No abstract

Volume 31 -Issue 12 -2020 BMT, bone marrow transplantation; CED, cyclophosphamide equivalent dose; ChT, chemotherapy; FSH, follicle-stimulating hormone; RT, radiotherapy. a Adapted from Lee et al. 10 Table contains examples and is not a complete list.M. Lambertini et al.

The clinical and research questions identified and the ethical and legal issues raised are highly relevant to the multi-disciplinary teams developing treatment strategies to preserve the fertility of prepubertal and adolescent boys who have a high risk of fertility loss due to ablative interventions, trauma or genetic pre-disposition.

The present study demonstrates that spermatogonia are able to survive and proliferate after cryopreservation and long-term transplantation. Complete regeneration of normal spermatogenesis was not observed since, beyond the pachytene stage, no adequate characterization of germ cells was obtained. Further studies are thus required to investigate the differentiation potential of cryopreserved germ cells.

While additional evidence is required to define optimal conditions for ITT cryopreservation with a view to transplantation or IVM, the putative indications for such techniques, as well as their limitations according to disease, are outlined.

Through our orthotopic xenografting model, we have demonstrated the survival and proliferative activity of spermatogonia and Sertoli cells in cryopreserved immature human cryptorchid tissue. Testicular tissue banking may thus prove to be a promising technique for the preservation of fertility in prepubertal boys undergoing oncological treatments. As the stem cell niche is maintained, the cryopreserved tissue can potentially be used for future autotransplantation. In addition, whole tissue freezing does not exclude alternative clinical uses, including isolated cell transplantation after dissociation, selection and enrichment. However, as this work was done on cryptorchid tissue, studies on normal immature testicular tissue, involving longer grafting periods, are needed to demonstrate a differentiation capacity before clinical implementation. Ethical and safety issues should also be addressed.

ClinicalTrials.gov Registration ID: CRYOFONOV01.

The present study was supported by a grant from the Fonds National de la Recherche Scientifique de Belgique (grant Télévie N° 7. 4.572.09.F). The authors declare that there is no conflict of interest.