Autologous spermatogonial stem cell transplantation in man: current obstacles for a future clinical application.

Fertility preservation is becoming an important issue in the management of the quality of life of prepubertal boys undergoing cancer treatment. At present, the only theoretical option for preservation of fertility in these boys is the preservation of the spermatogonial stem cells for autologous intratesticular stem cell transplantation. In animal models, this technique has shown promising results. However, before translation to the clinic, some major concerns should be evaluated. Improving the efficiency of the technique is one of the first goals for further research, besides evaluation of the safety of the clinical application. Also, the cryopreservation of the spermatogonial stem cells needs extra attention, since this first step will be crucial in the success of any clinical application. Another concern is the risk of malignant contamination of the testicular tissue in childhood cancer patients. Extensive research in this field and especially on the feasibility of decontaminating the testicular tissue will be inevitable. Another important, though overlooked, issue is the prevention of damage to the testicular niche cells. Finally, xenografting and in vitro proliferation/maturation of the spermatogonia should be studied as alternatives for the transplantation technique.