The effects of sericin on cryopreserved sperm cells and subsequent embryo development in mice

BACKGROUND: Sericin, because of its ability to remove free radicals and its antioxidant properties, has been used to successfully cryopreserve various mammalian cell types. However, the effects of sericin on cryopreservation of mouse sperm has not been reported. OBJECTIVE: The current study intended to determine the protective role of different concentrations of sericin (0, 0.25, 0.5, and 0.75%) on mouse spermatozoa during cryopreservation, in addition to its effect on in vitro fertilization and subsequent embryo development. MATERIALS AND METHODS: Mouse sperm from epididymides were frozen in cryoprotective agent with 18% raffinose, 3% skim milk, and different concentrations of sericin (0, 0.25, 0.5, 0.75%). Thawed sperm were used for in vitro fertilization. The obtained embryos were cultured in Ksom medium for 6 days. The post-thawed motility, viability, fertilizing ability, and subsequent development to the 2-cell embryo and blastocyst stages were evaluated. RESULTS: Our findings show that frozen-thawed sperm cells with 5% sericin indicate significantly (p≤0.0001) percentages of survivability and motility, the best fertilizing ability, as well as 2-cell embryo and blastocyst development compared to the other treated groups. There was no significant difference in survivability (p=0.8781), fertilizing ability (p=0.2458) and development of 2-cell (p=0.5136) and blastocysts embryos (p=0.0896) between 0.75% sericin and control groups. CONCLUSION: Supplementation by 0.5% sericin in cryoprotective agent improved frozen-thawed mouse epididymal sperm cell quality and resulted in increased embryo development.