Metabolic Activity of Boar Semen Stored in Different Extenders Supplemented with Ostrich Egg Yolk Lipoproteins

Viability longevity and quality of epididymal sperm stored in the liquid state of European red deer (Cervus elaphus elaphus)

The aim of the study was to evaluate viability longevity and quality of liquid-stored epididymal sperm of European red deer (Cervus elaphus elaphus). Sperm samples were recovered from epididymides of 15 mature stags. Samples were diluted to 100 × 10⁶ sperm⁄mL in modified Salomon's extender and stored at 5 °C for 25 days. Sperm were analyzed to determine total motility (TMOT), progressive motility (PMOT) and motion variables [CASA system], acrosomes with normal apical ridges (NAR), viability and acrosomal status (FITC-PNA/PI), plasma membrane integrity (PMI) and mitochondrial membrane potential (MMP) on the first day (D1) and every other day of storage (D3-D25). Data were analyzed using a one-way analysis of variance (ANOVA). Spermatozoa remained motile until D25, whereas TMOT exceeded 60%, NAR and PMI exceeded 80%, FITC-PNA/PI exceeded 75%, and MMP approximated 70% until D11. There was a lesser (P < 0.05) value for these variables on D5 (relative to D1). Furthermore, there was a decrease in values for motility variables as duration of storage increased, excluding amplitude of lateral head displacement, on D3. The results indicate that liquid-stored epididymal sperm of European red deer are characterized as having a long viability (25 days) with a retention of sperm quality for as long as 11 days in the liquid storage state. In vitro or in vivo studies, however, are required to confirm the findings in the present study.

Differential motility parameters and identification of proteomic profiles of human sperm cryopreserved with cryostraw and cryovial

Background

Although sperm cryopreservation has been widely used in human reproductive medicine as an integral infertility management in infertility clinics and for banking sperm in sperm banks, the freezing/thawing protocols are not optimal. The freezing and thawing processes result in changes at both structural and molecular levels, some even detrimental, in human sperm when compared with fresh sperm. The change of sperm proteins after cryopreservation may play negative roles for fertilization and early embryo development. Conventionally, cryostraws (CS) and cryovials (CV) are the most widely used cryopreservation carriers (CPCs) for human sperm cryopreservation accompanied with the use of egg yolk free commercial media. However, the influence of cryopreservation on the proteomic profile of human sperm preserved with the two CPCs is unknown. Therefore the purpose of the present study was to compare the frozen-thawed motility, investigate the proteomic profile of human sperm cryopreserved with the two types of CPCs, and identify the susceptible proteins that play key roles for sperm function and fertility.

Methods

The present study compared the cryosurvival of human sperm frozen with the two different CPCs and identified the sperm proteomic changes by using the isobaric tags for relative and absolute quantification labeling technique coupled with 2D LC–MS/MS analysis after freezing and thawing.

Results

Our results indicated that sperm cryopreserved with CV showed higher values for percentage of motile sperm and forward activity rate than those with CS. Compared to fresh sperm, 434 and 432 proteins were differentially identified in human sperm cryopreserved with CS and CV, respectively.

Conclusion

The proteomic profiles of human sperm are greatly affected by cryopreservation with either type of CPC. GO analysis revealed that most of the differentially identified sperm proteins enriched in the extracellular membrane-bounded organelles, cytoplasm and cytosol. In addition, 106 susceptible proteins having known identities related to sperm functions were identified. In general, cryovial seems to be the preferred CPC for human sperm cryopreservation based on the post-thaw motility parameters and the effect on sperm proteomic profiles. These results are beneficial for the insight into the understanding of the cryoinjury mechanism of sperm and the development of human sperm cryopreservation strategies.

Electronic supplementary material

The online version of this article (10.1186/s12014-019-9244-2) contains supplementary material, which is available to authorized users.