Aims: Truong and Gardner (2017) demonstrated that the addition of three antioxidants to sperm preparation media incubated for 1h had no effect on mouse embryo development. In IVF clinics, human sperm can be incubated for several hours before insemination. This study aimed to further previous mouse studies by utilising a clinically relevant sperm incubation time of 3h in the presence or absence of antioxidants, and evaluate the impact on subsequent embryo development.
Methods: Sperm were collected via backflushing the epididymis of F1-hybrid male mice. Sperm incubation occurred at 20% oxygen in the presence or absence of a combination of antioxidants (10µM Acetyl-L-Carnitine, 10µM N-Acetyl-L-Cysteine, 5µM α-Lipoic Acid). IVF was conducted under 5% oxygen and resulting embryos were cultured without antioxidants. After 4 days, the impact of antioxidants in sperm preparation on embryo development was analysed via time-lapse morhokinetics and by differential nuclear staining to determine cell counts.
Results: Antioxidant treatment during sperm incubation had no impact on fertilisation (87% vs 92%, control vs antioxidant) or blastocyst rate (90% vs 84%), but did result in a significant increase in trophectoderm (73.3 ± 2.8 vs 91.0 ± 2.5, P<0.01), inner cell mass (25.8 ±1 .1 vs 30.8 ± 0.9, P<0.01) and total blastocyst cell numbers (99.1 ± 3.5 vs 121.8 ± 3.2, P<0.01; n>60). Embryos derived from the antioxidant-treated sperm also developed more quickly at the 8-cell and morula stage (t8: 49.48 ± 0.49 vs 48.30 ± 0.32, P<0.05; tM: 56.86 ± 0.67 vs 54.79 ± 0.50 P<0.05; n>69).
Conclusion: The presence of antioxidants during mouse sperm incubation for 3h prior to IVF imparts a significant benefit on embryo quality and development. The data indicates that antioxidants could be beneficial for IVF clinics which currently incubate sperm at 20% oxygen for several hours before use.