An article published in the journal Theriogenology demonstrates that it is possible to cryopreserve mouse spermatozoa at −80 °C. What is more, the cryopreserved sperm can be stored at -80 °C for at least one year before being placed in liquid nitrogen for indefinite storage. The team involved in this research have used a simple and efficient method for freezing spermatozoa of wild type and mutant mouse lines on a C57BL/6N background. Mice with this genetic background are used for a variety of projects, including the IMPC. This technique has the potential to transform the sperm storage process, as it simplifies freezing and facilitates storage and transportation.
In particular, this new method will be useful for laboratories with limited access to liquid nitrogen as well as projects that generate mutant lines using CRISPR/Cas9 who want a more accessible −80 °C freezer option. The results of the study also highlight that mouse spermatozoa are extremely robust and can be stored and transported at −80 °C for a significant amount of time without loss of viability.
Below is a recent video that explains how mouse sperm is currently shipped and stored using dry ice, featuring Martin Fray who was one of the authors of this latest development.