Summary

Puberty blockers (drugs that pause puberty) are often called a reversible pause, but little is known about their effect on the testicles. Mayo Clinic researchers examined tissue stored from children having surgery to preserve fertility. All 16 born-male patients with gender dysphoria in their tissue bank had taken puberty blockers. Treated children's tissue showed mild to severe shrinking of the sperm-making tubes; one 12-year-old on a blocker plus oestrogen had 59% of tubes completely shrunken. Detailed cell tests on one 14-year-old after more than four years on blockers found sperm-forming cells stuck at an early stage, and computer models judged the tissue to be like a child's before puberty. The authors say this raises 'a potential concern' about full reversibility. It is an early, unchecked signal: few treated patients, mixed drugs, no follow-up after stopping, no fertility measure.

Key findings

• Dos 87 pacientes de um banco de tecido testicular infantil da Mayo Clinic, 16 (18%) tinham disforia de gênero. Todos os 16 haviam tomado bloqueadores da puberdade, e 9 (56%) os usavam no momento da cirurgia de preservação da fertilidade.
• Os medicamentos contados como 'bloqueadores da puberdade' incluíam bloqueadores verdadeiros (leuprolida, histrelina, triptorrelina), mas também estrogênio e outros medicamentos hormonais (medroxiprogesterona, espironolactona), tomados por 3 a 52 meses. A idade média na cirurgia foi de 12,5 anos.
• Todos os pacientes com disforia de gênero optaram por cirurgia para retirar tecido em vez de fornecer uma amostra de esperma, porque não queriam ou não conseguiam ejacular. 2 dos 9 pacientes tratados tinham anormalidades nos testículos quando examinados.
• Analisando cerca de 50 túbulos por doador em 19 doadores sem câncer, a densidade de células nos túbulos aumentava com a idade nas crianças não tratadas, mas não mostrava mudança com a idade nas tratadas. Um menino de 12 anos que tomou um bloqueador mais estrogênio por 14 meses tinha 59% dos túbulos completamente encolhidos, com minúsculos depósitos de cálcio.
• Testes genéticos detalhados em células individuais de um jovem de 14 anos após mais de 52 meses de tratamento (11.199 células, combinadas com dados públicos para 130.100 células) encontraram mais de 90% das células formadoras de esperma paradas em um estágio inicial, e estados incomuns nas células de sustentação que nutrem o esperma em desenvolvimento.
• Um modelo de computador treinado com apenas 10 pessoas (5 crianças antes da puberdade, 5 adultos jovens) avaliou o tecido do jovem de 14 anos tratado como semelhante ao de uma criança antes da puberdade. Os próprios autores dizem que o pequeno grupo de treinamento é uma grande limitação.
• Os autores concluem que o encolhimento e as células imaturas 'levantam uma possível preocupação' quanto à reversibilidade completa e à fertilidade futura. O estudo não testou a recuperação após a interrupção nem mediu a fertilidade.

Abstract

Spermatogonial stem cell (SSC) acquisition of meiotogenetic state during puberty to produce genetically diverse gametes is blocked by drugs collectively referred as 'puberty blocker' (PB). Investigating the impact of PB on juvenile SSC state and function is challenging due to limited tissue access and clinical data. Herein, we report largest clinically annotated juvenile testicular biorepository with all children with gender dysphoria on chronic PB treatment highlighting shift in pediatric patient demography in US. At the tissue level, we report mild-to-severe sex gland atrophy in PB treated children. We developed most extensive integrated single-cell RNA dataset to date (>100K single cells; 25 patients), merging both public and novel (52 month PB-treated) datasets, alongside innovative computational approach tailed for germ cells and evaluated the impact of PB and aging on SSC. We report novel constitutional ranges for each testicular cell type across the entire age spectrum, distinct effects of treatments on prepubertal vs adult SSC, presence of spermatogenic epithelial cells exhibiting post-meiotic-state, irrespective of age, puberty status, or PB treatment. Further, we defined distinct effects of PB and aging on testicular cell lineage composition, and SSC meiotogenetic state and function. Using single cell data from prepubertal and young adult, we were able to accurately predict sexual maturity based both on overall cell type proportions, as well as on gene expression patterns within each major cell type. Applying these models to a PB-treated patient that they appeared pre-pubertal across the entire tissue. This combined with the noted gland atrophy and abnormalities from the histology data raise a potential concern regarding the complete 'reversibility' and reproductive fitness of SSC. The biorepository, data, and research approach presented in this study provide unique opportunity to explore the impact of PB on testicular reproductive health.

Conclusion

The authors report mild-to-severe testicular tubule atrophy in puberty-blocker-treated children and an immature, prepubertal-like profile in the testis of a patient treated for more than 52 months. They conclude that, combined with the gland atrophy and histological abnormalities, this raises 'a potential concern regarding the complete reversibility and reproductive fitness' of spermatogonial stem cells. They also report rare post-meiotic (spermatid-like) cells in prepubertal tissue, irrespective of age, puberty status or treatment. They say the biorepository, data and research approach 'provide unique opportunity to explore the impact of PB on testicular reproductive health.'