Preservation of Women's Fertility: Evaluation of Innovative Methods for Ovarian Tissue Cryopreservation

The recent innovations in cancer diagnosis and therapy have improved the five-year survival for patients. However, anticancer treatments may impair patient fertility; therefore fertility preservation is recommended before therapy initiation. The sole method for preserving young prepubescent girls' fertility, which can also be used for pubescent women, is ovarian tissue cryopreservation (OTC) with later auto-transplantation. Although 200 births have been reported worldwide after OTC and transplantation, significant improvements are required. Indeed, freezing and thawing protocols vary according to laboratories (media, cryoprotectants, freezing curve, etc…) and selection criteria are not justified. In addition, most of the laboratories use unsafe devices (e.g. screw cap cryovials) for OTC, exposing ovarian tissues to biological hazards during sample storage in nitrogen tanks. To eliminate these risks, novel "high security" devices have been commercialized (welded cryotubes). However, while thermal welding could alter tissue quality, the functionality of the human ovarian tissue frozen with these innovative devices has not yet been evaluated. The objectives of this study are i) to optimize the freezing and the thawing protocols for human OTC according to thermodynamic properties of the freezing medium and the type of device (welded or screwed cryotube) and ii) to determine if the type of cryotube influences the quality of human ovarian tissue. This project will enable to reach a better understanding of the impact of freezing on ovarian tissue functionality, as well as the implementation of an optimal protocol for OTC within the ART laboratory of Clermont-Ferrand hospital to optimize patient care.