Suppression of spermatogenesis for cell transplantation in adult mice

Spermatogenesis occurs within the testis of adult males by a complex and ve ry well organized process. Breakthroughs in techniques such as cryopreserva tion and culture of spermatogenic cells and the maturation of these cells i n exogenous testes after transplantation renewed the interest in this proce ss. Transplantation of spermatogenic cells from a donor to a recipient anim al needs a preparatory step that consists in the elimination of the endogen ous population of spermatogenic cells. The most common method used to empty the seminiferous tubules is the treatment with busulfan (1,4-butanediol di methanesulfonate). Busulfan partially eliminates stem cells because of its alkylating nature, but a residual component of stem cells survives the trea tment and competes in the regeneration of the testis with transplanted cell s. Estradiol has also been used as an agent that causes a delay in the proc ess of spermatogenesis by altering its hormonal stimulation, although it do es not affect the spermatogonia population. Therefore, we have tested diffe rent treatments with busulfan, estradiol benzoate, and also an agonist of t he chorionic gonadotrophin-releasing hormone,leuprolide acetate, for the in hibition of endogenous spermatogenesis. We have found that a combination of estradiol, busulfan, and leuprolide can destroy the population of endogeno us spermatogenic cells without altering Sertoli cells and maintains the opt imal environment needed to allow the development of transplanted cells.