Histology of Testicular Biopsy Specimens Obtained for Cryopreservation and Future Re-Implantation as a Fertility-Preserving Technique
Purpose: Therapeutic advances resulting in increased cure rates of childhood cancers have allowed greater focus upon survivorship issues, such as fertility preservation. For adolescents and young men, sperm banking is a viable option and clinically available at most cancer centers. However, successful collection of a sperm specimen is generally not possible for pre- or peri-pubertal boys. We are currently examining the feasibility of cryopreservation of testicular biopsy with subsequent assisted reproduction/re-implantation of germ cells after completion of anti-cancer treatment. We hypothesize that the testis histology in these oncology patients will be normal for age and present the preliminary histologic findings of these specimens.
Methods: Young males unable to sperm bank, most of whom were pre-pubertal, at significant risk of therapy-associated gonadotoxicity were eligible for this study. Open testicular biopsy was performed while patients were under anesthesia for another treatment-related operation, such as central catheter placement. Half of each specimen was cryopreserved for future clinical use, while the other half was divided for histopathologic analysis and murine xenograft studies.
Results: Thirty-four patients (ages 4 months – 17.5 years) underwent open testicular biopsy. In 7, insufficient tissue was obtained for full histolgic analysis, although adequate tissue was obtained for cryopreservation. Most children had solid tumors (N = 22). Five children in this study had non-malignant diseases requiring cytotoxic conditioning for bone marrow transplantation. Twenty-two testis specimens (81.5%) had normal number of total germ cells per tubule for their age, while the remaining 5 specimens (18.5%) showed increased germ cells. When adjusted for their age, 11 children (40.7%) had neither adult dark spermatogonia nor primary spermatocytes, suggestive of possible abnormal maturation of germ cells. However, fetal gonocytes, another indicator of abnormal maturation if present after 6 months of age, were not present in any specimen. Only one child had an absence of leydig cells, this was also the only child with evidence of testicular fibrosis and atrophy. One child also had microlithiasis. No specimens had evidence of either carcinoma in-situ or metastatic cancer.
Conclusion: Cryopreservation of testicular tissue with subsequent surgical re-implantation is a novel experimental approach that may allow future fertility for children following anti-cancer treatment. Murine xenograft studies with implanted testicular tissue are ongoing to evaluate the feasibility of the ART/re-implantation process and the viability of the tissue. Although the human germ cell re-implantation component has not yet been evaluated clinically, our testicular histologic analyses demonstrate age-adjusted delayed maturation of spermatogenesis in many of these biopsy specimens. Further investigation on the impact of these preliminary histologic findings is warranted with the goal of improving future fertility for children treated with gonadotoxic therapies.