Rat Spermatogonial Stem Cell-Mediated Gene Transfer

More than 20 years have passed since the advent of genetic manipulation of the mouse germline using cultures of pluripotent embryonic stem cells. Still, despite remarkable successes in the mouse, the application of stem cell cultures for transgenesis in other mammalian species has been comparatively nonexistent. By focusing on the laboratory rat as a widely popular model species in science, this chapter highlights several advantages of the spermatogonium as an alternative type of germline stem cell for transgenesis. Protocols for isolating, propagating, genetically modifying, and determining the germline transmission rates of spermatogonial cultures for the production of transgenic rats are introduced in detail. Although the full potential of spermatogonia has yet to be realized in animal genetics, this chapter illustrates how their application as novel germline vectors would open new doors to advance transgenic technology. Most notably, gene manipulations directly in the spermatogonium simplify production of germline founders while bypassing the intermediate production of chimeric progeny using micromanipulated embryos. Once experimental conditions for producing genetically modified animals using spermatogonial cultures are optimized, the approach holds the potential to facilitate targeted germline modifications by gene replacement, gene-insertion and/or restriction endonuclease technologies in a diversity of mammalian species.