New research from Stanford and Montana State University shows that stem cells made from the skin of adult, infertile men can be used to create primordial germ cells, which are cells that normally become sperm, when transplanted into the reproductive system of mice.
The findings hold the potential to shed light on the earliest steps of human reproduction and could lead to the development of future therapies for men diagnosed with azoospermia, the most severe form of male factor infertility, or those rendered sterile after cancer treatments. My colleague Krista Conger explains the work in a release:
The research used skin samples from five men to create what are known as induced pluripotent stem cells, which closely resemble embryonic stem cells in their ability to become nearly any tissue in the body. Three of the men carried a type of mutation on their Y chromosome known to prevent the production of sperm; the other two were fertile.
The germ cells made from stem cells stopped differentiating in the mice before they produced mature sperm (likely because of the significant differences between the reproductive processes of humans and mice) regardless of the fertility status of the men from whom they were derived. However, the fact that the infertile men’s cells could give rise to germ cells at all was a surprise.
Previous research in mice with a similar type of infertility found that although they had germ cells as newborns, these germ cells were quickly depleted. The Stanford findings suggest that the infertile men may have had at least a few functioning germ cells as newborns or infants. Although more research needs to be done, collecting and freezing some of this tissue from young boys known to have this type of infertility mutation may give them the option to have their own children later in life, the researchers said.
The findings were published today in Cell Reports.