ-like cells could be created from fertile men in 2012. "Our results are the first to offer an experimental model to study sperm development," lead researcher Dr. Reijo Pera told The Telegraph. "It might even be possible to transplant stem-cell-derived germ cells directly into the testes of men with problems producing sperm." However, researchers did state that sons borne out of this future procedure would inherit infertility.