Spermatogonial Stem Cells and Animal Transgenesis

Abstract

Spermatogonial stem cells (SSCs) are unipotent adult stem cells responsible for the maintenance of the spermatogenesis throughout the entire life of the male. We could say that the mammalian spermatogenesis is a classic adult stem cell-dependent process, sustained by self renewal and differentiation of SSCs. They are the only germline stem cells in adults. These cells can be found in the seminiferous tubule, lying near to the basement membrane. The SSC may choose to self-renewal or generate a daughter cell committed to differentiation. Studying SSCs provides a model to better understand adult stem cell biology and decipher the mechanisms that control SSC functions. It was reported that these cells hold the ability to colonize the seminiferous tubules after transplantation, restoring spermatogenesis. Besides the biomedical potential to perform studies of infertility in many species, SSCs present a promising application in biotechnology in the production of transgenic animals. This alternative route for transgenesis is of interest because a single male will generate by regular mate a variety of transgenic progenies. The production of a transgenic gonad can overcome the obstacles faced with the sperm-mediated gene transfer (SMGT) due to the high specialization of sperm. The use of SSC for transgenesis relies on targeting a much more undifferentiated germ cell and the potential permanent modification of the germ line. In this manner, this chapter aims to review the following topics regarding SSCs: (1) Mammalian spermatogenesis and SSCs; (2) Characterization of SSCs; (3) Isolation and in vitro culture of SSCs; (4) Transplantation of SSCs and animal transgenesis.