Is cell-free DNA in spent embryo culture medium an alternative to embryo biopsy for preimplantation genetic testing? A systematic review

Abstract

Spent culture medium (SCM) represents a possible source of embryonic DNA for non-invasive preimplantation genetic testing (PGT). Before considering routine clinical use, methodologies need to be improved to increase detection of embryo DNA in SCM while preventing contamination by exogenous and maternal DNA. The identification of DNA origin (in particular, maternal versus embryonic) is necessary for improved reliability of SCM-PGT. ABSTRACTPreimplantation genetic testing (PGT) is increasingly used worldwide. It currently entails the use of invasive techniques, i.e. polar body, blastomere, trophectoderm biopsy or blastocentesis, to obtain embryonic DNA, with major technical limitations and ethical issues. Evidence suggests that invasive PGT can lead to genetic misdiagnosis in the case of embryo mosaicism, and, consequently, to the selection of affected embryos for implantation or to the destruction of healthy embryos. Recently, spent culture medium (SCM) has been proposed as an alternative source of embryonic DNA. An increasing number of studies have reported the detection of cell-free DNA in SCM and highlighted the diagnostic potential of non-invasive SCM-based PGT for assessing the genetic status of preimplantation human embryos obtained by IVF. The reliability of this approach for clinical applications, however, needs to be determined. In this systematic review, published evidence on non-invasive SCM-based PGT is presented, and its current benefits and limitations compared with invasive PGT. Then, ways of optimizing and standardizing procedures for non-invasive SCM-based PGT to prevent technical biases and to improve performance in future studies are discussed. Finally, clinical perspectives of non-invasive PGT are presented and its future applications in reproductive medicine highlighted.

Preimplantation Genetic Testing for Monogenic Disorders

“…This procedure is considered less invasive than TE biopsy and results in embryo collapse which is a manipulation applied in routine vitrification practice to maximize embryo survival post-vitrification [33]. A true non-invasive alternative is to rely on cfDNA present in the spent blastocyst medium (SBM) [34]. Several studies showed that the karyotype concordance between blastocoel fluid samples and inner cell mass and/or TE cells varied widely, indicating that genetic analysis following blastocentesis is insufficiently accurate for clinical PGT-A/PGT-SR [35].…”

A Review on Microfluidics: An Aid to Assisted Reproductive Technology

“…Spent culture medium (SCM) has been proposed as an alternative source for embryonic DNA. Several studies have reported the detection of cell-free DNA in SCM and highlighted the diagnostic potential of non-invasive SCM-based PGT to assess the genetic status of preimplantation human embryos obtained with IVF [ 97 ]. Fluorescent magnetic beads (FMB) were used to capture hCG β, which β-galactosidase (β-Gal) was used to label.…”

Noninvasive preimplantation genetic testing for aneuploidy in spent culture medium as a substitute for trophectoderm biopsy

“…Following the first report of successful live births after the transfer of embryos selected based on an analysis of cfDNA in a culture medium (10), numerous studies have shown the high reliability of detection and amplification of cfDNA for niPGT-A (27). However, the assessment of copy number variation may be hindered in some cfDNA samples because of noisy profiles (6,7,13) and/or contamination due to either the culture medium's constituents (4,28,29) or cumulus cells (2,4,30).…”