Spermatogonial survival after grafting human testicular tissue to immunodeficient mice.

BACKGROUND The xenografting of pre-pubertal human testicular tissue to an immunodeficient mouse is a theoretical strategy for restoring fertility in childhood cancer patients, while circumventing the risk of malignant recurrence. This study aimed at comparing the grafting of pre-pubertal and adult murine testicular tissue, as well as that of human adult testicular tissue, to two immunodeficient recipients, i.e. Swiss Nude mice and SCID-NOD mice. MATERIALS AND METHODS In this study, we evaluated the survival of pre-pubertal and adult murine testicular tissues, and that of adult human testicular tissue after subcutaneous grafting to immunodeficient mice. RESULTS After allografting pre-pubertal testicular tissue pieces, meiotic cells were observed in 69.1% of the grafts, while complete spermatogenesis was observed in 30.9%. All grafts of adult murine testicular tissue and 59.5% of the adult human testicular grafts showed sclerosis. However, in 21.6% of the adult human testicular grafts, spermatogonia were still observed, with increasing sclerosis in time. No significant differences were observed between the two mouse models under evaluation. CONCLUSION After xenografting human adult testicular tissue to a recipient mouse, spermatogonia were maintained over a period of >195 days. However, in order to prove xenografting as a method for external germ line storage, the transplants should have a more immature developmental stage. Moreover, not only the developmental status of the tissue at the time-point of grafting, but also the structural organisation of the seminiferous epithelium, might influence the development of the testicular tissue.