Cryopreservation: Introduction

The Transgenic Production Service is now offering cryopreservation and related services. We are happy to announce that the RRC will provide a subsidy for Embryo Cryopreservation, with approximately 50% of the projected labor cost for this service covered by the RRC. In addition, fees for storage of cryopreserved embryos and sperm will be 100% subsidized by the RRC. These subsidies will be in effect until January 2004, at which time operating costs will be evaluated and fee adjustments made, as necessary.

INTRODUCTION: Cryogenic freezing of mouse embryos and sperm provides security against loss of valuable mouse lines due to disease, environmental disaster and human error; it provides a cost-effective method to store lines not currently in use; and it provides a convenient way to ship important mouse strains to other investigators world-wide. In addition to cryogenic freezing , we also offer services to recover cryopreserved lines (see Cryopreservation: Instructions for Investigators).

Two-cell embryos are cryopreserved using a vitrification method, performed by briefly exposing the embryos to a cryopreservative containing DMSO and sucrose before plunging them into liquid nitrogen. Upon thawing and transfer to surrogate mothers, an average of 30% of cryopreserved embryos will develop to pups.

The embryo vitification service includes a test-thaw of one vial of frozen embryos for each line frozen. Embryos will be thawed 1-2 weeks after freezing and transferred to surrogate mothers for development to term to verify recoverability. At this point the investigator will be notified as to the success of the procedure and the decision to sacrifice the line may be made. At the investigator's discretion the test-thaw will not be performed, with a reduction in fees.

Sperm are cryopreserved by freezing in a cryopreservation solution of raffinose and skim milk. It is a simple procedure requiring only 1 male for sperm collection. Recovering the line from frozen sperm is performed by in vitro fertilization (IVF). The success rate of IVF is quite variable between strains, and for some strains IVF performed with frozen sperm is not feasible.

Please read Cryopreservation: Instructions for Investigators, which will assist you in meeting the requirements for cryopreserving embryos and sperm.

A separate application form must be submitted for each strain to be cryopreserved.