Antioxidants improve IVF outcome and subsequent embryo development in the mouse

Area of Science:

• Reproductive biology and assisted reproductive technologies (ART).
• Cellular and molecular mechanisms of oxidative stress in gametes and embryos.
• Developmental biology and embryogenesis.

Background:

• The combination of Acetyl-L-Carnitine, N-Acetyl-L-Cysteine, and α-Lipoic Acid has demonstrated beneficial effects on in vitro fertilized mouse oocyte development.
• These antioxidants are particularly effective in mitigating the negative impacts of oxidative stress on early embryonic development.
• Previous research indicates a significant positive impact when these antioxidants are included in embryo culture media.

Purpose of the Study:

• To investigate the effect of a specific antioxidant combination (Acetyl-L-Carnitine, N-Acetyl-L-Cysteine, and α-Lipoic Acid) on mouse fertilization and embryo development.
• To determine the impact of these antioxidants when present in the in vitro fertilization (IVF) medium during oocyte and sperm collection.
• To assess the role of antioxidants in reducing intracellular hydrogen peroxide (H2O2) levels during early embryonic stages.

Main Methods:

• In vitro fertilization (IVF) was performed using mouse oocytes and sperm, with a combination of antioxidants (10 μM Acetyl-L-Carnitine, 10 μM N-Acetyl-L-Cysteine, 5 μM α-Lipoic Acid) added to the IVF medium during gamete collection and fertilization.
• Oocytes were exposed to antioxidants for 4 hours, and sperm for 1 hour, under 20% oxygen conditions.
• Embryo development was monitored using time-lapse microscopy, and blastocyst cell numbers were determined by differential staining. Intracellular H2O2 levels were measured using an aryl boronate probe.

Main Results:

• Antioxidant treatment during IVF and subsequent culture significantly accelerated embryo development from the 2-cell stage to the expanded blastocyst stage.
• Resultant blastocysts exhibited significantly increased inner cell mass (ICM) and trophectoderm (TE) cell numbers, leading to higher total cell counts.
• A significant reduction in intracellular H2O2 levels was observed in oocytes treated with the antioxidant combination, with faster developmental rates observed when antioxidants were present in oocyte IVF medium or both oocyte and sperm IVF medium.

Conclusions:

• The combination of Acetyl-L-Carnitine, N-Acetyl-L-Cysteine, and α-Lipoic Acid enhances mouse embryo development by increasing blastocyst cell number and reducing oxidative stress.
• The beneficial effects are most pronounced when antioxidants are present during oocyte collection and fertilization, and during subsequent embryo culture.
• These findings suggest potential applications for antioxidant supplementation in human assisted reproductive technologies (ART) to improve embryo viability.