Sperm cryopreservation update: Cryodamage, markers, and factors affecting the sperm freezability in pigs.

Cryopreservation of spermatozoa is becoming more important because of new clinical requirements and current clinical practice. Despite the success of sperm cryopreservation this routinely used procedure induces serious detrimental changes in sperm function. Some researchers believe that cryopreservation is associated with DNA fragmentation and DNA single strand breaks in sperm. Mechanisms of cryodamage to human spermatozoa are thought to be multifactorial including: cold shock, osmotic stress, intracellular ice crystal formation, oxidative stress, and combinations of these conditions. Additives showing antioxidative properties reported to reduce the impact of ROS-induced and cold shock damages. Many studies exist as regards the effects of antioxidants on the cryopreservation aimed at improving the quality of post-thaw semen. Hence, this review will clarify results of recent applications of various antioxidants used in numerous research efforts to improve cryopreservation of spermatozoa. This review is to increase the understanding of the roles of these antioxidants concerning mechanisms which enhance resistance to cryodamage of spermatozoa.

The role of antioxidants in sperm freezing: a review

Spermatozoa interact with their immediate environment and this contact remodels the sperm surface in preparation for fertilisation. These fundamental membrane changes will be critically covered in this review with special emphasis on the very specific surface destabilisation event, capacitation. This process involves very subtle and intricate modifications of the sperm membrane including removal of suppression (decapacitation) factors and changes in the lateral organisation of the proteins and lipids of the sperm surface. Processing of sperm for assisted reproduction (storage, sex-sorting, etc.) subjects spermatozoa to numerous stressors, and it is possible that this processing overrides such delicate processes resulting in sperm instability and cell damage. To improve sperm quality, novel mechanisms must be used to stabilise the sperm surface during handling. In this review, different types of membrane stress are considered, as well as novel surface manipulation methods to improve sperm stability.

https://rep.bioscientifica.com/downloadpdf/journals/rep/142/6/759.pdf

Sperm surface changes and physiological consequences induced by sperm handling and storage

Contents


Sperm cryosurvival rates are not optimal for most species. Therefore, new cryopreservation strategies are needed with the objective of increasing the number of surviving sperm and the quality of those sperm after thawing. Cholesterol plays important roles in many sperm functions, including effects on membrane properties. One of these effects is to stabilize membranes at low temperatures. Thus, species that produce sperm which possess high membrane cholesterol : phospholipid ratios are more resistant to cold shock than sperm with low cholesterol : phospholipid ratios. Therefore, increasing the cholesterol content of sperm membranes may be a strategy that can improve sperm quality after freeze-thawing. In this review, information is presented related to using cyclodextrins pre-loaded with cholesterol for cryopreserving sperm from different species. The topics discussed include both in vitro and in vivo assessments of sperm quality after cryopreservation, as well as how increasing sperm cholesterol content affects other sperm functions.

Christelle Brèque

Papers

Cryopreservation of Boar Semen and Its Future Importance to the Industry