Genomic DNA in human blastocoele fluid

ART strategies in Klinefelter syndrome

PURPOSE

Patients with Klinefelter syndrome (KS) who receive assisted reproductive technology (ART) treatment often experience poor pregnancy rates due to decreased fertilization, cleavage, and implantation rates and even an increased miscarriage rate. Mounting evidence from recent studies has shown that various technological advances and approaches could facilitate the success of ART treatment for KS patients. In this review, we summarize the methods for guiding KS patients during ART and for developing optimal strategies for preserving fertility, improving pregnancy rate and live birth rate, and avoiding the birth of KS infants.

METHODS

We searched PubMed and Google Scholar publications related to KS patients on topics of controlled ovarian stimulation protocols, sperm extraction, fertility preservation, gamete artificial activation, round spermatid injection (ROSI), and non-invasive prenatal screening (PGD) methods.

RESULTS

This review outlines the different ovulation-inducing treatments for female partners according to the individual sperm status in the KS patient. We further summarize the methods of retrieving sperm, storing, and freezing rare sperm. We reviewed different methods of gamete artificial activation and discussed the feasibility of ROSI for sterile KS patients who absolutely lack sperm. The activation of eggs in the process of intracytoplasmic sperm injection and non-invasive PGD are urgently needed to prevent the birth of KS infants.

CONCLUSION

The integrated strategies will pave the way for the establishment of ART treatment approaches and improve the clinical outcome for KS patients.

Preimplantation Genetic Testing: Where We Are Today

Background: Preimplantation genetic testing (PGT) is widely used today in in-vitro fertilization (IVF) centers over the world for selecting euploid embryos for transfer and to improve clinical outcomes in terms of embryo implantation, clinical pregnancy, and live birth rates. Methods: We report the current knowledge concerning these procedures and the results from different clinical indications in which PGT is commonly applied. Results: This paper illustrates different molecular techniques used for this purpose and the clinical significance of the different oocyte and embryo stage (polar bodies, cleavage embryo, and blastocyst) at which it is possible to perform sampling biopsies for PGT. Finally, genetic origin and clinical significance of embryo mosaicism are illustrated. Conclusions: The preimplantation genetic testing is a valid technique to evaluated embryo euploidy and mosaicism before transfer.

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

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

Preimplantation Genetic Testing for Chromosomal Abnormalities: Aneuploidy, Mosaicism, and Structural Rearrangements

There is a high incidence of chromosomal abnormalities in early human embryos, whether they are generated by natural conception or by assisted reproductive technologies (ART). Cells with chromosomal copy number deviations or chromosome structural rearrangements can compromise the viability of embryos; much of the naturally low human fecundity as well as low success rates of ART can be ascribed to these cytogenetic defects. Chromosomal anomalies are also responsible for a large proportion of miscarriages and congenital disorders. There is therefore tremendous value in methods that identify embryos containing chromosomal abnormalities before intrauterine transfer to a patient being treated for infertility—the goal being the exclusion of affected embryos in order to improve clinical outcomes. This is the rationale behind preimplantation genetic testing for aneuploidy (PGT-A) and structural rearrangements (-SR). Contemporary methods are capable of much more than detecting whole chromosome abnormalities (e.g., monosomy/trisomy). Technical enhancements and increased resolution and sensitivity permit the identification of chromosomal mosaicism (embryos containing a mix of normal and abnormal cells), as well as the detection of sub-chromosomal abnormalities such as segmental deletions and duplications. Earlier approaches to screening for chromosomal abnormalities yielded a binary result of normal versus abnormal, but the new refinements in the system call for new categories, each with specific clinical outcomes and nuances for clinical management. This review intends to give an overview of PGT-A and -SR, emphasizing recent advances and areas of active development.

Minimally Invasive Cell-Free Human Embryo Aneuploidy Testing (miPGT-A) Utilizing Combined Spent Embryo Culture Medium and Blastocoel Fluid -Towards Development of a Clinical Assay

Preimplantation genetic testing for aneuploidies (PGT-A) using trophectoderm (TE) biopsy samples is labour intensive, invasive, and subject to sampling bias. In this study, we report on the efficacy and factors affecting accuracy of a technique we pioneered for minimally invasive preimplantation genetic testing for aneuploidy (miPGT-A). Our technique uses cell-free embryonic DNA (cfeDNA) in spent embryo culture medium (SEM) combined with blastocoel fluid (BF) to increase the amount of assayable cfeDNA. We compared miPGT-A results (n = 145 embryos) with standard PGT-A analysis of the corresponding trophectoderm biopsy. We found that accuracy of miPGT was not related to blastocyst morphological grade. The overall concordance rate per sample for euploidy/aneuploidy status between miPGT-A and TE biopsy samples was 88/90 (97.8%), and was not different between good 47/48 (97.9%) and moderate/low quality blastocysts 41/42 (97.9%) (p > 0.05). Importantly, we also discovered that for cfeDNA analysis, the SurePlex whole genome amplification (WGA) kit can be utilized without an additional cell lysis/extraction DNA step; this efficiency likely reduces the risk of maternal contamination. Regarding origin of embryonic cfeDNA, the average amount of miPGT-A WGA-DNA we obtained from blastocysts with different morphological grades, as well as the size miPGT-A WGA-DNA fragments, suggest that it is unlikely that apoptosis and necrosis are only mechanisms of DNA release from the inner cell mass (ICM) and TE into BF and SEM.

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

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

Embryo Biopsy Can Offer More Information Than Just Ploidy Status

As a byproduct of increasing infertility cases, the use of medically assisted reproduction (MAR) has increased. As such, the need to gain information regarding the implantation potential of specific MAR preimplantation embryos prior to transfer has become increasingly critical. One potential source of this information is contained in the blastocoel fluid from day 5/6 embryos. This fluid contains cell-free DNA, proteins, RNA, metabolites, exosomes, etc., and analysis of these contents provides clinicians with an opportunity to gain more data regarding potential of each embryo. While application of preimplantation genetic testing for aneuploidies (PGT-A) may be limited to women of advanced maternal age or with recurrent pregnancy loss, the fluid taken at the time of embryo biopsy can be analyzed for any frozen embryo as well as PGT-A embryos. In both cases, blastocoel fluid analysis provides information regarding a preimplantation embryo's potential for implantation. Moreover, as remnants of apoptosis, embryonic cell-free DNA (cfDNA) and mRNA may lead clinicians to better understand and predict the extent of self-correction occurring within the preimplantation embryo. While analysis of blastocoel components are not yet viable replacements for PGT-A, their study may still reveal critical clinical information about the implantation potential for any given embryo.

Preimplantation genetic diagnosis (PGD) and genetic testing for aneuploidy (PGT-A): status and future challenges

The world's first in vitro fertilization (IVF) baby was born in July 1978 in the UK. Since then, more than 7 million infants have been born worldwide as a result of IVF. Preimplantation genetic diagnosis (PGD) was introduced in the late 1980s for couples at risk of transmitting a genetic abnormality to their children. From the mid-1990s, this technology has been employed as an embryo selection tool for patients undergoing IVF and has been known as preimplantation genetic screening (PGS). The aim of this practice has been to identify and select euploid embryos for transfer, in order to increase efficacy of IVF cycle, ensure higher implantation rates or at least decreased time to pregnancy. In the early days, fluorescent in situ hybridization (FISH) technology was used for genetic analysis. New advancements in both biopsy and cytogenetic have made possible the improvement of PGD and PGT-A analysis. Currently, a variety of technologies have been implemented to individuate euploid embryos to be preferentially transferred in IVF treatments. The purpose of this review is to clarify the differences between PGD and PGT-A, and to discuss current indications and requirements for embryo biopsy and genetic methodologies used.

Less-invasive chromosome screening of embryos and embryo assessment by genetic studies of DNA in embryo culture medium

PURPOSE

To perform a preliminary exploration of a new embryo rank in clinical practice by combining the embryo chromosome copy number and mitochondrial copy number analysis of DNA extracted from embryo culture medium and blastocoel fluid.

METHOD

Eighty-three ICSI embryos from day 2 or day 3 were cultured to day 5 or day 6. Thirty-two blastocysts of 3 cc or above were obtained. Culture medium and blastocoel fluid were collected at 24 h before blastocyst formation. The genomic DNA and mitochondrial DNA (mtDNA) from the culture medium combined with blastocoel fluid and the whole blastocyst were amplified and sequenced by MALBAC-NGS. We compared the chromosomal information generated by the new protocol from the culture medium and the information employed by the whole embryo method. A multivariable linear regression was performed to study the impact of the blastocyst morphological score, chromosomal abnormality, embryo mtDNA copy number, and female age on the culture medium mtDNA copy number.

RESULTS

(1) The DNA from 31 blastocysts was successfully amplified, and the successful amplification rate was 96.9% (31/32). The success rate of the amplification of genomic DNA extracted from the culture medium was 87.5% (28/32). (2) There were 18 blastocysts in which the less invasive method and the whole embryo method revealed the same results. The consistency rate was 66.7% (18/27). (3) The culture medium mitochondrial DNA copy number (MCN) had a significantly positive correlation with the blastocyst mitochondrial DNA copy number (P = 0.001), female age (P = 0.012), and blastocyst score (P = 0.014), but there was no obvious correlation with blastocyst chromosome (P = 0.138).

CONCLUSIONS

The preliminary exploration result of the less invasive approach for having an embryo rank was not satisfying, which still awaits further long-term evaluation.

A prospective study of non-invasive preimplantation genetic testing for aneuploidies (NiPGT-A) using next-generation sequencing (NGS) on spent culture media (SCM)

PURPOSE

This study was to evaluate if spent culture media (SCM) of embryos could be used as a non-invasive tool to achieve aneuploidy screening. Ploidy calls, as well as concordance rates between PGT-A results from trophectoderm (TE) and SCM, were compared. Clinical outcomes of single euploid transfers were also evaluated.

METHODS

The study was conducted from March 2017 to June 2018 in a university-based ART center. SCM of day 3 to the day(s) of TE biopsy of all biopsied blastocysts were collected for testing. PGT-A results of SCM were compared with the standard results of TE, with clinical relevance and outcomes examined.

RESULTS

NiPGT-A using SCM gave a sensitivity of 81.6%, specificity of 48.3%, positive predictive value of 82.6%, and negative predictive value of 46.7% in ploidy calling. The concordance rates for autosomes and sex determination were 62.1% and 82.4%, respectively. There were 14 single embryo transfer cycles of euploids as determined by TE biopsy. Clinical outcomes not only confirmed 3 false positive results from SCM but also reflected the true ploidy status of the transferred embryo in one case. If ploidy calls were dichotomized without mosaic embryos, the sensitivity and NPV would increase to 91.0% and 66.7% (p = 0.60 and p = 0.25), respectively.

CONCLUSIONS

Cell-free DNA found in SCM could provide ploidy information of an embryo as in PGT-A from its TE. Given its potential to reflect the comprehensive chromosomal profile of the whole embryo, more research based on clinical outcomes is required to determine if SCM could be a reliable selection tool in PGT-A.

Minimally invasive preimplantation genetic testing using blastocyst culture medium

STUDY QUESTION

Is minimally invasive chromosome screening (MICS) using blastocyst culture medium (BCM) sufficiently fast and accurate for preimplantation genetic testing (PGT)

SUMMARY ANSWER

A new assay for MICS, named MICS-Inst achieved high-resolution, comprehensive chromosome ploidy detection using BCM.

WHAT IS KNOWN ALREADY

BCM is a viable source of genomic DNA for use in PGT.

STUDY DESIGN, SIZE, DURATION

Forty-one vitrified blastocysts donated by 22 couples known to carry a chromosome rearrangement and 21 vitrified blastocysts donated from 8 couples with normal karyotypes were used in this study. Good-quality blastocysts, defined as Day 5 and Day 6 embryos ≥ BB (AA, AB, BA, BB) based on the Gardner system were used for analysis. Recruitment took place from May 2018 to August 2018. We performed PGT for structural rearrangements (PGT-SR) on 41 BCM, trophectoderm (TE) biopsy and blastocyst-stage embryo (BE) samples as well as PGT for aneuploidies (PGT-A) on 21 BCM, TE biopsy and BE samples.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We made several significant modifications to the BCM composition (mixing blastocoel fluid and spent blastocyst medium) as well as the pre-existing multiple annealing and looping-based amplification cycles (MALBAC) techniques and library generation procedures. The design of a quasilinear preamplification (Pre-AMP) primer and AMP primers 1 and 2 enables the preparation of a next-generation sequencing library after the exponential amplification stage by introducing the Illumina P5 and P7 primers into the final products, which are then ready for sequencing. Sequencing was performed on the Illumina Hiseq 2500 platform with 2.0 Mb raw reads generated for each sample.

MAIN RESULTS AND THE ROLE OF CHANCE

For PGT-A, BCM and TE biopsy samples showed 90% and 86% clinical concordance with the corresponding BE samples, respectively. In addition, both BCM and TE biopsy samples showed 76% karyotype concordance with the corresponding BE samples. For PGT-SR, we successfully obtained ploidy information for all 23 chromosomes with the exception of any rearrangements involving the Y chromosome. Both BCM and TE biopsy samples showed 100% clinical concordance with the corresponding BE samples in detecting chromosomal rearrangements. BCM and TE biopsy samples showed 90% and 100% karyotype concordance with the corresponding BE samples, respectively. Additionally, no statistically significant differences were detected in the aforementioned values of the BCM and TE biopsy samples in either PGT-A or PGT-SR (P > 0.05). Moreover, we achieved accurate quantification of segmental abnormalities using BCM samples. In addition, MICS-Inst reduced the number of steps required for library preparation through the use of new primer designs, resulting in an overall time reduction of 7.5 h. This time reduction allows for the performance of fresh blastocyst transfers.

LIMITATIONS, REASONS FOR CAUTION

The main limitation is that BE, rather the inner cell mass, was used as the standard to evaluate the chromosome screening results.

WIDER IMPLICATIONS OF THE FINDINGS

These results show that MICS-Inst is effective in procedure and precision for PGT, and that it is possible to achieve fresh blastocyst transfer following PGT. The implications are significant, as these findings may lead to minimally invasive PGT methods in the future.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Natural Science Foundation of China (No. 81671423 and No. 81402130), the National Key Research and Development Program of China (No. 2018YFC1003100), Liaoning Provincial Key Research and Development Program (No. 2018225090), the Fok Ying Tung Education Foundation (No. 151039) and Distinguished Talent Program of Shengjing Hospital (No. ME76). No competing interests declared.

Non-invasive pre-implantation genetic testing of human embryos: an emerging concept

The accurate genetic screening of pre-implantation embryos currently entails the use of technically challenging and biologically invasive biopsies of the human embryos. Investigating a more conservative sampling approach has emerged as a timely and desired alternative. Circulating cell-free embryonic DNA is present in the blastocoel fluid and spent culture media of blastocysts, and this has lately been sought as an attractive source of genetic information. The genetic analysis of cell-free embryonic DNA has been reported, to be useful in evaluating the genetic constitution of embryos; thus, providing a potential alternative to conventional biopsy-derived pre-implantation genetic testing (PGT). In this review, we have summarized these non-invasive alternative applications of PGT and discussed their current limitations and future clinical implications.

Mitochondrial DNA and genomic DNA ratio in embryo culture medium is not a reliable predictor for in vitro fertilization outcome

To investigate the ratio of mitochondrial DNA to genomic DNA (mt/gDNA) in embryo culture medium as a possible predictor for embryonic development and pregnancy outcome, we collected a total of 93 embryo biopsy specimens from 52 women at the corresponding Day 3 (D3) and Day 5 (D5) embryo culture medium of in vitro fertilization. With the multiple annealing and looping-based amplification cycles method of next-generation sequencing for whole genome amplification, we examined the karyotype of the biopsy samples and the mt/gDNA ratio in the culture medium. Results showed that the ratio of mt/gDNA had an upward trend with decreasing trophectoderm levels with no significant difference. At the same time, from D3 to D5, the mt/gDNA ratio in the medium of embryos that failed to become blastocysts showed an upward trend, and the mt/gDNA ratio of medium from embryos that reached blastulation with successful pregnancy showed a decreasing trend, but the differences were not statistically significant. We conclude that there is a certain correlation between mt/gDNA ratio and early embryonic development, but it does not reach a level that can be used as a clinical predictor.

Chromosome screening using culture medium of embryos fertilised in vitro: a pilot clinical study

BACKGROUND

Previous studies from this as well as other research groups suggested that non-invasive chromosome screening (NICS) with embryo culture medium can be used to identify chromosomal ploidy and chromosomal abnormalities. We here report a series of clinical cases utilizing the technology.

METHODS

A total of 45 couples underwent in vitro fertilisation during a period between February 2016 and February 2017. Karyotyping revealed normal chromosomes in both partners in 23 couples, and chromosomal rearrangements in at least one partner in 22 couples. Intracytoplasmic sperm injection (ICSI) was used for fertilization. NICS was carried out using embryo culture medium at the blastocyst stage via multiple annealing and looping-based amplification cycles, whole-genome amplification and next-generation sequencing.

RESULTS

A total of 413 embryos were obtained; 170 blastocysts were subjected to NICS. The screening showed euploidy in 79 embryos, aneuploidy in 52 embryos, and mosaic ploidy for 33 embryos. The rate of euploidy was comparable in couples with normal karyotype (50.7%; 38/75) vs. chromosomal rearrangement (43.2%; 41/95). A total of 52 euploid embryos (50 oocyte retrieval cycles) were transferred in 43 women. Biochemical pregnancy rate was 72.0% (36/50). Clinical pregnancy rate was 58.0% (29/50). The rate of spontaneous miscarriage was 3/29 (none with chromosomal aneuploidy). A total of 27 healthy babies were delivered.

CONCLUSIONS

NICS could identify embryo chromosomal abnormalities in couples either with or without chromosomal rearrangement, with satisfying clinical outcomes.

Blastocoel Fluid Biopsy

The identification of viable embryos for transfer is one of the main challenges in reproductive medicine. As chromosomal abnormalities are the major cause of implantation failure, preimplantation genetic testing of aneuploidy plays an important role in embryo selection. To make this approach more efficient, the possibility to retrieve informative DNA through a moderately invasive technique compared to the traditional forms of biopsy is appealing. Blastocoelic fluid is a valuable source of DNA. Its presence, as detected by whole genomic amplification, and the following analysis by comprehensive chromosome screening could add important information on the blastocyst ploidy condition and developmental potential.

Identification of extracellular vesicles and characterization of miRNA expression profiles in human blastocoel fluid

In this study, for the first time, we demonstrated the presence of microRNAs and extracellular vesicles in human blastocoel fluid. The bioinformatic and comparative analyses identified the biological function of blastocoel fluid microRNAs and suggested a potential role inside the human blastocyst. We found 89 microRNAs, expressed at different levels, able to regulate critical signaling pathways controlling embryo development, such as pluripotency, cell reprogramming, epigenetic modifications, intercellular communication, cell adhesion and cell fate. Blastocoel fluid microRNAs reflect the miRNome of embryonic cells and their presence, associated with the discovery of extracellular vesicles, inside blastocoel fluid, strongly suggests their important role in mediating cell communication among blastocyst cells. Their characterization is important to better understand the earliest stages of embryogenesis and the complex circuits regulating pluripotency. Moreover, blastocoel fluid microRNA profiles could be influenced by blastocyst quality, therefore, microRNAs might be used to assess embryo potential in IVF cycles.

Deoxyribonucleic acid detection in blastocoelic fluid: a new predictor of embryo ploidy and viable pregnancy

OBJECTIVE

To investigate blastocysts, defined as euploid and aneuploid by trophectoderm (TE) cell analysis, for the presence of DNA in the blastocoelic fluid (BF) detected by whole-genomic amplification (WGA); and to correlate the presence of DNA in BF with the clinical outcome after the transfer of TE-euploid blastocysts.

DESIGN

Retrospective study.

SETTING

In vitro fertilization unit.

PATIENT(S)

This study included 91 patients performing preimplantation genetic testing for aneuploidy on TE cells from January 2015 to December 2017. In the case of ET, only single blastocyst transfers were performed.

INTERVENTION(S)

Blastocoelic fluids and TE cells were retrieved from 256 blastocysts before vitrification. All blastocysts were diagnosed by array-comparative genomic hybridization (a-CGH) on TE cells. Amplification and a-CGH of DNA from BFs was performed at a later time after TE biopsy and ET.

MAIN OUTCOME MEASURE(S)

Whole-genomic amplification of BFs, evaluation of the chromosome condition in BFs and TE cells, and correlation of BF results with the clinical outcome of TE-euploid transferred blastocysts.

RESULT(S)

The incidence of amplification after WGA was significantly lower in BFs from TE-euploid blastocysts (n = 32, 45%) when compared with the aneuploid ones (n = 150, 81%), resulting in 182 BFs with successful DNA amplification. When submitted to a-CGH, informative results were obtained from 172 BFs. Comparison of these results with those from the corresponding TE cells gave a ploidy concordance of 93.6% and a mean number of aneuploid events per sample that was higher in BFs than in TE cells (2.0 vs. 1.4, respectively). After the transfer of 53 TE-euploid blastocysts, the clinical pregnancy rate was 77% in the group with BF-failed amplification, and 37% after BF-successful amplification. The same trend was found for the ongoing pregnancy rate (68% vs. 31.5%, respectively).

CONCLUSION(S)

The presence of DNA in BFs detected by WGA is correlated with the blastocyst ploidy condition defined by TE cell biopsy and with the implantation potential of TE-euploid blastocysts. These findings could have a clinical implication for the selection of the most viable embryo for transfer because, after submitting BFs to WGA, priority would be given to TE-euploid blastocysts with BF-failed amplification. Similarly, BF-failed amplification could be an additional selection criterion to prioritize embryos for transfer even in conventional IVF cycles with blastocysts that were vitrified after BF aspiration.

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

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

Relationship between blastocoel cell-free DNA and day-5 blastocyst morphology

PURPOSE

Cell-free DNA (cfDNA) which is present in the blastocoel cavity of embryos is believed to result from physiological apoptosis during development. This study assessed cfDNA content and caspase-3 protease activity in day-5 IVF blastocysts to determine if there was a correlation with embryo morphology.

METHODS

Day-5 IVF blastocysts were scored according to the Gardner and Schoolcraft system (modified to generate a numerical value) and cfDNA was collected following laser-induced blastocoel collapsing prior to cryopreservation in 25 μL of media. cfDNA was quantified via fluorospectrometry and apoptotic activity was assessed via a caspase-3 protease assay using a fluorescent peptide substrate. Data were compared by linear regression.

RESULTS

A total of 32 embryos were evaluated. There was a significant (p < 0.01) and positive correlation (cfDNA = 104.753 + (11.281 × score); R² = 0.200) between embryo score and cfDNA content. A significant (p < 0.05) and positive correlation (cfDNA = 115.9 + (0.05 × caspase-3); R²= 0.128) was observed between caspase-3 activity and cfDNA levels. There was no significant relationship between caspase-3 activity and embryo morphology score.

CONCLUSIONS

This study provides further evidence that cfDNA is present in blastocoel fluid, can be quantified, and positively correlates with embryonic morphology. There is also evidence that at least a portion of the cfDNA present is from intracellular contents of embryonic cells that underwent apoptosis. Additional studies are warranted to determine other physiological sources of the cfDNA in blastocyst fluid and to determine the relationship with cfDNA content, embryo morphology, and chromosomal ploidy status plus implantation potential.

Evaluation of a novel non-invasive preimplantation genetic screening approach

OBJECTIVE

To assess whether embryonic DNA isolated from blastocyst culture conditioned medium (BCCM) combined with blastocoel fluid (BF) could be used for blastocyst stage non-invasive preimplantation genetic testing for chromosomal aneuploidy (non-invasive preimplantation genetic screening, NIPGS).

PATIENTS

47 embryos from 35 patients undergoing IVF.

INTERVENTIONS

DNA analysis of combined BCCM plus BF in comparison with trophectoderm (TE) biopsy and/or whole blastocyst (WB)using next generation sequencing (NGS).

RESULTS

Embryonic DNA was successfully amplified in 47/47 NIPGS samples (28 frozen-thawed and 19 fresh culture samples) ranging from 6.3 to 44.0 ng/μl. For frozen-thawed embryos, the concordance rate for whole chromosome copy number per sample was equivalent between NIPGS vs. TE biopsy, NIPGS vs. WB and TE vs. WB samples taken from the same embryo was 87.5%; 96.4% and 91.7% respectively (P>0.05), and the rate of concordance per single chromosome was 99.3%, 99.7% and 99.7%, respectively (P>0.05). In fresh cases (Day 4 to Day 5/6 culture), the concordance rate for whole chromosome copy number per sample between NIPGS vs. TE samples taken from the same embryo was 100%, and the rate of concordance per single chromosome was 98.2% (P>0.05).

CONCLUSIONS

A combination of BCCM and BF contains sufficient embryonic DNA for whole genome amplification and accurate aneuploidy screening. Our findings suggest that aneuploidy screening using BCCM combined with BF could potentially serve as a novel NIPGS approach for use in human IVF.

Preimplantation Genetic Testing: Its Evolution, Where Are We Today?

Preimplantation genetic testing (PGT) is an early form of prenatal genetic diagnosis where abnormal embryos are identified, thereby allowing transfer of genetically normal embryos. This technology has become an integral part of Assisted Reproductive Technology (ART) procedures. Initial experiments with animals as early as 1890 and those in the mid and later part of the last century paved the forward path of ART and PGT. This review article covers the evolution of PGT and is a pointer toward current and fast-evolving technology, allowing scientists and doctors to better comprehend human reproduction, and ensure healthy pregnancy outcomes.

Presence of embryonic DNA in culture medium

Preimplantation genetic diagnosis (PGD) has successfully assisted couples with genetic diseases to conceive healthy babies during the past decades. However, biopsy of the blastomere has potential lesion to the embryos which commonly results in abortion. Thus, a noninvasive PGD is needed. In the past, the presence of genetic materials in maternal plasma or serum has triggered a great innovation of noninvasive prenatal diagnosis. Nevertheless, it is not clear whether embryonic DNA is also present in embryonic culture medium. Here, a rapid-boiling method has been used to harvest DNA from the medium or the discarded embryos, following Polymerase Chain Reaction (PCR) was applied to detect the dissociative DNA by amplifying SRY gene (Y-chromosome). For the first time, the Y sequences were detected in the medium which were used to culture embryo for above 3 days. None of the positive signal was examined in Day 1 and Day 2 embryonic culture medium. Our findings suggest that the Y chromosome fragments from the embryo may release into its culture medium. If validated in a larger cohort, detection of SRY gene may prove to be a useful method to screen Y-linked genetic disease. More importantly, detecting the free DNA in the embryonic culture medium may represent a novel strategy for noninvasive PGD.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Non-invasive preimplantation genetic screening using array comparative genomic hybridization on spent culture media: a proof-of-concept pilot study

The aim of this pilot study was to assess if array comparative genomic hybridization (aCGH), non-invasive preimplantation genetic screening (PGS) on blastocyst culture media is feasible. Therefore, aCGH analysis was carried out on 22 spent blastocyst culture media samples after polar body PGS because of advanced maternal age. All oocytes were fertilized by intracytoplasmic sperm injection and all embryos underwent assisted hatching. Concordance of polar body analysis and culture media genetic results was assessed. Thirteen out of 18 samples (72.2%) revealed general concordance of ploidy status (euploid or aneuploid). At least one chromosomal aberration was found concordant in 10 out of 15 embryos found to be aneuploid by both polar body and culture media analysis. Overall, 17 out of 35 (48.6%) single chromosomal aneuploidies were concordant between the culture media and polar body analysis. By analysing negative controls (oocytes with fertilization failure), notable maternal contamination was observed. Therefore, non-invasive PGS could serve as a second matrix after polar body or cleavage stage PGS; however, in euploid results, maternal contamination needs to be considered and results interpreted with caution.

Next-generation molecular diagnosis: single-cell sequencing from bench to bedside

Single-cell sequencing (SCS) is a fast-growing, exciting field in genomic medicine. It enables the high-resolution study of cellular heterogeneity, and reveals the molecular basis of complicated systems, which facilitates the identification of new biomarkers for diagnosis and for targeting therapies. It also directly promotes the next generation of genomic medicine because of its ultra-high resolution and sensitivity that allows for the non-invasive and early detection of abnormalities, such as aneuploidy, chromosomal translocation, and single-gene disorders. This review provides an overview of the current progress and prospects for the diagnostic applications of SCS, specifically in pre-implantation genetic diagnosis/screening, non-invasive prenatal diagnosis, and analysis of circulating tumor cells. These analyses will accelerate the early and precise control of germline- or somatic-mutation-based diseases, particularly single-gene disorders, chromosome abnormalities, and cancers.

Novel technologies emerging for preimplantation genetic diagnosis and preimplantation genetic testing for aneuploidy

INTRODUCTION

Preimplantation genetic diagnosis (PGD) was introduced as an alternative to prenatal diagnosis: embryos cultured in vitro were analysed for a monogenic disease and only disease-free embryos were transferred to the mother, to avoid the termination of pregnancy with an affected foetus. It soon transpired that human embryos show a great deal of acquired chromosomal abnormalities, thought to explain the low success rate of IVF - hence preimplantation genetic testing for aneuploidy (PGT-A) was developed to select euploid embryos for transfer. Areas covered: PGD has followed the tremendous evolution in genetic analysis, with only a slight delay due to adaptations for diagnosis on small samples. Currently, next generation sequencing combining chromosome with single-base pair analysis is on the verge of becoming the golden standard in PGD and PGT-A. Papers highlighting the different steps in the evolution of PGD/PGT-A were selected. Expert commentary: Different methodologies used in PGD/PGT-A with their pros and cons are discussed.

Characterizing nuclear and mitochondrial DNA in spent embryo culture media: genetic contamination identified

OBJECTIVE

To characterize nuclear and mitochondrial DNA (mtDNA) in spent culture media from normally developing blastocysts to determine whether it could be used for noninvasive genetic assessment.

DESIGN

Prospective embryo cohort study.

SETTING

Academic center and private in vitro fertilization (IVF) clinic.

PATIENT(S)

Seventy patients undergoing intracytoplasmic sperm injection (ICSI) and 227 blastocysts.

INTERVENTION(S)

Culture media assessment, artificial blastocoele fluid collapse and DNA analysis using digital polymerase chain reaction (dPCR), long-range PCR, quantitative PCR (qPCR), and DNA fingerprinting.

MAIN OUTCOME MEASURE(S)

Presence of nuclear and mtDNA in three different commercial culture media from Vitrolife and Irvine Scientific, spent embryo media assessment at the cleavage and blastocyst stages of development, and analysis of the internal media controls for each patient that had been exposed to identical conditions as embryo media but did not come into contact with embryos.

RESULT(S)

Higher levels of nuclear and mtDNA were observed in the culture media that had been exposed to embryos compared with the internal media controls. Nuclear DNA (∼4 copies) and mtDNA (∼600 copies) could be detected in spent media, and the levels increased at the blastocyst stage. No increase in DNA was detected after artificial blastocoele fluid collapse. Mixed sex chromosome DNA was detected. This originated from contamination in the culture media and from maternal (cumulus) cells. Due to the limited amount of template, the presence of embryonic nuclear DNA could not be confirmed by DNA fingerprinting analysis.

CONCLUSION(S)

Currently DNA from culture media cannot be used for genetic assessment because embryo-associated structures release DNA into the culture medium and the DNA is of mixed origin.

Noninvasive chromosome screening of human embryos by genome sequencing of embryo culture medium for in vitro fertilization

Preimplantation genetic screening (PGS) is widely used to select in vitro-fertilized embryos free of chromosomal abnormalities and to improve the clinical outcome of in vitro fertilization (IVF). A disadvantage of PGS is that it requires biopsy of the preimplantation human embryo, which can limit the clinical applicability of PGS due to the invasiveness and complexity of the process. Here, we present and validate a noninvasive chromosome screening (NICS) method based on sequencing the genomic DNA secreted into the culture medium from the human blastocyst. By using multiple annealing and looping-based amplification cycles (MALBAC) for whole-genome amplification (WGA), we performed next-generation sequencing (NGS) on the spent culture medium used to culture human blastocysts (n = 42) and obtained the ploidy information of all 24 chromosomes. We validated these results by comparing each with their corresponding whole donated embryo and obtained a high correlation for identification of chromosomal abnormalities (sensitivity, 0.882, and specificity, 0.840). With this validated NICS method, we performed chromosome screening on IVF embryos from seven couples with balanced translocation, azoospermia, or recurrent pregnancy loss. Six of them achieved successful clinical pregnancies, and five have already achieved healthy live births thus far. The NICS method avoids the need for embryo biopsy and therefore substantially increases the safety of its use. The method has the potential of much wider chromosome screening applicability in clinical IVF, due to its high accuracy and noninvasiveness.

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

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

Recent advances in preimplantation genetic diagnosis and screening

Preimplantation genetic diagnosis/screening (PGD/PGS) aims to help couples lower the risks of transmitting genetic defects to their offspring, implantation failure, and/or miscarriage during in vitro fertilization (IVF) cycles. However, it is still being debated with regard to the practicality and diagnostic accuracy of PGD/PGS due to the concern of invasive biopsy and the potential mosaicism of embryos. Recently, several non-invasive and high-throughput assays have been developed to help overcome the challenges encountered in the conventional invasive biopsy and low-throughput analysis in PGD/PGS. In this mini-review, we will summarize the recent progresses of these new methods for PGD/PGS and discuss their potential applications in IVF clinics.

Nuclear and mitochondrial DNA in blastocoele fluid and embryo culture medium: evidence and potential clinical use

The ability to screen embryos for aneuploidy or inherited disorders in a minimally invasive manner may represent a major advancement for the future of embryo viability assessment. Recent studies have demonstrated that both blastocoele fluid and embryo culture medium contain genetic material, which can be isolated and subjected to downstream genetic analysis. The blastocoele fluid may represent an alternative source of nuclear DNA for aneuploidy testing, although the degree to which the isolated genetic material is solely representative of the developing embryo is currently unclear. In addition to nuclear DNA, mitochondrial DNA (mtDNA) can be detected in the embryo culture medium. Currently, the origin of this nuclear and mtDNA has not been fully evaluated and there are several potential sources of contamination that may contribute to the genetic material detected in the culture medium. There is however evidence that the mtDNA content of the culture medium is related to embryo fragmentation levels and its presence is predictive of blastulation, indicating that embryo development may influence the levels of genetic material detected. If the levels of genetic material are strongly related to aspects of embryo quality, then this may be a novel biomarker of embryo viability. If the genetic material does have an embryo origin, the mechanisms by which DNA may be released into the blastocoele fluid and embryo culture medium are unknown, although apoptosis may play a role. While the presence of this genetic material is an exciting discovery, the DNA in the blastocoele fluid and embryo culture medium appears to be of low yield and integrity, which makes it challenging to study. Further research aimed at assessing the methodologies used for both isolating and analysing this genetic material, as well as tracing its origin, are needed in order to evaluate its potential for clinical use. Should such methodologies prove to be routinely successful and the DNA recovered demonstrated to be embryonic in origin, then they may be used in a minimally invasive and less technical methodology for genetic analysis and embryo viability assessment than those currently available.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Artificial shrinkage of blastocysts prior to vitrification improves pregnancy outcome: analysis of 1028 consecutive warming cycles

PURPOSE

This study aims to compare implantation, pregnancy, and delivery rates in frozen transfer cycles with blastocysts that were vitrified either with artificial shrinking (AS group) or without (NAS group).

METHODS

Retrospective comparative study of artificial shrinking of blastocysts prior to vitrification and frozen embryo transfer cycles in infertile patients undergoing frozen embryo transfer (FET) was done at the Humanitas Fertility Center between October 2009 and December 2013. Main outcome measure(s) were implantation (IR), pregnancy (PR), and delivery rates (DR) between the two groups.

RESULTS

A total of 1028 consecutive warming blastocyst transfer cycles were considered. In 580 cycles (total of 822 blastocysts), artificial shrinking was performed prior to vitrification (AS group), while in the remaining 448 cycles (total of 625 blastocysts), the artificial shrinking was not performed (NAS group). There were no differences in patient age (36.4 ± 3.7 vs. 36.3 ± 3.9) and number of embryos transferred (1.41 ± 0.49 vs. 1.38 ± 0.50) between groups. The IR, PR, and DR in the AS group were significantly higher (p < 0.05) than in the NAS group (29.9 vs. 23.0 %, 36.3 vs. 27.9 %, and 26.5 vs. 18.1 %, respectively).

CONCLUSIONS

Performing AS of blastocysts prior to vitrification appears to improve implantation, pregnancy, and delivery rates probably related to a decreased risk of ultrastructural cryodamages, plausible when cryopreserving expanded blastocysts.

Preimplantation genetic testing: polar bodies, blastomeres, trophectoderm cells, or blastocoelic fluid?

OBJECTIVE

To investigate the blastocoelic fluid (BF) for the presence of DNA that could be amplified and analyzed; the extent to which its chromosomal status corresponds to that found in trophectoderm (TE) cells, polar bodies (PBs), or blastomeres; and the identification of segmental abnormalities.

DESIGN

Longitudinal cohort study.

SETTING

In vitro fertilization unit.

PATIENT(S)

Fifty-one couples undergoing preimplantation genetic screening or preimplantation genetic diagnosis for translocations by array-comparative genomic hybridization on PBs (n = 21) or blastomeres (n = 30).

INTERVENTION(S)

BFs and TE cells were retrieved from 116 blastocysts, whose chromosome status had already been established by PB or blastomere assessment. Separate chromosome analysis was performed in 70 BFs.

MAIN OUTCOME MEASURE(S)

Presence of DNA in BFs, evaluation of the chromosome condition, and comparison with the diagnosis made in TE cells and at earlier stage biopsies.

RESULT(S)

DNA detection was 82%, with a net improvement after refinement of the procedure. In 97.1% of BFs, the ploidy condition corresponded to that found in TE cells, with one false positive and one false negative. The rate of concordance per single chromosome was 98.4%. Ploidy and chromosome concordance with PBs were 94% and 97.9%, respectively; with blastomeres, the concordances were 95% and 97.7%, respectively. Segmental abnormalities, which were detected in PBs or blastomeres of 16 blastocysts, were also identified in the corresponding BFs.

CONCLUSION(S)

BF represents to a good extent the blastocyst ploidy condition and chromosome status when compared with TE cells. If the proportion of clinically useful BFs is improved, blastocentesis could become the preferred source of DNA for chromosomal testing.

Extracellular embryo genomic DNA and its potential for genotyping applications

Background:

Preimplantation genetic diagnosis (PGD) currently relies on biopsy of one or few embryo cells. Our aim was to evaluate the embryo extracellular matrices (spent medium and blastocoele fluid) as source of DNA for embryo genotyping.

Results/methodology:

We first evaluated the amplifiability and the amount of genomic DNA in spent embryo culture media from day 3 (n = 32) and day 5/6 (n = 54). Secondly, we evaluated the possibility to genotype the MTHFR polymorphism C677T from media at day 5/6 (n = 8) and blastocoele fluids (n = 9) by direct sequencing. The C677T polymorphism detection rate was 62.5 and 44.4% in medium and fluid, respectively.

Conclusion:

A noninvasive approach for embryo genotyping was possible, but still with limitations due to low detection rate and possible allele dropout.

PGD currently relies on biopsy of embryo cells, which could imply some risk of embryo damage. Since embryo DNA was retrieved both in blastocoele cavity and culture medium, we evaluated if this extracellular DNA could be useful to obtain medical-related genetic information from the embryo. First, we used multicopy genes to verify amplifiability and amount of DNA in medium, then we amplified and sequenced one gene fragment containing a polymorphism of medical importance in a subset of samples. The polymorphism detection rate was not yet high enough to warrant clinical application but we demonstrated that this approach was possible.

Pre-implantation genetic diagnosis and screening: now and the future

Since 1989, the year of the first pre-implantation genetic diagnosis (PGD), many developments occurred both in assisted reproduction techniques and in molecular tools. While PGD is a well-established and documented application, pre-implantation genetic screening (PGS) for the detection of aneuploid embryos is still debated due to the presence of mosaicism in the embryo, but especially to the knowledge of the limits that label an embryo as healthy or as appropriate to the life. The aim of this review is to present the state-of-the-art in the field of PGD and PGS, illustrating its benefits and limitations, along with biopsy techniques and the use of new high-throughput technologies.

A comparison of different vitrification devices and the effect of blastocoele collapse on the cryosurvival of in vitro produced porcine embryos

The aim of this study was to determine the optimum conditions for vitrifying in vitro produced day 7 porcine embryos using different vitrification devices and blastocoele collapse methods. Firstly embryos were collapsed by micro-pipetting, needle puncture and sucrose with and without conducting vitrification. In the next experiment, non-collapsed embryos were vitrified in an open device using either superfine open-pulled straws (SOPS) or the CryoLoop^TM system, or vitrified in a closed device using either the CryoTip^TM or Cryo Bio^TM’s high security vitrification system (HSV). The post-thaw survival of embryos vitrified in the open devices did not differ significantly (SOPS: 37.3%; CryoLoop^TM: 37.3%) nor did the post-thaw survival of embryos vitrified in the closed devices (CryoTip™: 38.5%; HSV: 42.5%). The re-expansion rate of embryos that were collapsed via micro-pipetting (76.0%) did not differ from those that were punctured (75.0%) or collapsed via sucrose (79.6%) when vitrification was not performed. However, embryos collapsed via sucrose solutions (24.5%) and needle puncture (16.0%) prior to vitrification were significantly less likely to survive vitrification than the control (non-collapsed) embryos (53.6%, P < 0.05). The findings show that both open and closed vitrification devices were equally effective for the vitrification of porcine blastocysts. Collapsing blastocysts prior to vitrification did not improve survival, which is inconsistent with the findings of studies in other species. This may be due to the extremely sensitive nature of porcine embryos, and/or the invasiveness of the collapsing procedures.

Blastocoel fluid from differentiated blastocysts harbors embryonic genomic material capable of a whole-genome deoxyribonucleic acid amplification and comprehensive chromosome microarray analysis

OBJECTIVE

To obtain embryonic molecular karyotypes from genomic DNA (deoxyribonucleic acid) isolated from blastocoel fluid (BF) and to compare these karyotypes with the karyotypes from the remaining inner cell mass (ICM) and trophectoderm (TE) of the blastocyst.

DESIGN

Prospective cohort study.

SETTING

Academic center and preimplantation genetics laboratory.

PATIENT(S)

Ninety-six donated cryopreserved embryos.

INTERVENTION(S)

Embryo biopsy, BF aspiration, DNA analysis using a comparative genomic hybridization microarray (aCGH).

MAIN OUTCOME MEASURE(S)

The aCGH of a single blastomere, BF-DNA, and ICM-TE.

RESULT(S)

The BF-DNA samples resulted in a successful aCGH in 63% of cases. Discordance in karyotypes was found between the BF-DNA and the ICM-TE in 52% of cases. A total of 70% of aneusomic (mosaicism), cleavage-stage embryos differentiated into euploid blastocysts. Probabilities for diagnostic accuracy were calculated and demonstrated the following: sensitivity of 0.88 (95% confidence interval [CI]: 0.62-0.98); specificity of 0.55 (95% CI: 0.39-0.70); positive predictive value of 0.41 (95% CI: 0.25-0.60); negative predictive value of 0.92 (95% CI: 0.75-0.99).

CONCLUSION(S)

Genomic DNA from the BF can be amplified and characterized by comprehensive chromosome microarrays. The results demonstrated that aneusomic cleavage-stage embryos differentiated into euploid blastocysts, possibly using a mechanism that marginalizes aneuploid nuclei into the blastocoel cavity. In addition, owing to the high discordance between the karyotypes obtained from the BF-DNA and the ICM-TE, using BF-DNA for preimplantation genetic testing is not yet advised.

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

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