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

• Av 87 pasienter i en bank med barns testikkelvev ved Mayo Clinic hadde 16 (18 %) kjønnsdysfori. Alle 16 hadde brukt pubertetsblokkere, og 9 (56 %) brukte dem på tidspunktet for operasjonen for å bevare fruktbarheten.
• Legemidlene som ble regnet som «pubertetsblokkere» inkluderte ekte blokkere (leuprolid, histrelin, triptorelin), men også østrogen og andre hormonmedisiner (medroksyprogesteron, spironolakton), brukt i 3 til 52 måneder. Gjennomsnittsalder ved operasjonen var 12,5 år.
• Alle pasientene med kjønnsdysfori valgte en operasjon for å fjerne vev i stedet for å gi en sædprøve, fordi de ikke ønsket eller ikke kunne ejakulere. 2 av de 9 behandlede pasientene hadde avvik i testiklene ved undersøkelse.
• Ved å se på omtrent 50 tubuli per donor hos 19 donorer uten kreft økte celletettheten i tubuli med alderen hos ubehandlede barn, men viste ingen endring med alderen hos behandlede barn. En 12-åring på blokker pluss østrogen i 14 måneder hadde 59 % av tubuli helt krympet, med bittesmå kalkavleiringer.
• Detaljerte gentester på enkeltceller fra én 14-åring etter mer enn 52 måneders behandling (11 199 celler, kombinert med offentlige data til 130 100 celler) fant at over 90 % av de sæddannende cellene satt fast i et tidlig stadium, og uvanlige tilstander i støtteceller som nærer sæd under utvikling.
• En datamodell trent på bare 10 personer (5 barn før puberteten, 5 unge voksne) vurderte den behandlede 14-åringens vev som likt et barns før puberteten. Forfatterne sier selv at den lille treningsgruppen er en stor svakhet.
• Forfatterne konkluderer med at krympingen og de umodne cellene «gir grunn til mulig bekymring» for full reversibilitet og fremtidig fruktbarhet. Studien testet ikke gjenoppretting etter at behandlingen ble avsluttet og målte ikke fruktbarhet.

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.'