Technological Advances of Cryopreservation in Ovarian Tissue for Female Children: Exploring the Molecular Insights and Mechanisms.

Ovarian tissue cryopreservation (OTC) has emerged as the only viable fertility preservation strategy for prepubertal girls and adolescent cancer patients facing gonadotoxic treatments. While OTC has transitioned from an experimental procedure to an established clinical practice, the functional longevity of transplanted grafts remains limited by massive follicle depletion. This review synthesizes recent technological advances in OTC for female children, with a particular focus on the underlying molecular mechanisms and innovative protective strategies. We systematically evaluate pre-cryopreservation assessments, surgical harvesting techniques such as medulla-sparing biopsies, and the comparative efficacy of slow freezing versus vitrification in preserving stromal and follicular integrity. Central to this discussion are the molecular drivers of post-transplantation injury, including ischemia-reperfusion-induced oxidative stress and the iatrogenic over-activation of the PI3K/Akt/mTOR signaling pathway, which leads to follicular "burnout." Furthermore, we explore targeted pharmacological interventions, such as the dual-drug application of VEGFA and rapamycin, alongside emerging bioengineering frontiers including decellularized extracellular matrix scaffolds and 3D-printed bioprosthetic ovaries. Clinical outcomes are also summarized, highlighting high rates of endocrine recovery (~95%) and promising live birth rates (~28%), predominantly through natural conception. By integrating deep molecular insights with advanced tissue engineering, this review provides a comprehensive framework for optimizing long-term fertility restoration and improving the quality of survivorship for young female cancer survivors.