Current embryo selection techniques in the implementation of assisted reproductive technology programs

Objective. To carry out a systematic analysis of the data available in the world literature on current methods for screening and selection of embryos to enhance the efficiency of assisted reproductive technology (ART) programs in a group of late reproductive age women. Material and methods. The review includes the data of Russian and foreign articles found in Pubmed on this topic. General provisions. There are recent trends towards late marriage and late childbearing. With increasing age, reproductive function realization is known to have a number of problems. First, women older than 35 years have diminished ovarian reserve. After 40 years, the rate of follicular atresia doubles. Second, this group of women has frequently a family history of gynecological problems. Third, patients older than 35 years of age even with intact ovarian reserve are at increased risk for the aneuploidy of oocytes and, as a consequence, embryos, which also reduces the chance of getting pregnant. Accordingly, the assessment of embryo quality is a key component of success in ART programs. Existing methods for selection of embryos are based on their detailed morphological and genetic evaluation using preimplantation genetic screening (PGS). However, even the use of PGS does not improve the efficiency of ART programs above 50%. Therefore, there is a need for additional methods to identify viable embryos. In this connection, great importance has been recently attached to the mitochondrial potential of gametes and embryos. Results. The paper comparatively characterizes main PGS techniques (array-based comparative genomic hybridization (aCGH) and high-throughput sequencing (next generation sequencing (NGS)), considers the advantages of NGS, and describes the new potential marker for the quality of oocytes and embryos, the level of mitochondrial DNA (mtDNA), which can improve the outcomes of ART programs in the group of female patients of late reproductive age. Conclusion. In the near future, it seems likely that NGS will be put into wide practical use due to its advantages. In addition, the world literature contains data that a study of the mitochondrial potential of oocytes and embryos may become an additional reliable predictor for the outcomes of ART programs in different groups of patients, including in the group of late reproductive age patients.

preimplantation genetic screening (PGS), array-based comparative genomic hybridization (aCGH), high-throughput sequencing (new generation sequencing (NGS)), real-time polymerase chain reaction (RT-PCR), polymerase chain reaction (PCR), cumulus cells, trophectoderm, mitochondrial DNA (mtDNA), aneuploidies, mosaicism, unbalanced restructurings