Jackson Laboratory scientists announce mouse sperm cryopreservation
breakthrough
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 rates with mouse eggs. The
breakthrough will greatly reduce the cost of developing and
distributing new mouse models of human disease.
Freezing sperm is an efficient, cost-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 under-achieve woefully after
being frozen and thawed. What's worse: the thawed sperm of the most
popular mouse strain in the scientific world, the C57BL/6 or "Black
6", are known to under-perform 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 open-access journal PLoS ONE, where it can
be freely accessed online.
The technology has already attracted interest from international
academic and pharmaceutical laboratories.
The Jackson team reports that their technique consistently yields
fertilization rates of about 70 percent – a six-fold increase over
previous mouse sperm freezing techniques. The results were achieved
by collecting the sperm into a cocktail of raffinose (a plant-based
sugar complex), skim milk and the antioxidant monothioglycerol. The
sperm suspension is loaded into narrow plastic straws about the size
of a swizzle stick, and then slowly cooled before storage in liquid
nitrogen.
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 costs about $10,000 a year to
maintain a particular mouse strain, and worldwide only a few hundred
strains are in actual laboratory experiments at any given time."
Since the 1970s, the Laboratory has addressed this problem by
cryopreserving – 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 only count on about 125 live
pups. But a single male mouse can produce millions of sperm, which
can give rise to 100s or even 1,000s of offspring. Thus, 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 3,500 mouse models are available from the Laboratory, far
more than any other source. 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:
Joyce Peterson
Communications Office
The Jackson Laboratory
Tel: +1 207-288-6058
joyce.peterson@
Citation: Ostermeier GC, Wiles MV, Farley JS, Taft RA (2008)
Conserving, Distributing and Managing Genetically Modified Mouse
Lines by Sperm Cryopreservation. PLoS ONE 3(7): e2792.
doi:10.1371/
PLEASE ADD THE LINK TO THE PUBLISHED ARTICLE IN ONLINE VERSIONS OF
YOUR REPORT (URL live from July 30):
http://www.plosone.
PRESS-ONLY PREVIEW: http://www.plos.
Public release date: 29-Jul-2008
Contact: Joyce Peterson
joyce.peterson@
Public Library of Science
http://www.eurekale
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StemCells subscribers may also be interested in these sites:
Children's Neurobiological Solutions
http://www.CNSfoundation.org/
Cord Blood Registry
http://www.CordBlood.com/at.cgi?a=150123
The CNS Healing Group
http://groups.yahoo.com/group/CNS_Healing
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