The application of biomarkers of spermatogonial stem cells for restoring male fertility.

Spermatogonial stem cells (SSCs) are defined by their ability to both self-renew and produce differentiated germ cells that will develop into functional spermatozoa. Because of this ability, SSCs can reestablish spermatogenesis after testicular damage caused by cytotoxic agents or after transplantation into an infertile recipient. Therefore, SSCs are an important target cell for restoring male fertility, particularly for cancer patients who have to undergo sterilizing cancer therapies. In the mouse, the identification of SSC markers allows for the isolation of a highly enriched population of stem cells. This enriched stem cell population can be expanded in culture for an indefinite period of time, cryopreserved, and transplanted into infertile recipients to restore fertility. Thus, the identification of markers and the establishment of a long-term culture system for human SSCs will be crucial for realizing the potential of these cells in a clinical setting. In this article, we focus on the markers that have been identified for mouse SSCs and discuss how human SSC markers may be used in the restoration of fertility.