Freezing, Vitrification, and Freeze-Drying of Equine Spermatozoa: Impact on Mitochondrial Membrane Potential, Lipid Peroxidation, and DNA Integrity.
Authors: Restrepo Giovanni, Varela Elizabeth, Duque Juan Esteban, Gómez Jorge Enrique, Rojas Mauricio
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Equine Sperm Preservation and Cellular Integrity Three cryopreservation techniques—conventional freezing, vitrification, and freeze-drying—were compared for their effects on equine spermatozoa quality in this Colombian study of four stallions across eight ejaculates. Using flow cytometry to measure mitochondrial membrane potential (ΔΨM), lipid peroxidation, and DNA fragmentation index, researchers found markedly different outcomes: freeze-drying preserved the highest proportion of sperm with intact mitochondrial function (40.26%) and minimal oxidative damage (35.98% of viable cells without lipid peroxidation), whilst vitrification produced the poorest results, with only 5.32% of cells maintaining healthy mitochondrial potential and a significantly elevated DNA fragmentation index of 0.12% compared to 0.03% in frozen and 0.02% in freeze-dried samples. Conventional freezing occupied a middle position across most parameters, though motility data presented here suggest preservation quality varied by technique. For practitioners engaged in equine reproduction programmes, these findings indicate that freeze-drying warrants serious consideration as an alternative to standard cryopreservation, particularly where long-term storage and cellular viability are priorities, though the clinical implications for fertility outcomes and the practical feasibility of freeze-drying protocols in routine breeding operations require further investigation.
Read the full abstract on PubMed
Practical Takeaways
- •For equine breeding programs using assisted reproduction, freeze-drying may be superior to vitrification for preserving sperm quality based on mitochondrial function and oxidative stress markers
- •Vitrification should be avoided or reconsidered as a preservation method for equine spermatozoa due to higher DNA damage and cellular stress compared to conventional freezing
- •Freeze-drying shows promise as an alternative preservation technique that maintains better cellular integrity and metabolic function in equine sperm
Key Findings
- •Freeze-drying preserved higher mitochondrial membrane potential (40.26%) compared to freezing (21.82%) and vitrification (5.32%)
- •Freeze-drying resulted in higher rates of non-peroxidized viable sperm (35.98%) versus frozen (10.34%) and vitrified (7.07%) samples
- •Vitrified sperm showed significantly higher DNA fragmentation index (0.12%) compared to frozen (0.03%) and freeze-dried (0.02%) samples
- •Vitrification generated the greatest sperm alterations among the three preservation methods tested