Addition of seminal plasma to thawed stallion spermatozoa did not repair cryoinjuries.

The research investigated whether adding seminal plasma (SP) from stallions to thawed sperm could repair damage caused by freezing and thawing processes. They found that adding SP, whether from stallions with high or low-quality semen after thawing, did not provide any beneficial effects, suggesting that it couldn’t repair the cryoinjuries to the sperm.

Research Context

• The freezing and thawing process of sperm for preservation purposes often results in structural and functional damages to the sperm plasma and internal organelles. This is referred to as ‘cryoinjury’.
• In some species, adding seminal plasma (SP) has been shown to reduce or repair these cryoinjuries.
• Previous studies have shown varying results on the effects of SP addition to thawed stallion spermatozoa. This study sought to provide clarity by testing the effect of adding SP from stallions known for good and bad freezability.

Methodology

• Semen was collected from eight warmblood stallions, each providing three ejaculates.
• The semen was processed through Single Layer Centrifugation (SLC) to separate seminal plasma from the spermatozoa.
• Post-thawing, the spermatozoa were treated with pooled SP (5%) from either stallions known for good or bad freezing characteristics.
• The quality of the post-threw sperm was assessed using flow cytometry to examine various parameters such as chromatin integrity, membrane integrity, mitochondrial membrane potential (MMP), reactive oxygen species (ROS), and MitoSOX.
• Sperm movement was also analyzed using computer-assisted sperm analysis.

Findings

• The study found that the proportion of spermatozoa with intact cell membranes and a high MMP was higher in the control group than in the SP treated groups.
• Spermatozoa treated with SP from stallions with good freezing qualities produced more ROS than those treated with SP from stallions with poor freezing qualities.
• Adding SP to the spermatozoa post-thawing did not improve motility parameters.

Conclusion

• This research concluded that the addition of SP after thawing did not have a positive impact on sperm quality.
• It appears to demonstrate that SP is unable to repair the cryoinjuries that occur as a result of the freezing and thawing process in stallion spermatozoa.
• This finding prevailed regardless of whether the SP came from stallions with good or bad freezing qualities.