Background

Storage of cryopreserved in liquid nitrogen is very demanding in terms of maintenance, storage space, equipment, and costs. Such demands are predicted to increase as more women are resorting to oocyte preservation to preserve their future fertility options. This study therefore sought an alternative method for gamete-preservation: lyophilization and dry storage.

Methodology

20 human oocytes were vitrified using minimum drop size in DMSO and HSA at a cooling rate > 20,000⁰C/minute. The lyophilization process was carried out with the VirTis wizard for 24 hours with shelf temperature of -55⁰ C and vacuum 10 mTorr. The rehydration process took place at room temperature using equilibrated TCM199 supplemented with 0.5M trehalose. Oocyte survival was assessed with the live/dead staining (SYTO/PI).

Principal findings

50% of the oocytes were recovered.

Conclusions

Lyophilization of oocytes is a groundbreaking innovation for gamete bio-banking; 2) Vitrification is confirmed as an essential method not only for preservation in liquid nitrogen but also for a dry state.

Source

Cryopreservation of Oocytes and Embryos
A. Arav
Theriogenology, vol. 81, 96-102 (2014)
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Supporting information

Figure 1: Frozen-dried human oocyte

Figure 2: Frozen-dried human oocyte

Figure 3: Frozen-dried human oocyte

Figure 4: Frozen-dried human oocyte