Alginate encapsulation of stallion sperm for increasing storage stability.

The research focuses on the encapsulation of stallion sperm in alginate, a compound which could potentially enhance the sperm’s longevity and survival rates during cold storage and cryopreservation. Test results, however, indicated a varying impact depending upon the encapsulation process and the substances used.

Sperm Encapsulation and Alginate

• Given its potential to increase the storage stability of sperm, alginate encapsulation was the main focus of the study. Alginate is a naturally-occurring polysaccharide that has been used in various fields, including biotechnology, for cell encapsulation.
• The procedure involves enrobing or embedding sperm in alginate structure, creating a protective environment that could potentially increase the longevity and survival rate of the sperm during cold storage and cryopreservation.

Experiment and Procedure

• The study began by testing the biocompatibility of the compounds required for encapsulation and identifying the factors that determine capsule structure.
• The scientists encapsulated the sperm by either depositing 20µL droplets of sperm solution supplemented with barium or calcium chloride in alginate solution or by adding sperm-alginate droplets to a solution containing barium or calcium chloride, followed by a hardening process for 10 minutes.
• Two unique procedures resulted in different structures: the first method created structures where the sperm resided in a liquid core, surrounded by a spherical alginate shell, while the second method led to sperm embedded in solid beads of alginate matrix.

Findings of the Research

• Findings indicated that using calcium for alginate gelation caused a decrease in sperm motility as compared to using barium.
• Encapsulation in solid beads negatively affected the intactness of the sperm plasma membrane, a vital aspect in terms of fertilization capacity.
• Barium-alginate core-shell structures maintained the same percentage of membrane-intact sperm over 4 days of cold storage, similar to that found in ordinary diluted sperm.
• Although sperm motility was reduced after immediate recovery from core-shell structures, it stabilized over the 4-day storage period, achieving similar values to the un-encapsulated sperm at the end of this period.
• Unfortunately, the cryosurvival rate of sperm encapsulated in solid beads or core-shell structures was determined to be lower than that of ordinary diluted sperm, indicating a need for optimization of the encapsulation procedure.