Oocyte mitochondrial function and reproduction

Abstract

Purpose of review Mitochondria are cellular organelles that are required for energy production. Emerging evidence demonstrates their role in oocyte development and reproduction. In this review, we examine recent animal and clinical studies on the role of mitochondria in fertility. We also analyse the impact of assisted reproductive techniques (ARTs) on mitochondrial function and discuss the future clinical implications of mitochondrial nutrients and mitochondrial replacement. Recent findings Mitochondria affect all aspects of mammalian reproduction. They are essential for optimal oocyte maturation, fertilization and embryonic development. Mitochondrial dysfunction causes a decrease in oocyte quality and interferes with embryonic development. ART procedures affect mitochondrial function, while mitochondrial nutrients may increase mitochondrial performance in oocytes. New mitochondrial replacement procedures using mitochondria obtained from polar bodies or from the patient’s own oogonial stem cells are promising and may address concerns related to the induction of high-levels of heteroplasmy, which could potentially result in negative long-term health effects. Summary Optimal energy production is required for oocyte and embryo development, and mitochondrial abnormalities have devastating reproductive consequences. Improvement of oocyte mitochondrial function via intake of compounds that boost mitochondrial activity may have clinical benefits, and mitochondrial replacement could potentially be used for the prevention of mitochondrial diseases.

Reproductive aging is associated with changes in oocyte mitochondrial dynamics, function, and mtDNA quantity

“…Mitochondria affect all aspects of mammalian reproduction, including oocyte maturation, fertilization and embryonic development [13]. It was proposed that decreased oocyte quality and increased aneuploidy rate with aging could be explained with abnormal mitochondria numbers and/or function [10, 13, 14, 17–19, 21, 22].…”

“…It was proposed that decreased oocyte quality and increased aneuploidy rate with aging could be explained with abnormal mitochondria numbers and/or function [10, 13, 14, 17–19, 21, 22]. Therefore, we set out to determine mitochondria dynamics in oocytes and compare young and old mice oocytes at different stages of follicular development using various electron microscopic parameters.…”

“…Delayed childbearing is associated with aged oocytes at conception, which are of poor quality primarily due to increased aneuploidy rates [11, 12]. Altered mitochondrial function and quantity are thought to be contributory to decreased oocyte quality in mammals (reviewed in [13]).…”

“…Age-related increase in unfavorable reproductive outcomes is believed to be secondary to decreased oocyte quality (reviewed in [13]). Alterations in mitochondrial DNA copy number, mitochondrial mutation load and mitochondrial function have been demonstrated in aged mammalian oocytes and thought to be either contributory to or a hallmark of oocyte aging [14–19].…”

Mitochondrial contributions to oocyte and embryonic quality in bovine

“…Mitochondrial genome copy number has been studied as a potential marker of cellular viability and health and it was hypothesized that oocytes without sufficient mtDNA (Mitochondrial DNA) are not able to generate enough ATP to sustain early development (Ge et al 2012;Babayev and Seli, 2015).…”