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Cryopreservation Services

Cryopreservation, the process of freezing viable germplasm for stable, long-term storage in liquid nitrogen, is an essential service for modern mouse based genomics. It is a safe method for preserving both pre-implantation embryos and sperm that can be easily recovered to revive the line.

The TTML now offers cryopreservation, storage, and recovery (cryorecovery) of mouse embryos and sperm from several different mouse strains.

Cryopreservation of pre-implantation embryos has been available through the TTML since May 2007. Using the method known as “speed cryogenics”, hundreds of embryos can be generated by IVF when oocytes collected from hormonally-treated females are incubated with freshly isolated sperm. However, not all mouse strains are suitable for embryo cryopreservation. Embryos from some strains are not hardy enough to withstand the freeze/thaw process. Other strains have low fertilization capacity and do not readily yield sufficient numbers of fertilized embryos. In addition, individual mouse lines as well as individual mice within a line can vary substantially in their fertilization capacity regardless of background strain. Surprisingly, C57BL/6 and B6 hybrid strains are among the best performing strains in IVF and embryo cryopreservation.

While this is a robust, reliable cryopreservation method, it is costly and, due to inherent technical inefficiencies associated with the procedure and strain differences, can be difficult to accomplish quickly.

Sperm cryopreservation is a simple, highly cost effective alternative to embryo cryopreservation. Recent technical advances on traditional methods have resulted in improved and reliable fertility rates of cryopreserved sperm following thaw, particularly for common strains such as C57BL/6 and BALB/c. Although there are some disadvantages of preserving lines as frozen sperm as compared to embryos, cryopreservation of sperm is significantly more cost effective and faster. It can also be used to complement embryo cryopreservation.

Comparison of two methods

Embryo Cryopreservation

Advantages Disadvantages
  • Robust and reliable (gold standard for mouse cryopreservation)
  • Donor genotype is preserved
  • Homozygous embryo can be frozen
  • Recovery of line is inexpensive and simple
  • Cost to freeze: expensive upfront resources (requires lots of females donors)
  • Additional per diems costs associated with maintaining homozygous males
  • Longer queues: can take several months to complete
  • Does not work efficiently for all lines/strains

Sperm Cryopreservation

Advantages Disadvantages
  • Simple and inexpensive
  • Lots of material is preserved (30 million sperm/male)
  • Sperm can be isolated from unhealthy/dead male in emergency situation and line recovered by ICSI
  • Much faster turn-around time (takes a few weeks to complete)
  • Preserves only one half of the genome
  • More expensive to recover a line (embryos must be created by IVF/ICSI)
  • May not work work efficiently for all lines/strains

Cryopreserved Strains

Strains we have cryopreserved and successfully recovered live pups from following thaw (cryorecovery) include:

Embryos Sperm
C57BL/6 C57BL/6
B6SJL B6SJL
FVB FVB
BALB/c BALB/c
SJL SJL
CD-1/ICR CD-1/ICR
129S1/SvImJ 129S1/SvImJ
B6129PF1
B6129SF1
Cryopreservation Details
Cryopreservation Details
Cryopreservation Details
Transgenic and Targeted Mutagenesis Core
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