STUDY QUESTION What clinical practices, patient management strategies and experimental methods are currently being used to preserve and restore the fertility of prepubertal boys and adolescent males? SUMMARY ANSWER Based on a review of the clinical literature and research evidence for sperm freezing and testicular tissue cryopreservation, and after consideration of the relevant ethical and legal challenges, an algorithm for the cryopreservation of sperm and testicular tissue is proposed for prepubertal boys and adolescent males at high risk of fertility loss. WHAT IS KNOWN ALREADY A known late effect of the chemotherapy agents and radiation exposure regimes used to treat childhood cancers and other non-malignant conditions in males is the damage and/or loss of the proliferating spermatogonial stem cells in the testis. Cryopreservation of spermatozoa is the first line treatment for fertility preservation in adolescent males. Where sperm retrieval is impossible, such as in prepubertal boys, or it is unfeasible in adolescents prior to the onset of ablative therapies, alternative experimental treatments such as testicular tissue cryopreservation and the harvesting and banking of isolated spermatogonial stem cells can now be proposed as viable means of preserving fertility. STUDY DESIGN, SIZE, DURATION Advances in clinical treatments, patient management strategies and the research methods used to preserve sperm and testicular tissue for prepubertal boys and adolescents were reviewed. A snapshot of the up-take of testis cryopreservation as a means to preserve the fertility of young males prior to December 2012 was provided using a questionnaire. PARTICIPANTS/MATERIALS, SETTING, METHODS A comprehensive literature review was conducted. In addition, survey results of testis freezing practices in young patients were collated from 24 European centres and Israeli University Hospitals. MAIN RESULTS AND THE ROLE OF CHANCE There is increasing evidence of the use of testicular tissue cryopreservation as a means to preserve the fertility of pre- and peri-pubertal boys of up to 16 year-old. The survey results indicate that of the 14 respondents, half of the centres were actively offering testis tissue cryobanking as a means of safeguarding the future fertility of boys and adolescents as more than 260 young patients (age range less than 1 year old to 16 years of age), had already undergone testicular tissue retrieval and storage for fertility preservation. The remaining centres were considering the implementation of a tissue-based fertility preservation programme for boys undergoing oncological treatments. LIMITATIONS, REASONS FOR CAUTION The data collected were limited by the scope of the questionnaire, the geographical range of the survey area, and the small number of respondents. WIDER IMPLICATIONS OF THE FINDINGS 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. STUDY FUNDING/COMPETING INTEREST(S) The work was funded by the European Society of Human Reproduction and Embryology (ESHRE).

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A European perspective on testicular tissue cryopreservation for fertility preservation in prepubertal and adolescent boys

Testicular function and fertility preservation in male cancer patients.

The majority of children, adolescents, and young adults diagnosed with cancer today will become long-term survivors. The threat to fertility that cancer treatments pose to young patients cannot be prevented in many cases, and thus research into methods for fertility preservation is developing, aiming at offering cancer patients the ability to have biologically related children in the future. This paper discusses the current status of fertility preservation methods when infertility risks are related to surgical oncologic treatments, radiation therapy, or chemotherapy. Several scientific groups and societies have developed consensus documents and guidelines for fertility preservation. Decisions about fertility and imminent potentially gonadotoxic therapies must be made rapidly. Timely and complete information on the impact of cancer treatment on fertility and fertility preservation options should be presented to all patients when a cancer treatment is planned.

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Fertility preservation during cancer treatment: clinical guidelines

BACKGROUND
Approximately 80% of childhood cancers can now be cured but a side effect of treatment results in about one-third of the surviving boys being infertile or severely subfertile when they reach reproductive age. Currently, more than 1 in 5000 men of reproductive age who are childhood cancer survivors suffer from this serious quality of life problem. It is possible to obtain a testicular biopsy before treatment to preserve the spermatogonial stem cells (SSCs) of the male by cryopreservation, but the results of long-term storage of SSCs on their subsequent functional ability to generate normal offspring has not been examined in any mammalian species. Moreover, it will be necessary to increase the number of these cryopreserved SSCs to remove any contaminating malignant cells and assure regeneration of spermatogenesis.

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Fertile offspring derived from mouse spermatogonial stem cells cryopreserved for more than 14 years

Chromosomal analysis of 240 spermatozoa from 18 normal men was performed using in vitro fertilization of zona-free golden hamster eggs. The frequency of chromosome abnormalities in this population was 9.2% (22/240). Of the abnormal complements, 18 were aneuploid (13 hyperploid and five hypoploid) and four had a chromosome break. The sex ratio of Y-bearing to X-bearing sperm was .68. The frequency and type of sperm chromosome abnormalities is compared with those seen in spontaneous abortions.

Direct chromosomal analysis of human spermatozoa: Preliminary results from 18 normal men

BACKGROUND Sperm banking is a suitable procedure to prevent infertility after cancer therapy in male adolescents. We evaluated the feasibility of semen preservation in 156 adolescents aged between 13 and 20 years and then we assessed fertility outcome after treatment. METHODS Age, urogenital history, indications for cryopreservation, histological diagnosis and semen parameters were recorded. Fertility status after treatment was assessed by a questionnaire addressed to those patients who had utilized sperm storage. Post-treatment semen analysis was performed for 22 patients. RESULTS Cryopreservation was possible in 88.5% of cases. Azoospermia was detected in 2.6% of the patients at the time of diagnosis. Malignant disease accounted for 84% of our male adolescents. In this type of disease, semen parameters were significantly altered only among patients with metastatic malignant bone tumour. After treatment, nine patients presented azoospermia, five patients achieved pregnancy spontaneously, two achieved it after assisted reproductive technique using fresh ejaculated spermatozoa and one following sperm donation. Three failed with cryopreserved sperm. CONCLUSIONS Semen cryopreservation is possible for most adolescents and, regardless of disease type, may be a means of preserving fertility prior to gonadotoxic treatment that might impair the spermatogenesis process.

Fertility preservation in adolescent males: experience over 22 years at Rouen University Hospital

Chromosome meiotic pairing during male meiosis is a major event for chromosome segregation during anaphase I and spermatogenesis normal process. Chromosome non-disjunctions responsible for aneuploidy in male gametes can be observed during the first and the second meiotic divisions. The analysis of sperm nuclei chromosome constitution is a major and indirect tool for assessing male meiotic non-disjunctions and the genesis of chromosomal abnormalities. This evaluation has been performed initially by the human sperm/hamster oocyte fusion assay and more recently by fluorescence in situ hybridisation (FISH). Therefore, male populations with increased risk of aneuploidy for their progeny could be identified before entering an in vitro fertilization procedure, and depending on the potential risk a preimplantation or prenatal genetic diagnosis could be performed. For males with constitutional chromosome abnormalities, a specific genetic counselling could also be proposed.

Anomalies chromosomiques du spermatozoïde

Purpose:
Fluorescence in situ hybridization (FISH) using whole-chromosome paint probes was performed to evaluate disomy and diploidy frequency for chromosomes 1, 18, 19, and 22 in human sperm nuclei.
 Methods:
 Ten subjects of proven fertility and normal spermatic parameters were included in the study. A dual-color FISH method was carried out.
 Results:
 A total of 157,896 spermatozoa was scored. The mean frequencies of disomic sperm for chromosomes 1, 18, 19, and 22 were 0.22% (range, 0.19 to 0.28%), 0.24% (range, 0.14 to 0.37%), 0.22% (range, 0.17 to 0.30%), and 0.25% (range, 0.21 to 0.29%), respectively. The mean frequency of diploidy was 0.14% (range, 0.09 to 0.18%). No interindividual and interchromosomal variations in the aneuploidy frequency were observed between the different subjects.
 Conclusions:
 FISH with whole-chromosome paint probes provides a novel and efficient approach for disomy assessment in human sperm nuclei.

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V. Duchesne

Papers

Fertility preservation in adolescent males: experience over 22 years at Rouen University Hospital

Anomalies chromosomiques du spermatozoïde

Fluorescence In Situ Hybridization with Chromosome Paint Probes: A Novel Approach To Assess Aneuploidy in Human Sperm Nuclei