Sperm Cryodamage in Ruminants: Understanding the Molecular Changes Induced by the Cryopreservation Process to Optimize Sperm Quality

Abstract

Sperm cryopreservation represents a powerful tool for livestock breeding. Several efforts have been made to improve the efficiency of sperm cryopreservation in different ruminant species. However, a significant amount of sperm still suffers considerable cryodamage, which may affect sperm quality and fertility. Recently, the use of different “omics” technologies in sperm cryobiology, especially proteomics studies, has led to a better understanding of the molecular modifications induced by sperm cryopreservation, facilitating the identification of different freezability biomarkers and certain proteins that can be added before cryopreservation to enhance sperm cryosurvival. This review provides an updated overview of the molecular mechanisms involved in sperm cryodamage, which are in part responsible for the structural, functional and fertility changes observed in frozen–thawed ruminant sperm. Moreover, the molecular basis of those factors that can affect the sperm freezing resilience of different ruminant species is also discussed as well as the molecular aspects of those novel strategies that have been developed to reduce sperm cryodamage, including new cryoprotectants, antioxidants, proteins, nanoparticles and vitrification.

ProAKAP4 as Novel Molecular Marker of Sperm Quality in Ram: An Integrative Study in Fresh, Cooled and Cryopreserved Sperm

“…In addition, molecular markers based on protein characterization could reinforce this novel deep level of analysis. These biomolecules could provide new insights into the mechanisms underlying sperm cryodamage and could act as freezability biomarkers as well as for the development of new strategies to improve sperm cryopreservation outcomes in ruminants [ 45 ]. Novel proteins such as AKAP4 and ProAKAP4 have recently taken on great relevance in the sperm quality assessment field as predictors of fertilization success in different mammal species [ 46 , 47 , 68 ] due to their close correlation with sperm motility.…”

“…Surprisingly, when we analyzed the correlation of sperm quality parameters with this novel marker, the highest correlation rates were registered for ProAKAP4, viability and sORP ( Figure 4 D,H), confirmed by the very close distribution in the component plot graph of the principal component analysis to reduce the dimensionality of the dataset ( Appendix A , Figure A1 g). Although ProAKAP4 has been widely correlated with sperm motility traits by different authors [ 41 , 42 , 43 , 44 , 45 ], the protein concentration has never been correlated with several sperm quality parameters such as viability or sORP.…”

“…Specific biomolecules could act as freezability biomarkers providing new insights into the mechanisms underlying sperm cryodamage. Some of these proteins have been recently characterized in ruminants presenting different roles on sperm functionality: stress related proteins (glutathione s-transferase mu 5 [ 36 ], GSMT5, superoxide dismutase [ 37 ], SOD, and reduced glutathione [ 37 ], GSH), ion transportation (voltage-dependent anion-selective channel protein 2 [ 36 ], VDAC2), sperm motility (ATP synthase subunit beta [ 36 ], ATPB1), acrosome reaction (such as Phospholipase A2, PLA2 [ 38 ]), chaperone proteins (heat-shock proteins, HSPs, specifically HSP90 [ 39 , 40 ] and HPSPA8 [ 41 ]) carbonylated proteins related to oxidative modifications [ 42 ], lipid peroxidation (acidic seminal fluid protein [ 43 ], aSFP) capacitating proteins [ 44 ] (14 proteins related to mitochondrial activity, sperm motility, oocyte recognition, signaling, spermatogenesis, and the apoptosis-stress response), among others [ 44 , 45 ].…”

A Polyphenol-Rich Extract From Entada abyssinica Reduces Oxidative Damage in Cryopreserved Ram Semen

“…Ice crystals formation around the cell membranes and increasing of the permeability are the most probable reasons. Formation of ROS, on the other side, affects plasma membrane integrity, nuclear structure, and leads to apoptosis ( 42 ). Previous reports described the antioxidant effect of caffeic acid and its derivatives on normal cells.…”

Cellular and Functional Physiopathology of Bull Sperm With Altered Sperm Freezability

“…These gaps in the knowledge and technology bases are important because they are preventing advances both in cryobiology of mammalian male gamete and in the ART. Causes underlying differing freezability remain to be elusive, although physical damage to the membranes and biochemical changes have been associated with cryo-induced oxidative stress (32)(33)(34). The overall goal of this study was to test the central hypothesis that sperm cellular and functional phenomes are associated with sperm integrity and freezability.…”