Evaluation of blastomere biopsy using a mouse model indicates the potential high risk of neurodegenerative disorders in the offspring

Preimplantation genetic testing as a preventive strategy for the transmission of mitochondrial DNA disorders

Mitochondrial diseases are distinct types of metabolic and/or neurologic abnormalities that occur as a consequence of dysfunction in oxidative phosphorylation, affecting several systems in the body. There is no effective treatment modality for mitochondrial disorders so far, emphasizing the clinical significance of preventing the inheritance of these disorders. Various reproductive options are available to reduce the probability of inheriting mitochondrial disorders, including in vitro fertilization (IVF) using donated oocytes, preimplantation genetic testing (PGT), and prenatal diagnosis (PND), among which PGT not only makes it possible for families to have genetically-owned children but also PGT has the advantage that couples do not have to decide to terminate the pregnancy if a mutation is detected in the fetus. PGT for mitochondrial diseases originating from nuclear DNA includes analyzing the nuclear genome for the presence or absence of corresponding mutations. However, PGT for mitochondrial disorders arising from mutations in mitochondrial DNA (mtDNA) is more intricate, due to the specific characteristics of mtDNA such as multicopy nature, heteroplasmy phenomenon, and exclusive maternal inheritance. Therefore, the present review aims to discuss the utility and challenges of PGT as a preventive approach to inherited mitochondrial diseases caused by mtDNA mutations.

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.

Long-term health risk of offspring born from assisted reproductive technologies

Since the world's first in vitro fertilization baby was born in 1978, there have been more than 8 million children conceived through assisted reproductive technologies (ART) worldwide, and a significant proportion of them have reached puberty or young adulthood. Many studies have found that ART increases the risk of adverse perinatal outcomes, including preterm birth, low birth weight, small size for gestational age, perinatal mortality, and congenital anomalies. However, data regarding the long-term outcomes of ART offspring are limited. According to the developmental origins of health and disease theory, adverse environments during early life stages may induce adaptive changes and subsequently result in an increased risk of diseases in later life. Increasing evidence also suggests that ART offspring are predisposed to an increased risk of non-communicable diseases, such as malignancies, asthma, obesity, metabolic syndrome, diabetes, cardiovascular diseases, and neurodevelopmental and psychiatric disorders. In this review, we summarize the risks for long-term health in ART offspring, discuss the underlying mechanisms, including underlying parental infertility, epigenetic alterations, non-physiological hormone levels, and placental dysfunction, and propose potential strategies to optimize the management of ART and health care of parents and children to eliminate the associated risks. Further ongoing follow-up and research are warranted to determine the effects of ART on the long-term health of ART offspring in later life.

The mammalian preimplantation embryo: Its role in the environmental programming of postnatal health and performance

During formation of the preimplantation embryo several cellular and molecular milestones take place, making the few cells forming the early embryo vulnerable to environmental stressors than can impair epigenetic reprogramming and controls of gene expression. Although these molecular alterations can result in embryonic death, a significant developmental plasticity is present in the preimplantation embryo that promotes full-term pregnancy. Prenatal epigenetic modifications are inherited during mitosis and can perpetuate specific phenotypes during early postnatal development and adulthood. As such, the preimplantation phase is a developmental window where developmental programming can take place in response to the embryonic microenvironment present in vivo or in vitro. In this review, the relevance of the preimplantation embryo as a developmental stage where offspring health and performance can be programmed is discussed, with emphasis on malnutrition and assisted reproductive technologies; two major environmental insults with important implications for livestock production and human reproductive medicine.

Non-Invasive Preimplantation Genetic Testing for Aneuploidy and the Mystery of Genetic Material: A Review Article

This review focuses on recent findings in the preimplantation genetic testing (PGT) of embryos. Different preimplantation genetic tests are presented along with different genetic materials and their analysis. Original material concerning preimplantation genetic testing for aneuploidy (PGT-A) was sourced by searching the PubMed and ScienceDirect databases in October and November 2021. The searches comprised keywords such as ‘preimplantation’, ‘cfDNA’; ‘miRNA’, ‘PGT-A’, ‘niPGT-A’, ‘aneuploidy’, ‘mosaicism’, ‘blastocyst biopsy’, ‘blastocentesis’, ‘blastocoel fluid’, ‘NGS’, ‘FISH’, and ‘aCGH’. Non-invasive PGT-A (niPGT-A) is a novel approach to the genetic analysis of embryos. The premise is that the genetic material in the spent embryo culture media (SECM) corresponds to the genetic material in the embryo cells. The limitations of niPGT-A are a lower quantity and lesser quality of the cell-free genetic material, and its unknown origin. The concordance rate varies when compared to invasive PGT-A. Some authors have also hypothesized that mosaicism and aneuploid cells are preferentially excluded from the embryo during early development. Cell-free genetic material is readily available in the spent embryo culture media, which provides an easier, more economic, and safer extraction of genetic material for analysis. The sampling of the SECM and DNA extraction and amplification must be optimized. The origin of the cell-free media, the percentage of apoptotic events, and the levels of DNA contamination are currently unknown; these topics need to be further investigated.

Improved Non-Invasive Preimplantation Genetic Testing for Beta-Thalassemia Using Spent Embryo Culture Medium Containing Blastocoelic Fluid

OBJECTIVES

To compare successful beta-thalassemia (β-thalassemia) detection rates obtained using spent culture medium and spent culture medium containing blastocoelic fluid (BF).

METHOD

This study involved data from 10 couples who underwent preimplantation genetic testing (PGT) for β-thalassemia. A total of 26 samples of spent culture medium containing BF (group A) and 33 samples without BF (group B) were collected and analyzed. The DNA concentration and β-thalassemia detection rates were evaluated.

RESULTS

The HBB mutation analysis results of 34 samples were concordant with the biopsy results (34/59, 57.6%). In group A, the HBB mutation analysis results of 19 of 26 samples (73.1%) were concordant with the biopsy results. The concordance rate in group A was higher than that in group B (15/33, 45.5%; P < 0.05). The haplotyping results of 38 samples were concordant with the biopsy results (38/59, 64.4%). The concordance rate in group B was 17/33 (51.5%), which was significantly lower than that in group A (21/26, 80.8%) (P < 0.05). In group A, the mean DNA concentration of samples with <10% fragmentation was 107.3 ± 70.1 ng/μL, which was lower than that of samples with ≥10% fragmentation (194.6 ± 28.0 ng/μL) (P < 0.05). However, the detection rates of <10% and ≥10% fragmentation were not significantly different (P > 0.05).

CONCLUSION

The β-thalassemia detection rate with non-invasive PGT using the spent culture medium containing BF was higher than that using the spent culture medium alone. Fragmentation is associated with DNA concentration in the spent culture medium containing BF.

The effect of blastomere loss during frozen embryo transfer on the transcriptome of offspring's umbilical cord blood

Blastomere loss is a common issue during frozen-thawed embryo transfer (FET). Our previous study showed that blastomere loss was associated with an increased risk of small-for-gestational-age (SGA) neonates. The present study assessed the impact of blastomere loss during cryopreservation by comparing the mRNA profiles of umbilical cord blood of FET offspring from the prospective cohort study. Umbilical cord blood samples were collected from 48 neonates, including 12 from the loss group, 11 from the intact group, and 25 from the matched spontaneous pregnancy group. RNA-seq technology was used to compare the global gene expression profiles of the lymphocytes. Then, we used TopHat software to map the reads and quantitative real-time PCR to validate some important differentially expressed genes (DEGs). We identified 92 DEGs between the loss group and the spontaneous pregnancy group, including IGF2 and H19. Ingenuity Pathway Analysis (IPA) showed that the DEGs were most affected in the blastomere loss group. Downstream analysis also predicted the activation of organismal death pathways. In conclusions, our pilot study sheds light on the mechanism underlying how human blastomere loss may affect offspring at the gene expression level. These conclusions are, however, only suggestive, as the current study is based on a very limited sample size and type or nature of biological samples. Additional studies with larger sample sizes and independent experiments with placental samples should be conducted to verify these findings.

Non-invasive preimplantation genetic testing (niPGT): the next revolution in reproductive genetics?

BACKGROUND

Preimplantation genetic testing (PGT) encompasses methods that allow embryos to be tested for severe inherited conditions or for chromosome abnormalities, relevant to embryo health and viability. In order to obtain embryonic genetic material for analysis, a biopsy is required, involving the removal of one or more cells. This invasive procedure greatly increases the costs of PGT and there have been concerns that embryo viability could be compromised in some cases. The recent discovery of DNA within the blastocoele fluid (BF) of blastocysts and in spent embryo culture media (SCM) has led to interest in the development of non-invasive methods of PGT (niPGT).

OBJECTIVE AND RATIONALE

This review evaluates the current scientific evidence regarding non-invasive genetic assessment of preimplantation embryos. The success of different PGT methodologies in collecting and analysing extra-embryonic DNA is evaluated, and consideration is given to the potential biological and technical hindrances to obtaining a reliable clinical diagnosis.

SEARCH METHODS

Original research and review papers concerning niPGT were sourced by searching PubMed and Google Scholar databases until July 2019. Searches comprised the keywords: 'non-invasive'; 'cell-free DNA'; 'blastocentesis'; 'blastocoel fluid'; 'spent culture media'; 'embryo culture medium'; 'preimplantation genetic testing'; 'preimplantation genetic diagnosis'; 'preimplantation genetic screening'; and 'aneuploidy'.

OUTCOMES

Embryonic DNA is frequently detectable in BF and SCM of embryos produced during IVF treatment. Initial studies have achieved some success when performing cytogenetic and molecular genetic analysis. However, in many cases, the efficiency has been restricted by technical complications associated with the low quantity and quality of the DNA. Reported levels of ploidy agreement between SCM/BF samples and biopsied embryonic cells vary widely. In some cases, a discrepancy with respect to cytogenetic data obtained after trophectoderm biopsy may be attributable to embryonic mosaicism or DNA contamination (usually of maternal origin). Some research indicates that aneuploid cells are preferentially eliminated from the embryo, suggesting that their DNA might be over-represented in SCM and BF samples; this hypothesis requires further investigation.

WIDER IMPLICATIONS

Available data suggest that BF and SCM samples frequently provide DNA templates suitable for genetic analyses, offering a potential means of PGT that is less expensive than traditional methods, requires less micromanipulation skill and poses a lower risk to embryos. Critically, DNA isolation and amplification protocols must be optimised to reproducibly obtain an accurate clinical diagnosis, whilst minimising the impact of confounding factors such as contamination. Further investigations are required to understand the mechanisms underlying the release of embryonic DNA and to determine the extent to which this material reflects the true genetic status of the corresponding embryo. Currently, the clinic al potential of niPGT remains unknown.

A blastocyst biopsy approach for preimplantation genetic diagnosis technique that affects the expression of SNAP-α in mice

Preimplantation genetic diagnosis (PGD) is a technique that is commonly used during assisted reproduction in the clinics to eliminate genetically abnormal embryos before implantation. The blastomere biopsy technique has risks related to the embryo, but blastocyst biopsy has not been systematically evaluated in relation to effects after birth, and the resulting offspring have not been followed up on. We designed a series of experiments to evaluate the risk of blastocyst biopsy on the resulting progeny. Mice were divided into a PGD group and a control group. The former was the progeny of mice that underwent blastocyst biopsy and the latter was delivered through a normal pregnancy without blastocyst biopsy. Each group consisted of 15 animals. We found no effects of blastocyst biopsy on reproductive capacities and weight gain. As for neurobehavioral evaluation between both groups, there were no significant differences in tail suspension test, sucrose preference test, the open field test and the elevated plus maze. Western blotting, immunohistochemistry and quantitative RT-PCR results showed that the expression levels of MBP, PRDX5 and UCHL1 in the PGD group were not significantly different compared to the control group, but SNAP-α expression in the PGD group was lower than that in control group. In summary, we concluded that blastocyst biopsy had no adverse effect on the general growth and behavior in mice. However, blastocyst biopsy effected the expression of SNAP-α. Therefore, the safety of blastocyst biopsy requires further evaluation.

Cleavage-stage embryo micromanipulation in the clinical setting

Embryo micromanipulation was developed after introduction of microinjection to overcome infertility. Embryo micromanipulation may be performed at any embryo stage from pronuclear to blastocyst. The technique started out as basic and turned out to be increasingly more complex. Embryo micromanipulation at the cleavage-stage includes a wide range of techniques, from opening the zona pellucida in order to improve the chance of implantation, to removing detrimental components from the embryo to enhance embryo development or blastomeres for preimplantation genetic diagnosis and embryo splitting. Evaluating the impact(s) of different micromanipulation techniques on epigenetics of the embryo and considering quality control during these techniques are important issues in this regard. This review aims to discuss the micromanipulation of cleavage-stage embryos in clinical assisted reproductive technology (ART).

ABBREVIATIONS

ART: assisted reproductive technology; ICSI: intracytoplasmic sperm injection; IVF: in vitro fertilization; PGD: preimplantation genetic diagnosis; PZD: partial zona dissection; ZP: zona pellucida; SUZI: subzonal insemination; PVS: perivitelline space; AH: assisted hatching; LAH: laserassisted hatching; ZT: zona thinning; UV: ultraviolet; IR: infrared; PCR: polymerase chain reaction; FISH: fluorescent in situ hybridization; NGS: next generation sequencing; QC: quality control; QA: quality assurance.

Public Perceptions of Ethical, Legal and Social Implications of Pre-implantation Genetic Diagnosis (PGD) in Malaysia

Pre-implantation genetic diagnosis (PGD) became well known in Malaysia after the birth of the first Malaysian 'designer baby', Yau Tak in 2004. Two years later, the Malaysian Medical Council implemented the first and only regulation on the use of Pre-implantation Genetic Diagnosis in this country. The birth of Yau Tak triggered a public outcry because PGD was used for non-medical sex selection thus, raising concerns about PGD and its implications for the society. This study aims to explore participants' perceptions of the future implications of PGD for the Malaysian society. We conducted in-depth interviews with 21 participants over a period of one year, using a semi-structured questionnaire. Findings reveal that responses varied substantially among the participants; there was a broad acceptance as well as rejection of PGD. Contentious ethical, legal and social issues of PGD were raised during the discussions, including intolerance to and discrimination against people with genetic disabilities; societal pressure and the 'slippery slope' of PGD were raised during the discussions. This study also highlights participants' legal standpoint, and major issues regarding PGD in relation to the accuracy of diagnosis. At the social policy level, considerations are given to access as well as the impact of this technology on families, women and physicians. Given these different perceptions of the use of PGD, and its implications and conflicts, policies and regulations of the use of PGD have to be dealt with on a case-by-case basis while taking into consideration of the risk-benefit balance, since its application will impact the lives of so many people in the society.

Embryo biopsy and development: the known and the unknown

Preimplantation genetic diagnosis (PGD) has been introduced in clinical practice as a tool for selecting ‘healthy’ embryos before their transfer in utero. PGD protocols include biopsy of cleaving embryos (blastomere biopsy (BB)) or blastocysts (trophectoderm biopsy (TB)), followed by genetic analysis to select ‘healthy’ embryos for transfer in utero. Currently, TB is replacing the use of BB in the clinical practice. However, based on the European Society of Human Reproduction and Embryology Preimplantation Genetic Diagnosis Consortium reports, BB has been used in >87% of PGD cycles for more than 10 years. An exhaustive evaluation of embryo biopsy (both BB and TB) risks and safety is still missing. The few epidemiological studies available are quite controversial and/or are limited to normalcy at birth or early childhood. On the other hand, studies on animals have shown that BB can be a risk factor for impaired development, during both pre- and postnatal life, while little is known on TB. Thus, there is an urgent need of focused researches on BB, as it has contributed to give birth to children for more than 10 years, and on TB, as its application is significantly growing in clinical practice. In this context, the aim of this review is to provide a complete overview of the current knowledge on the short-, medium- and long-term effects of embryo biopsy in the mouse model.

A potential high risk for fatty liver disease was found in mice generated after assisted reproductive techniques

Abnormal gametogenesis and embryonic development may lead to poor health status of the offspring. The operations involved in the assisted reproductive technologies (ARTs) occur during the key stage of gametogenesis and early embryonic development. To assess the potential risk of abnormal lipid metabolism in the liver of adult ARTs offspring, two ARTs mice models derived from preimplantation genetic diagnosis (PGD group) and in vitro cultured embryos without biopsy (IVEM group) were constructed. And control mice were from in vivo naturally conceived (Normal group). The results showed that ARTs offspring had increased body weight and body fat content comparing to normal group. An increasing volume and amount of lipid droplets as well as lipid droplet fusion were found in the hepatocytes of ARTs mice, and a significantly increased liver TG content was also shown in the ARTs mice, which due to the increased TG synthesis and decreased TG transport in the liver. All the results indicated that the manipulations involved in ARTs might play an important role in the lipid accumulation of adult offspring. By analyzing the DNA methylation profiles of 7.5dpc embryos, we proposed that methylation deregulation of the genes related to liver development in ARTs embryos might contribute to the abnormal phenotype in the offspring. The study demonstrated that ARTs procedures have adverse effect on liver development which resulted in abnormal lipid metabolism and induced the potential high risk of fatty liver in adulthood.

Genetic and epigenetic risks of assisted reproduction

Assisted reproductive technology (ART) is used primarily for infertility treatments to achieve pregnancy and involves procedures such as in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), and cryopreservation. Moreover, preimplantation genetic diagnosis (PGD) of ART is used in couples for genetic reasons. In ART treatments, gametes and zygotes are exposed to a series of non-physiological processes and culture media. Although the majority of children born with this treatment are healthy, some concerns remain regarding the safety of this technology. Animal studies and follow-up studies of ART-borne children suggested that ART was associated with an increased incidence of genetic, physical, or developmental abnormalities, although there are also observations that contradict these findings. As IVF, ICSI, frozen-thawed embryo transfer, and PGD manipulate gametes and embryo at a time that is important for reprogramming, they may affect epigenetic stability, leading to gamete/embryo origins of adult diseases. In fact, ART offspring have been reported to have an increased risk of gamete/embryo origins of adult diseases, such as early-onset diabetes, cardiovascular disease, and so on. In this review, we will discuss evidence related to genetic, especially epigenetic, risks of assisted reproduction.

Reproductive medicine involving genome editing: clinical uncertainties and embryological needs

Genome editing based on site-directed nucleases facilitated efficient and versatile genetic modifications in human cells. However, recent reports, demonstrating CRISPR/Cas9-mediated genome editing in human embryos have raised profound concerns worldwide. This commentary explores the clinical justification and feasibility of reproductive medicine using germline genome editing. Despite the perceived utility of reproductive medicine for treating intractable infertility, it is difficult to justify germline genome editing from the perspective of the prospective child. As suggested by the UK legalization regarding mitochondrial donation, the prevention of genetic disease in offspring by genome editing might be acceptable in limited cases of serious or life-threatening conditions, where no alternative medicine is available. Nonetheless, the mosaicism underlying human embryos as well as the off-target effect by artificial nucleases will likely hamper preimplantation genetic diagnosis prior to embryo transfer. Such considerations suggest that this type of reproductive medicine should not be developed toward a clinical application. However, the clinical uncertainties underscore the need for embryology that can address fundamental questions regarding germline aneuploidy and mosaicism using genome editing.

Blastomere removal from cleavage-stage mouse embryos alters placental function, which is associated with placental oxidative stress and inflammation

Blastomere biopsy is an essential technique in preimplantation genetic diagnosis (PGD), a screening test that can detect genetic abnormalities of embryos before their transfer into uterus. Our results showed that the weights of fetuses derived from biopsied embryos were lower than that of non-biopsied counterparts at E12.5, E15.5, and E18.5. The ratio of fetal/placental (F/P) weights in the biopsied group was significantly lower than that in the non-biopsied group at E18.5. At E18.5, the mRNAs for selected glucose transporters, system A amino acid transporters, system L amino acid transporters, and imprinted genes were downregulated in the placentae of biopsied group, and the GLUT1 and CAT3 protein levels were decreased too. More apoptotic cells were detected by TUNEL in the placentae of biopsied group. Placentae from biopsied embryos exhibited lower levels of SOD and GSH. Furthermore, the concentration of MDA increased in the placentae from biopsied group. The levels of IL1B, IL6, and TNFA also significantly increased in the placentae of biopsied group. This study suggested that placental function may be sensitive to blastomere biopsy procedures, and placental oxidative stress and inflammation associated with blastomere biopsy may be critical factors of abnormal placental function and further influence the fetal development.

Obstetric and neonatal outcomes in blastocyst-stage biopsy with frozen embryo transfer and cleavage-stage biopsy with fresh embryo transfer after preimplantation genetic diagnosis/screening

OBJECTIVE

To study whether embryo biopsy for preimplantation genetic diagnosis/preimplantation genetic screening (PGD/PGS) can influence pregnancy complications and neonatal outcomes.

DESIGN

Retrospective analysis.

SETTING

University-affiliated center.

PATIENT(S)

This study included data from women and their neonates born after PGD/PGS (n = 317).

MAIN OUTCOME MEASURE(S)

Questionnaires were designed to obtain information relating to pregnancy complications and neonatal outcomes.

INTERVENTION(S)

Two major strategies for PGD/PGS were evaluated. Blastocyst-stage biopsy and frozen embryo transfer (BB-FET) was carried out in 166 patients, and cleavage-stage biopsy and fresh embryo transfer (CB-ET) was carried out in 129 patients.

RESULT(S)

The incidence of gestational hypertension was significantly higher in BB-FET compared with in CB-ET (9.0% vs. 2.3%, adjusted odds ratio [OR] and 95% confidence interval [CI], 4.85 [1.34, 17.56]). In twins, the birthweight (median [range], 2.70 kg [1.55-3.60 kg] vs. 2.50 kg [1.23-3.75 kg]) was higher in BB-FET than in CB-ET and the gestational age was longer in BB-FET than in CB-ET (median [range], 36.71 weeks [31.14-39.29 weeks] vs. 35.57 weeks [30.57-38.43 weeks]). There was no difference in the incidence of singleton births between the two groups except in the incidence of preterm births (28-37 weeks; 5.3% vs. 16.5% in CB-ET and BB-FET). No significant differences were detected in the incidence of perinatal deaths, birth defects, gender of neonates, and large for gestational age in both singletons and twins, although the numbers of some events were small.

CONCLUSION(S)

BB-FET is associated with a higher incidence of gestational hypertension but better neonatal outcomes compared with CB-ET, especially in twins.

Superovulation Induced Changes of Lipid Metabolism in Ovaries and Embryos and Its Probable Mechanism

This research was intended to investigate the fetal origins of changed birth weight of the offspring born through assisted reproductive technology (ART). The association between hormone and lipid metabolism or body weight has been generally accepted, and as the basic and specific treatment in ART procedure, gonadotropin stimulation might have potential effects on intrauterine lipid metabolism. In our studies, the mice were superovulated with two doses of gonadotropin. The cholesterol metabolism in ovaries and the triglyceride metabolism in embryos were analyzed. The results showed gonadotropin probably accelerated luteinization and induced a longer time follicle development and ovulation, which resulted in histological and morphological alteration of ovary, and increased the cholesterol content and the expressions of steroidogenesis-related genes. In embryos, gonadotropin increased lipid accumulation and decreased fatty acid synthesis in a dose-dependent manner. Moreover, the changes of fatty acid composition were also shown in superovulation groups. Our studies firstly provided the evidence that the superovulation might affect the maternal and fetal lipid metabolism. These variations of lipid metabolism in our results may be associated with birth weight of ART infants.

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.

Mitochondrial replacement: from basic research to assisted reproductive technology portfolio tool-technicalities and possible risks

Mitochondrial DNA (mtDNA) mutations are a relatively common cause of progressive disorders that can be severe or even life-threatening. There is currently no cure for these disorders; therefore recent research has been focused on attempting to prevent the transmission of these maternally inherited mutations. Here we highlight the challenges of understanding the transmission of mtDNA diseases, discuss current genetic management options and explore the use of germ-line reconstruction technologies to prevent mtDNA diseases. In particular we discuss their potential, indications, limitations and possible safety concerns.

Chromosomal aberrations in in-vitro matured oocytes influence implantation and ongoing pregnancy rates in a mouse model undergoing intracytoplasmic sperm injection

Implantation failure and early pregnancy loss have been reported to be closely related to the quality of mammalian oocytes; however, the pregnant outcome of embryos from in-vitro matured (IVM) oocytes remains unknown. In this study we examined spindle assembly and chromosome segregation during differentiation, and the duration of IVM of mouse oocytes. The resulting implantation and pregnancy outcomes were analyzed to clarify the relationship between the spindle and chromosomes of IVM oocytes and implantation and early pregnancy. Cumulus-enclosed germinal vesicle oocytes were collected and randomly cultured in IVM medium with different IVM durations. One part of IVM oocytes were analyzed the spindle and chromosome morphology by immunofluorescence method, and the other part of them were fertilized by intracytoplasmic sperm injection. The resulting embryos were transferred into pseudo-pregnant female mice, and the post-implantation and full term development was observed. The chromosome aberrations and incorrect spindle assembly seems not affect the early development and blastocyst cell number derived from IVM oocytes, however the development potential of the resulting embryos after implantation were significant decreased with the ratio increasing of chromosome aberrations and incorrect spindle assembly. Accordingly, the full-term development was also decreased. In conclusion, the present study showed the spindle assembly of in vitro-matured oocytes was one of the most important factors that affected the implantation and ongoing pregnancy rates of IVM oocytes, and the improvement by an appropriate duration of maturation in vitro will enhance the post-implantation development potential of the resulting embryos, and decrease implantation failure and early pregnancy loss.

Blastomere biopsy influences epigenetic reprogramming during early embryo development, which impacts neural development and function in resulting mice

Blastomere biopsy is used in preimplantation genetic diagnosis; however, the long-term implications on the offspring are poorly characterized. We previously reported a high risk of memory defects in adult biopsied mice. Here, we assessed nervous function of aged biopsied mice and further investigated the mechanism of neural impairment after biopsy. We found that aged biopsied mice had poorer spatial learning ability, increased neuron degeneration, and altered expression of proteins involved in neural degeneration or dysfunction in the brain compared to aged control mice. Furthermore, the MeDIP assay indicated a genome-wide low methylation in the brains of adult biopsied mice when compared to the controls, and most of the genes containing differentially methylated loci in promoter regions were associated with neural disorders. When we further compared the genomic DNA methylation profiles of 7.5-days postconception (dpc) embryos between the biopsy and control group, we found the whole genome low methylation in the biopsied group, suggesting that blastomere biopsy was an obstacle to de novo methylation during early embryo development. Further analysis on mRNA profiles of 4.5-dpc embryos indicated that reduced expression of de novo methylation genes in biopsied embryos may impact de novo methylation. In conclusion, we demonstrate an abnormal neural development and function in mice generated after blastomere biopsy. The impaired epigenetic reprogramming during early embryo development may be the latent mechanism contributing to the impairment of the nervous system in the biopsied mice, which results in a hypomethylation status in their brains.

Aberrant epigenetic modification in murine brain tissues of offspring from preimplantation genetic diagnosis blastomere biopsies

Preimplantation genetic diagnosis (PGD) has been prevalent in the field of assisted reproductive technology, yet the long-term risks of PGD to offspring remain unknown. In the present study, the early development of PGD embryos, postimplantation characteristics, and birth rate following PGD were determined. Moreover, the behavior of the offspring conceived from the biopsied embryos was evaluated with the Morris water maze and pole climbing tests. Finally, the epigenetic modification of the global genome and methylation patterns for the H19, Igf2, and Snrpn imprinted genes were identified. The results indicated a significant delay in the blastocoel formation of PGD embryos and a decrease in the implantation ability of these embryos, which was related to the decreased number of cells in the PGD blastocysts. The PGD mice spent more time on both the nontrained quadrant of the water maze and climbing down the pole. Furthermore, the 5-hydroxymethylcytosine content in the brain tissues of PGD mice was significantly increased, but no difference was found in 5-methylcytosine content. The differentially methylated regions of H19/Igf2 exhibited decreased methylation patterns, but that of Snrpn was normal, compared to the control group. Quantitative RT-PCR indicated that Igf2 mRNA expression was significantly decreased but that H19 and Snrpn mRNAs were expressed normally. In conclusion, blastomere biopsies in PGD procedures carry potential risks to embryo development and the behavior of resulting offspring; these risks may arise from aberrant epigenetic modification and methylation patterns in brain tissues. Further studies are needed to better understand the risks associated with PGD.

Preimplantation genetic diagnosis (PGD) influences adrenal development and response to cold stress in resulting mice

Preimplantation genetic diagnosis (PGD) has gained widespread application in clinical medicine and hence the health of PGD offspring needs to be systematically assessed. Given the critical role of the stress response in growth and health, assessments of the development and function of the stress system might help to clarify the health outcomes of PGD. In this study, we constructed a PGD-conceived mouse model and used naturally conceived mice as controls; we used this model to evaluate the potential effect of PGD procedures on the stress system of the offspring. Serum and tissues of stress organs, namely the hypothalamus, locus coeruleus and adrenal gland, were collected from 5-week-old mice in the basal state or after cold stress. The serum levels of stress-related hormones and the structural and functional indices of the stress organs were then examined. In the basal state, ultrastructural abnormalities and low expression of genes involved in steroid hormone synthesis were found in the adrenals of the PGD mice, which had low corticosterone and high epinephrine levels compared with those of control mice. After acute cold stress, the PGD mice continued to show structural and glucocorticoid secretion abnormalities resulting in a late response to the environmental change. Thus, our study indicates that PGD manipulations affect adrenal development, result in structural and functional abnormalities of the adrenals in the offspring and influence their reactivity and adaptability to cold stress.

Comparative analysis of dynamic proteomic profiles between in vivo and in vitro produced mouse embryos during postimplantation period

Assisted reproductive technology (ART) increasingly is associated with long-term side-effects on postnatal development and behaviors. High-throughput gene expression analysis has been extensively used to explore mechanisms responsible for these disorders. Our study, for the first time, provides a comparative proteomic analysis between embryos after in vivo fertilization and development (IVO, control) and in vitro fertilization and culture (IVP). By comparing the dynamic proteome during the postimplantation period, we identified 300 and 262 differentially expressed proteins (DEPs) between IVO and IVP embryos at embryonic day 7.5 (E7.5) and E10.5, respectively. Bioinformatic analysis showed many DEPs functionally associated with post-transcriptional, translational, and post-translational regulation, and these observations were consistent with correlation analysis between mRNA and protein abundance. In addition to altered gene expression due to IVP procedures, our findings suggest that aberrant processes at these various levels also contributed to proteomic alterations. In addition, numerous DEPs were involved in energy and amino acid metabolism, as well as neural and sensory development. These DEPs are potential candidates for further exploring the mechanism(s) of ART-induced intrauterine growth restriction and neurodevelopmental disorders. Moreover, significant enrichment of DEPs in pathways of neurodegenerative diseases implies the potentially increased susceptibility of ART offspring to these conditions as adults.

Comparative proteomics analysis reveals roles for FADD in the regulation of energy metabolism and proteolysis pathway in mouse embryonic fibroblast

Fas-associated death domain-containing protein (FADD) is a classical apoptotic pathway adaptor. Further studies revealed that it also plays essential roles in nonapoptotic processes, which is assumed to be regulated by its phosphorylation. However, the exact mechanisms are still poorly understood. To study the nonapoptotic effects of FADD, a comprehensive strategy of proteomics identification combined with bioinformatic analysis was undertaken to identify proteins differentially expressed in three cell lines containing FADD and its mutant, FADD-A and FADD-D. The cell lines were thought to bear wild-type FADD, unphosphorylated FADD mimic and constitutive phosphorylated FADD mimic, respectively. A total of 47 proteins were identified to be significantly changed due to FADD phosphorylation. Network analysis using MetaCore™ identified a number of changed proteins that were involved in cellular metabolic process, including lipid metabolism, fatty acid metabolism, glycolysis, and oxidative phosphorylation. The finding that FADD-D cell line showed an increase in fatty acid oxidation argues that it could contribute to the leaner phenotype of FADD-D mice as reported previously. In addition, six proteins related to the ubiquitin-proteasome pathway were also specifically overexpressed in FADD-D cell line. Finally, the c-Myc gene represents a convergent hub lying at the center of dysregulated pathways, and was upregulated in FADD-D cells. Taken together, these studies allowed us to conclude that impaired mitochondrial function and proteolysis might play pivotal roles in the dysfunction associated with FADD phosphorylation-induced disorders.

Y chromosome AZFc microdeletion may not affect the outcomes of ICSI for infertile males with fresh ejaculated sperm

PURPOSE

To explore whether the presence of a Y chromosome AZFc microdeletion confers any adverse effect on the outcomes of intracytoplasmic sperm injection (ICSI) with fresh ejaculated sperm.

METHODS

A total of 143 oligozoospermia patients with Y chromosome AZFc microdeletion in ICSI cycles in a five-year period were studied. Infertile men with normal Y chromosome in ICSI at the same time-frame were used as controls matched to the study group for age of female, female's body mass index, male's age, infertility duration and number of oocytes retrieved. Retrospective case-control study was used.

RESULTS

There were no significant differences between groups in clinical outcomes of endometrial thickness, transferred embryos, good embryo rates, implantation rates, biochemical pregnancy rates, clinical pregnancy rates, ectopic pregnancy rates, miscarriage rates, preterm birth rates, the ratio of male and female babies, newborn body height, newborn weight, low birth weight and birth defects (P > 0.05). Patients with Y chromosome AZFc microdeletion had a lower fertilization rate (61.8 % vs. 67.8 %, P < 0.05) and higher cleaved embryo rate (94.0 % vs. 88.1 %, P < 0.05).

CONCLUSIONS

ICSI clinical outcomes for oligozoospermic patients with Y chromosome AZFc microdeletion are basically comparable to that of infertile patients with normal Y chromosomes. The results of ICSI were not affected by the AZFc deletion. Preimplantation genetic diagnosis (PGD) before ICSI for Y chromosome AZFc microdeletion may not be a justifiable regular procedure if the couples didn't care the vertical transmission of Y chromosome deletion.

Biopsy of embryos produced by in vitro fertilization affects development in C57BL/6 mouse strain

Preimplantation genetic diagnosis is considered highly successful with respect to its accuracy in detecting genetic anomalies, although the effects of embryo biopsy on embryonic and fetal growth and development are less known, particularly in conjunction with IVF. Here, we compared biopsied (B) and nonbiopsied (NB) mouse embryos for developmental competence. Embryos C57BL/6 (B6) and B6D2F2 (F2) generated by IVF were subjected to single blastomere biopsy at the four-cell stage, and were either cultured for 120 h and subjected to differential inner cell mass (ICM) and trophoblast staining, or were transferred into the uterine tubes of surrogate mothers after 72 h of culture, to examine their pre- and postimplantation development, respectively. NB embryos from the same IVF cohorts served as controls. Embryo biopsy negatively affected preimplantation development to blastocyst in C57BL/6 (69% vs. 79%; P < 0.01), but not in B6D2F1 mice (89% vs. 91%; P = not significant [NS]). Although B6 embryos had lower total cell number than F2 (B6: 47 and 61 vs. F2: 53 and 70; B and NB, respectively; P < 0.05) there were no differences between B and NB blastocysts in percentage of ICM (B6: 19.8 vs. 19.8; F2: 20.9 vs. 20.4; P = NS) and ICM:trophoblast ratio (B6: 4.7 vs. 4.7; F2: 4.4 vs. 4.7) in both mouse strains. Postimplantation development to live fetuses of B embryos as compared with NB counterparts was impaired in C57BL/6 (6% vs. 18%; P < 0.001) but not in B6D2F1 mice (26% vs. 35%; P = NS). We concluded that blastomere biopsy impaired embryonic and fetal development in mice known to be sensitive to in vitro culture and manipulations. Such mice are models for infertile couples with poor quality gametes seeking assisted reproduction technologies.

Blastomere removal from cleavage-stage mouse embryos alters steroid metabolism during pregnancy

Preimplantation genetic diagnosis (PGD) is a genetic screening of embryos conceived with assisted reproduction technologies (ART). A single blastomere from an early-stage embryo is removed and molecular analyses follow to identify embryos carrying genetic defects. PGD is considered highly successful for detecting genetic anomalies, but the effects of blastomere biopsy on fetal development are understudied. We aimed to determine whether single blastomere removal affects steroid homeostasis in the maternal-placental-fetal unit during mouse pregnancy. Embryos generated by in vitro fertilization (IVF) were biopsied at the four-cell stage, cultured to morula/early blastocyst, and transplanted into the oviducts of surrogate mothers. Nonbiopsied embryos from the same IVF cohorts served as controls. Cesarean section was performed at term, and maternal and fetal tissues were collected. Embryo biopsy affected the levels of steroids (estradiol, estrone, and progesterone) in fetal and placental compartments but not in maternal tissues. Steroidogenic enzyme activities (3beta-hydroxysteroid dehydrogenase, cytochrome P450 17alpha-hydroxylase, and cytochrome P450 19) were unaffected but decreased activities of steroid clearance enzymes (uridine diphosphate-glucuronosyltransferase and sulfotransferase) were observed in placentas and fetal livers. Although maternal body, ovarian, and placental weights did not differ, the weights of fetuses derived from biopsied embryos were lower than those of their nonbiopsied counterparts. The data demonstrate that blastomere biopsy deregulates steroid metabolism during pregnancy. This may have profound effects on several aspects of fetal development, of which low birth weight is only one. If a similar phenomenon occurs in humans, it may explain low birth weights associated with PGD/ART and provide a plausible target for improving PGD outcomes.

Abnormal development at early postimplantation stage in mouse embryos after preimplantation genetic diagnosis

Preimplantation genetic diagnosis (PGD) is an established procedure for the genetic analysis of embryos. To assess the effect of the procedure on early embryonic development, we generated a murine experimental system, including mice implanted with biopsied in vitro cultured embryos, control mice implanted with in vitro cultured embryos without biopsy, and mice with naturally conceived embryos. Embryos at the 7.5-dpc stage were isolated from all three groups and the embryo implantation rate, the survival rate of implanted embryos, and the developmental stage of surviving embryos were carefully assessed and compared among all three groups. We found the implantation rate was similar between biopsied and control group embryos (67.92% vs. 66.67%). However, the survival rate of implanted embryos in the biopsied group (49.31%) was significantly lower than that of the control (60.91%) and normal groups (96.24%) at 7.5 dpc. In addition, the survival rate of control group embryos was significant lower than that of normal group embryos. Classification of the precise developmental stages of randomly selected live implanted embryos at 7.5 dpc revealed no differences among the three groups. Our results indicate that blastomere biopsy does not adversely affect embryo implantation. The PGD procedure, in particular blastomere biopsy, increases the rate of embryo death at 4.5-7.5 dpc, but does not affect the development of surviving 7.5 dpc embryos.

Microinjection manipulation resulted in the increased apoptosis of spermatocytes in testes from intracytoplasmic sperm injection (ICSI) derived mice

The invention of intracytoplasmic sperm injection (ICSI) has possibly been the most important development in reproductive medicine, one that has given hope to thousands of infertile couples worldwide. However, concerns remain regarding the safety of this method since it is a more invasive procedure than in vitro fertilization (IVF), since a spermatozoon is injected into the oocyte cytoplasm. Using mice derived from IVF technology as a control, we assessed the influence of invasive microinjection in the process of transferring sperm into oocyte cytoplasm in ICSI procedure on the development and physiologic function of resultant offspring. Our results demonstrated that mice produced from ICSI and IVF had no significant difference in phenotypic indices including body weight, forelimb physiology, and learning and memory ability. However, increased spermatocyte apoptosis was observed in the testis of adult ICSI mice, when compared with IVF mice. And, decreased testis weight and marked damage of spermatogenic epithelia were found in aged ICSI mice. Furthermore, proteomic analysis verified that most of the differentiated proteins in testes between adult ICSI and IVF mice were those involved in regulation of apoptosis pathways. Our results demonstrated that the microinjection manipulation used in the ICSI procedure might pose potential risks to the fertility of male offspring. The changed expression of a series of proteins relating to apoptosis or proliferation might contribute to it. Further studies are necessary to better understand all the risks of ICSI.