Cryopreservation of genetically modified mouse strains: preserving valuable material, saving resources and reducing animal usage

Abstract

Russell and Burch proposed the concept of the 3Rs, Replacement, Reduction and Refinement, in 1959 as a basis for ethical standards governing animal experimentation. Despite sincere attempts to implement these practices, increased use of genetically modified animals has created potential challenges to this framework. Specifically, genetically modified animals can be difficult to derive, and are therefore maintained continuously as a colony despite their transient experimental use.

As an alternative, the use of embryo or sperm cryopreservation provides a means to efficiently archive strains and eliminate unutilized strains, avoiding the birth and use of animals to maintain them. It also provides substantial reductions to cost and cage occupancy. Surprisingly, recent work by Zeller et al. (2017) indicates that only 56% of professionals working with laboratory animals are aware of cryopreservation as a technique for colony management.

This study shows that cryopreservation, within our institution, where the animal facility features a housing capacity of 3,000 cages and 10,000 to 15,000 mice, has allowed us to eliminate efficiently 115 unutilized genetically modified mouse strains during the past five years. This has i) liberated 19% of the animal house capacity, ii) prevented the birth of 21,189 unutilized mice, iii) lead to a saving of 382,800 € for our institution.