タイトル； Emergency protocol for cryopreservation of genetically engineered mice sperm.
（熊本大学 生命資源研究・支援センター 資源開発分野）
Due to the outbreak of new coronavirus, researchers and breeders were restricted to go outside, and the number of mice that could be kept in laboratories was limited. Therefore, it was needed to cryopreserve the mice sperm for making the backup. However, the cryopreservation technique requires special skill, materials, and equipment, and many facilities couldn’t cope with it quickly. Therefore, in emergency, simple method that enables researchers to preserve mice strains on their own is needed. In this study, we developed a simple sperm cryopreservation method that anyone can easily implement by using some instruments commonly used in laboratory.
Sperm were collected from matured male mice in cryopreservation solution. The sperm suspension cryopreserved using cryotubes in a program-deep-freezer at various temperatures. After freezing and thawing the sperm, motility was assessed. In addition, sperm prepared by the same method and cryopreserved using a deep-freezer at -79℃. After freezing and thawing the sperm, motility, in vitro fertilization ability and embryo developmental ability were assessed.
As the results, at freezing temperatures below -40℃, motility was maintained even after freezing and thawing. And frozen/thawed sperm prepared by deep-freezer maintained motility and two-cell embryos were obtained by in vitro fertilization. In addition, the embryos developed into live pups by embryo transfer. In conclusion, using the deep-freezer and cryotube, it has become possible to easily preserve mice sperm. This finding can be used to temporarily store mice for researchers who need a backup in emergencies.