The Jackson Laboratory

Reliable New Sperm Cryopreservation Service Developed at The Jackson Laboratory

JAX^® NOTES Issue 504, Winter 2006

The Jackson Laboratory recently developed the first truly reliable and cost-effective sperm cryopreservation and recovery service for transgenic and knockout mice. The service uses new techniques developed at the Jackson Laboratory and is suitable for cryopreserving and recovering the sperm from transgenic and knockout strains with C57BL/6, FVB, DBA/2, and C3H backgrounds, F1 hybrid backgrounds of these strains, and B6;129 hybrid backgrounds. This service promises to be a reliable, space-saving, and cost-effective alternative to maintaining transgenic and knockout strains on the shelf. Its advent is timely and should be welcome news to biomedical researchers. The new Service offers several advantages over previous sperm cryopreservation and recovery techniques:

Better fertilization rates. The fertilization rates (percent of oocytes fertilized) by sperm cryopreserved and recovered using traditional methods have averaged only about 5%. The fertilization rates by sperm frozen using The Jackson Laboratory's new techniques are nearly 50%, comparable to the 65% average fertilization rates by fresh sperm (Fig. 1).

More live births. The percentage of embryos developing into live mice is comparable to that from using fresh sperm and twice that from using sperm cryopreserved and recovered by traditional techniques (Fig. 2).

Saves mouse room space. Low-use colonies can now be removed from the shelf through cryopreservation, freeing up space for other projects. If the colony is needed again in the future, it can be quickly and economically recovered and expanded from frozen sperm.

More mice. The new service enables large numbers of same-age mice (or frozen embryos) to be quickly produced from frozen sperm. All mice are produced at a high health status and are certified specific pathogen free (SPF).

More versatile. Whereas previous techniques worked to a degree with DBA/2, C3H, and F1 hybrids between DBA/2 and C57BL/6 (and very poorly with transgenics and knockouts), the new techniques can successfully cryopreserve and recover the sperm of transgenic and knockout strains with C57BL/6, FVB, DBA/2, and C3H backgrounds, F1 hybrids of these backgrounds, and B6;129 hybrid backgrounds (Fig. 3).

Cryopreserving Your Strain

Our standard service for cryopreserving sperm from transgenic and knockout strains with C57BL/6, FVB, DBA/2, and C3H backgrounds, F1 hybrid backgrounds of these strains, and B6;129 hybrid backgrounds other backgrounds will be evaluated upon request. To cryopreserve a strain's sperm, only two fertile 10- to 16-week old males are needed. For the standard service, a minimum of 16 straws of sperm per strain will be cryopreserved and stored for three years, in three liquid nitrogen tanks, at two sites. Additional years of storage can be purchased for $175/yr. Throughout the cryopreservation process, stringent quality control checks are implemented, including sperm motility tests and an IVF fertilization test to two-cell embryos. Optional recovery of live born mice (for verification of recoverability) is only $500 per strain and is strongly recommended.

Recovering Your Strain

The service's standard procedure for recovering a strain from cryopreserved sperm includes performing IVF and two embryo transfers. Typically, 10 or more pups are produced from each recovery attempt. The cost for the standard recovery attempt is $1,095. Weaned (four-week old) pups are usually available 9-12 weeks after an order is placed. Larger quantities of mice can be produced to meet specific project requirements. Price will depend on fertilization and recovery rates for the background strain.

Rather than recovering live mice from cryopreserved sperm, two-cell embryos can be produced. If the strain has been previously recovered, the cost for this option is $1,095 to produce approximately 60 embryos for the same standard background strains (other backgrounds will be priced upon request). More embryos can be produced. Price will depend on the quantity of embryos desired, strain background, and fertilization rate of the strain. If the strain has not been previously recovered, a test recovery to live born is required for an additional $500.

The Jackson Laboratory's new service has been developed at a particularly appropriate time. In the last 20 years, the use of knockout and transgenic mice in biomedical research has risen sharply. Approximately 10,000 peer-reviewed scientific journal articles per year mention using such mice. The use of knockout and transgenic mice is expected to increase even more in the future (see the article describing the Knockout Mouse Project in this issue of JAX® NOTES). Keeping a genetically modified mouse strain in "maintenance mode" on the shelf costs an average of $6,000 to $10,000 a year. The same strain can be maintained as cryopreserved sperm for a fraction of that cost, and, when needed, can be quickly and conveniently recovered at an SPF status.

In summary, the Jackson Laboratory's new Sperm Cryo Service is a reliable and cost-effective option for cryopreserving mice and managing colonies of transgenic and knockout mice. It saves money, time, resources, and is inexpensive insurance against catastrophic loss of a strain from disease, fire, flood, breeding mishaps, and other accidents.

For more information about The Jackson Laboratory's new Sperm Cryo Service, call 1-800-422-MICE (6423) or e-mail jaxservices@jax.org.