Laboratory practice in an oncology cryopreservation service: What and how?

In humans, oocyte and embryo vitrification is a routinely used method for fertility preservation (FP). Sperm vitrification is currently applied to samples with low sperm concentration and volume, whereas slow freezing remains the preferred method for larger sperm volumes. Although ovarian tissue cryopreservation and testicular tissue cryopreservation are not yet routinely used for FP, the cryopreservation methods are a matter of debate. Slow freezing is the most commonly applied method for the ovarian cortex, while ovarian tissue vitrification remains clinically uncertain due to the limited number of successful births. It is important to underline that the guidelines for gametes, embryos, and tissue cryopreservation have a key role for both providers and patients, which is to minimize the risks associated with an unsafe FP choice and cryostorage.