With the recent retirement of our long-serving Biological Resources Manager, Martin Fray, we decided to look back at how cryopreservation has changed at the Mary Lyon Centre over the last 20 years.
After about 9 years at the Institute for Animal Health at Compton, managing a bovine IVF clinic and performing cryopreservation of cattle embryos and sperm, Martin was presented with the opportunity to join Peter Glenister’s archiving team at MRC Harwell in November 2001 and, as he says, he “jumped at it”. For the last 20 years, Martin has been managing the National Mouse Archive and has overseen many changes, such as increased cryopreservation of sperm, reduced shipments of live mice, and the development of a hugely successful training programme.
The origins of the National Mouse Archive date back to the 1970s, following separate publications, from David Whittingham and Ian Wilmut, that demonstrated successful cryopreservation of mouse embryos. Mary Lyon immediately recognised the value of archiving mouse lines to reduce the number of animals that had to be bred, while ensuring that mutant lines were kept for future research, and began working with David Whittingham and Peter Glenister to develop the archive and test the feasibility of long-term storage. The Archive now holds well over half a million embryos and has more than 3,000 different mouse lines that are available to the scientific community.
One important change that Martin has seen is a transition away from embryo freezing to sperm freezing, as it requires far fewer animals. Successful sperm cryopreservation was developed much later than embryo freezing, but one of the mouse strains most commonly used at Harwell and the wider research community, C57BL/6J, was not permissive to sperm freezing when Martin first joined Peter Glenister’s team. Through collaborations with colleagues at the Jackson Laboratory and the CARD Institute, they were able to bring techniques developed elsewhere to Harwell and now most mouse strains are frozen as sperm.
Reducing the numbers of animals used has always been a core objective of the Archive, with the aim of promoting a cooperative future in mouse genetics whereby open sharing of archived mouse strains discourages researchers from unnecessarily using animals to recreate existing strains. Alongside transitioning to increased use of sperm freezing and other technical improvements in efficiency that reduce the numbers of animals used, Martin’s team has also supported this core objective by reducing the numbers of live shipments they make, with a 6-fold reduction in the percentage of exports sent overseas as live mice between 2017 and 2022.
The team’s policy to only send live shipments when there is no alternative has been made possible by technological advancements and the provision of training. Martin and his team have also made an important contribution in this area, as they have run our Mouse Embryo and Spermatozoa Cryopreservation course more than 30 times in the last 20 years, reaching more than 200 participants from 27 different countries.
An ongoing challenge for the team is curation of the Archive to make it as useful as possible to the scientific community and to demonstrate the current research value of the strains we have archived. One way in which we have been doing this is via our recent #MouseMuse campaign on social media to highlight individual strains we have available and the types of research they can support. However, with a growing repository of thousands of unique lines, the most important thing will be to continue to improve the online database to make it as useful as possible.
We thank Martin for his dedication, loyalty, and humour and wish him all the best for all the running and cycling he’s planning on doing with the extra time he has on his hands now!
