Human ovarian tissue preservation: is vitrification acceptable method for assisted reproduction?

The aim of this study was to evaluate the most successful vitrification protocol. The ovarian tissue pieces were randomly distributed into seven groups including fresh control. Each experimental group was divided into three subgroups according to the following cooling modes: a) in 1.8 ml cryo-vials with 1ml vitrification medium, b) in 1.8 ml cryo-vials with 0.1 ml vitrification medium, or c) by direct dropping with 0.05 ml vitrification medium into liquid nitrogen. The best results were observed in the protocol using 2.62 M dimethylsulphoxide + 2.6 M acetamide + 1.31 M propylene glycol + 0.0075M polyethylene glycol in combination with direct dropping of ovarian tissue pieces into liquid nitrogen. The vitrified and rewarmed samples after in vitro culture with this protocol showed 86 percent normally developed follicles, compared with 92 percent in fresh non-treated control. The concentrations of hormones in spent medium from culture of the same samples were 319 pg/ml for 17beta-estradiol and 2.6 ng/ml for progesterone compared with fresh non-treated control (253 pg/ml and 6 ng/ml, respectively). The results obtained by vitrification of ovarian tissue with this protocol were compatible with those of the fresh ovarian tissue.