Transplantation and Culture of Spermatogonial Stem Cells

Abstract

Spermatogonial stem cells (SSCs), also called postnatal male germline stem cells, continuously undergo self-renewal and produce daughter spermatogonia that commit to differentiation to spermatozoa, thereby maintaining spermatogenesis and fertility throughout postnatal life. Development of the SSC transplantation technique, in which donor testis cells from a fertile male are microinjected into the seminiferous tubules of an infertile male where SSCs reconstitute donor-derived spermatogenesis and restore fertility, provides a powerful means to unequivocally identify SSCs in a quantitative manner. SSC transplantation is a remarkable breakthrough for SSC research and has established a crucial foundation to study the biology of SSCs. In this chapter, we first describe the transplantation technique that allows characterization of SSCs and their niche, cryopreservation of the germline, and transgenesis. We subsequently describe SSC culture systems that establish a platform for studying SSCs in vitro and enormously enhance their biological value. SSC transplantation, culture, and cryopreservation were originally developed in mice and subsequently in rats, and have since then been extending to other species including domestic animals, endangered or rare species, and primates. Therefore, in the final section, we discuss potential applications of SSCs, for example, the transplantation technique and SSC culture, in human medicine.