Dry ice is a reliable substrate for the distribution of frozen mouse spermatozoa: A multi-centric study

Abstract

Disseminating mouse stocks as frozen materials offers both ethical and logistical advantages over live animal shipment, minimizing the welfare issues and avoiding some of the complex custom regulations that are associated with live animal transportation. Embryo freezing in liquid nitrogen (LN) at -196 °C has traditionally been the method of choice for archiving mouse lines. However, spermatozoa freezing is emerging as a more convenient alternative due to the application of innovative cryopreservation and recovery protocols. In addition, frozen spermatozoa are less sensitive to post-freezing temperature fluctuations. Here we demonstrated that spermatozoa frozen using standard laboratory protocols can be safely stored in dry ice (-79 °C) for at least seven days. The protocol we report here is robust and has been validated in a multi-centric study involving mouse spermatozoa samples exchanged between five European Mouse Mutant Archive (EMMA) nodes. Furthermore, following shipment on dry ice the spermatozoa can be returned to LN for long term storage without any noticeable detrimental effect. This protocol permits frozen spermatozoa to be shared and shipped in dry ice between biorepositories, networks and scientific institutions at low cost, using common courier companies, while avoiding the complexities, risks and hazards associated with using a traditional LN dry-shipper.

Freezing sperm in short straws reduces storage space and allows transport in dry ice

“…Moreover, dry ice is less costly than LN 2 . Our results strongly support that dry ice is a reliable substrate for distributing mouse sperm [6] and demonstrate that sperm frozen by the ST method are suitable for shipping in dry ice.…”

“…The ST method may also be applied for promoting the distribution of mouse sperm. Although a recent study reported that frozen mouse sperm can be transported in dry ice without losing fertility [6], the most common transport method currently used by the scientific community is shipment in LN 2 using dry shippers. Shipping in dry ice has several advantages compared to shipping in LN 2 : it is safer, does not require a special dry-shipper container, and can be conducted in a Styrofoam box, which does not need to be returned to the sender.…”

Dimethyl sulfoxide and quercetin prolong the survival, motility, and fertility of cold-stored mouse sperm for 10 days†

“…Sperm cryopreservation is the best way to preserve mouse resource because the sperm can permanently maintain motility and fertility and applicable to IVF after thawing [ 8 ]. More than 22,000 strains of cryopreserved sperm were archived in mouse repositories, and the sperm can be transported at −196°C in dryshipper or −79°C using dry ice [ 5 , 28 , 29 ]. However, the motility of frozen–thawed mouse sperm declined compared with that of fresh sperm, and the quality of cryopreserved sperm depends on protocol, skill, and mouse strains.…”

Quercetin-treated rat sperm enables refrigerated transport with motility and fertility for five days

“…On the other hand, the transport of cryopreserved sperm and embryos could be a useful means to avoid such risks. The cryopreservation of sperm and embryos requires ultra-low temperatures using special containers (dry shippers) and proficient skills to handle the cryopreserved samples 1 , 2 . Furthermore, the use of freeze-dried sperm in the production of pups via intracytoplasmic sperm injection is associated with technical barriers 3 .…”