The embryo non-invasive pre-implantation diagnosis era: how far are we?

Abstract

Advancements in assisted reproduction (AR) methodologies have allowed significant improvements in live birth rates of women who otherwise would not be able to conceive. One of the tools that allowed this improvement is the possibility of embryo selection based on genetic status, performed via preimplantation genetic testing (PGT). Even though the widespread use of PGT from TE biopsy helped to decrease the interval from the beginning of the AR intervention to pregnancy, especially in older patients, in AR, there are still many concerns about the application of this invasive methodology in all cycles. Therefore, recently, researchers started to study the use of cell free DNA (cfDNA) released by the blastocyst in its culture medium to perform PGT, in a method called non-invasive PGT (niPGT). The development of a niPGT would bring the diagnostics power of conventional PGT, but with the advantage of being potentially less harmful to the embryo. Its implementation in clinical practice, however, is under heavy discussion since there are many unknowns about the technique, such as the origin of the cfDNA or if this genetic material is a true representative of the actual ploidy status of the embryo. Available data indicates that there is high correspondence between results observed in TE biopsies and the ones observed from cfDNA, but these results are still contradictory and highly debatable. In the present review, the advantages and disadvantages of niPGT are presented and discussed in relation to tradition TE biopsy-based PGT. Furthermore, there are also presented some other possible non-invasive tools that could be applied in the selection of the best embryo, such as quantification of other molecules as quality biomarkers, or the use artificial intelligence (AI) to identify the best embryos based on morphological and/or morphokitetic parameters.

Retinoic Acid Action in Cumulus Cells: Implications for Oocyte Development and In Vitro Fertilization

“…Therefore, other approaches able to improve implantation rates by finding the best embryos continue to be pursued. Of these more recent attempts, preimplantation genetic testing has gained a foothold in clinical practice [1,2]. In this process, a small number of trophectoderm cells are removed from blastocysts, which are then assessed for ploidy status.…”

Heterogeneity of nucleolar morphology in four‐cell mouse embryos after IVF: association with developmental potential

“…After IVF, non‐invasive embryo selection for embryo transfer has become widely utilized across species, including humans, to improve the chances of achieving pregnancy because of lower birth rates. Various methods for selection related to aneuploidy have been developed, based on morphological features of cleavage embryos and blastocysts, the timing of cleavages, as well as the integration of artificial intelligence (AI) with time‐lapse imaging technology and omics analysis of embryo waste products in culture media (Cimadomo et al, 2023; Del Collado et al, 2023; Gardner & Lane, 2017; Mashiko et al, 2022; Nguyen et al, 2020; Salih et al, 2023; Shenoy et al, 2021). In contrast, embryo selection or evaluation methods using the nucleolus/nucleolus precursor body (NPB) as a marker are primarily limited to the zygotic stage (Chen & Kattera, 2006; Coskun et al, 2003; Fulka et al, 2015; Inoue et al, 2021; Nagy et al, 2003; Tesarik & Greco, 1999).…”