Cryopreservation of testicular tissue in young cancer patients.

Cryopreservation of testicular tissue might benefit prepubertal boys who must undergo chemotherapy or radiotherapy. Cryopreservation of testicular tissue and testicular cells for intracytoplasmic sperm injection (ICSI) is feasible and widely applied. Testicular tissue from prepubertal boys can also be frozen, by applying techniques used with other tissues and with testicular tissue from adult men before ICSI. Good results have been obtained when propanediol is used as a cryoprotectant, but glycerol has also been used when freezing testicular tissue. Spermatogonia might also be isolated and cryopreserved as a cell suspension, though practical experience in humans is lacking. Transplantation of the frozen-thawed cells back to the testes after cancer treatment might result in restoration of spermatogenesis. Live offspring have been born to mice after transplantation of fresh, but not cryopreserved, testicular cells. Transplantation is technically feasible also in larger species, but to date no offspring have been born. Spermatogenesis in vitro would be an excellent option for boys with haematological malignancies who carry a risk of relapse after transplantation; however, at present the method is feasible only for the late stages of spermatogenesis.