Effects of bovine serum albumin on function of cryopreserved stallion spermatozoa during medium culture and uterine tube epithelial cell coculture.

The research focuses on the cryopreservation of stallion sperm and its function in varying conditions, specifically comparing the effects of including bovine serum albumin in the culture medium or co-culturing the sperm with uterine tube epithelial cells. The study found that the removal of bovine serum albumin from the medium improved sperm function and longevity.

Objective of the Research

• The purpose of this research was to investigate the functional attributes of cryopreserved stallion spermatozoa when exposed to different conditions, typically a modified Tyrode’s medium (TM), with or without bovine serum albumin (BSA), or when they were co-cultured with uterine tube (oviduct) epithelial cells (OEC) in TM, again either with or without BSA.

Research Methods

• The researchers used cryopreserved sperm from six proven stallions and OEC from the bovine reproductive tracts in the follicular phase, meaning that egg cells were in the process of maturation.
• Thawed spermatozoa were cultured under different conditions to evaluate how different mediums and the presence or absence of BSA affected their function.
• The percentage of capacitated and acrosome-reacted spermatozoa in each culture method was measured at a fixed period (5 hours for TM cultures). Sperm survival and motility characteristics were observed and analyzed over time for all culture methods.
• The number of spermatozoa attaching to OEC in the co-culturers were also compared to understand any variations impacted by BSA.

Research Findings

• The results showed using TM without BSA modified sperm functional attributes in the cell-free medium and when co-cultured with OEC.
• In comparison, a higher percentage of spermatozoa were acrosome-reacted in TM containing BSA, i.e., sperm were more ready to fertilize, but the percentage of capacitated spermatozoa, i.e., sperm undergoing the physiological changes necessary for fertilizing an egg, remained the same.
• The longevity and superior motion of the spermatozoa were maintained in TM without BSA and in OEC co-cultures indicating it to be a better method to maintain sperm functions.
• Furthermore, more spermatozoa were able to attach to OEC in the absence of BSA, indicating better interaction with OEC.

Conclusions

• Adding BSA to the incubation media resulted in a rapid decrease in the percentage of motile, intact spermatozoa, and limited their ability to interact with OEC.
• The study concludes that the current culture media used for assisted reproduction techniques in horses are not capable of providing functionally capacitated spermatozoa.
• Improvements in sperm quality and longevity can be achieved by removing BSA from such culture mediums.