Directional freezing: a solution to the methodological challenges to preserve large organs.

Although 60 years have passed since the first successful freezing of cells, whole organ freezing is in its initial phase. Heat and mass transfer has limited the success of large tissue and organ cryopreservation either by slow freezing or vitrification. In this article we discuss the limiting factors for the successful freezing of whole organs, such as homogeneous cooling rate, supercooling, latent heat, and recrystallization. We show how the use of directional freezing technology provides solutions to these problems. Whole ovary cryopreservation and transplantation has been proposed as a new method for preserving long-term ovarian function as opposed to ovarian cortical slices. Fertility preservation will benefit from the success of whole ovary freezing and transplantation.