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

• Af 87 patienter i en Mayo Clinic-bank med børns testikelvæv havde 16 (18 %) kønsdysfori. Alle 16 havde taget pubertetsblokkere, og 9 (56 %) tog dem på tidspunktet for fertilitetsbevarende kirurgi.
• Lægemidlerne, der blev regnet som ‘pubertetsblokkere’, omfattede ægte blokkere (leuprolid, histrelin, triptorelin), men også østrogen og andre hormonlægemidler (medroxyprogesteron, spironolacton), taget i 3 til 52 måneder. Gennemsnitsalderen ved operationen var 12,5 år.
• Alle patienter med kønsdysfori valgte kirurgi til fjernelse af væv frem for at give en sædprøve, fordi de ikke ønskede eller kunne få udløsning. 2 af de 9 behandlede patienter havde testikelabnormiteter ved undersøgelsen.
• Ved at se på omkring 50 kanaler pr. donor hos 19 donorer uden kræft steg tætheden af celler i kanalerne med alderen hos ubehandlede børn, men viste ingen ændring med alderen hos behandlede børn. En 12-årig på en blokker plus østrogen i 14 måneder havde 59 % af kanalerne helt skrumpede, med små kalkaflejringer.
• Detaljerede gentest på enkeltceller fra én 14-årig efter mere end 52 måneders behandling (11.199 celler, kombineret med offentlige data til 130.100 celler) fandt, at over 90 % af de sæddannende celler sad fast på et tidligt stadie, og usædvanlige tilstande i støtteceller, der plejer sæd under udvikling.
• En computermodel trænet på blot 10 personer (5 børn før puberteten, 5 unge voksne) vurderede den behandlede 14-åriges væv som lig et barns før puberteten. Forfatterne selv siger, at den lille træningsgruppe er en stor svaghed.
• Forfatterne konkluderer, at svindet og de umodne celler ‘giver anledning til potentiel bekymring’ for fuld reversibilitet og fremtidig fertilitet. Studiet testede ikke genopretning efter ophør eller målte fertilitet.

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.'