Genexpression und Morphologie der Follikel nach konventionellem Einfrieren und Vitrifikation von humanem Ovarialgewebe [Gene-expression and morphology of follicles after conventional freezing and vitrification of human ovarian tissue]

Purpose: Cryopreservation, the most important stage of the cryobanking of ovarian tissue, can be carried out using one of two methods: conventional ("slow") freezing, and vitrification (direct and immediate immersion into liquid nitrogen). For human oocytes and embryos vitrification is more effective compared to conventional freezing. However, these comparative data are limited for human ovarian tissue. The aim of this study was to compare conventional freezing of ovarian tissue with vitrification. Material and Methods: Ovarian tissue from 5 patients was transported to the laboratory within 20 min at 32 to 34 °C, divided into smaller pieces (1 × 1 to 1,5 × 0,7 to 1 mm) and randomly distributed into three groups: Group 1: control (fresh tissue), group 2: pieces after vitrification/warming, Group 3: pieces after conventional freezing/thawing. All pieces were cultured in vitro for 12 days. The viability of the tissue was evaluated by the development of the follicles and GAPDH gene expression after in vitro culture. Results: 93, 74 and 78 % of the follicles of groups 1, 2 or 3 were morphologically normal. Molecular analysis showed that the intensity of GAPDH gene expression in the tissue after conventional freezing was greatly increased compared to after vitrification. Conclusion: It was concluded that for the cryopreservation of human ovarian tissue conventional freezing is more suitable than vitrification