Optimization of protocols for human ovarian tissue cryopreservation with sucrose, 1,2-propanediol and human serum

Chemotherapy and/or radiotherapy protocols have improved the long-term survival of cancer patients. Frequent consequences of antiblastic treatments, used to eradicate malignancies, are the partial loss of ovarian function, which in children and young women can result in permanent sterility. Ovarian tissue cryopreservation implemented before the beginning of treatment may potentially restore fertility. However, the physical effects of cryopreservation can damage oocyte survival and decrease follicular cell integrity and stromal preservation. The aim of this study was to examine the effects of different concentrations of 1,2-propanediol (PROH) and sucrose as cryoprotectants and human serum as protein support. Particular concentrations tested were 1.26, 1.5 and 1.08 mol/l PROH, 0.175, 0.2, 0.224 and 0.3 mol/l of sucrose and 20%, 30% and 40% human serum in the freezing solutions and normal or raised sucrose concentrations in the dilution solutions. Ovarian cortical slices from 13 patients, aged 5-38 years, were cryopreserved using slow freezing-rapid thawing. Tests were conducted using light and transmission electron microscopy. Cryo-damage occurred predominantly in the stromal and follicular cells. The best preservation of morphological characteristics was obtained using the freeze-thaw protocol in which concentrations of cryoprotectants were among the lowest (1.26 mol/l PROH+0.175 mol/l sucrose) with 30% human serum.