Is the time right for transplanting immature testicular tissue or cells to restore male fertility? Expert perspectives on clinical implementation of autotransplantation of cryopreserved testicular tissue or cells for fertility restoration

Transplantations of cryopreserved immature testicular tissue (ITT) or spermatogonial stem cells (SSCs) represent promising approaches to restore fertility in patients with testicular tissue or cell suspension cryopreserved for fertility preservation. With over 3000 testicular samples cryopreserved globally, clinically viable and standardized protocols restoring fertility using cryopreserved testicular tissue/cells are urgently needed. Decades of research demonstrate the feasibility of immature testicular tissue transplantation (ITTT) or spermatogonial stem cell transplantation (SSCT) in animal models, including non-human primates. However, significant challenges remain in translating these options to human clinical practice. Critical factors include rigorous patient selection, robust pre-transplant evaluations to mitigate risks of malignant cell reintroduction, and the optimization of transplantation timing to support spermatogenesis. Developing comprehensive follow-up protocols and international data-sharing frameworks is essential to optimize outcomes. While offering the potential for genetic parenthood and enhanced quality of life for cancer survivors, these techniques require further refinement to ensure safety, efficacy, and realistic expectations. This paper outlines the framework for advancing the clinical translation of autotransplantation of testicular tissue/cells through collaboration and innovation.