Preimplantation Genetic Screening with Spent Culture Medium/Blastocoel Fluid for in Vitro Fertilization

Abstract

Preimplantation genetic screening (PGS) detects chromosomal aneuploidy from DNA extracted from trophectodermal biopsy of the embryos before implantation. Although a controlled study showed no difference in pregnancy rates between this invasive cell biopsy technique and a non-biopsied control group, the potential long-term damage by the current PGS method has not be completely ruled out. We therefore tested a less-invasive protocol which utilizes spent culture medium combining with blastocoel fluid (ECB) to assess chromosomal aneuploidy. We compared the new protocol with the currently employed trophectodermal biopsy method against chromosomal information obtained from the remaining embryo. We found that the new technique generated information about aneuploidy that was not entirely identical to obtained from the biopsied trophectoderm or the remaining embryo. As the origins of the DNA extracted from the three sample types were not the same, the significance and interpretation of each result would have its own meaning. The possible implications derived from the ECB results as well as those from cell biopsy were discussed. The effectiveness of this new approach in selecting the best embryo for uterine implantation awaits further long term evaluation.

Divining the genetic status of embryos: consult the medium?

“…If it is assumed that the TE biopsy result is an accurate representation of the cytogenetic status of the embryo, the sensitivity for SCM samples was 94.5%. This rate exceeds sensitivity values reported in two previous niPGT-A studies conducted on day 3-5 spent media (3,4), in which rates of 88.2% and 89.5% were recorded with respect to the remaining whole blastocyst.…”

“…However, the overall accuracy of the SCM diagnoses was compromised by an appreciable incidence of false positive (FP) aneuploidy detection, resulting in a specificity of only 71.7%. The problem was particularly pronounced for day 4-5 SCM, where the specificity was just 42.1%-considerably lower than the 84% and 64.8% reported for day 3-5 SCM by Xu et al (3) and Li et al (4), respectively. An important note, however, was that FPs were less prevalent when the culture period was extended by an additional 24-48 hours (to day 6-7), resulting in an increase of specificity rates to 82.1%.…”

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

“…The sample size ranged from seven (Shamonki et al, 2016;Liu et al, 2017) to 70 (Hammond et al, 2017) couples undergoing assisted reproductive technology procedures. Gamete fertilization was carried out mainly by intracytoplasmic sperm injection (ICSI) (86.7% [13 out of 15]) (Stigliani et al, 2013;Wu et al, 2015;Shamonki et al, 2016;Xu et al, 2016;Feichtinger et al, 2017;Hammond et al, 2017;Liu et al, 2017;Yang et al, 2017;Capalbo et al, 2018;Ho et al, 2018;Kuznyetsov et al, 2018;Li et al, 2018;Vera-Rodriguez et al, 2018) and the other two studies did not report the fertilization method Galluzzi et al, 2015). In 86.6% (13 out of 15) of studies, Cf-DNA from SCM alone was evaluated (Stigliani et al, 2013;Assou et al, 2014;Galluzzi et al, 2015;Wu et al, 2015;Shamonki et al, 2016;Xu et al, 2016;Feichtinger et al, 2017;Liu et al, 2017;Capalbo et al, 2018;Ho et al, 2018;Vera-Rodriguez et al, 2018), whereas a mixture of SCM and blastocoel fluid was assessed in 26.7% (four out of 15) of them (Hammond et al, 2017;Yang et al, 2017;Kuznyetsov et al, 2018;Li et al, 2018).…”

“…The characteristics of the embryos associated with each SCM sample were also heterogeneous. Specifically, 93.3% (14 out of 15) studies evaluated cf-DNA released from fresh embryos (Stigliani et al, 2013;Galluzzi et al, 2015;Wu et al, 2015;Shamonki et al, 2016;Xu et al, 2016;Hammond et al, 2017;Liu et al, 2017;Yang et al, 2017;Feichtinger et al, 2017;Capalbo et al, 2018;Ho et al, 2018;Kuznyetsov et al, 2018;Li et al, 2018;Vera-Rodriguez et al, 2018), and 20.0% (three out of 15) of studies Kuznyetsov et al, 2018;Ho et al, 2018) assessed cf-DNA secreted from cryopreserved embryos. Moreover, embryo micromanipulation, e.g.…”

Assessment of pre‐implantation genetic testing for embryo aneuploidies: A SWOT analysis

“…[66][67][68][69] Recently, cell-free DNA has also been detected in blastocyst-spent culture media but no agreement on concordance rate with the genetic status of embryos has been found. [70][71][72][73][74] Although both strategies appear to be attractive methods, they are characterized by some limitations including the incomplete representation of the whole embryonic genome, the potential maternal DNA contamination, the poor nucleic acid integrity and the unknown sampling time points to obtain acceptable amplification rates. 75 Well-designed studies are needed to evaluate the efficacy of cell-free DNA employment on clinical outcomes.…”