Multicenter prospective study of concordance between embryonic cell-free DNA and trophectoderm biopsies from 1301 human blastocysts

Non-invasive preimplantation genetic testing for aneuploidy using cell-free DNA in blastocyst culture medium

PURPOSE

This study evaluated the performance of preimplantation genetic testing for aneuploidies (PGT-A) using cell-free DNA (cfDNA) from spent culture media (SCM) of blastocyst embryos (non-invasive PGT-A; NiPGT-A) compared with conventional trophectoderm (TE) biopsy samples.

METHODS

This prospective study was conducted at IVFMD, My Duc Hospital, Vietnam, from August to December 2020, and included patients with an indication for PGT-A. The culture medium was replaced on day 3, and SCM from day 3 to the day of TE biopsy (days 5 or 6) of all biopsied blastocysts was tested using next-generation sequencing. The total concordance rate, sensitivity, and specificity of NiPGT-A versus PGT-A for detecting aneuploid embryos were calculated. Outcomes after single blastocyst transfer are also reported.

RESULTS

Forty-four couples participated; 100 paired TE PGT-A biopsies and SCM samples were evaluated. The whole-genome amplification success rate for SCM was 82%; 77 samples had clear NGS results and were further evaluated. The total concordance rate between NiPGT-A and PGT-A was 63.6%. For detecting aneuploidy, NiPGT-A had a sensitivity of 57.1%, specificity of 67.3%, positive predictive value of 50.0%, and negative predictive value of 73.3%. Of the 35 single euploidy embryo transfers, 8 had no NiPGT-A results, 21 were classified as NiPGT-A euploid, and 6 were classified as NiPGT-A aneuploid; the live birth rate was 51.4% (18/35). Four of the 6 NiPGT-A aneuploid blastocysts resulted in live births.

CONCLUSIONS

cfDNA in SCM has the potential for NiPGT-A. However, the NiPGT-A process is unreliable enough to replace traditional PGT-A using TE biopsy.

A systematic review and meta-analysis of the diagnostic accuracy after preimplantation genetic testing for aneuploidy

OBJECTIVE

Aneuploidy accounts for many pregnancy failures and congenital anomalies. Preimplantation genetic testing for aneuploidy (PGT-A) is a screening test applied to embryos created from in vitro fertilization to diminish the chance of an aneuploid conception. The rate of misdiagnosis for both false aneuploidy (false positive) and false euploidy (false negative) test results is unknown. The objective of this study was to determine the rate of misclassification of both aneuploidy and euploidy after PGT-A.

DATA SOURCES

We conducted a systematic review and meta-analysis. We searched Medline, Embase, Cochrane Central, CINAHL and WHO Clinical Trials Registry from inception until April 10, 2024. The protocol was registered in International Prospective Register of Systematic Reviews (PROSPERO CRD 42020219074).

METHODS OF STUDY SELECTION

We included studies that conducted either a pre-clinical validation of the genetic platform for PGT-A using a cell line, studies that compared the embryo biopsy results to those from the whole dissected embryo or its inner cell mass (WE/ICM), and studies that compared the biopsy results to prenatal or postnatal genetic testing.

TABULATION, INTEGRATION, AND RESULTS

Two independent reviewers extracted true and false positives and negatives comparing biopsy results to the reference standard (known karyotype, WE/ICM, pregnancy outcome). For preclinical studies, the main outcome was the positive and negative predictive values. Misdiagnosis rate was the outcome for pregnancy outcome studies. The electronic search yielded 6674 citations, of which 109 were included. For WE/ICM studies (n=40), PPV was 89.2% (95% CI 83.1-94.0) and NPV was 94.2% (95% CI 91.1-96.7, I2=42%) for aneuploid and euploid embryos, respectively. The PPV for mosaic embryos of either a confirmatory mosaic or aneuploid result was 52.8% (95% CI 37.9-67.5). For pregnancy outcome studies (n=43), the misdiagnosis rate after euploid embryo transfer was 0.2% (95% CI 0.0-0.7%, I2=65%). However, the rate for mosaic transfer, with a confirmatory euploid pregnancy outcome, was 21.7% (95% CI: 9.6-36.9, I2=95%).

CONCLUSION

The accuracy of an aneuploid result from PGT-A is excellent and can be relied upon as a screening tool for embryos to avoid aneuploid pregnancies. Similarly, the misdiagnosis rate after euploid embryo transfer is less than 1%. However, there is a significant limitation in the accuracy of mosaic embryos.

Non-Invasive Preimplantation Genetic Testing

To minimise the influence of chromosomal abnormalities during IVF treatment, embryos can be screened before transfer using preimplantation genetic testing. This typically involves an invasive trophectoderm biopsy at the blastocyst stage, where 4-8 cells are collected and analysed. However, emerging evidence indicates that, as embryos develop in vitro in culture media, they release cell-free DNA into the media, providing an alternative source of genetic material that can be accessed non-invasively. Spent blastocyst media samples that contain embryo cell-free DNA demonstrate high informativity rates and ploidy concordance when compared with the corresponding trophectoderm, inner cell mass, or whole blastocyst results. However, optimising this non-invasive approach requires several changes to embryo culture protocols, including additional embryo washes to tackle contamination and extending embryo culture time to maximise the amount of cell-free DNA released into the culture media. In this review, we discuss this novel non-invasive approach for aneuploidy detection and embryo prioritisation, as well as the current data and future prospects for utilising cell-free DNA analysis to identify structural rearrangements and single gene disorders.

Predictive potential of combined secretomics and image-based morphometry as a non-invasive method for selecting implanting embryos

BACKGROUND

Non-invasive selection of human embryos for in vitro fertilization purposes is still a major challenge to pursue. Therefore, this study aims to identify non-invasive morphometric and secretomic parameters that reliably select the embryos with the highest likelihood of implantation prior to embryo transfer (ET).

METHODS

Prospective single-centre cohort study. Thirty-two day 5 blastocysts derived from 28 couples undergoing intracytoplasmic sperm injection (ICSI) and ET between January 2023 and April 2023. Patients were split according to their implantation outcome, confirmed with serum beta-human chorionic gonadotropin (b-hCG) levels > 5 mIU/mL nine days post-SET. Ninety-two proteins involved in embryonic developmental programming were measured in spent blastocyst media (SBM) using a protein extension assay. Sparse PLS-DA (sPLS-DA) was used for principal component analysis. Forty-seven morphometric parameters related to the trophoblast, inner cell mass and blastocele dimension were evaluated in microphotographs of day 5 embryos with ImageJ software. T-test and Mann-Whitney tests were respectively used to compare morphometric measurements and normalized expression of secreted protein (NPx) levels between embryos that implanted or not. Predictive value of models of implantation based on embryo morphometric parameters and secreted proteins.

RESULTS

Chi-squared tests showed no significant differences in transferred blastocyst stage, quality, and state between subgroups. Implanting blastocysts (n = 14) presented significantly different morphometric shape descriptors (i.e., internal circularity, internal roundness, internal axis ratio, internal angle and trophoblast mean width) than non-implanting blastocysts (n = 13). Among the quantifiable proteins (86/92) in SBM from eleven implanting and nine non-implanting blastocysts, NPx and sPLS-DA analysis revealed three differentially expressed proteins. Matrilin-2 (MATN2) and legumain (LGMN) were significantly elevated (p < 0.01 in both cases) while thymosin beta-10 (TMSB10) was significantly decreased (p < 0.05) in implanting embryos. Predictive models based exclusively on morphometric or secreted protein profiles accurately discriminated implantation outcomes (AUC > 0.71). The model integrating the blastocysts' internal circularity, internal roundness, internal axis ratio and the NPx of MATN2 and TMSB10 in SBM had exceptional negative and positive predictive power for implantation outcomes (100% and 90.91%, respectively; AUC = 0.93).

CONCLUSIONS

Morphometric shape descriptors and NPx levels of MATN2 and TMSB10 in SBM emerge as promising candidate markers for non-invasive embryo selection.

A computational DNA methylation method to remove contaminated DNA from spent embryo culture medium for noninvasive preimplantation genetic testing

BACKGROUND

In the last fifty years, assisted reproductive technology (ART) has achieved remarkable breakthroughs, culminating in the birth of 12 million infants. At the heart of ART success is preimplantation genetic testing (PGT), which enables the detection of chromosomal anomalies, single-gene disorders, and structural rearrangements, enhancing embryo selection and mitigating genetic risk. However, current PGT methods, including trophectoderm (TE) biopsy, face limitations such as challenges related to convenience and potential impacts on embryonic health. In this evolving field, noninvasive PGT (niPGT) has emerged as a promising alternative. By analysing cell-free DNA (cfDNA) in spent embryo culture medium (SECM), niPGT offers a less intrusive approach. However, maternal DNA contamination within SECM remains a marked barrier to its clinical application as underscored by our research and other studies. There is an urgent need for innovation and optimisation in niPGT methodologies.

METHODS

We developed a computational algorithm to eliminate contaminated nonembryonic DNA from spent embryo culture medium. The rationale is based on the phenomenon that the DNA methylation level of a mammalian preimplantation embryo reaches its minimum at the blastocyst stage during a global DNA demethylation wave. Therefore, selecting hypomethylated reads is expected to enrich blastocyst DNA over nonembryonic DNA. To investigate this, we retrieved single-cell-resolution DNA methylation data from oocytes (n = 33), inner cell masses (ICMs, n = 74), TEs (n = 71) and sperm cells (n = 21), bulk DNA methylation data from cumulus cells, and DNA methylation data from SECM samples (n = 194) from our previously published database, and conducted a comparative analysis of DNA methylation patterns among them. Then, we constructed a decontamination algorithm based on single read and applied it to remove contamination originating from cumulus cells, polar bodies, and sperm cells.

FINDINGS

By selecting hypomethylated reads, we successfully enriched blastocyst DNA over DNA originating from cumulus cells, polar bodies and sperm (enrichment factors = 4, 1.2, and 2.5, respectively). By testing simulated SECM samples, the method demonstrated a substantial reduction in the false-negative rate even with up to 75% cumulus cell contamination. In real clinical SECM samples, the method improved aneuploidy detection sensitivity at a cumulus cell contamination ratio of 50%.

INTERPRETATION

Our study introduces a novel computational strategy for reducing nonembryonic DNA contamination, thereby enhancing aneuploidy detection sensitivity in SECM cfDNA methylation analyses. In combination with DNA methylation methodologies, this approach holds considerable promise for advancing niPGT applications in ART.

FUNDING

This study was supported by grants from the Beijing Natural Science Foundation (7232203), the National Key R&D Program of China (2023YFC2705600, 2023YFC2705602), the National Natural Science Foundation of China (82301889, 82371706), the Key Clinical Projects of Peking University Third Hospital (BYSYZD2022029), the Young Elite Scientists Sponsorship Program by CAST (2023QNRC001), the Peking University Medicine Sailing Program for Young Scholars' Scientific & Technological Innovation (BMU2023YFJHPY001) and the special fund of the National Clinical Key Specialty Construction Program, P. R. China (2023). We thank support from the High Performance Computing Platform of the Centre for Life Sciences (Peking University) and Open Research Fund of the National Centre for Protein Sciences at Peking University in Beijing.

The diagnostic accuracy of preimplantation genetic testing (PGT) in assessing the genetic status of embryos: a systematic review and meta-analysis

BACKGROUND

Preimplantation genetic testing (PGT) is widely used in assisted reproduction to assess the genetic status of embryos. However, increasing evidence suggests that the trophectoderm (TE) may not fully reflect the genetic status of the inner cell mass (ICM), raising controversy about the accuracy of TE biopsy. Research in recent years has focused on cell-free DNA (cfDNA) found in blastocoel fluid (BF) and spent culture medium (SCM), as these may contain genetic information from both the TE and ICM. Therefore, further research and validation are essential to determine the reliability and clinical applicability of these diagnostic methods in PGT.

METHODS

Relevant studies published between January 2000 and August 2024 were identified through PubMed and Web of Science (WOS). Risk assessment and publication bias were evaluated using QUADAS-2 and Deek's test. Diagnostic meta-analysis was performed using a bivariate model to combine sensitivity and specificity, with results visualized through forest plots and summary receiver operating characteristic (SROC) curves.

RESULTS

Out of 6,407 initially screened records, 36 studies involving 4,230 embryos were included. TE biopsy was identified as the best method for diagnosing the genetic status of embryos (sensitivity: 0.839; specificity: 0.791, AUC: 0.878), while SCM had slightly lower accuracy (sensitivity: 0.874; specificity: 0.719, AUC: 0.869). The effectiveness of BF (AUC: 0.656) was significantly lower than that of TE biopsy and SCM. Despite this, TE biopsy has not yet achieved ideal diagnostic performance. However, TE biopsies demonstrate a high level of accuracy in diagnosing PGT-SR (AUC: 0.957). Additionally, multiple TE biopsies (AUC: 0.966) or TE biopsies combined with SCM (AUC: 0.927) can enhance the diagnostic efficiency of PGT.

CONCLUSION

The findings of this study suggest that TE biopsy has yet to achieve optimal diagnostic accuracy, which may result in a significant number of missed embryo diagnoses and misdiagnoses. Our results confirm that SCM has the potential to serve as a supplementary test. Employing multiple biopsies or combining TE with SCM may enhance diagnostic efficiency and yield optimal results.

Noninvasive preimplantation genetic testing for aneuploidy using blastocyst spent culture medium may serve as a backup of trophectoderm biopsy in conventional preimplantation genetic testing

BACKGROUND

To investigate whether the noninvasive preimplantation genetic testing (niPGT) complement conventional preimplantation genetic testing (PGT) in the embryos for aneuploidy.

RESULTS

40 spent culture medium (SCM) samples from routine embryo culture were collected, and half of each SCM (10 µL) sample was used for whole genome amplification, while the other half was stored at -80 °C for 3-6 months. Thirty-six out of 40 fresh SCM samples were successfully amplified and sequenced. Thirty-six paired frozen-thawed SCM samples showed 100% concordance with the freshly amplified SCM samples. Then, SCM and trophectoderm (TE) samples from 149 blastocysts from 51 couples were collected. A 98.0% successful SCM sample amplification rate (146/149) was achieved. For the 146 paired TE biopsy and SCM samples, the overall concordance rate was 82.9% (121/146). Ten embryos with aneuploid TE results but euploid niPGT results were donated. A 70.0% (7/10) true negative rate was achieved by niPGT with respect to the inner cell mass (ICM) results (TE-positive embryos).

CONCLUSIONS

These results suggested that SCM stored at -80 °C for 6 months without affecting niPGT results based on NICSInst amplification.

Could metabolic imaging and artificial intelligence provide a novel path to non-invasive aneuploidy assessments? A certain clinical need

Pre-implantation genetic testing for aneuploidy (PGT-A) via embryo biopsy helps in embryo selection by assessing embryo ploidy. However, clinical practice needs to consider the invasive nature of embryo biopsy, potential mosaicism, and inaccurate representation of the entire embryo. This creates a significant clinical need for improved diagnostic practices that do not harm embryos or raise treatment costs. Consequently, there has been an increasing focus on developing non-invasive technologies to enhance embryo selection. Such innovations include non-invasive PGT-A, artificial intelligence (AI) algorithms, and non-invasive metabolic imaging. The latter measures cellular metabolism through autofluorescence of metabolic cofactors. Notably, hyperspectral microscopy and fluorescence lifetime imaging microscopy (FLIM) have revealed unique metabolic activity signatures in aneuploid embryos and human fibroblasts. These methods have demonstrated high accuracy in distinguishing between euploid and aneuploid embryos. Thus, this review discusses the clinical challenges associated with PGT-A and emphasizes the need for novel solutions such as metabolic imaging. Additionally, it explores how aneuploidy affects cell behaviour and metabolism, offering an opinion perspective on future research directions in this field of research.

Non Invasive Preimplantation Testing for Aneuploidies in Assisted Reproduction: A SWOT Analysis

The implementation of non-invasive PGT-A offers a new strategy to genetically assess the preimplantation embryo and to enhance IVF results. The extraction of DNA from the embryo culture medium has been sufficiently demonstrated, and the ability to obtain chromosomal information as a result is particularly interesting. As morphological criteria have proven to have a weak correlation with embryo ploidy status, this technique emerges as a promising alternative for embryo selection. It also appears reasonable that avoiding biopsy may enhance further embryo development. However, there are growing concerns regarding several aspects of this technique, such as the origin of this cell free DNA, the degree of representativeness of the whole embryo, the need for extended culture or the absence of standardized protocols. Despite the published data on good prognosis couples are promising, niPGT-A is yet to be considered a substitute for trophectoderm biopsy. The current SWOT analysis aims to summarize both resolved and unresolved issues, as well as limiting aspects of niPGT-A.

Comparison of Non-Invasive and Minimally Invasive Preimplantation Genetic Testing for Aneuploidy Using Samples Derived from the Same Embryo Culture

Background/Objectives: To assess the ploidy status of embryos via preimplantation genetic testing for aneuploidy (PGT-A), a biopsy of trophectoderm (TE) cells can be performed. However, this approach is considered invasive, and therefore the aim of this study was to identify the optimal sample type and sampling day for non-invasive or minimally invasive PGT-A (ni/miPGT-A) in terms of data quality and concordance rates with TE biopsies derived from the same embryos. Methods: This study was performed using 239 embryo cultures. After optimization using 96 embryos, non-invasive spent culture media (SCM) and a minimally invasive combination of blastocoel fluid and SCM (BF+SCM), along with the corresponding TE samples, were collected from 143 embryos cultured for 5 days (n = 70) or 6 days (n = 73), and all were subjected to ni/miPGT-A with whole-genome amplification followed by next-generation sequencing. Results: The amplification failure rate was lower for SCM samples than for BF+SCM (SCM: 0.7%, 1/143 vs. BF+SCM: 7.7%, 11/143; p = 0.005). The rate of ploidy concordance with TE was significantly higher for SCM samples than for BF+SCM samples (SCM: 83.7%, 118/141 vs. BF+SCM: 58%, 76/131; p < 0.001). Among SCM samples, concordance rates were higher for samples derived from embryos cultured for 6 days (87.5%, 63/72) than for 5 days (79.7%, 55/69). In the embryos cultured for 6 days, discordant cases included five (6.9%) SCM samples with falsely negative (euploid) results that were deemed to be mosaic according to TE and four (5.6%) samples falsely found to be aneuploid. Conclusions: SCM samples derived from embryos cultured for 6 days can be applied in niPGT-A with subsequent verification of aneuploid samples using TE biopsy.

Effects of first and second division modes on euploidy acquisition in human embryo

The aim of this study was to non-invasively investigate euploid embryos using methods other than pre-implantation genetic testing for aneuploidy. The study focused on direct cleavage (DC) observed during early embryo development. We also investigated the relationship between the mode of early embryo division and embryo ploidy. Embryos were divided into the normal cleavage (NC) and DC groups, and the DC group was further subdivided into the DC-First (DC-F) and DC-Second (DC-S) groups, depending on whether DC was observed at the first or second cleavage, respectively. The acquisition rates of euploid embryos and embryos appropriate for transfer were compared between the groups. Our results revealed that the timing of the first division did not differ between blastocyst grades or in embryos with varying degrees of ploidy. Further, the timing of the first cleavage did not affect the acquisition rate of embryos appropriate for transfer and euploid embryo formation rate did not significantly differ between the DC and NC groups. We also noted that for embryos appropriate for transfer, euploidy acquisition rate did not differ significantly between the DC and NC groups. Further, the euploidy acquisition rate of embryos did not differ between the DC-F and DC-S groups. However, the acquisition rate of embryos appropriate for transfer, including those with low mosaicism, was significantly higher in the DC-S group than in the DC-F group. These findings indicated that the number of good-quality blastocysts formed was significantly higher in the NC group than in the DC group and the acquisition rate of embryos appropriate for transfer, including those with low mosaicism, was significantly higher in the DC-S group than in the DC-F group.

The biological characteristics of long cell-free DNA in spent embryos culture medium as noninvasive biomarker in in-vitro embryo selection

An improved understanding of the cfDNA fragmentomics has proved it as a promising biomarker in clinical applications. However, biological characteristics of cfDNA in spent embryos culture medium (SECM) remain unsolved obstacles before the application in non-invasive in-vitro embryo selection. In this study, we developed a Tn5 transposase and ligase integrated dual-library construction sequencing strategy (TDual-Seq) and revealed the fragmentomic profile of cfDNA of all sizes in early embryonic development. The detected ratio of long cfDNA (>500 bp) was improved from 4.23 % by traditional NGS to 12.80 % by TDual-Seq. End motif analysis showed long cfDNA molecules have a more dominance of fragmentation intracellularly in apoptotic cells with higher predominance of G-end, while shorter cfDNA undergo fragmentation process both intracellularly and extracellularly. Moreover, the mutational pattern of cfDNA and the correlated GO biological process were well differentiated in cleavage and blastocyst embryos. Finally, we developed a multiparametric index (TQI) that employs the fragmentomic profiles of cfDNA, and achieved an area under the ROC curve of 0.927 in screening top quality embryos. TDual-Seq strategy has facilitated characterizing the fragmentomic profile of cfDNA of all sizes in SECM, which are served as a class of non-invasive biomarkers in the evaluation of embryo quality in in-vitro fertilization. And this improved strategy has opened up potential clinical utilities of long cfDNA analysis.

Current research status and clinical applications of noninvasive preimplantation genetic testing: A review

Noninvasive preimplantation genetic testing (ni-PGT) is conducted by obtaining genetic information from embryos through the analysis of free DNA released by embryos in spent embryo culture medium or blastocoel fluid. Compared to conventional preimplantation genetic testing relying on trophectoderm biopsy, ni-PGT is characterized by its noninvasiveness. It has demonstrated early advancements in the detection of embryonic chromosomal aneuploidies and the diagnosis of monogenic diseases, showcasing considerable potential for clinical application. However, there are substantial controversies in the literature concerning the reliability of ni-PGT, the source of cell-free DNA, and maternal contamination. This paper elaborates on the principles, research advancements, effectiveness, and limitations of ni-PGT to provide a basis for clinical applications.

A study on methods for preimplantation genetic testing (PGT) on in vivo- and in vitro-produced equine embryos, with emphasis on embryonic sex determination

Two methods for preimplantation genetic testing (PGT) have been described for equine embryos: trophoblast cell biopsy (TCB) or blastocoele fluid aspiration (BFA). While TCB is widely applied for both in vivo- and in vitro-produced embryos, BFA has been mostly utilized for in vivo-produced embryos. Alternative methods for PGT, including analysis of cell-free DNA (CFD) in the medium where in vitro-produced embryos are cultured, have been reported in humans but not for equine embryos. In Experiment 1, in vivo- (n = 10) and in vitro-produced (n = 13) equine embryos were subjected to BFA, cultured for 24 h, then subjected to TCB, and cultured for additional 24 h. No detrimental effect on embryonic diameter or re-expansion rates was observed for either embryo group (P > 0.05). In Experiment 2, the concordance (i.e., agreement on detecting the same embryonic sex using two techniques) among BFA, TCB, and the whole embryo (Whole) was studied by detecting the sex-determining region Y (SRY) or testis-specific y-encoded protein 1 (TSPY) (Y-chromosome), and androgen receptor (AR; X-chromosome) genes using PCR. Overall, a higher concordance for detecting embryonic sex was observed among techniques for in vivo-produced embryos (67-100 %; n = 14 embryos) than for in vitro-produced embryos (31-92 %; n = 13 embryos). The concordance between sample types increased when utilizing TSPY (77-100 %) instead of SRY (31-100 %) as target gene. In Experiment 3, CFD analysis was performed on in vitro-produced embryos to determine embryonic sex via PCR (SRY [Y-chromosome] and amelogenin - AMEL [X- and Y-chromosomes]). Overall, CFD was detected in all medium samples, and the concordance between CFD sample and the whole embryo was 60 % when utilizing SRY and AMEL genes. In conclusion, equine embryos can be subjected to two biopsy procedures (24 h apart) without apparent detrimental effects on embryonic size. For in vivo-, but not for in vitro-produced equine embryos, BFA can be considered a potential alternative to TCB for PGT. Finally, CFD can be further explored as a non-invasive method for PGT in in vitro produced equine embryos.

Non-invasive pre-implantation genetic testing's reliability for aneuploidy using Cell-free DNA in embryo culture media

OBJECTIVE

The presence of embryonic cell-free DNA (cfDNA) in spent embryo culture media (SECM) may offer valuable advantages for non-invasive testing of embryo ploidy or genetic characteristics compared to trophectoderm (TE) biopsy. This study aimed to assess the diagnostic potential of SECM cfDNA as a non-invasive sample for chromosomal copy number testing in blastocysts within the clinical setting of in-vitro fertilization.

METHOD

This prospective observational study collected 28 SECM cfDNA samples matched with TE biopsy samples from 21 infertile couples who underwent IVF-PGT-A cycles. SECM samples were obtained from blastocysts that were cultured for approximately 5/6 days in an uninterrupted time-lapse incubator. Both sets of samples were collected during the biopsy procedure. The Variseq Illumina platform was utilized for ploidy measurement. The study evaluated the informativity and interpretability of SECM cfDNA, concordance of general ploidy status, and sex chromosome agreement between the two sample types.

RESULTS

SECM cfDNA had a high informativity rate (100 %) after double amplification procedure, with a result interpretability of 93 %. Two out of the 28 SECM cfDNA samples were uninterpretable and regarded as overall noise samples. The diagnostic potential of SECM cfDNA, when compared to TE biopsy the standard reference, was relatively low at 50 %. Maternal DNA contamination remains the major obstacle that hinders the widespread clinical adoption of SECM cfDNA in the routine practice of pre-implantation genetic testing for aneuploidy within IVF settings.

CONCLUSION

A significant modification must be implemented in the IVF laboratory to minimize DNA contamination and this necessitates suggesting adjustments to oocyte denudation, embryo culture media preparation, and sample collection procedures.

Blastocoel fluid as an alternative source of DNA for minimally invasive PGT and biomarker of embryo competence

The discovery of DNA in blastocoel fluid (BF-DNA) generated new perspectives in the potential development of simpler and safer alternative non-invasive tests in reproductive genetics. Short DNA fragments of apoptotic origin, together with specific expression patterns of pro- and anti-apoptotic genes in the blastocoel fluid of euploid and aneuploid embryos, suggest a self-correction mechanism to preferentially eliminate aneuploid cells, and purge defective and non-viable cells. The correlation of blastocoel fluid content with the genetic status of the whole embryo, and therefore its potential use in minimally invasive preimplantation genetic testing (miPGT), or as an indicator of embryo potential, remains uncertain and needs to be determined. The limited amount and compromised integrity of BF-DNA, with likely apoptotic origination, constrains its amplification, leading to low concordance and reproducibility rates for both aneuploidy screening and monogenic testing. While embryo genotyping constitutes a more ambitious goal, the presence of analysable DNA after amplification in blastocoel fluid may be used as a clinical biomarker of embryo competency to select the most viable embryo(s) for transfer, and potentially improve the implantation rate. Although blastocentesis remains a promising area for future research, several technical and methodological limitations are currently constraining its consideration for clinical practice.

Bovine embryo production in vitro: evolution of culture media and commercial perspectives

In vitro produced embryos exhibit lower viability compared to their in vivo counterparts. Mammalian preimplantation embryos have the ability to reach the blastocyst stage in diverse culture media, showcasing considerable metabolic adaptability, which complicates the identification of optimal developmental conditions. Despite embryos successfully progressing to the blastocyst stage, adaptation to suboptimal culture environments may jeopardize blastocyst viability, cryotolerance, and implantation potential. Enhancing our capacity to support preimplantation embryonic development in vitro requires a deeper understanding of fundamental embryo physiology, including preferred metabolic substrates and pathways utilized by high-quality embryos. Armed with this knowledge, it becomes achievable to optimize culture conditions to support normal, in vivo-like embryo physiology, mitigate adaptive stress, and enhance viability. The objective of this review is to summarize the evolution of culture media for bovine embryos, highlighting significant milestones and remaining challenges.

Clinical-grade whole genome sequencing-based haplarithmisis enables all forms of preimplantation genetic testing

High-throughput sequencing technologies have increasingly led to discovery of disease-causing genetic variants, primarily in postnatal multi-cell DNA samples. However, applying these technologies to preimplantation genetic testing (PGT) in nuclear or mitochondrial DNA from single or few-cells biopsied from in vitro fertilised (IVF) embryos is challenging. PGT aims to select IVF embryos without genetic abnormalities. Although genotyping-by-sequencing (GBS)-based haplotyping methods enabled PGT for monogenic disorders (PGT-M), structural rearrangements (PGT-SR), and aneuploidies (PGT-A), they are labour intensive, only partially cover the genome and are troublesome for difficult loci and consanguineous couples. Here, we devise a simple, scalable and universal whole genome sequencing haplarithmisis-based approach enabling all forms of PGT in a single assay. In a comparison to state-of-the-art GBS-based PGT for nuclear DNA, shallow sequencing-based PGT, and PCR-based PGT for mitochondrial DNA, our approach alleviates technical limitations by decreasing whole genome amplification artifacts by 68.4%, increasing breadth of coverage by at least 4-fold, and reducing wet-lab turn-around-time by ~2.5-fold. Importantly, this method enables trio-based PGT-A for aneuploidy origin, an approach we coin PGT-AO, detects translocation breakpoints, and nuclear and mitochondrial single nucleotide variants and indels in base-resolution.

Development of a Novel Non-invasive Metabolomics Assay to Predict Implantation Potential of Human Embryos

Can a set of metabolites present in embryo culture media correlate with embryo implantation? Case-control study in two phases: discovery phase (101 samples) and validation phase (169 samples), collected between 2018 and 2022, with a total of 218 participants. Culture media samples with known implantation outcomes were collected after blastocyst embryo transfer (including both PGT and non-PGT cycles) and were analyzed using chromatography followed by mass spectrometry. The spectra were processed and analyzed using statistical and machine learning techniques to identify biomarkers associated with embryo implantation, and to develop a predictive model. In the discovery phase, 148 embryo implantation biomarkers were identified using high resolution equipment, and 47 of them were characterized. Our results indicate a significant enrichment of tryptophan metabolism, arginine and proline metabolism, and lysine degradation biochemical pathways. After transferring the method to a lower resolution equipment, a model able to assign a Metabolite Pregnancy Index (MPI) to each embryo culture media was developed, taking the concentration of 36 biomarkers as input. Applying this model to 20% of the validation samples (N=34) used as the test set, an accuracy of 85.29% was achieved, with a PPV (Positive Predictive Value) of 88% and a NPV (Negative Predictive Value) of 77.78%. Additionally, informative results were obtained for all the analyzed samples. Metabolite concentration in the media after in vitro culture shows correlation with embryo implantation potential. Furthermore, the mathematical combination of biomarker concentrations using Artificial Intelligence techniques can be used to predict embryo implantation outcome with an accuracy of around 85%.

The impact of implementing a non-invasive preimplantation genetic testing for aneuploidies (niPGT-A) embryo culture protocol on embryo viability and clinical outcomes

STUDY QUESTION

Are modifications in the embryo culture protocol needed to perform non-invasive preimplantation genetic testing for aneuploidies (niPGT-A) affecting clinical reproductive outcomes, including blastocyst development and pregnancy outcomes?

SUMMARY ANSWER

The implementation of an embryo culture protocol to accommodate niPGT-A has no impact on blastocyst viability or pregnancy outcomes.

WHAT IS KNOWN ALREADY

The recent identification of embryo cell-free (cf) DNA in spent blastocyst media has created the possibility of simplifying PGT-A. Concerns, however, have arisen at two levels. First, the representativeness of that cfDNA to the real ploidy status of the embryo. Second, the logistical changes that need to be implemented by the IVF laboratory when performing niPGT-A and their effect on reproductive outcomes. Concordance rates of niPGT-A to invasive PGT-A have gradually improved; however, the impact of culture protocol changes is not as well understood.

STUDY DESIGN, SIZE, DURATION

As part of a trial examining concordance rates of niPGT-A versus invasive PGT-A, the IVF clinics implemented a specific niPGT-A embryo culture protocol. Briefly, this involved initial culture of fertilized oocytes following each laboratory standard routine up to Day 4. On Day 4, embryos were washed and cultured individually in 10 μl of fresh media. On Day 6 or 7, blastocysts were then biopsied, vitrified, and media collected for the niPGT-A analysis. Six IVF clinics from the previously mentioned trial were enrolled in this analysis. In the concordance trial, Clinic A cultured all embryos (97 cycles and 355 embryos) up to Day 6 or 7, whereas in the remaining clinics (B-F) (379 cycles), nearly a quarter of all the blastocysts (231/985: 23.5%) were biopsied on Day 5, with the remaining blastocysts following the niPGT-A protocol (754/985: 76.5%). During the same period (April 2018-December 2020), the IVF clinics also performed standard invasive PGT-A, which involved culture of embryos up to Days 5, 6, or 7 when blastocysts were biopsied and vitrified.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In total, 428 (476 cycles) patients were in the niPGT-A study group. Embryos from 1392 patients underwent the standard PGT-A culture protocol and formed the control group. Clinical information was obtained and analyzed from all the patients. Statistical comparisons were performed between the study and the control groups according to the day of biopsy.

MAIN RESULTS AND THE ROLE OF CHANCE

The mean age, number of oocytes, fertilization rates, and number of blastocysts biopsied were not significantly different for the study and the control group. Regarding the overall pregnancy outcomes, no significant effect was observed on clinical pregnancy rate, miscarriage rate, or ongoing pregnancy rate (≥12 weeks) in the study group compared to the control group when stratified by day of biopsy.

LIMITATIONS, REASONS FOR CAUTION

The limitations are intrinsic to the retrospective nature of the study, and to the fact that the study was conducted in invasive PGT-A patients and not specifically using niPGT-A cases.

WIDER IMPLICATIONS OF THE FINDINGS

This study shows that modifying current IVF laboratory protocols to adopt niPGT-A has no impact on the number of blastocysts available for transfer and overall clinical outcomes of transferred embryos. Whether removal of the invasive biopsy step leads to further improvements in pregnancy rates awaits further studies.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by Igenomix. C.R., L.N.-S., and D.V. are employees of Igenomix. D.S. was on the Scientific Advisory Board of Igenomix during the study.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov (NCT03520933).

Culture time to optimize embryo cell-free DNA analysis for frozen-thawed blastocysts undergoing noninvasive preimplantation genetic testing for aneuploidy

OBJECTIVE

To investigate the ideal time in culture to optimize embryo cell-free deoxyribonucleic acid (cfDNA) analysis in frozen-thawed blastocysts undergoing noninvasive preimplantation genetic testing for aneuploidy (PGT-A). Cell-free DNA is released into the spent blastocyst media (spent media) by the embryo. However, the optimal timing to determine maximal cfDNA in the case of frozen-thawed blastocysts undergoing noninvasive PGT-A remains to be elucidated.

DESIGN

In this prospective observational study, 135 spent media and corresponding whole blastocysts were collected from January 2021 through March 2022.

SETTING

Private fertility clinics.

PATIENTS

Day-5 frozen-thawed blastocysts were cultured for 8 hours (Day-5 Short) or 24 hours (Day-5 Long), whereas day-6 frozen-thawed blastocysts were cultured for 8 hours (Day-6 Short). The spent media and whole blastocysts were then collected for further analysis. Spent media and whole blastocysts were amplified using whole genome amplification and sequenced using next-generation sequencing.

MAIN OUTCOME MEASURES

Informativity and concordance rates between cfDNA in spent media and whole blastocyst DNA were compared according to the different times in culture.

RESULTS

When comparing time in culture, informativity rates for spent media were significantly higher for Day-5 Long and Day-6 Short (>91%) compared with the Day-5 Short group (<60%). A similar trend was observed for cases with and without a previous PGT-A. Regarding blastocyst expansion grade, informativity rates were lower on Day-5 Short compared with Day-5 Long and Day-6 Short, regardless of expansion degree. This decrease was significant for Gardner-grade expansion grades 3, 4, and 5-6. In addition, for a similar time in culture, the grade of expansion did not have an impact on the informativity rates. For concordance rates, no significant differences were observed among the 3 groups. In all cases, concordance rates were 90.5% for Day-5 Short, 93.6% for Day-5 Long, and 92.3% for Day-6 Short. No impact of the expansion grade was observed on concordance rates.

CONCLUSION

Noninvasive PGT-A in frozen-thawed blastocysts yields very high concordance rates with whole blastocysts, possibly limiting the need for invasive PGT-A and making it available for a wider range of patients.

The current clinical applications of preimplantation genetic testing (PGT): acknowledging the limitations of biology and technology

INTRODUCTION

Preimplantation Genetic Testing (PGT) is a cutting-edge test used to detect genetic abnormalities in embryos fertilized through Medically Assisted Reproduction (MAR). PGT aims to ensure that embryos selected for transfer are free of specific genetic conditions or chromosome abnormalities, thereby reducing chances for unsuccessful MAR cycles, complicated pregnancies, and genetic diseases in future children.

AREAS COVERED

In PGT, genetics, embryology, and technology progress and evolve together. Biological and technological limitations are described and addressed to highlight complexity and knowledge constraints and draw attention to concerns regarding safety of procedures, clinical validity, and utility, extent of applications and overall ethical implications for future families and society.

EXPERT OPINION

Understanding the genetic basis of diseases along with advanced technologies applied in embryology and genetics contribute to faster, cost-effective, and more efficient PGT. Next Generation Sequencing-based techniques, enhanced by improved bioinformatics, are expected to upgrade diagnostic accuracy. Complicating findings such as mosaicism, mt-DNA variants, variants of unknown significance, or variants related to late-onset or polygenic diseases will however need further appraisal. Emphasis on monitoring such emerging data is crucial for evidence-based counseling while standardized protocols and guidelines are essential to ensure clinical value and respect of Ethical, Legal and Societal Issues.

Non-invasive preimplantation genetic testing for aneuploidy: is the promise real?

Recent advances in preimplantation genetic testing for aneuploidy (PGT-A) have significantly enhanced its application in ART, providing critical insights into embryo viability, and potentially reducing both the time spent in fertility treatments and the risk of pregnancy loss. With the integration of next-generation sequencing, PGT-A now offers greater diagnostic precision, although challenges related to segmental aneuploidies and mosaicism remain. The emergence of non-invasive PGT-A (niPGT-A), which analyzes DNA in spent embryo culture media, promises a simpler aneuploidy screening method. This mini review assesses the methodological criteria for test validation, the current landscape of PGT-A, and the potential of niPGT-A, while evaluating its advantages and potential pitfalls. It underscores the importance of a robust three-phase validation process to ensure the clinical reliability of PGT-A. Despite initial encouraging data, niPGT-A not only confronts issues of DNA amplification failure and diagnostic inaccuracies but also has yet to meet the three-prong criteria required for appropriate test validation, necessitating further research for its clinical adoption. The review underscores that niPGT-A, like traditional PGT-A, must attain the high standards of precision and reliability expected of any genetic testing platform used in clinical settings before it can be adopted into routine ART protocols.

Efficacy of non-invasive chromosome screening, preimplantation genetic testing for aneuploidy, and morphological grading in selecting embryos of patients with advanced maternal age: a three-armed prospective cohort study

BACKGROUND

Non-invasive chromosome screening (NICS) and trophectoderm biopsy preimplantation genetic testing for aneuploidy (TE-PGT) were both applied for embryo ploidy detection, However, the cumulative live birth rates (CLBR) of NICS and TE-PGT in older age groups have yet to be reported. This study aimed to ascertain whether NICS and TE-PGT could enhance the cumulative live birth rates among patients of advanced maternal age.

METHODS

A total of 384 couples aged 35-40 years were recruited. The patients were assigned to three groups: NICS, TE-PGT, and intracytoplasmic sperm injection (ICSI). All patients received frozen single blastocyst transfer. Patients in the NICS and TE-PGT groups underwent aneuploidy screening.

RESULTS

When compared to the ICSI group, the CLBR was significantly higher in the NICS and TE-PGT groups (27.9% vs. 44.9% vs. 51.0%, p = 0.003 for NICS vs. ICSI, p < 0.001 for TE-PGT vs. ICSI). There were no significant differences in the clinical outcomes between the NICS and TE-PGT groups. Adjusting for confounding factors, the NICS and TE-PGT groups still showed a higher CLBR than the ICSI group (adjusted odds ratio (OR) 3.847, 95% confidence interval (CI) 1.939 to 7.634; adjusted OR 3.795, 95% CI 1.981 to 7.270). Additionally, the cumulative pregnancy loss rates of the NICS and TE-PGT groups were significantly lower than that of the ICSI group (adjusted OR 0.277, 95% CI 0.087 to 0.885; adjusted OR 0.182, 95% CI 0.048 to 0.693). There was no significant difference in the birth weights of the three groups (p = 0.108).

CONCLUSIONS

In women 35-40 years old, the CLBR can be increased by selecting euploid embryos using NICS and TE-PGT. For elderly women at high risk of embryonic aneuploidy, NICS, characterized by its safety and non-invasive nature, may emerge as an alternative option for preimplantation genetic testing.

Role of genetic analysis of products of conception and PGT in managing early pregnancy loss

This article considers the addition of comprehensive 24-chromosomal microarray (CMA) analysis of products of conception (POC) to a standard evaluation for recurrent pregnancy loss (RPL) to help direct treatment towards expectant management versus IVF with preimplantation genetic testing for aneuploidies (PGT-A). The review included retrospective data from 65,333 miscarriages, a prospective evaluation of 378 couples with RPL who had CMA testing of POC and the standard workup, and data from an additional 1020 couples who were evaluated for RPL but did not undergo CMA testing of POC. Aneuploidy in POC explained the pregnancy loss in 57.7% (218/378) of cases. In contrast, the full RPL evaluation recommended by the American Society for Reproductive Medicine identified a potential cause in only 42.9% (600/1398). Combining the data from the RPL evaluation and the results of genetic testing of POC provides a probable explanation for the loss in over 90% (347/378) of women. Couples with an unexplained loss after the standard evaluation with POC aneuploidy accounted for 41% of cases; PGT-A may be considered after expectant management. Conversely, PGT-A would have a limited role in those with a euploid loss and a possible explanation after the standard workup. Categorizing a pregnancy loss as an explained versus unexplained loss after the standard evaluation combined with the results of CMA testing of POC may help identify patients who would benefit from expectant management versus PGT-A.

A pilot study to investigate the clinically predictive values of copy number variations detected by next-generation sequencing of cell-free deoxyribonucleic acid in spent culture media

OBJECTIVE

To investigate the positive predictive value and false positive risk of copy number variations (CNV's) detected in cell free deoxyribonucleic acid (DNA) from spent culture media for nonviable or aneuploid embryos.

DESIGN

Diagnostic/prognostic accuracy study.

PATIENT(S)

Patients aged 35 and younger with an indication for IVF-ICSI and elective single frozen embryo transfer at a single, private IVF center.

INTERVENTION

Embryo selection was performed according to the conventional grading, blinded to noninvasive preimplantation genetic testing for aneuploidy (niPGT-A) results. After clinical outcomes were established, spent culture media samples were analyzed.

MAIN OUTCOME MEASURES

Prognostic accuracy of CNVs according to niPGT-A results to predict nonviability or clinical aneuploidy.

RESULTS

One hundred twenty patients completed the study. Interpretations of next-generation sequencing (NGS) profiles were as follows: 7.5% (n = 9) failed quality control; 62.5% (n = 75) no CNVs detected; and 30% (n = 36) abnormal copy number detected. Stratification of abnormal NGS profiles was as follows: 15% (n = 18) whole chromosome and 15% (n = 18) uncertain reproductive potential. An intermediate CNV was evident in 27.8% (n = 5) of the whole chromosome abnormalities. The negative predictive value for samples with no detected abnormality was 57.3% (43/75). Whole chromosome abnormality was associated with a positive predictive value of 94.4% (17/18), lower sustained implantation rate (5.6%, 1/18), and higher relative risk (RR) for nonviability compared with no detected abnormalities (RR 2.21, 95% CI: 1.66-2.94). No other CNVs were associated with significant differences in the sustained implantation or RRs for nonviability. Unequal sex chromosome proportions suggested that maternal contamination was not uncommon. A secondary descriptive analysis of 705 supernumerary embryos revealed proportions of NGS profile interpretations similar to the transferred cohort. Significant median absolute pairwise differences between certain subcategories of CNV abnormalities were apparent.

CONCLUSION

Whole chromosome abnormalities were associated with a high positive predictive value and significant RR for nonviability. Embryos associated with other CNVs had sustained implantation rates similar to those with no abnormalities detected. Further studies are required to validate the clinical applicability of niPGT-A.

CLINICAL TRIAL REGISTRATION NUMBER

clinicaltrials.gov (NCT04732013).

Effect of time post warming to embryo transfer on human blastocyst metabolism and pregnancy outcome

PURPOSE

This study is aiming to test whether variation in post warming culture time impacts blastocyst metabolism or pregnancy outcome.

METHODS

In this single center retrospective cohort study, outcomes of 11,520 single frozen embryo transfer (FET) cycles were analyzed from January 2015 to December 2020. Patient treatments included both natural and programmed cycles. Time categories were determined using the time between blastocyst warming and embryo transfer: 0 (0- <1h), 1 (1-<2h), 2 (2-<3h), 3(3-<4h), 4 (4-<5), 5 (5-<6), 6 (6-<7) and 7 (7-8h). Non-invasive metabolic imaging of discarded human blastocysts for up to 10h was also performed using Fluorescence lifetime imaging microscopy (FLIM) to examine for metabolic perturbations during culture.

RESULTS

The mean age of patients across all time categories were comparable (35.6 ± 3.9). Live birth rates (38-52%) and miscarriage rate (5-11%) were not statistically different across post-warming culture time. When assessing pregnancy outcomes based on the use of PGT-A, miscarriage and live birth rates were not statistically different across culture hours in both PGT-A and non-PGT cycles. Further metabolic analysis of blastocysts for the duration of 10h of culture post warming, revealed minimal metabolic changes of embryos in culture.

CONCLUSION

Overall, our results show that differences in the time of post warming culture have no significant impact on miscarriage or live birth rate for frozen embryo transfers. This information can be beneficial for clinical practices with either minimal staffing or a high number of patient cases.

Expression of miRNA from spent pre-implantation embryos culture media

This study examines the expression of three microRNAs (hsa-miR-661, hsa-miR-21-5p, hsa-miR-372-5p) in spent pre-implantation embryos culture media to identify possible new non-invasive biomarkers of embryo competence, predictive of development to the blastocyst stage. A preliminary analysis on 16 patients undergoing IVF cycles was performed by collecting and stored spent culture media on the fifth/sixth day of embryo culture. Expression of miRNAs was evaluated according to the embryos' fate: 1) NE/DG: non-evolved or degenerate embryos; 2) BLOK: embryos developed to the blastocyst stage. Preliminary results revealed a higher miRNAs expression in NE/DG spent media. To elucidate the roles of these miRNAs, we employed a robust bioinformatics pipeline involving: 1) in-silico miRNA Target Prediction using RNAHybrid, which identified the most-likely gene targets; 2) Construction of a Protein-Protein Interaction network via GeneMania, linking genes with significant biological correlations; 3) application of modularity-based clustering with the gLay app in Cytoscape, resulting in three size-adapted subnets for focused analysis; 4) Enrichment Analysis to discern the biological pathways influenced by the miRNAs. Our bioinformatics analysis revealed that hsa-miR-661 was closely associated with pathways regulating cell shape and morphogenesis of the epithelial sheet. These data suggest the potential use of certain miRNAs to identify embryos with a higher likelihood of developing to the blastocyst stage. Further analysis will be necessary to explore the reproducibility of these findings and to understand if miRNAs here investigated can be used as biomarkers for embryo selection before implantation into the uterus or if they may be reliable predictors of IVF outcome.

Preimplantation genetic testing in the current era, a review

BACKGROUND

Preimplantation genetic testing (PGT), also referred to as preimplantation genetic diagnosis (PGD), is an advanced reproductive technology used during in vitro fertilization (IVF) cycles to identify genetic abnormalities in embryos prior to their implantation. PGT is used to screen embryos for chromosomal abnormalities, monogenic disorders, and structural rearrangements.

DEVELOPMENT OF PGT

Over the past few decades, PGT has undergone tremendous development, resulting in three primary forms: PGT-A, PGT-M, and PGT-SR. PGT-A is utilized for screening embryos for aneuploidies, PGT-M is used to detect disorders caused by a single gene, and PGT-SR is used to detect chromosomal abnormalities caused by structural rearrangements in the genome.

PURPOSE OF REVIEW

In this review, we thoroughly summarized and reviewed PGT and discussed its pros and cons down to the minutest aspects. Additionally, recent studies that highlight the advancements of PGT in the current era, including their future perspectives, were reviewed.

CONCLUSIONS

This comprehensive review aims to provide new insights into the understanding of techniques used in PGT, thereby contributing to the field of reproductive genetics.

How should the best human embryo in vitro be? Current and future challenges for embryo selection

In-vitro fertilization (IVF) aims at overcoming the causes of infertility and lead to a healthy live birth. To maximize IVF efficiency, it is critical to identify and transfer the most competent embryo within a cohort produced by a couple during a cycle. Conventional static embryo morphological assessment involves sequential observations under a light microscope at specific timepoints. The introduction of time-lapse technology enhanced morphological evaluation via the continuous monitoring of embryo preimplantation in vitro development, thereby unveiling features otherwise undetectable via multiple static assessments. Although an association exists, blastocyst morphology poorly predicts chromosomal competence. In fact, the only reliable approach currently available to diagnose the embryonic karyotype is trophectoderm biopsy and comprehensive chromosome testing to assess non-mosaic aneuploidies, namely preimplantation genetic testing for aneuploidies (PGT-A). Lately, the focus is shifting towards the fine-tuning of non-invasive technologies, such as "omic" analyses of waste products of IVF (e.g., spent culture media) and/or artificial intelligence-powered morphologic/morphodynamic evaluations. This review summarizes the main tools currently available to assess (or predict) embryo developmental, chromosomal, and reproductive competence, their strengths, the limitations, and the most probable future challenges.

Optimizing non-invasive preimplantation genetic testing: investigating culture conditions, sample collection, and IVF treatment for improved non-invasive PGT-A results

PURPOSE

This study aimed to optimize the non-invasive preimplantation genetic testing for aneuploidy (niPGT-A) in the laboratory by comparing two collection timing of the spent culture medium (SCM), two embryo rinsing protocols, and the use of conventional insemination instead of intracytoplasmic sperm injection (ICSI).

METHODS

Results of two embryo rinsing methods (one-step vs sequential) and SCM collected on day 5 vs day 6 after retrieval were compared against trophectoderm (TE) biopsies as reference. Results from day 6 SCM in cycles fertilized by conventional insemination were compared with PGT-A using ICSI.

RESULTS

The rate of concordance was higher in day 6 samples than in day 5 samples when the sequential method was used, in terms of total concordance (TC; day 6 vs day 5: 85.0% vs 60.0%, p = 0.0228), total concordance with same sex (TCS, 82.5% vs 28,0%, p < 0.0001), and full concordance with same sex (FCS, 62.5% vs 24.0%, p = 0.0025). The sequential method significantly out-performed the one-step method when SCM were collected on day 6 (sequential vs one-step, TC: 85.0% vs 64.5%, p = 0.0449; TCS: 82.5% vs 54.8%, p = 0.0113; FCS: 62.5% vs 25.8%, p = 0.0021). There was no significant difference in niPGT-A results between cycles fertilized by the conventional insemination and ICSI.

CONCLUSION

We have shown a higher concordance rate when SCM was collected on day 6 and the embryos were rinsed in a sequential manner. Comparable results of niPGT-A when oocytes were fertilized by conventional insemination or ICSI. These optimization steps are important prior to commencement of a randomized trial in niPGT-A.

Conditions for improved accuracy of noninvasive preimplantation genetic testing for aneuploidy: Focusing on the zona pellucida and early blastocysts

Purpose

Recently, noninvasive preimplantation genetic testing for aneuploidy (niPGT-A) using cell-free deoxyribonucleic acid has been developed; however, there are few reports on this and the results are inconsistent. This study was conducted to optimize the cultural environment.

Methods

We used 35 blastocysts that had been discarded after in-vitro fertilization. The concordance rate of karyotype analysis results between whole embryos (WEs), spent culture mediums (SCMs), and trophectoderms after 8, 16, and 24 h of culture was examined. Next, zona pellucida (ZP)-free blastocysts and then early blastocysts were cultured for 24 h each.

Results

Regarding the optimal culture times, the concordance rate between WEs and SCMs was 20%, 60%, and 100% at 8, 16, and 24 h, respectively. Significant differences were found between 8 and 24 h. The concordance rate with ZP cultures was 40.0%, and no significant differences were found. The concordance rate of early blastocysts thawed and cultured for 24 h was 40.0%, which was significantly lower than that of day 5 blastocysts.

Conclusions

The optimal culture times for niPGT-A were 24 h, and the concordance rate with free ZP was higher. The concordance rate for early blastocysts was low, suggesting that optimization of the conditions may be necessary.

The Comparison of Two Whole-Genome Amplification Approaches for Noninvasive Preimplantation Genetic Testing (ni-PGT) and the Application Scenario of ni-PGT during the Fresh Cycle

Recently, noninvasive preimplantation genetic testing (ni-PGT) using degenerate oligonucleotide primer PCR (DOP-PCR) and multiple annealing and looping-based amplification cycle (MALBAC)-based whole-genome amplification (WGA) methods has demonstrated predictable results in embryo testing. However, a considerable heterogeneity of results has been reported in numerous studies on these two WGA methods. Our aim was to evaluate the current WGA method for ni-PGT while further clarifying the applicable scenarios of ni-PGT in the fresh cycle. A total of 173 embryos were tested with trophectoderm biopsy and ni-PGT. In the whole preimplantation genetic testing, the clinical concordance rates of the detection results of DOP-PCR and MALBAC with the corresponding trophectoderm biopsy results were 64.12% (84/131) and 68.99% (89/129), respectively (P = 0.405). However, in the detection of abnormal embryos, the detection efficiency of ni-PGT is significantly improved [MALBAC: 96.55% versus 68.99% (P < 0.001); and DOP-PCR: 89.09% versus 64.12% (P < 0.001)]. In addition, the diagnostic efficiency of ni-PGT in low-quality blastocysts was significantly higher than that in high-quality blastocysts [MALBAC: 95.24% versus 51.85% (P = 0.001); and DOP-PCR: 91.30% versus 48.15% (P = 0.001)]. These results contribute to further understanding ni-PGT and to clarifying its application scenario in the fresh cycle.

Preimplantation Genetic Testing for Genetic Diseases: Limits and Review of Current Literature

Preimplantation genetic testing (PGT) has emerged as a revolutionary technique in the field of reproductive medicine, allowing for the selection and transfer of healthy embryos, thus reducing the risk of transmitting genetic diseases. However, despite remarkable advancements, the implementation of PGT faces a series of limitations and challenges that require careful consideration. This review aims to foster a comprehensive reflection on the constraints of preimplantation genetic diagnosis, encouraging a broader discussion about its utility and implications. The objective is to inform and guide medical professionals, patients, and society overall in the conscious and responsible adoption of this innovative technology, taking into account its potential benefits and the ethical and practical challenges that it presents.

SCM is potential resource for non-invasive preimplantation genetic testing based on human embryos single-cell sequencing

The ongoing development of assisted reproductive technologies has provided hope to individuals struggling with infertility, promising the potential for a healthy pregnancy. One significant innovation in field of pre-implantation genetic screening (PGS) requires the biopsy of embryos or oocytes, which has potential implications for the health and development of the resultant offspring. Therefore, a non-invasive approach to preimplantation genetic screening is highly sought after. The clinical application of non-invasive preimplantation genetic testing (ni-PGT) is currently limited, with its sensitivity and specificity requiring further investigation. In this study, we used 218 human embryos for single-cell whole genome amplification (WGA), along with ni-PGT of blastocoele fluid (BF) and spent culture medium (SCM). Whole blastocyst (WB), trophectoderm biopsy (TB), and inner cell mass (ICM) from embryo biopsies were used as controls to track genomic signal alterations. Our results showed that the overall genome similarity between SCM and ICM was higher than that of BF. Apart from the Y chromosome, both SCM and ICM demonstrated numerous variant sites across other chromosomes.Further categorization of gene variants in these two sample types revealed that missense variants were the most prevalent, single nucleotide polymorphisms were more common than insertions or deletions, and C > T was the dominant single nucleotide variants in both ICM and SCM. Lastly, we found that the mutant genes in SCM and ICM had different biological functions and pathways. This study indicates that SCM provides a more effective source of embryonic DNA for preimplantation genetic screening, offering a novel reference point for genetic screening research.

Development of preimplantation genetic testing for monogenic diseases in China

Preimplantation genetic testing for monogenic diseases (PGT-M) can effectively interrupt the transmission of genetic diseases from parents to the offspring before pregnancy. In China, there are over ten million individuals afflicted with monogenic disorders. This literature review summarizes the development of PGT-M in China for the past 24 years, covering the general steps such as the indications and contraindications, genetic and reproductive counselling, biopsy methods, detecting techniques and strategies during PGT-M application in China. The ethical considerations of PGT-M are also be emphasized, including sexual selection, transferring for mosaic embryos, the three-parent baby, and the different opinions for serious adult-onset conditions. Some key policies of the Chinese government for the application of PGT-M are also considered. Methods for regulation of this technique, as well as specific management to increase the accuracy and reliability of PGT-M, are regarded as priority issues in China. The third-generation sequencing and variants testing from RNA level, and non-invasive preimplantation genetic testing using blastocoel fluid and free DNA particles within spent blastocyst medium might be potential techniques and strategies for PGT-M in future.

Update on preimplantation genetic testing for aneuploidy and outcomes of embryos with mosaic results

Preimplantation genetic testing for aneuploidy (PGT-A) is used as a frequent add-on for in-vitro fertilization (IVF) to improve clinical outcomes. The purpose is to select a euploid embryo following chromosomal testing on embryo biopsies. The current practice includes comprehensive chromosome screening (CCS) technology applied on trophectoderm (TE) biopsies. Despite its widespread use, PGT-A remains a controversial topic mainly because all of the RCTs comprised only good prognosis patients with 2 or more blastocysts available; hence the results are not generalizable to all groups of patients. Furthermore, with the introduction of the highly-sensitive platforms into clinical practice (i.e. next-generation sequencing [NGS]), a result consistent with intermediate copy number surfaced and is termed "Mosaic," consistent with a mixture of euploid and aneuploid cells within the biopsy sample. The optimal disposition and management of embryos with mosaic results is still an open question, as many 'mosaics' generated healthy live births with no identifiable congenital anomalies. The present article provides a complete and comprehensive up-to-date review on PGT-A. It discusses in detail the findings of all the published RCTs on PGT-A with CCS, comments on the subject of "mosaicism" and its current management, and describes the latest technique of non-invasive PGT-A.

Effect of noninvasive embryo viability testing versus conventional IVF on the live birth rate in IVF/ICSI patients: a study protocol for a double-blind, multicenter, randomized controlled trial

BACKGROUND

Preimplantation genetic testing for aneuploidy (PGT-A) was demonstrated to be superior to conventional IVF in reducing the incidence of miscarriage and abnormal offspring after the first embryo transfer (ET). PGT-A requires several embryo trophectoderm cells, but its negative impacts on embryo development and long-term influence on the health conditions of conceived children have always been a concern. As an alternative, noninvasive PGT-A (niPGT-A) approaches using spent blastocyst culture medium (SBCM) achieved comparable accuracy with PGT-A in several pilot studies. The main objective of this study is to determine whether noninvasive embryo viability testing (niEVT) results in better clinical outcomes than conventional IVF after the first embryo transfer. Furthermore, we further investigated whether niEVT results in higher the live birth rate between women with advanced maternal age (AMA, > 35 years old) and young women or among patients for whom different fertilization protocols are adopted.

METHODS

This study will be a double-blind, multicenter, randomized controlled trial (RCT) studying patients of different ages (20-43 years) undergoing different fertilization protocols (in vitro fertilization [IVF] or intracytoplasmic sperm injection [ICSI]). We will enroll 1140 patients at eight reproductive medical centers over 24 months. Eligible patients should have at least two good-quality blastocysts (better than grade 4 CB). The primary outcome will be the live birth rate of the first embryo transfer (ET). Secondary outcomes will include the clinical pregnancy rate, ongoing pregnancy rate, miscarriage rate, cumulative live birth rate, ectopic pregnancy rate, and time to pregnancy.

DISCUSSION

In this study, patients who undergo noninvasive embryo viability testing (niEVT) will be compared to women treated by conventional IVF. We will determine the effects on the pregnancy rate, miscarriage rate, and live birth rate and adverse events. We will also investigate whether there is any difference in clinical outcomes among patients with different ages and fertilization protocols (IVF/ICSI). This trial will provide clinical evidence of the effect of noninvasive embryo viability testing on the clinical outcomes of the first embryo transfer.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR) Identifier: ChiCTR2100051408. 9 September 2021.

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

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.

Making and selecting the best embryo in the laboratory

Over the past 4 decades our ability to maintain a viable human embryo in vitro has improved dramatically, leading to higher implantation rates. This has led to a notable shift to single blastocyst transfer and the ensuing elimination of high order multiple gestations. Future improvements to embryo culture systems will not only come from new improved innovative media formulations (such as the inclusion of antioxidants), but plausibly by moving away from static culture to more dynamic perfusion-based systems now made a reality owing to the breakthroughs in three-dimensional printing technology and micro fabrication. Such an approach has already made it feasible to create high resolution devices for intracytoplasmic sperm injection, culture, and cryopreservation, paving the way not only for improvements in outcomes but also automation of assisted reproductive technology. Although improvements in culture systems can lead to further increases in pregnancy outcomes, the ability to quantitate biomarkers of embryo health and viability will reduce time to pregnancy and decrease pregnancy loss. Currently artificial intelligence is being used to assess embryo development through image analysis, but we predict its power will be realized through the creation of selection algorithms based on the integration of information related to metabolic functions, cell-free DNA, and morphokinetics, thereby using vast amounts of different data types obtained for each embryo to predict outcomes. All of this will not only make assisted reproductive technology more effective, but it will also make it more cost effective, thereby increasing patient access to infertility treatment worldwide.

Embryo biopsies for genomic selection in tropical dairy cattle

Genomic selection has transformed the livestock industry, enabling early-life selection of animals. Biopsy sampling of pre-implantation embryos has been described since 1968. However, it was only after 2010, with the advancement of molecular biology techniques such as whole genomic amplification and SNP Chips, that next-generation sequencing became commercially available for bovine embryos. It is now possible to make decisions about which embryos to transfer not only based on recipients' availability or embryo morphology but also on genomic estimates. This technology can be implemented for a wide spectrum of applications in livestock. In this review, we discuss the use of embryo biopsy for genomic selection and share our experience with Gir and Girolando Brazilian breeding programs, as well as future goals for implementing it in Brazilian bovine in vitro embryo production practices.

Evaluation of non-invasive gene detection in preimplantation embryos: a systematic review and meta-analysis

BACKGROUND

Genetic abnormalities in embryos are responsible for most miscarriages and repeated embryo implantation failures, so a reliable preimplantation genetic screening method is urgently needed. Non-invasive preimplantation genetic testing (niPGT) is a potential method for embryo genetic diagnosis. However, the value of its application is controversial. This meta-analysis aimed to investigate and validate the diagnostic value of niPGT in patients undergoing in vitro fertilization (IVF).

METHODS

This review used the "Preferred Reporting Items" as a systematic review and meta-analysis of the diagnostic test accuracy (PRISMA-DTA) statement. We searched PubMed, Embase, Web of Science Core Collection, and Cochrane Library up to May 2022 to retrieve non-invasive preimplantation gene detection studies. The eligible research quality was evaluated following the quality assessment study-2 system for diagnostic accuracy. The pooled receiver operator characteristic curve (SROC) and the area under SROC (AUC) were used to evaluate diagnostic performance quantitatively. Threshold effect, subgroup analysis, and meta-regression analysis were used to explore the source of heterogeneity. Deeks' funnel plots and sensitivity analyses were used to test the publication bias and stability of the meta-analysis, respectively.

FINDINGS

Twenty studies met the inclusion criteria. The pooled sensitivity, specificity, and AUC were 0.84 (95% CI 0.72-0.91), 0.85 (95% CI 0.74-0.92), and 0.91 (95% CI 0.88-0.93), respectively. Subgroup analysis showed that the spent culture medium (SCM) subgroup had higher sensitivity and lower specificity than the SCM combined with the blastocoel fluid (BF) subgroup. Subgroup analysis showed that the study sensitivity and specificity of < 100 cases were higher than those of ≥ 100. Heterogeneity (chi-square) analysis revealed that sample size might be a potential source of heterogeneity. Sensitivity analysis and Deeks' funnel plots indicated that our results were relatively robust and free from publication bias.

INTERPRETATION

The present meta-analysis indicated that the pooled sensitivity, specificity, and AUC of niPGT in preimplantation genetic testing were 0.84, 0.85, and 0.91, respectively. niPGT may have high detection accuracy and may serve as an alternative model for embryonic analysis. Additionally, by subgroup analysis, we found that BF did not improve the accuracy of niPGT in embryos. In the future, large-scale studies are needed to determine the detection value of niPGT.

The origin and possible mechanism of embryonic cell-free DNA release in spent embryo culture media: a review

The presence of cell-free DNA in spent embryo culture media (SECM) has unveiled its possible utilization for embryonic ploidy determination, opening new frontiers for the development of a non-invasive pre-implantation genetic screening technique. While a growing number of studies have shown a high concordance between genetic screening using cell-free DNA (cfDNA) and trophectoderm (TE), the mechanism pertaining to the release of cfDNA in SECM is largely unknown. This review aims to evaluate research evidence on the origin and possible mechanisms for the liberations of embryonic DNA in SECM, including findings on the self-correction abilities of embryos which might contribute to the presence of cfDNA. Several databases including EMBASE, PUBMED, and SCOPUS were used to retrieve original articles, reviews, and opinion papers. The keywords used for the search were related to the origins and release mechanism of cfDNA. cfDNA in SECM originates from embryonic cells and, at some levels, non-embryonic cells such as maternal DNA and exogenous foreign DNA. The apoptotic pathway has been demonstrated to eliminate aneuploid cells in developing mosaic embryos which might culminate to the release of cfDNA in SECM. Nonetheless, there is a recognized need for exploring other pathways such as cross-talk molecules called extracellular vesicles (EVs) made of small, round bi-layer membranes. During in vitro development, embryos physiologically and actively expel EVs containing not only protein and microRNA but also embryonic DNA, hence, potentially releasing cfDNA of embryonic origin into SECM through EVs.

DNA methylation protocol for analyzing cell-free DNA in the spent culture medium of human preimplantation embryos

Cell-free DNA (cfDNA) in spent embryo culture media (SECM) provides prospects for noninvasive preimplantation genetic testing. Here, we present a post-bisulfite-adapter-tagging (PBAT)-based whole-genome DNA methylation sequencing protocol (SECM-PBAT) for human SECM cfDNA analysis. We describe steps for SECM lysis, bisulfite conversion and purification, preamplification by random priming, tagging adapter II, and library establishment. We then detail library quality control, sequencing, and bioinformatics analysis. This approach simultaneously detects chromosome aneuploidy and deduces the proportional contributions of cellular components. For complete details on the use and execution of this protocol, please refer to Chen et al. (2021).¹.

Effectiveness of non-invasive chromosomal screening for normal karyotype and chromosomal rearrangements

Purpose: To study the accuracy of non-invasive chromosomal screening (NICS) results, in normal chromosomes and chromosomal rearrangement groups and to investigate whether using trophoblast cell biopsy along with NICS, to choose embryos for transfer can improve the clinical outcomes of assisted pregnancy.

Methods: We retrospectively analyzed 101 couples who underwent preimplantation genetic testing at our center from January 2019 to June 2021 and collected 492 blastocysts for trophocyte (TE) biopsy. D3-5 blastocyst culture fluid and blastocyst cavity fluid were collected for the NICS. Amongst them, 278 blastocysts (58 couples) and 214 blastocysts (43 couples) were included in the normal chromosomes and chromosomal rearrangement groups, respectively. Couples undergoing embryo transfer were divided into group A, in which both the NICS and TE biopsy results were euploid (52 embryos), and group B, in which the TE biopsy results were euploid and the NICS results were aneuploid (33 embryos).

Results: In the normal karyotype group, concordance for embryo ploidy was 78.1%, sensitivity was 94.9%, specificity was 51.4%, the positive predictive value (PPV) was 75.7%, and the negative predictive value (NPV) was 86.4%. In the chromosomal rearrangement group, concordance for embryo ploidy was 73.1%, sensitivity was 93.3%, specificity was 53.3%, the PPV was 66.3%, and the NPV was 89%. In euploid TE/euploid NICS group, 52 embryos were transferred; the clinical pregnancy rate was 71.2%, miscarriage rate was 5.4%, and ongoing pregnancy rate was 67.3%. In euploid TE/aneuploid NICS group, 33 embryos were transferred; the clinic pregnancy rate was 54.5%, miscarriage rate was 5.6%, and ongoingpregnancy rate was 51.5%. The clinical pregnancy and ongoing pregnancy rates were higher in the TE and NICS euploid group.

Conclusion: NICS was similarly effective in assessing both normal and abnormal populations. Identification of euploidy and aneuploidy alone may lead to the wastage of embryos due to high false positives. More suitable reporting methods for NICS and countermeasures for a high number of false positives in NICS are needed. In summary, our results suggest that combining biopsy and NICS results could improve the outcomes of assisted pregnancy.

Concordance of PGT for aneuploidies between blastocyst biopsies and spent blastocyst culture medium

RESEARCH QUESTION

Non-invasive preimplantation genetic testing for aneuploidies (niPGT-A) avoids the possible detrimental impact of invasive PGT-A on embryo development and clinical outcomes. Does cell-free DNA (cfDNA) from spent blastocyst culture medium (BCM) reflect embryonic chromosome status better than trophectoderm (TE) biopsy?

DESIGN

In this study, 35 donated embryos were used for research and the BCM, TE biopsy, inner cell mass (ICM) and residual blastocyst (RB) were individually picked up from these embryos. Whole genome amplification (WGA) was performed and amplified DNA was subject to next-generation sequencing. Chromosome status concordance was compared among the groups of samples.

RESULTS

The WGA success rates were 97.0% (TE biopsy), 100% (ICM), 97.0% (RB) and 88.6% (BCM). Using ICM as the gold standard, the chromosomal ploidy concordance rates for BCM, TE biopsy and RB were 58.33% (14/24), 68.75% (22/32) and 78.57% (22/28); the diagnostic concordance rates were 83.33% (20/24), 87.50% (28/32) and 92.86% (26/28); and the sex concordance rates were 92.31% (24/26), 100% (32/32) and 100% (28/28), respectively. Considering RB the gold standard, the chromosome ploidy concordance rates for BCM and TE biopsy were 61.90% (13/21) and 81.48% (22/27); the diagnostic concordance rates were 71.43% (15/21) and 88.89% (24/27); and the sex concordance rates were 91.30% (21/23) and 100% (27/27), respectively.

CONCLUSIONS

The results of niPGT-A of cfDNA of spent BCM are comparable to those of invasive PGT-A of TE biopsies. Modifications of embryo culture conditions and testing methods will help reduce maternal DNA contamination and improve the reliability of niPGT-A.

A comprehensive characterization of cell-free RNA in spent blastocyst medium and quality prediction for blastocyst

The rate of pregnancy can be affected by many factors in assisted reproductive technology (ART), and one of which is the quality of embryos. Therefore, selecting the embryos with high potential is crucial for the outcome. Fifteen spent blastocyst medium (SBM) samples were collected from 14 patients who received in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI), seven from high-grade embryos and eight from low-grade embryos. Cell-free RNA (cf-RNA) profile of SBM samples were analyzed by RNA sequencing in the present study. It was found that a large amount of cf-RNA were released into SBM, including protein-coding genes (68.9%) and long noncoding RNAs (lncRNAs) (17.26%). Furthermore, a high correlation was observed between blastocyst genes and SBM genes. And the cf-mRNAs of SBM were highly fragmented, and coding sequence (CDS) and untranslated (UTR) regions were released equally. Two hundred and thirty-two differentially expressed genes were identified in high-grade SBM (hSBM) and low-grade SBM (lSBM), which could be potential biomarker in distinguishing the embryos with different quality as an alternative or supplementary approach for subjective morphology criteria. Hence, cf-RNAs sequencing revealed the characterization of circulating transcriptomes of embryos with different quality. Based on the results, the genes related to blastocyst quality were screened, including the genes closely related to translation, immune-signaling pathway, and amino acid metabolism. Overall, the present study showed the types of SBM cf-RNAs, and the integrated analysis of cf-RNAs profiling with morphology grading displayed its potential in predicting blastocyst quality. The present study provided valuable scientific basis for noninvasive embryo selection in ART by RNA-profiling analysis.

Clinical application of noninvasive chromosomal screening for elective single-blastocyst transfer in frozen-thawed cycles

BACKGROUND

The objective of this study was to explore the clinical application of noninvasive chromosomal screening (NICS) for elective single-blastocyst transfer (eSBT) in frozen-thawed cycles.

METHODS

This study retrospectively analysed the data of 212 frozen-thawed single-blastocyst transfers performed in our centre from January 2019 to July 2019. The frozen embryos were selected based on morphological grades and placed in preincubation for 6 h after warming. Then spent microdroplet culture media of frozen-thawed blastocysts were harvested and subjected to NICS. The clinical outcomes were evaluated and further stratified analysis were performed, especially different fertilization approaches.

RESULTS

The clinical pregnancy, ongoing pregnancy, and live birth rates in the euploidy group were significantly higher than those in the aneuploidy group (56.2% versus 29.4%) but were nonsignificantly different from those in the chaotic abnormal/NA embryos group (56.2% versus 60.4%). Compared with day6 (D6) blastocysts, D5 blastocysts had a nonsignificantly different euploidy rate (40.4% versus 48.1%, P = 0.320) but significantly increased clinical pregnancy (57.7% versus 22.2%, P < 0.001), ongoing pregnancy (48.1% versus 14.8%, P < 0.001), and live birth rates (48.1% versus 13.0%, P < 0.001). The percentage of chaotic abnormal/NA embryos group was significantly higher among D5 embryos than among D6 embryos (30.1% versus 11.1%, P = 0.006). The percentage of aneuploid embryos was higher among the embryos with lower morphological quality(21.5% among 'good' embryos versus 34.6% among 'fair' embryos versus 46.0% among 'poor' embryos, P = 0.013); correspondingly, the overall clinical pregnancy, ongoing pregnancy and live birth rate rates showed similar declines.

CONCLUSIONS

NICS combined with morphological assessment is an effective tool to guide frozen-thawed SBT. The optimal embryo for SBT is a 'euploid embryo with good morphology', followed sequentially by a 'chaotic abnormal/NA embryo with good morphology', 'euploid embryo with fair morphology', and 'chaotic abnormal/NA embryo with fair morphology'.

An Update on Non-invasive Approaches for Genetic Testing of the Preimplantation Embryo

Preimplantation Genetic Testing (PGT) aims to reduce the chance of an affected pregnancy or improve success in an assisted reproduction cycle. Since the first established pregnancies in 1990, methodological approaches have greatly evolved, combined with significant advances in the embryological laboratory. The application of preimplantation testing has expanded, while the accuracy and reliability of monogenic and chromosomal analysis have improved. The procedure traditionally employs an invasive approach to assess the nucleic acid content of embryos. All biopsy procedures require high technical skill, and costly equipment, and may impact both the accuracy of genetic testing and embryo viability. To overcome these limitations, many researchers have focused on the analysis of cell-free DNA (cfDNA) at the preimplantation stage, sampled either from the blastocoel or embryo culture media, to determine the genetic status of the embryo non-invasively. Studies have assessed the origin of cfDNA and its application in non-invasive testing for monogenic disease and chromosomal aneuploidies. Herein, we discuss the state-of-the-art for modern non-invasive embryonic genetic material assessment in the context of PGT. The results are difficult to integrate due to numerous methodological differences between the studies, while further work is required to assess the suitability of cfDNA analysis for clinical application.

Clinical Outcome, Socioeconomic Status and Psychological Constrains of Patients Undergoing Preimplantation Genetic Testing (PGT) in Northern Greece

Background and objectives: Preimplantation genetic testing (PGT) offers patients the possibility of having a healthy baby free of chromosomal or genetic disorders. The present study focuses on the application of PGT for patients located in Northern Greece, investigating their clinical outcomes, their motives, and their overall physical and emotional experience during the treatment, in association with their socioeconomic background. Materials and Methods: Couples who underwent PGT for a monogenic condition (PGT-M, n = 19 cycles) or aneuploidy (PGT-A, n = 22 cycles) participated in the study. Fertilization, implantation, and pregnancy rates were recorded for all cycles. The couples were asked to fill in a questionnaire about the consultation they had received prior to treatment, their sociodemographic information, and the psychological impact PGT had on both the female and male partner. Results: The fertilization, implantation, and ongoing pregnancy rates for the PGT-M and PGT-A cycles were 81.3%, 70.6%, and 52.9%, and 78.2%, 64.3%, and 57.1%, respectively. Females experienced more intense physical pain than their male partners while psychological pain was encountered by both partners and occasionally in higher instances in males. No typical socioeconomic background of the patients referred for PGT in Northern Greece was noticed. Conclusion: PGT is an attractive alternative to prenatal diagnosis (PND), aiming to establisha healthy pregnancy by identifying and avoiding the transfer of chromosomally or genetically abnormal embryos to the uterus. Although the benefits of PGT were well-received by all patients undergoing the procedure, psychological pain was evident and especially prominent in patients with a previous affected child or no normal embryos for transfer. Holistic counseling is of utmost importance in order to make patients' experience during their journey to have a healthy baby less emotionally demanding and help them make the right choices for the future.