Impact of Cryopreservation on Spermatozoa Freeze-Thawed Traits and Relevance OMICS to Assess Sperm Cryo-Tolerance in Farm Animals

Abstract

Sperm cryopreservation is a powerful tool for the livestock breeding program. Several technical attempts have been made to enhance the efficiency of spermatozoa cryopreservation in different farm animal species. However, it is well-recognized that mammalian spermatozoa are susceptible to cryo-injury caused by cryopreservation processes. Moreover, the factors leading to cryo-injuries are complicated, and the cryo-damage mechanism has not been methodically explained until now, which directly influences the quality of frozen-thawed spermatozoa. Currently, the various OMICS technologies in sperm cryo-biology have been conducted, particularly proteomics and transcriptomics studies. It has contributed while exploring the molecular alterations caused by cryopreservation, identification of various freezability markers and specific proteins that could be added to semen diluents before cryopreservation to improve sperm cryo-survival. Therefore, understanding the cryo-injury mechanism of spermatozoa is essential for the optimization of current cryopreservation processes. Recently, the application of newly-emerged proteomics and transcriptomics technologies to study the effects of cryopreservation on sperm is becoming a hotspot. This review detailed an updated overview of OMICS elements involved in sperm cryo-tolerance and freeze-thawed quality. While also detailed a mechanism of sperm cryo-injury and utilizing OMICS technology that assesses the sperm freezability potential biomarkers as well as the accurate classification between the excellent and poor freezer breeding candidate.

Keywords: cryo-injuries; cryo-tolerance fingerprints; functional traits; molecular tools; spermatozoa cryo-biology.

Figure 1

Scheme represents cryopreservation damages in the sperm cell, whereas an excess induction of oxidative stress in resulting ROS production can deteriorate the sperm plasma membrane and acrosomal membrane and eventually alter the molecular structure (DNA). ROS, Reactive oxygen species; H₂O₂, Hydrogen peroxide; ^•${\text{O}}_2^{-}$, Superoxide radical; NADPH, Nicotinamide adenine dinucleotide phosphate; ONOO⁻, Peroxy nitrate, NO; Nitric oxide.

Figure 2

Schemes showed five important phases of sperm biotechnology: Phase I highlighted the semen collection from farm animals, phase II showed semen cryo-storage at liquid nitrogen where temperature is −196°C and produces various stresses which changed the omics elements, phase III highlighted the sperm thawing process, phase IV suggested utilization of OMICS tools for development of cryo-markers, and the last phase supposed the sperm cryo-tolerance efficacy and led to successful fertilization. OS, Osmotic stress; CS, Cold shock; ICIC, Intracellular ice crystal Formation; ROS, Reactive oxygen species.