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 patienter i en Mayo Clinic-bank med barns testikelvävnad hade 16 (18 %) könsdysfori. Alla 16 hade tagit pubertetsblockerare, och 9 (56 %) stod på dem vid tidpunkten för operationen för att bevara fertilitet.
• Läkemedlen som räknades som ‘pubertetsblockerare’ omfattade äkta blockerare (leuprolid, histrelin, triptorelin) men också östrogen och andra hormonläkemedel (medroxiprogesteron, spironolakton), som togs i 3 till 52 månader. Medelåldern vid operationen var 12,5 år.
• Alla patienter med könsdysfori valde kirurgi för att ta bort vävnad i stället för att lämna ett spermaprov, eftersom de inte ville eller kunde få utlösning. 2 av de 9 behandlade patienterna hade avvikelser i testiklarna vid undersökning.
• Vid undersökning av cirka 50 kanaler per donator hos 19 donatorer utan cancer ökade celltätheten i kanalerna med åldern hos obehandlade barn, men visade ingen förändring med åldern hos behandlade barn. En 12-åring på en blockerare plus östrogen i 14 månader hade 59 % helt krympta kanaler, med små kalkavlagringar.
• Detaljerade gentester på enskilda celler från en 14-åring efter mer än 52 månaders behandling (11 199 celler, kombinerade med offentliga data till 130 100 celler) fann att över 90 % av de spermiebildande cellerna fastnat i ett tidigt stadium, och ovanliga tillstånd i de stödjeceller som vårdar spermier under utveckling.
• En datormodell tränad på bara 10 personer (5 barn före puberteten, 5 unga vuxna) bedömde den behandlade 14-årigens vävnad som lik ett barns före puberteten. Författarna säger själva att den lilla träningsgruppen är en stor svaghet.
• Författarna drar slutsatsen att krympningen och de omogna cellerna ‘väcker en potentiell oro’ för full reversibilitet och framtida fertilitet. Studien testade inte återhämtning efter att behandlingen avslutats och mätte inte 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.'