Advances in ovarian tissue cryopreservation and transplanta-tion for fertility preservation in prepubertal patients

Ovarian tissue cryopreservation and transplantation is currently the only feasible method for preserving both fertility and ovarian endocrine function in prepubertal females. It is indicated for those requiring gonadotoxic therapies such as chemotherapy, radiotherapy, or bone marrow transplantation for malignant diseases, as well as for non-malignant diseases, including immunologic, metabolic, and hematologic benign diseases requiring bone marrow transplantation, and other populations at high risk of premature ovarian insufficiency. The procedure involves laparoscopic retrieval of ovarian tissue, followed by slow-programmed cryopreservation. When the primary disease is cured and fertility or hormonal function restoration is desired, the tissue is thawed and transplanted, most commonly to an orthotopic site. For patients at high risk of ovarian malignancy, pre-transplantation assessment of minimal residual disease in the ovarian cortex is performed using histopathology and molecular biology techniques. Globally, while ovarian tissue cryopreservation and transplantation has led to over 300 live births, the majority result from tissue cryopreserved after puberty. Successful restoration of puberty and subsequent live births following transplantation of tissue frozen before puberty, although demonstrated in reported cases, remain less common. This review systematically summarizes recent advances in the indications, current application status, timing and strategies of ovarian tissue cryopreservation and transplantation, risk assessment of tumor cell reintroduction, and clinical outcomes in prepubertal patients. It also discusses the potential value and current challenges of combining this approach with <i>in</i><i>vitro</i> oocyte maturation techniques, aiming to provide practical references for clinical practice.