Germ cell transplantation in the male: animal studies with a human perspective

Germ cell transplantation has been developed in rodent models. The transfer of donor germ cells into the seminiferous tubules of mice leads to re-initiation of donor spermatogenesis in the host testis and restoration of fertility. Furthermore, cryopreservation of donor cells or culture of germ cells before the transfer is feasible. Xenologous transfer of rat and hamster germ cells results in the production of foreign gametes in the mouse testis. From a clinical perspective, this methodology has the potential to restore fertility in patients whose testes have been damaged due to oncological therapy. This review summarizes the existing data on animal models and introduces the first preclinical attempts for preserving germ cells in patients undergoing oncological treatment. As improved therapeutic regimens have markedly increased the life expectancy of oncological patients, it seems timely to develop improved strategies for restoring the maximum quality of life after recovery from the disease. The loss of fertility is one of the most problematic negative side effects in young male oncological patients. Germ cell transplantation offers the potential for protection of the male germ line during gonadotoxic therapy and restoration of fertility.