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

• 在梅奧診所兒童睪丸組織庫的 87 名患者中，有 16 人（18%）有性別焦慮。這 16 人全都使用過青春期阻斷劑，其中 9 人（56%）在保存生育能力的手術當時仍在使用。
• 被算作「青春期阻斷劑」的藥物包括真正的阻斷劑（leuprolide、histrelin、triptorelin），也包括雌激素和其他荷爾蒙藥物（medroxyprogesterone、spironolactone），使用了 3 至 52 個月。手術時平均年齡為 12.5 歲。
• 所有有性別焦慮的患者都選擇以手術取出組織，而不是提供精液樣本，因為他們不願意或無法射精。9 名接受治療的患者中，有 2 人在檢查時發現睪丸異常。
• 在 19 名沒有癌症的捐贈者中，每人檢查約 50 條管，未接受治療的兒童，管內細胞密度隨年齡上升，但接受治療的兒童則沒有隨年齡變化。一名 12 歲、使用阻斷劑加雌激素 14 個月的孩子，有 59% 的管完全萎縮，並有微小的鈣沉積。
• 對一名 14 歲、治療超過 52 個月的患者進行單細胞的詳細基因檢測（11,199 個細胞，與公開資料合併後為 130,100 個細胞），發現超過 90% 的生精細胞停滯在早期階段，並且滋養發育中精子的支持細胞處於不尋常的狀態。
• 一個只用 10 人（5 名青春期前兒童、5 名年輕成人）訓練的電腦模型，判定這名接受治療的 14 歲患者的組織類似青春期前的兒童。作者自己也表示，訓練組很小是重大缺點。
• 作者的結論是，萎縮和未成熟的細胞「引發了對完全可逆性與未來生育能力的潛在疑慮」。這項研究沒有測試停藥後的恢復情況，也沒有測量生育能力。

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.'