Mouse Sperm Cryopreservation and Recovery of Genetically Modified Mice

Highly definable genetically, the humble mouse is the "reagent" mammal of choice with which to probe and begin to understand the human condition in all its complexities. With the recent advance in direct genome editing via targeted nucleases, e.g., TALEN and CRISPR/Cas9, the possibilities in using these sophisticated tools have increased substantially leading to a massive increase in the variety of strain numbers of genetically modified lines. With this increase comes a greater need to economically and creatively manage their numbers. Further, once characterized, lines may be of limited use but still need to be archived in a format allowing their rapid resurrection. Further, maintaining colonies on "the shelf" is financially draining and carries potential risks including natural disaster loss, disease, and strain contamination. Here we outline a simple and economic protocol to cryopreserve mouse sperm from many different genetic backgrounds, and outline its recovery via in vitro fertilization (IVF). The combined use of sperm cryopreservation and IVF now allows a freedom and versatility in mouse management facilitating rapid line close down with the option to later recover and rapidly expand as needed.