Nicotinamide mononucleotide supplementation improves oocyte developmental competence in different ovarian damage conditions

Abstract

Background

Chemotherapy-induced ovarian damage represents a major challenge for women of reproductive age undergoing cancer treatments. In mice, nicotinamide mononucleotide enhances the developmental competence of aged oocytes by preventing oxidative stress, inflammation, and apoptosis; however, its potential to restore oocyte quality following chemotherapy-induced ovarian damage remains unexplored.

Objective

To investigate the effects of nicotinamide mononucleotide treatment against the deleterious effects of chemotherapy and aging in mice and human oocytes.

Study design

We used mouse models with different degrees of chemotherapy-induced ovarian damage, mimicking diminished ovarian reserve and premature ovarian insufficiency, and young healthy females as a reference group. Mice of each ovarian condition were treated with or without 2 g/L nicotinamide mononucleotide in drinking water for a complete cycle (4 weeks) or during the later stages (14 days) of folliculogenesis. After treatments, mice underwent ovarian hyperstimulation and were euthanized to collect ovaries and oocytes to evaluate follicular counts, oocyte quality, and maturation. Part of the collected metaphase II oocytes underwent in vitro fertilization and embryo culture to assess preimplantation embryo development.

Finally, we also explored the benefits of in vitro nicotinamide mononucleotide supplementation in aged infertile patients using germinal vesicle oocytes from advanced maternal age (>38) and young (≤35 years old) women. Maturation and artificial oocyte activation potential were assessed following the germinal vesicle rescue approach.

Results

Nicotinamide mononucleotide supplementation over a complete folliculogenesis cycle (4 weeks) improved the quality of oocytes exposed to chemotherapy by recovering nicotinamide adenine dinucleotide levels (P=.006), redistributing mitochondria to promote proper meiotic spindle assembly, and ultimately, recovering fertilization rate (P=.003) in diminished ovarian reserve mice. In the premature ovarian insufficiency model, reduced reactive oxygen species abundance (P=.039), increased mitochondria quantity (P=.030), and improved expression of the DNA repair gene apurinic/apyrimidinic endonuclease 1 [Apex1] were found, thereby enhancing proper meiotic spindle formation and chromosome alignment. Similarly, when nicotinamide mononucleotide supplementation was restricted to the later stages of folliculogenesis (14 days), positive effects on oocyte quality were observed, though to a lesser extent. Increased nicotinamide adenine dinucleotide levels (P˂.001) and embryo development rates (P=.048) were found in the diminished ovarian reserve group, while reduced reactive oxygen species abundance (P=.040), and increased mitochondrial DNA copy number (P=.006) and DNA repair gene expression (Apex1: P=.041; AlkB homolog 2, alpha-ketoglutarate dependent dioxygenase (Alkbh2): P=.029) were observed in premature ovarian insufficiency mice. Finally, in vitro supplementation with 100 µM nicotinamide mononucleotide was able to improve the nuclear competence (P=.039) and parthenogenetic activation of immature oocytes from women with advanced maternal age (>38 years old).

Conclusion

These results highlight the regenerative role of nicotinamide mononucleotide in mouse and human oocytes exposed to the deleterious effects of chemotherapy and aging, representing a potential therapeutic alternative for fertility preservation and aged patients seeking to achieve motherhood with autologous oocytes.