Jackson scientists announce mouse sperm cryopreservation breakthrough
| Date: July 30, 2008 |
Bar Harbor, Maine – A team of Jackson Laboratory scientists have figured out a simple, cost-effective process to freeze mouse sperm and get it to achieve high fertilization and recovery rates with mouse eggs. The breakthrough enables scientists worldwide to manage mouse colonies in a new way, greatly reducing husbandry costs and the number of animals used in biomedical research.
The ability to freeze mouse sperm reliably also provides a cost-effective way to safeguard unique and valuable mouse models of human disease.
Freezing sperm has proven to be effective way to conserve and distribute genetics in the agricultural industry and putting male sex cells on ice is a fundamental part of human fertility programs. But the sperm of certain varieties of mice have until now under-performed woefully after being frozen and thawed. What’s worse: the thawed sperm of the most popular mouse strain in the scientific world, the C57BL/6J or “Black 6”, are notorious slackers when it comes to fertilizing mouse eggs.
Drs. Michael Wiles and Chuck Ostermeier in Jackson’s Technology Evaluation and Development group, and Dr. Robert Taft and Ms. Jane Farley in the Reproductive Sciences group, have published a paper on the new technique in the Public Library of Sciences journal PLoS One, where it can be freely accessed around the world.
The Jackson team reports that their technique consistently yields a six-fold increase over previous mouse sperm freezing techniques. The results were achieved by systematically optimizing all the steps in the process and reengineering the solution in which the sperm is frozen.
When frozen sperm are needed for fertilization, they are thawed and incubated in in vitro fertilization media for an hour before adding oocyte cumulus masses (clusters of egg cells).
Dr. Wiles noted, “The world research community is making literally thousands of new mouse models,” using stem cells to introduce specific genetic variations that mimic the mutations identified in human diseases. “The problem is that it can cost thousands of dollars a year to maintain a particular mouse strain, and worldwide there are many strains that are not under active study at any given time.”
The technology has already attracted interest from international academic and pharmaceutical laboratories. The Jackson Laboratory has been offering services related to this new technology for the last 18 months, and scientists around the world have used these services to reduce their colony management costs, rederive their mouse colonies and safeguard them from floods and other disasters.
Dr. Peter Mombaerts, currently director of the Department of Molecular Neurogenetics with the Max Planck Institute of Biophysics in Frankfurt, Germany, recently utilized The Jackson Laboratory’s Sperm Cryo service to preserve more than 170 novel mouse strains, and to transfer these strains from his former laboratory at The Rockefeller University in New York. “JAX has recently developed a new technique of sperm cryopreservation that is likely to facilitate enormously, and in a long-term fashion, the preservation and distribution of mouse strains.”
Since the 1970s, the Laboratory has pioneered the use of cryopreservation to efficiently manage numerous mouse colonies. However, until now, the only effective option was to cryopreserve – freezing and storing – mouse embryos from little-used strains, which allows the live mice from those strains to be safely removed from the mouse room. However, freezing embryos is far less efficient and cost-effective than freezing sperm. “If you freeze 250 embryos,” Dr. Wiles said, “you can count on about 125 live pups. But a single male mouse can produce millions of sperm, which can give rise to hundreds or even thousands of offspring. So making sperm cryopreservation work has long been a goal of ours.”
The Jackson Laboratory is a nonprofit research laboratory with 37 research groups investigating the genetic basis of human diseases. In addition, the Laboratory has a unique role of creating, maintaining and distributing mouse models to the worldwide research community. More than 4,000 mouse models are available from the Laboratory, far more than any other source. Through JAX® Services, scientists can immediately employ the new Sperm Cryo service to cryopreserve, recover and rederive their unique mouse colonies. The Laboratory has published this paper and teaches the new sperm cryopreservation technique in its annual Cryopreservation course as part of its nonprofit research mission supporting biomedical research. Drs. Taft, Wiles and Ostermeier, Ms. Farley and others make up the Laboratory’s team of resource scientists who innovate techniques to improve and streamline mouse model-based research.
Contact(s): Joyce Peterson, 207-288-6058
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