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.

Morphology and cleavage rate remain the mainstay of embryo assessment. However, a number of additional technologies for this application are under investigation. These include the measurement of glucose, lactate, pyruvate or amino acid levels in the embryo culture media, assessment of oxygen consumption by the embryo, genomic and proteomic profiling, and most recently, analytical examination of the embryonic metabolome. As the number of assisted reproduction cycles increases worldwide, improvements in the ability to quickly and non-invasively identify the best embryos for transfer remain a critical goal for reproductive medicine. Recent studies suggest that metabolomic profiling of embryo culture media using optical and non-optical spectroscopies may provide a useful adjunct to the current embryo assessment strategies and provide insight into the phenotype of embryos with increasing reproductive potential.

We aimed to determine whether intraovarian injection of autologous platelet rich plasma (PRP) improves response to ovarian stimulation and in vitro fertilization (IVF) outcome in women with primary ovarian insufficiency (POI). Women (N=311; age 24-40) diagnosed with POI based on ESHRE criteria underwent intraovarian PRP injection. Markers of ovarian reserve, and IVF outcome parameters were followed. PRP treatment resulted in increased antral follicle count (AFC) and serum antimullerian hormone (AMH), while serum follicle stimulating hormone (FSH) did not change significantly. After PRP injection, 23 women (7.4%) conceived spontaneously, 201 (64.8%) developed antral follicle(s) and attempted IVF, and 87 (27.8%) had no antral follicles and therefore did not receive additional treatment. Among the 201 women who attempted IVF, 82 (26.4% of total) developed embryos; 25 of these women preferred to cryopreserve embryos for transfer at a later stage, while 57 underwent embryo transfer resulting in 13 pregnancies (22.8% per transfer, 4% of total). In total, of the 311 women treated with PRP, 25 (8.0%) achieved livebirth/sustained implantation (spontaneously or after IVF), while another 25 (8.0%) cryopreserved embryos. Our findings suggest that in women with POI, intraovarian injection of autologous PRP might be considered as an alternative experimental treatment option.