ISSN 1662-4009 (online)

ESPE Yearbook of Paediatric Endocrinology (2022) 19 9.11 | DOI: 10.1530/ey.19.9.11 Andrology. 2022; 10: 279–290. PMID: 34628730.

Brief Summary: This multicentric prospective study performed an accurate evaluation of testicular tissue after frozen-thawing to investigate if this testicular tissue freezing (TTF) alters testicular architecture and integrity in pre-pubertal and pubertal boys with cancer. Promising histological outcomes were found.

Spermatogonial stem cells (SSCs) are the testicular cells most sensitive to chemo- and radiotherapy-induced damage. Sperm cryopreservation is easily performed in adolescents and young adults. Testicular tissue cryopreservation is more difficult in pre-pubertal and pubertal boys. Currently, testicular tissue freezing (TTF) is suggested before cancer treatment, especially in young patients with high-risk of fertility impairment, but there is very little data on the histological assessment and quality of (pre)pubertal testicular tissue before and after thawing. This study explored the impact on human testicular tissue of a controlled slow freezing (CSF) protocol without seeding previously developed in mice (1, 2).

This study included 87 boys (aged 6 months-16 years) with cancer diagnosis and relapse after remission or incomplete response to the initial treatment. All patients had received chemotherapy before TTF and were candidates to highly sterilizing treatments (i.e. conditioning for HSCT with either total body irradiation or myeloablative chemotherapy).

The most interesting result is that histological analysis conducted in 74 patients revealed that CSF without seeding technique was able to maintain seminiferous tubule architecture, integrity and concentration of spermatogonia, and expression of DNA replication and repair marker in spermatogonia and Sertoli cells. The global “cryodamage score” did not vary significantly according to patient’s age, pubertal stage or cancer types. Testicular tissue abnormalities were rare and similarly found on fresh tissue or after thawing, suggesting that they were generated by previous cancer treatment.

The capacity of human spermatogonia to differentiate after thawing was not analysed. The Authors had previously studied differentiation using testicular tissue grafting and in vitro maturation in mice. Sperm production was demonstrated in testicular tissue cryopreserved without seeding after allograft into nude mice or after in vitro spermatogenesis. Future research is needed to add clinical relevance to this promising technique confirming its feasibility and reliability in humans.

References: 1. Milazzo JP, Travers A, Bironneau A, et al. Rapid screening of cryopreservation protocols for murine prepubertal testicular tissue by histology and PCNA immunostaining. J Androl. 2010; 31: 617–30. 2. Uijldert M, Meißner A, de Melker AA, et al. Development of the testis in pre-pubertal boys with cancer after biopsy for fertility preservation. Hum Reprod. 2017; 32: 2366–72.

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