Current Status of Freeze‐Drying Technology to Preserve Domestic Animals Sperm

Abstract

ContentsIn recent years, there has been an increased interest in new preservation techniques that facilitate sperm storage and distribution, with freeze-drying (FD) having been proposed as an alternative method for sperm preservation and maintenance of genetic resources in different animal species. FD is a method in which frozen material is dried by sublimation of ice, thereby involving a direct transition from a solid (ice) to a vapour (gas) phase. One of the main advantages of FD is that nitrogen and dry ice are no longer required for the storage and shipment of frozen sperm, which can be stored at room temperature or 4°C, thereby resulting in enormous reductions in storage and shipping costs. Unlike sperm cryopreserved after gradual freezing, the sperm membrane may be further damaged by both snap-freezing and drying stresses during the FD procedure. As mammalian spermatozoa lose their motility, viability and, at least partially, their DNA integrity when freeze-dried, they must be microinjected into an oocyte by intracytoplasmic sperm injection (ICSI). Although the efficiency of ICSI is limited when freeze-dried spermatozoa are used, embryos and live offspring can be produced. DNA fragmentation in freezedried spermatozoa is one of the main causes of failure of embryonic development and successful pregnancy. In this regard, it has been suggested that endonucleases are among the leading causes of DNA fragmentation in spermatozoa along with oxidative stress caused by the release of reactive oxygen species (ROS). Many factors influence the FD process, and it is not clear how FD affects specific components of sperm from different animal species. As such, a sound understanding of the FD process would result in increased production of embryos and/or live offspring. The aim of this review was to study the various stages and techniques used in the FD process and to further evaluate the results obtained.

Freeze‐dried spermatozoa: A future tool?

“…Rehydration is the process used to restore the lyophilized product to its original formulation. Freeze‐dried sperm are normally rehydrated by adding pure water, the volume of which should be the same as the original volume of the sperm suspension before FD (Gil et al., ). It is known that the DNA damage is induced by mechanical or oxidative stress not only during FD but also during the holding period before ICSI after rehydration (Kusakabe et al., ).…”

Comparison of different mathematical models to assess seasonal variations in the longevity of DNA integrity of cooled‐stored stallion sperm

“…It is also well known that stallion semen cooling affects routine sperm quality parameters and pregnancy rates (Brinkerhoff et al, ; Foster et al, ; Heckenbichler, Deichsel, Peters, & Aurich, ; Henderson, Capewell, & Johnson, ; Kiser et al, ; Love et al, ; Urbano et al, ), mostly attributable to the relatively short longevity of cooled‐stored semen of approximately 24–48 hr. Other studies have shown that semen cooling increases SDF values after 48 hr of storage (Blottner et al, ; Fraser, Strzezek, & Kordan, ; Gil et al, ; Linfor & Meyers, ; Love & Kenney, ; Love et al, ; Ortiz et al, ).…”

“…It is also well known that stallion semen cooling affects routine sperm quality parameters and pregnancy rates (Brinkerhoff et al, 2010;Foster et al, 2011;Heckenbichler, Deichsel, Peters, & Aurich, 2011;Henderson, Capewell, & Johnson, 1998;Kiser et al, 2013;Love et al, 2015;Urbano et al, 2013), mostly attributable to the relatively short longevity of cooled-stored semen of approximately 24-48 hr. Other studies have shown that semen cooling increases SDF values after 48 hr of storage (Blottner et al, 2001;Fraser, Strzezek, & Kordan, 2011;Gil et al, 2014;Linfor & Meyers, 2002;Love & Kenney, 1998;Love et al, 2015;Ortiz et al, 2017). SDF can be evaluated as a static or dynamic parameter, static assessment involves measuring SDF at one time point whereas dynamic assessment involves evaluating the SDF at multiple time points over a period of incubation at a temperature that mimics the female reproductive tract (usually 37°C).…”

Dry Preservation of Spermatozoa: Considerations for Different Species

“…96 There are also many underexplored options in terms of the drying modality and many processing considerations that can be optimized, including establishing the optimal moisture content to minimize degradation during storage and developing storage systems to maintain these levels. 103,104 Optimization of drying and rehydration media and postinjection culture conditions can also lead to increased success rates. 78,81,87,88,96 Initial attempts to optimize drying media have mainly focused on sugars, with successes reported with Trehalose and 3-O-methyl-d-glucose, but there are many other natural protectants that can be evaluated in future studies, including the late embryogenic abundant proteins and many other compatible osmolytes that occur naturally in desiccationtolerant organisms.…”