Cryopreservation and Dry Storage of Gametes and Embryos

Cryopreservation and dry storage represent two complementary strategies for long-term preservation of reproductive cells and early embryos. Cryopreservation traditionally relies on ultra-low temperatures—most often in liquid nitrogen—to arrest metabolism and prevent ice crystal formation, enabling the banking of sperm, oocytes and embryos for assisted reproduction, biodiversity conservation and livestock management. Advances in vitrification have reduced cryoinjury by achieving glass-like solidification, obviating the need for slow cooling. In parallel, non-cryogenic approaches such as lyophilisation (freeze-drying), evaporative and convective drying have emerged, inspired by natural anhydrobiosis. These methods remove intracellular water under carefully controlled conditions to stabilise cellular structures at ambient or refrigeration temperatures. Early successes have demonstrated that dried sperm and somatic cell nuclei, once rehydrated and introduced into oocytes, can direct embryonic development, offering a simpler and more robust alternative to liquid nitrogen storage. Collectively, these technologies promise global accessibility to genetic resources, reduced logistical burden, resilience against power failures and novel applications ranging from ex situ conservation to potential off-Earth biobanking.

Research from Nature Portfolio

A landmark study demonstrated that nuclei from freeze-dried somatic cells, stored at −30 °C for several months, can support nuclear transfer to enucleated oocytes, yielding healthy, fertile cloned mice. This work established freeze-drying of nuclei as a viable, low-cost alternative for genetic resource banking. Another investigation refined freeze-drying protocols for ram sperm by comparing rapid plunging into liquid nitrogen with a slow-cooling regime. The latter reduced double-strand DNA breaks and improved blastocyst rates after intracytoplasmic sperm injection, signalling that optimisation of cooling steps can minimise mechanical stress during lyophilisation and enhance developmental competence.

Cryopreservation and Dry Storage of Gametes and Embryos publication trend

The graph below shows the total number of articles in cryopreservation and dry storage of gametes and embryos across all publications each year (not limited to Nature Index journals).

Technical terms

Cryopreservation: the storage of biological samples at ultra-low temperatures to halt metabolic activity and preserve viability.

Vitrification: an ultra-rapid cooling process that transforms aqueous samples into a glass-like state, preventing ice crystal formation.

Lyophilisation (freeze-drying): removal of water by sublimation under low pressure and temperature to stabilise cells or tissues for dry storage.

Anhydrobiosis: a reversible state of suspended metabolism in organisms exposed to extreme desiccation.

Intracytoplasmic sperm injection (ICSI): a micromanipulation technique in which a single sperm is injected directly into an oocyte’s cytoplasm.

Somatic cell nuclear transfer (SCNT): transfer of a nucleus from a non-reproductive (somatic) cell into an enucleated oocyte to generate an embryo.

References

1. Advances in induced anhydrobiosis for cell and gamete storage. Trends in Biotechnology (2025).
2. Healthy cloned offspring derived from freeze-dried somatic cells. Nature Communications (2022).
3. Whole genome integrity and enhanced developmental potential in ram freeze-dried spermatozoa at mild sub-zero temperature. Scientific Reports (2020).
4. Live Pups from Evaporatively Dried Mouse Sperm Stored at Ambient Temperature for up to 2 Years. PLOS ONE (2014).
5. DNA fragmentation in epididymal freeze-dried ram spermatozoa impairs embryo development. Journal of Reproduction and Development (2018).