New advances of preimplantation and prenatal genetic screening and noninvasive testing as a potential predictor of health status of babies

microRNAs as A Biomarker to Predict Embryo Quality Assessment in In Vitro Fertilization

Embryo selection for in vitro fertilization (IVF) is an effort to increase the success rate of embryo implantation. Factors influencing the success of embryo implantation include embryo quality, endometrial receptivity, embryo characteristics, and maternal interactions. Some molecules have been found to influence these factors, but their regulatory mechanisms are unclear. MicroRNAs (miRNAs) are reported to play an essential role in the embryo implantation process. miRNAs are small non-coding RNAs consisting of only 20 nucleotides that play an essential role in the stability of gene expression regulation. Previous studies have reported that miRNAs have many roles and are released by cells into the extracellular environment for intracellular communication. In addition, miRNAs can provide information related to physiological and pathological conditions. These findings encourage research development in determining the quality of embryos in IVF to increase the implantation success rate. Moreover, miRNAs can provide an overview of embryo-maternal communication and potentially be noninvasive biological markers of embryo quality, which could increase assessment accuracy while reducing mechanical damage to the embryo itself. This review article summarizes the involvement of extracellular miRNAs and the potential applications of miRNAs in IVF.

Noninvasive sexing of human preimplantation embryos using RT-PCR in the spent culture media: A proof-of-concept study

Preimplantation genetic testing (PGT) routinely requires biopsy which is an invasive approach. The aim of this study was to examine a noninvasive approach for sexing of preimplantation embryos using polymerase chain reaction (PCR)/reverse transcriptase-PCR (RT-PCR) based on the presence of SRY DNA/RNA in the spent culture medium. Two groups were evaluated: in group 1, 40 embryos of routine PGT volunteers were cultured individually after biopsy and in group 2, 31 embryos were cultured individually until Day-5 post-fertilization. Each group was further divided into three subgroups: RNA extraction (RE), nucleic acid (NA) and DNase treated (DT). In the NA and DT subgroups, cDNA synthesis was performed directly on culture medium with or without DNase treatment in DT and NA subgroups, respectively. The results of sexing based on the PCR/RT-PCR in the culture medium, were compared with the results of sexing by fluorescence in situ hybridization (FISH) technique. In group 1, all samples were correctly diagnosed. In group 2, five female samples were misdiagnosed. Test's sensitivity, specificity and accuracy were 100 %, 94.44 % and 96.88 %, in RE, 100 %, 81.82 % and 93.55 % in DT and 100 %, 71.43 % and 85.71 % in NA, respectively. Preimplantation sexing without embryo biopsy, in the spent embryo culture media using RNA amplification based methods including RE and DT seem to be more reliable while nucleic acid based method, NA, led to the highest misdiagnoses probably due to DNA contamination. Since all male samples were correctly diagnosed in all subgroups of this preliminary study, preimplantation noninvasive sexing on culture medium seems feasible, however all sources of nucleic acid contamination must be carefully avoided.

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

Preimplantation 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.

Non-invasive pre-implantation aneuploidy screening and diagnosis of beta thalassemia IVSII654 mutation using spent embryo culture medium

BACKGROUND

Cell-free nuclear DNA has been isolated from spent embryo culture medium. Whether this small amount of DNA can be amplified at the whole genome level and the concordance rate of karyotypes and specific alleles between biopsied cells and media has not been evaluated.

METHODS

Seven couples were recruited, 88 donated embryos and their corresponding media were collected for whole genome amplification (WGA). The efficiency of WGA, the concordance of chromosome status, and the HBB gene IVSII654 allele between biopsied cells and media were investigated.

RESULTS

After WGA, the DNA detection rate was 90.90% with a mean concentration of 26.15 ng/μl. The full chromosome concordance rate between biopsied cells and medium was 64.52%, and it increased to 90.00% for diploid blastocyst samples. Analysis of the mutated IVSII654 locus and SNP linkage verified that the DNA present in the medium originated from embryonic cells.

CONCLUSION

We confirmed that nuclear DNA is present in spent culture medium and that the majority of this DNA can be amplified for subsequent analysis. Our results showed that non-invasive embryo genetic testing at the chromosomal-level using medium can concordant to the biopsied cells, but it needs further optimized before use in clinical applications. KEY MESSAGES The aggressive biopsy step during PGD/PGS procedure would have a negative effect on the future development of the embryo. Cell-free nuclear DNA has been observed in spent embryo culture medium, which holds promise for the development of non-invasive PGD/PGS approaches. The presence of DNA in medium, its efficiency for WGA, and the concordance between chromosome status and the HBB gene IVSII654 allele as diagnosed from biopsied cells or medium were investigated. Non-invasive embryo genetic testing at the chromosomal-level and allele site using medium can concordant to the biopsied cells, but it needs further optimized before use in clinical applications.

The performance of MALBAC and MDA methods in the identification of concurrent mutations and aneuploidy screening to diagnose beta-thalassaemia disorders at the single- and multiple-cell levels

AIM

To select an optimal whole-genome amplification (WGA) method to improve the efficiency of the preimplantation genetic diagnosis and screening (PGD/PGS) of beta-thalassaemia disorders.

METHODS

Fifty-seven fibroblast samples with defined beta-thalassaemia variations and forty-eight single-blastomere samples were amplified from single-, two-, and five-cell samples by multiple annealing and looping-based amplification cycles (MALBAC) and the multiple displacement amplification (MDA) method. Low-depth, high-throughput sequencing was performed to evaluate and compare the coefficiencies of the chromosomal copy number variation (CNV) detection rate and the allele dropout (ADO) rate between these two methods.

RESULTS

At the single-cell level, the success rates of the CNV detection in the fibroblast samples were 100% in the MALBAC group and 91.67% in the MDA group; the coefficient of variation in the CNV detection in the MALBAC group was significantly superior to that in the MDA group (0.15 vs 0.37). The total ADO rate in the HBB allele detection was 4.55% in the MALBAC group, which was significantly lower than the 22.5% rate observed in the MDA group. However, when five or more cells were used as the starting template, the ADO rate significantly decreased, and these two methods did not differ significantly.

CONCLUSIONS

For the genetic diagnosis of HBB gene variation at the single-cell level, MALBAC is a more suitable method due to its higher level of uniformity and specificity. When five or more cells are used as the starting template, both methods exhibit similar efficiency, increased accuracy, and a similar success rate in PGD/PGS.

Are there optimal numbers of oocytes, spermatozoa and embryos in assisted reproduction?

The aim of this overview is to discuss the current information about the search for the optimum yield of gametes in assisted reproduction, as one of the major pillars of IVF success. The first topic is focused on the number of male gametes and the possible impact of some genetic traits on these parameters. The number of spermatozoa did not seem to be crucial when there is no severe male factor of infertility. Genetic testing prior to using those sperm cells is very important. Different methods were applied in order to elect the "best" spermatozoa according to specific indications. The next problem discussed is the importance of the number of oocytes collected. Several studies have agreed that "15 oocytes is the perfect number," as the number of mature oocytes is more important. However, if elective single embryo transfer is performed, the optimal number of oocytes will enable a proper embryo selection. The third problem discussed concerns fertility preservation. Many educational programs promote and encourage procreation at maternal ages between 20-35 years, since assisted reproduction is unable to fully overcome the effects of female aging and fertility loss after that age. It is also strongly recommended to ensure a reasonable number of cryopreserved mature oocytes, preferably in younger ages (<35), for which an average of two stimulation cycles are likely required. For embryo cryopreservation, the "freeze all" strategy suggests the vitrification of good embryos, therefore quality is prior to number and patient recruitment for this strategy should be performed cautiously.

Molecular analysis of DNA in blastocoele fluid using next-generation sequencing

BACKGROUND

Preimplantation genetic testing (PGT) requires an invasive biopsy to obtain embryonic material for genetic analysis. The availability of a less invasive procedure would increase the overall efficacy of PGT. The aim of the study was to explore the potential of blastocoele fluid (BF) as an alternative source of embryonic DNA for PGT.

METHODS

Collection of BF was performed by aspiration with a fine needle prior to vitrification. BF DNA was subjected to whole-genome amplification (WGA) and analyzed by high-resolution next-generation sequencing (NGS).

RESULTS

A high-quality WGA product was obtained from 8 of 11 (72.7 %) samples. Comparison of matching BF and blastomere samples showed that the genomic representation of sequencing reads was consistently similar with respect to density and regional coverage across the 24 chromosomes. A genome-wide survey of the sample sequencing data also indicated that BF was highly representative of known single gene sequences, and this observation was validated by PCR analyses of ten randomly selected genes, with an overall efficiency of 84 %.

CONCLUSION

This study provides further evidence that BF is a promising alternative source of DNA for PGT.

Medium-based noninvasive preimplantation genetic diagnosis for human α-thalassemias-SEA

To develop a noninvasive medium-based preimplantation genetic diagnosis (PGD) test for α-thalassemias-SEA. The embryos of α-thalassemia-SEA carriers undergoing in vitro fertilization (IVF) were cultured. Single cells were biopsied from blastomeres and subjected to fluorescent gap polymerase chain reaction (PCR) analysis; the spent culture media that contained embryo genomic DNA and corresponding blastocysts as verification were subjected to quantitative-PCR (Q-PCR) detection of α-thalassemia-SEA. The diagnosis efficiency and allele dropout (ADO) ratio were calculated, and the cell-free DNA concentration was quantitatively assessed in the culture medium. The diagnosis efficiency of medium-based α-thalassemias-SEA detection significantly increased compared with that of biopsy-based fluorescent gap PCR analysis (88.6% vs 82.1%, P < 0.05). There is no significant difference regarding ADO ratio between them. The optimal time for medium-based α-thalassemias-SEA detection is Day 5 (D5) following IVF. Medium-based α-thalassemias-SEA detection could represent a novel, quick, and noninvasive approach for carriers to undergo IVF and PGD.