Advances in spermatogonial stem cell transplantation

Spermatogonial stem cell transplantation was first reported by Ralph Brinst er's laboratory in 1994. It has proven to be a technological breakthrough i n the study of both stem cells and Sertoli cell-germ cell interactions. Thi s technique can be used to transfer testicular stem cells successfully from one animal to another of the same species (referred to as syngeneic transp lants) and sometimes to an animal of a different species (xenogeneic transp lants). This transfer technique, combined with developments in cryopreserva tion, long-term culture, and the enrichment of stem cell populations makes more significant breakthroughs likely in the near future. Ultimately, the a pplication of spermatogonial stem cell transfer will allow transplantation of cultured stem cells manipulated genetically in vitro to give rise to fun ctional male gametes with an altered genotype. This achievement will have a pplications in basic science, human medicine, and domestic and wild animal reproduction. Although progress toward this goal has been swift, potentiall y significant barriers, such as the stable incorporation of genetic materia l into stem cells and immunological responses to the introduced germ cells, remain to be overcome. This article is a review of the scientific advances made since the initial report of successful transplantation in 1994.