High three pro-nuclei (3PN) zygotes proportion associated with normal embryo multinucleation at the two-cell stage: two cases report

Objective: Blastomere multinucleation at the two-cell stage (MN2) is a common nuclear abnormality observed in early human embryos and known to decrease the implantation rate. The aim of this study is to explore whether or not there is a link between high 3PN zygotes proportion and MN2 incidence.Methods: For embryo culture in the conventional incubator, the evaluation of nuclear status of two-cell stage is usually not performed. Therefore, the MN2 phenomenon is easily ignored. The time-lapse monitoring system (TLS) offers a promising new method to evaluate embryo development. We reported two cases who had single 2PN zygote and more than four 3PN zygotes in the conventional in-vitro fertilization (c-IVF) cycle.Results: We observed the MN2 incidence in the single normal embryo by TLS which suggested that it might be resulted from high 3PN zygotes proportion incidence. No available embryo was obtained in the first c-IVF cycle and the intracytoplasmic sperm injection (ICSI) treatment was performed in the second cycle. In subsequent ICSI cycles, we observed no 3PN zygotes incidence and transferred two day 3 embryos for the patients. Finally, the two couples successfully obtained healthy babies.Conclusions: High 3PN zygotes proportion might be associated with the MN2 incidence.

Genetic analysis of embryo in a human case of spontaneous oocyte activation: a case report

Parthenogenesis, a unique form of reproduction, is normally inhibited in mammals and a human embryo with parthenogenetic origin is not considered capable of producing offspring. The aim of this report is to analyze a parthenogenetic oocyte retrieved from a patient so as to have a better understanding on parthenogenesis and causes of infertility. A 38-year-old woman presented at our center with a history of primary infertility for 10 years and underwent an IVF-ICSI cycle. Three MII oocytes retrieved and one of which presented with 1 pronucleus before conducting ICSI and developed into an embryo 30 h post-retrieval. Blastomere biopsy, genome amplification, copy number variation (CNV) analysis and MultiSNPs analysis was performed on the embryo. The results showed that only one blastomere contains DNA and CNV analysis indicated a genotype of 48, XX, +17, +17 and the genetic contribution of biopsied embryo was of exclusively maternal origin. Such analysis might be beneficial for patients with a history of oocyte spontaneous activation in diagnosing case-specific aberrations and providing individualized therapeutic strategies such as preimplantation genetic diagnosis to choose a genetic normal embryo to transplant.

EVALUATION OF PREIMPLANTATION GENETIC ANEUPLOIDY SCREENING CASES AT A REFERENCE GENETICS CENTER: 10 YEARS' EXPERIENCE

The aim of this study is to review and evaluate our preimplantation genetic screening (PGS) records in terms of their demographic data, indications, cytogenetic results, pregnancy outcomes and discuss these findings in different aspects. PGS was performed in a total of 84 couples (87 cycles) between the period 2005 to 2015. Biopsied blastomeres from embryos on day 3 were fixed and fluorescence in situ hybridization was carried out for chromosomes 13, 16, 18, 21, 22, X and Y depending on the indication. The diagnostic and clinical data were retrospectively evaluated. A total of 450 blastomeres were biopsied. Ninety-eight of them were found to be suitable for transfer. They were transferred to 72 patients in 75 cycles resulting in 23 pregnancies and 20 healthy births. The most common indication was unexplained infertility. The implantation rate was calculated as 23.4% whereas the take-home baby rate was 26.6% per transfer. The highest rate of healthy living births is achieved in patients having low grade maternal mosaic sex chromosomal aneuploidy. All living births achieved by PGS had normal chromosomal structure which we can propose it as an alternative test for couples at risk to select normal embryos to improve the outcomes of assisted reproductive procedures and to avoid the transfer of chromosomally unbalanced and multiple embryos.

Live birth after PGD with confirmation by a comprehensive approach (karyomapping) for simultaneous detection of monogenic and chromosomal disorders

Preimplantation genetic diagnosis (PGD) for monogenic disorders has the drawback of time and cost associated with tailoring a specific test for each couple, disorder, or both. The inability of any single assay to detect the monogenic disorder in question and simultaneously the chromosomal complement of the embryo also limits its application as separate tests may need to be carried out on the amplified material. The first clinical use of a novel approach ('karyomapping') was designed to circumvent this problem. In this example, karyomapping was used to confirm the results of an existing PGD case detecting both chromosomal abnormalities and a monogenic disorder (Smith-Lemli-Opitz [SLO] syndrome) simultaneously. The family underwent IVF, ICSI and PGD, and both polar body and cleavage stage biopsy were carried out. Following whole genome amplification, array comparative genomic hybridisation of the polar bodies and minisequencing and STR analysis of single blastomeres were used to diagnose maternal aneuploidies and SLO status, respectively. This was confirmed, by karyomapping. Unlike standard PGD, karyomapping required no a-priori test development. A singleton pregnancy and live birth, unaffected with SLO syndrome and with no chromosome abnormality, ensued. Karyomapping is potentially capable of detecting a wide spectrum of monogenic and chromosome disorders and, in this context, can be considered a comprehensive approach to PGD.

Analysis of embryo morphokinetics, multinucleation and cleavage anomalies using continuous time-lapse monitoring in blastocyst transfer cycles

BACKGROUND

Time-lapse imaging combined with embryo morphokinetics may offer a non-invasive means for improving embryo selection. Data from clinics worldwide are necessary to compare and ultimately develop embryo classifications models using kinetic data. The primary objective of this study was to determine if there were kinetic differences between embryos with limited potential and those more often associated with in vitro blastocyst formation and/or implantation. We also wanted to compare putative kinetic markers for embryo selection as proposed by other laboratories to what we were observing in our own laboratory setting.

METHODS

Kinetic data and cycle outcomes were retrospectively analyzed in patients age 39 and younger with 7 or more zygotes cultured in the Embryoscope. Timing of specific events from the point of insemination were determined using time-lapse (TL) imaging. The following kinetic markers were assessed: time to syngamy (tPNf), t2, time to two cells (c), 3c (t3), 4c ( t4), 5c (t5), 8c (t8), morula (tMor), start of blastulation (tSB); tBL, blastocyst (tBL); expanded blastocyst (tEBL). Durations of the second (cc2) and third (cc3) cell cycles, the t5-t2 interval as well as time to complete synchronous divisions s1, s2 and s3 were calculated. Incidence and impact on development of nuclear and cleavage anomalies were also assessed.

RESULTS

A total of 648 embryos transferred on day 5 were analyzed. The clinical pregnancy and implantation rate were 72% and 50%, respectively. Morphokinetic data showed that tPNf, t2,t4, t8, s1, s2,s3 and cc2 were significantly different in embryos forming blastocysts (ET or frozen) versus those with limited potential either failing to blastulate or else forming poor quality blastocysts ,ultimately discarded. Comparison of embryo kinetics in cycles with all embryos implanting (KID+) versus no implantation (KID-) suggested that markers of embryo competence to implant may be different from ability to form a blastocyst. The incidence of multinucleation and reverse cleavage amongst the embryos observed was 25% and 7%, respectively. Over 40% of embryos exhibiting these characteristics did however form blastocysts meeting our criteria for freezing.

CONCLUSIONS

These data provide us with a platform with which to potentially enhance embryo selection for transfer.

[The specific features of the immunophenotype of blast cells in patients with de novo normal karyotype acute myeloid leukemia and FLT3-ITD mutation]

AIM

To study the specific features of de novo acute myeloid leukemia (AML) with FLT3-ITD mutation.

SUBJECTS AND METHODS

The results of examination were analyzed in 101 patients. Bone marrow morphological specimens were stained with Pappenheim stain. The karyotype was investigated using the standard GTG-banding method. Blast cells were immunotyped in a five-color analysis on a Cytomics FC 500 laser flow cytofluorometer.

RESULTS

FLT3-ITD mutation was identified in 21 patients who had a varying morphological nature of blasts, different karyotype variants, and frequently additional NPM1 gene mutation. The distinctive property of 10 patients with normal karyotype and FLT3-ITD mutation (without NPM1 gene mutation) was the larger number of cases with high expression of HLA-DR and CD7 than in the control group that included 18 patients with normal karyotype AML without FLT3-ITD nutation: 50% versus 6.2% (p = 0.007) and 100% versus 55.6% (p = 0.014), respectively.

CONCLUSION

Normal karyotype AML with FLT3-ITD mutation is a group that is homogeneous in the biological phenotype of leukemia cells.

[Preimplantation genetic diagnosis (PGD) for cancer predisposition syndromes]

INTRODUCTION

Most cases of cancer are sporadic and only 5%-10% are inherited with variable penetrance. Whenever the causative mutation is known, prevention of affected offspring birth may be achieved by prenatal or preimplantation genetic diagnosis (PGD).

AIM

To devise a scoring system (SS) that appraises the justification of PGD for each patient and to evaluate the efficacy, reliability and accuracy of PGD for cancer predisposition syndromes in 48 cycles.

METHODS

A semi-quantitative SS was developed by evaluating disease characteristics (onset, severity, inheritance pattern and penetrance) and patient clinical variables (infertility, objection to abortion and a need for diagnosis of additional genetic syndrome). PGD cycles were performed by blastomere biopsy of cleavage stage embryos, followed by single cell multiplex nested PCR for the cancer predisposition mutation and flanking polymorphic markers.

RESULTS

Seventeen couples referred to PGD for cancer predisposition. According to the devised SS, fourteen were accepted and 3 were declined. Of the 14 accepted couples, 13 had at Least one affected member and 11 couples required IVF anyway. A total of 48 PGD cycles were performed resulting in 8 pregnancies.

CONCLUSION

PGD for cancer predisposition genes is a possible and reliable procedure, suitable especiaLly for infertile carrier couples.

DISCUSSION AND SUMMARY

The assessment of the characteristics of the cancer syndrome and consideration of the variables of each couple enable, the justified application of PGD procedure. The continuous discovery of cancer predisposition mutations will result in an ever-increasing demand for PGD to prevent the transmission of Lethal mutations to the next generations.

FISH for pre-implantation genetic diagnosis

Pre-implantation genetic diagnosis (PGD) is an established alternative to pre-natal diagnosis, and involves selecting pre-implantation embryos from a cohort generated by assisted reproduction technology (ART). This selection may be required because of familial monogenic disease (e.g. cystic fibrosis), or because one partner carries a chromosome rearrangement (e.g. a two-way reciprocal translocation). PGD is available for couples who have had previous affected children, and/or in the case of chromosome rearrangements, recurrent miscarriages, or infertility. Oocytes aspirated following ovarian stimulation are fertilized by in vitro immersion in semen (IVF) or by intracytoplasmic injection of individual spermatocytes (ICSI). Pre-implantation cleavage-stage embryos are biopsied, usually by the removal of a single cell on day 3 post-fertilization, and the biopsied cell is tested to establish the genetic status of the embryo.Fluorescence in situ hybridization (FISH) on the fixed nuclei of biopsied cells with target-specific DNA probes is the technique of choice to detect chromosome imbalance associated with chromosome rearrangements, and to select female embryos in families with X-linked disease for which there is no mutation-specific test. FISH has also been used to screen embryos for sporadic chromosome aneuploidy (also known as PGS or PGD-AS) in order to try and improve the efficiency of assisted reproduction; however, due to the unacceptably low predictive accuracy of this test using FISH, it is not recommended for routine clinical use.This chapter describes the selection of suitable probes for single-cell FISH, assessment of the analytical performance of the test, spreading techniques for blastomere nuclei, and in situ hybridization and signal scoring, applied to PGD in a clinical setting.

Differential cytotoxic effects of mono-(2-ethylhexyl) phthalate on blastomere-derived embryonic stem cells and differentiating neurons

Potential applications of embryonic stem (ES) cells are not limited to regenerative medicine but can also include in vitro screening of various toxicants. In this study, we established mouse ES cell lines from isolated blastomeres of two-cell stage embryos and examined their potential use as an in vitro system for the study of developmental toxicity. Two ES cell lines were established from 69 blastomere-derived blastocysts (2.9%). The blastomere-derived ES (bm-ES) cells were treated with mono-(2-ethylhexyl) phthalate (MEHP) in an undifferentiated state or after directed differentiation into early neural cell types. We observed significantly decreased cell viability when undifferentiated bm-ES cells were exposed to a high dose of MEHP (1000 microM). The cytotoxic effects of MEHP were accompanied by increased DNA fragmentation, nuclear condensation, and activation of Caspase-3, which are biochemical and morphological features of apoptosis. Compared to undifferentiated bm-ES cells, considerably lower doses of MEHP (50 and 100 microM) were sufficient to induce cell death in early neurons differentiated from bm-ES cells. At the lower doses, the number of neural cells positive for the active form of Caspase-3 was greater than that for undifferentiated bm-ES cells. Thus, our data indicate that differentiating neurons are more sensitive to MEHP than undifferentiated ES cells, and that undifferentiated ES cells may have more efficient defense systems against cytotoxic stresses. These findings might contribute to the development of a new predictive screening method for assessment of hazards for developmental toxicity.

Preimplantation genetic diagnosis for alpha-thalassaemia in China

PURPOSE

To report the usage of PGD for alpha-thalassaemia with the - -(SEA) genotype.

METHOD

A PGD protocol using fluorescent gap PCR was performed for 51 cycles on 43 couples with the - -(SEA) genotype. Allele drop-out and amplification failure rates were retrospectively analyzed.

RESULTS

A total of 472 embryos were biopsied. Amplification was achieved in 390 blastomeres, accounting for an amplification rate of 82.6%. In total, 120 wild-type, 94 heterozygotes and 140 homozygous mutant embryos were diagnosed. The successful diagnosis rate was 75.0%. The ADO rate in 49 blastomeres from six donated embryos was 16.4%. One hundred and fifty four embryos were transferred, resulting in 25 clinical pregnancies with an implantation rate of 24.0%.

CONCLUSIONS

Single-round fluorescent gap PCR is a feasible and effective strategy in the PGD for alpha-thalassaemia with the - -(SEA) genotype.

Resumption of mitosis in frozen-thawed embryos is not related to the chromosomal constitution

OBJECTIVE

To study the relation between the resumption of mitosis after thaw and chromosomal constitution in frozen-thawed embryos. In addition, to evaluate the correlation among the three parameters of resumption of mitosis after thaw, postthaw blastomere loss, and multinucleation.

DESIGN

Frozen-thawed embryos were morphologically evaluated at thaw and after 24 hours of culture. Then, fluorescence in situ hybridization (FISH) analysis, including enumeration of 13 chromosomes, was performed by using a combination of peptide nucleic acid and DNA probes.

SETTING

In vitro fertilization laboratory.

PATIENT(S)

Forty IVF and/or intracytoplasmic sperm injection patients.

INTERVENTION(S)

Embryo thawing, morphological evaluation, and fluorescence in situ hybridization analysis for aneuploidy screening.

MAIN OUTCOME MEASURE(S)

Resumption of mitosis, blastomere loss, multinucleation, and chromosome enumeration.

RESULT(S)

No difference was observed in the chromosomal constitution of embryos with and without resumption of mitosis. Neither was the postthaw blastomere loss connected to the chromosomal constitution. The resumption of mitosis was not associated with postthaw loss of blastomeres or with multinuclearity.

CONCLUSION(S)

Resumption of mitosis and blastomere loss of frozen-thawed embryos is not related to chromosome aberrations in the embryo. Further, the resumption of mitosis is not correlated with multinucleation. However, the high incidence of multinucleated embryos after thawing indicates that the freezing and thawing procedure may affect this condition.

The Effects of Blastomere Biopsy and Oxygen Tension on Bovine Embryo Development, Rate of Apoptosis and Interferon-? Secretion

A series of experiments was performed to examine the effects of blastomere biopsies on subsequent development of IVF-derived bovine embryos. The first experiment was designed to assess the optimal time for blastomere removal. One blastomere was removed either 48 or 72 h after IVF. Biopsy at 48 h resulted in 17.2% of embryos proceeding to the blastocyst stage, which was lower than when biopsies were performed at 72 h (37.5%, p < 0.05). In the second experiment, embryos were cultured either under atmospheric or 5% O(2) following blastomere removal. Biopsies had no effect on rate of blastocyst formation with 36% of controls and 33.7% of biopsied embryos proceeding to that stage. However, culture under 5% O(2) significantly increased the number of blastocysts from 29.9% to 40.3% (p < 0.05). This effect was significant in both biopsied and control embryos. In the final experiment, biopsied embryos were again cultured under different oxygen tension. Blastocysts were collected and cultured individually for 48 h in medium droplets in their respective O(2) concentration after which time the medium was assayed for concentration of interferon-tau (IFN-tau). Reduced O(2) concentration again significantly increased blastocyst formation from 24.9% to 41.9% (p < 0.05). IFN-tau secretion was not affected by biopsies, but culture under atmospheric O(2) resulted in significantly increased IFN-tau concentration in medium droplets (12274.0 +/- 2825.9 pM vs 5046.5 +/- 2562.2 pM; p < 0.05).

Establishment of a simple and useful way for preimplantation genetic diagnosis of chromosomal diseases

In order to establish a simple and useful way for preimplantation genetic diagnosis (PGD) of chromosomal diseases in general IVF laboratory, the methods that are most commonly used in the embryo biopsy, fixation of blastomere and fluorescence in situ hybridization were compared. The three aspects of PGD were analyzed respectively. There was no significant difference in further development capacity of embryos between mechanical (79.7%) and chemical biopsy group (78.6%) (P>0.05). In this study, more cells were successfully fixed with the Tween/HCL method (93.8%) than with the methanol/acetic acid method (80.5%, P<0.05). There was no significant difference in cytoplasm remains between methanol/acetic acid method and Tween/HCL method (P>0.05). The hybridization efficiency of fluorescence in situ hybridization was 89.5% in successive denaturation method and 90.9% in codenaturation method with the difference being not significant (P>0.05). In conclusion, the mechanical or chemical method, Tween/HCL fixation method and codenaturation fluorescence in situ hybridization method can constitute a simple and useful way for PGD of chromosomal diseases.

Effects of removal of necrotic blastomeres from human cryopreserved embryos on pregnancy outcome

This study assessed whether the implantation potential of embryos that were partially damaged after freezing and thawing can be improved by removal of necrotic blastomeres. We retrospectively analyzed the pregnancy rate and implantation rate of 170 human frozen embryo transfer cycles. Laser-assisted hatching and micromanipulation were performed to remove the necrotic blastomeres. A higher clinical pregnancy rate (22.22%) and embryo implantation rate (10.17%) were observed when transferred embryos comprised fully intact and partially damaged embryos compared with partially damaged embryos alone (5.88% and 2.82%, respectively). When transferred embryos were fully intact and partially damaged embryos, removal of necrotic blastomeres from partially damaged embryos significantly increased the clinical pregnancy rate (43.90% versus 24.00%, P<0.05) and the implantation rate (19.44% versus 10.29%, P<0.05). The results indicated that the implantation potential of partially damaged cryopreserved embryos can be improved by removal of necrotic blastomeres with laser-assisted hatching and micromanipulation.

Genetics of cardiac septation defects and their pre-implantation diagnosis

Cardiac septation defects are among the most common birth defects in humans. The frequency of these defects reflects the complexity of cardiogenesis, which involves such processes as cell proliferation, migration, differentiation, and morphogenetic interactions. Major advances in the understanding of the underlying genetic etiologies of cardiac septation defects have provided insight into the genetic pathways involved. These genetic factors are most often transcription factors involved in the early stages of cardiogenesis. The ability to modify these genes in animal models is providing a better understanding of the role of these genes in common pathways leading to diverse forms of cardiac defects. Ultimately, our understanding of these basic processes should lead to molecular-based treatment and prevention options for those individuals most at risk for such birth defects.

Pregnancies and live births after trophectoderm biopsy and preimplantation genetic testing of human blastocysts

OBJECTIVE

To compare multiple-cell trophectoderm biopsy for preimplantation genetic diagnosis (PGD) from day-5 blastocysts with previously published experience with day-3 cleavage-stage embryos.

DESIGN

Retrospective review of laboratory and clinical experience.

SETTING

Sydney IVF, a private clinic in Australia.

PATIENT(S)

Preimplantation genetic diagnosis (PGD) patients age < 44 years with at least one IVF blastocyst suitable for biopsy, recruited from January 2002 through August 2004.

INTERVENTION(S)

Biopsy of trophectoderm from blastocysts on day 5 or 6, with same-day PGD for mutation testing, translocation testing, aneuploidy screening or sex selection. Spare, normal biopsied blastocysts were cryostored for possible later transfer.

MAIN OUTCOME MEASURE(S)

Fetal heart-positive pregnancy rate and accumulating live birth rate after adding results from biopsied fresh and frozen blastocysts for particular couples.

RESULT(S)

In 231 started PGD treatment cycles, unambiguous results were obtained from 974 of 1,050 biopsied blastocysts (93%); all blastocysts survived the biopsy procedure by reconstitution of their blastocele. One hundred nineteen women (median age, 36 years) have had 127 blastocysts transferred fresh (fetal heart-positive implantation rate, 41%). Of 146 blastocysts cryostored, 27 have been thawed (all with > 50% cell survival) and 24 transferred (implantation rate, 26%). To date, 53 pregnancies have been delivered or are ongoing, with an additional 4 clinical miscarriages (7%) and 6 subclinical miscarriages (total miscarriage rate, including biochemical pregnancies, 16%). There were no twin pregnancies.

CONCLUSION(S)

With technically appropriate blastocyst culture and freezing, blastocyst biopsy and cryostorage and later transfer of biopsied blastocysts is shown to be a practical and probably preferable path to preimplantation genetic testing of embryos compared with cleavage-stage embryo biopsy, being accompanied by a high implantation rate (and hence more conducive to elective single embryo transfer) and by a low rate of twinning and miscarriage.

Removal of lysed blastomeres from frozen–thawed embryos improves implantation and pregnancy rates in frozen embryo transfer cycles

OBJECTIVE

To evaluate the effect of degenerated (lysed) blastomere removal on implantation and pregnancy rates in cleavage-stage cryo-embryo transfer (ET) cycles.

DESIGN

Randomized clinical trial.

SETTING

Private reproductive medical center.

PATIENT(S)

A total of 88 patients who received frozen-thawed ET, divided into two groups.

INTERVENTION(S)

Embryo freezing and thawing; opening of the zona pellucida and removal of cryodamaged blastomeres (in the study group), followed by same-day ET.

MAIN OUTCOME MEASURE(S)

Extent of survival of cleavage-stage embryos after the freeze-thaw procedure; embryo implantation and clinical pregnancies.

RESULT(S)

Oocyte number per patient, fertilization rate, embryo development rate (and quality), and freezing rates were similar in the two groups in the fresh cycle. In the control group, a total of 55 embryos (25%) of the 217 thawed remained fully intact, and 53 (26%) of the 207 in the study group remained intact. The average number of embryos transferred per group was similar (control, 3.4 +/- 0.9; study, 3.3 +/- 0.9). Implantation rates were 12% and 26% in the control and study groups, respectively. The clinical pregnancy rate was 23% in the control group and 64% in the study group when lysed cell removal was performed.

CONCLUSION(S)

The results show that pregnancy and implantation rates are higher in the study group; therefore, the removal of degenerated blastomeres may be beneficial to all patients who undergo cleavage-stage, frozen-thawed ET.

Developmental potential of fully intact and partially damaged cryopreserved embryos after laser-assisted removal of necrotic blastomeres and post-thaw culture selection

OBJECTIVE

Partially damaged frozen and thawed embryos are currently considered to have a lower viability than intact ones. This study was undertaken to compare the performance of intact frozen and thawed embryos with that of partially damaged embryos after removal of the necrotic blastomeres.

DESIGN

Observational clinical series.

SETTING

Private hospital.

PATIENT(S)

Three hundred twenty-six infertile couples undergoing frozen embryo transfer.

INTERVENTION(S)

Removal of necrotic blastomeres from frozen-thawed human embryos.

MAIN OUTCOME MEASURE(S)

Pregnancy and implantations rates.

RESULT(S)

Outcomes of frozen embryo transfer cycles in which all embryos were fully intact (group 1) were compared with those in which all embryos have lost 1-2 blastomeres (group 2) or 3-4 blastomeres (group 3). Laser-assisted hatching was performed in all embryos, and necrotic blastomeres were removed from partially damaged embryos on this occasion. Only embryos that resumed mitotic activity after thawing were transferred. Comparable clinical pregnancy rates (PR) (38.7%, 39.6%, and 29.4%), delivery rates (34.4%, 34.0%, and 29.4%), and implantation rates (21.6%, 21.4%, and 17.2%) were obtained in groups 1, 2, and 3, respectively.

CONCLUSION(S)

The developmental potential of partially damaged frozen and thawed embryos can be equivalent to fully survived embryos if the necrotic blastomeres are removed from the partially damaged embryos and only those of them that show post-thaw cleavage are selected for transfer.

Impact of follicular-fluid meiosis-activating sterol in an albumin-based formulation on the incidence of human pre-embryos with chromosome abnormalities

OBJECTIVE

To evaluate the effect of adding follicular-fluid meiosis-activating sterol (FF-MAS) in a novel 0.2% recombinant human albumin-based formulation to cumulus-enclosed oocytes on chromosomal status and development of pre-embryos.

DESIGN

Multicenter, prospective, randomized, open (double-blind for vehicle and FF-MAS groups), four parallel groups, controlled trial.

SETTING

Four public IVF clinics in Denmark.

PATIENT(S)

Two hundred eighteen women undergoing IVF donated 483 oocytes.

INTERVENTION(S)

Follicle-stimulating hormone/hCG-primed cumulus-enclosed oocytes randomized to 4 hours of exposure to medium with 1 or 10 micromol/L of FF-MAS dissolved in 0.2% recombinant human albumin, medium with 0.2% recombinant human albumin (vehicle control), or medium alone (control) before insemination.

MAIN OUTCOME MEASURE(S)

Primary endpoint: incidence of human pre-embryos with chromosomal abnormalities. Secondary endpoint: fertilization rate, cleavage rate, and pre-embryo quality assessed after 68 hours of culture.

RESULT(S)

At pre-embryo level, the overall abnormality rates in the control, vehicle control, and 1- and 10-micromol/L FF-MAS groups were 53%, 39%, 42%, 53%, respectively, and at blastomere level 49%, 44%, 44%, and 48%, respectively. After 20 and 26 hours, the fertilization rates were between 67% and 71% in all groups. No differences in the cleavage rates were observed.

CONCLUSION(S)

The concentrations of FF-MAS in a novel 0.2% recombinant human albumin-based formulation of FF-MAS did not increase the risk of chromosomal abnormalities in pre-embryos or blastomeres. No statistically significant differences in fertilization rate, cleavage rate, or number of good quality pre-embryos were found among the four groups.

Effects of removal of necrotic blastomeres from mouse cryopreserved embryos on blastocyst formation and hatching

To evaluate whether the developmental potential of embryos that were partially damaged after freezing and thawing can be improved by removal of necrotic blastomeres. Eight-cell mouse embryos were cryopreserved using 1,2-propanediol and sucrose as cryoprotectant with slow cooling procedure. After thawing, blastocyst formation and hatching of fully intact embryos were compared between no treatment and with laser-assisted hatching. For partially intact embryos, the effects of removal of necrotic blastomeres with micromanipulation were evaluated. Laser-assisted hatching of mouse cryopreserved fully intact embryos significantly increased blastocyst hatching (63.4% versus 48.3%, P<0.05), but had little effect on blastocyst formation (72.0% versus 70.1%, P>0.05). The removal of necrotic blastomeres from partially damaged mouse cryopreserved embryos with micromanipulation significantly increased blastocyst formation (52.9% versus 32.0%, P<0.05) and blastocyst hatching (41.2% versus 22.0%, P>0.05) compared with the control group. The developmental potential of partially damaged cryopreserved embryos can be improved by removal of necrotic blastomeres with micromanipulation.

Preimplantation genetic diagnosis (PGD) for heritable neoplasia

Especially applicable for heritable neoplasia, preimplantation genetic diagnosis (PGD) is possible for any Mendelian disorder whose gene has been localized, whether the molecular basis is known or not.

METHODS AND RESULTS

PGD requires DNA from gametes (oocytes) or embryos before 6 days postconception, when implantation occurs. Approaches include 1) polar body biopsy, 2) blastomere biopsy (aspiration of one or two cells from the six- to eight-cell embryos at 2 or 3 days), and 3) trophectoderm biopsy, which allows recovery of 20 or more cells (20-50) from 125- to 150-cell, 5- to 6-day blastocysts. Of some 6000 PGD cycles worldwide, approximately 1500 have been performed for Mendelian indications. The approximately 25% live birth rates following PGD parallel the general U.S. experience for assisted reproductive technology. PGD has been accomplished for both cancer-specific disorders like adenomatous polyposis coli (APC), BRCA1, retinoblastoma, Li-Fraumeni syndrome, and von Hippel-Lindau syndrome (VHL), as well as disorders predisposing to neoplasia (Fanconi anemia, Wiskott-Aldrich syndrome). PGD also makes possible the identification and, hence, transfer of embryos of specific HLA genotypes. This allows cord blood harvesting for stem cell implantation into a moribund child, often an older sibling of the fetus.

CONCLUSIONS

PGD is a complex, but achievable, approach especially applicable to Mendelian forms of neoplasia. PGD is an attractive addition to the prenatal diagnostic armamentarium, especially relevant to heritable neoplasia. PGD also makes possible novel indications having special relevance to heritable neoplasia.

Duplex, triplex and quadruplex PCR for the preimplantation genetic diagnosis(PGD) of cystic fibrosis(CF), an exhaustive approach

Most of cystic fibrosis (CF) pre-implantation genetic diagnosis (PGD) cases described to date are limited to the detection of DeltaF508. Beside this predominant mutation, over 1000 mutations have been identified, rendering the development of a mutation-based PGD protocol impracticable. This is the reason why we, as well as the others, have developed PGD strategies on the basis of the identification of the pathogenic haplotype instead of the mutation(s). In a previous article, we reported the conditions for the co-amplification of two intragenic polymorphic markers and the F508 locus. Here we describe an improved protocol allowing the additional amplification of two new intragenic markers, intron 1 CA repeat (I1CA) and IVS17bTA. This new protocol should, theoretically, allow us to provide a diagnosis to all couples requiring PGD for CF. Using single lymphoblasts, we have tested four different PCR configurations, including one duplex, two triplexes and one quadruplex PCR. All of them gave results compatible with a clinical application. The number of single lymphoblasts tested in each series varied from 89 to 155. PCR efficiency ranged from 95.4 to 100%. A complete haplotype was achieved for 83.2 to 90.7% of the tested cells, with an allele drop out (ADO) rate comprised between 6.0 and 11.6%. We present here three cases that we performed either with the former test (one case using the triplex PCR combining F508, IVS8CA and IVS17bCA) or with the new one (one case using the triplex combining F508, I1CA and IVS17bTA and one case using a quadruplex test). We obtained two single pregnancies.

Critical evaluation of human blastocysts for assisted reproduction techniques and embryonic stem cell biotechnology

Critical examination of 30 blastocysts by transmission electron microscopy (TEM) reveals cellular features not usually evident, including abnormalities of cell structure and aberrations such as multinucleation, internal fragmentation, phagocytic or degenerating cells. Invariably, such blastocysts are inactive and delay or fail to expand and hatch in vitro. Hatching seems to be a major problem in ageing blastocysts due to inactivity of the surface epithelium of trophoblast cells that do not stretch and expand. These lack surface microvilli and contractile tonofilaments that anchor on to specialized cell junctions such as desmosomes. Trophoblast expansion and consequent thinning of the zona is a prerequisite to proper hatching aided by the hydrostatic pressure in the blastocoele and by specialized cells at hatching points. Proper assessment of the inner cell mass is required if a healthy population of cells is to be harvested for embryonic stem cell culture. An inactive blastocyst is obviously not good material and could have a defective inner cell mass (ICM). Normally approximately 3-5% of cells are mitotic in blastocysts and arrested cell division is also an indicator of inactivity. An attempt has been made to evaluate blastocyst internal structure for both assisted reproduction techniques and embryonic stem cell biotechnology.

Fluorescence in situ hybridization analysis of two blastomeres from day 3 frozen-thawed embryos followed by analysis of the remaining embryo on day 5

BACKGROUND

Chromosomal mosaicism in human embryos may give rise to false positive or false negative results in preimplantation genetic diagnosis for aneuploidy screening (PGD-AS). Therefore, we have investigated whether the results obtained from a 2-cell biopsy of frozen-thawed embryos and fluorescence in situ hybridization (FISH) analysis are representative for the chromosome constitution of the remaining embryo on day 5.

METHODS

Cryopreserved day 3 embryos were thawed and from surviving embryos two blastomeres were biopsied. FISH analysis was performed for chromosomes 1, 7, 13, 15, 16, 18, 21, 22, X and Y. After biopsy, the embryos were cultured until day 5 and further analysed using the same probe panels.

RESULTS

In all, 17 embryos were available with a diagnosis based on two blastomeres on day 3 and confirmatory studies on day 5. In 10 of these 17 cases the initial diagnosis could be confirmed. However, in only six cases cytogenetic results were concordant. Besides the 10 cases with a 'correct' diagnosis, there were six false positive results and one false negative, all involving mosaicism.

CONCLUSIONS

Investigating the chromosomal constitution of two blastomere nuclei offers a good opportunity to study the incidence of chromosomal mosaicism in early embryo development. The confirmation rate of the results obtained on day 3 depends on the interpretation and is higher when considered from a clinical than from a cytogenetic point of view.

Binucleated and micronucleated blastomeres in embryos derived from human assisted reproduction cycles

This prospective sequential, cohort study examined the two most common multinucleation phenotypes observed in the authors' clinic, binucleated (BN) and micronucleated (MN) blastomeres, and included all intracytoplasmic sperm injection (ICSI) patients <40 years of age with at least one multinucleated embryo in the cohort as observed on day 2 of development. Eighty ICSI cycles of 560 consecutive cycles had multinucleated embryos (14.3%). Of the 80 cycles, 770 embryos were derived; 183 (23.8%) were observed to be multinucleated. Blastocyst rates were significantly higher with BN than MN embryos. MN embryos were more often derived from embryos with poor pronuclear morphology (41/81 = 50.6%). Transferred mononucleated sibling embryos from the BN group had an ongoing pregnancy rate of 48% (12/25) compared with 15.4% (4/26 from the group with MN embryos (P = 0.03). The implantation rate for sibling embryos from the BN group was higher than for those from the MN group. Fluorescence in-situ hybridization (FISH) analysis showed that BN embryos had normal blastomeres significantly more frequently than MN embryos (9/28 (32.1%) versus 1/27 (3.7%), P = 0.016). Time-lapse photography showed that the nuclei of both morphologies dissolved independently before the next mitotic division and that BN blastomeres definitely have two distinct nuclei. These observations indicate two diverse morphologies and causal mechanisms. Time-lapse photography showed that both were subject to independent dissolution of their nuclear membrane suggesting an asynchrony between the nuclei and a possible interruption in proper nuclear and cell division. Multinucleation should definitely be looked for during IVF assessment. Excluding these embryos from transfer is prudent practice.

Randomized controlled study of human zona pellucida dissection using the zona infrared laser optical system: evaluation of blastomere damage, embryo development, and subsequent hatching

OBJECTIVE

To assess the effect of laser hatching on human embryo damage and subsequent development using the Zona Infrared Laser Optical System (ZILOS).

DESIGN

Randomized controlled study.

SETTING

Tertiary care fertility clinic.

PATIENT(S)

One hundred fourteen donated and discarded frozen human embryos.

INTERVENTION(S)

Embryos were thawed, cultured with cleavage and morphology evaluated periodically, and randomized into control, partial hatching, or complete hatching groups. The laser hatching procedure was performed by ZILOS. Zona thickness and embryo diameter were recorded. Complete hatching involved the production of a full-thickness defect in the zona and partial hatching, a defect in the outer half of the zona. No laser treatment was administered to the control group.

MAIN OUTCOME MEASURE(S)

Blastocyst development and completion of hatching process.

RESULT(S)

No significant difference was noted between the three study groups for their baseline characteristics. There was no significant difference in blastocyst development among the three groups. However, the complete hatching group showed a significant increase in hatching compared to the control group.

CONCLUSION(S)

Complete laser hatching of human embryos using the ZILOS does not have an adverse effect on subsequent development and increases the rate of completion of hatching.

Effect of blastomere loss on the outcome of frozen embryo replacement cycles

OBJECTIVE

To assess the impact of survival of cryopreservation and thawing with all blastomeres intact on the outcome of frozen embryo replacement (FER) cycles.

DESIGN

Prospective observational study.

SETTING

University-affiliated tertiary referral assisted conception unit.

PATIENT(S)

The number of intact blastomeres before cryopreservation and after thawing was prospectively recorded in 1,687 cleavage-stage embryos thawed in 377 FER cycles. The cycles were categorized into two groups: group A (n = 184) included cycles in which all embryos transferred survived the cryopreservation and thawing process with all their original blastomeres intact; group B (n = 193) included cycles in which embryos transferred included at least one partially damaged embryo that has lost up to 50% of its original blastomere number.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Pregnancy and embryo implantation rates.

RESULT(S)

Groups A and B were comparable with respect to mean age at cryopreservation, mean number of oocytes retrieved and fertilized normally in the fresh cycle, and mean age at frozen transfer. No significant difference was found between the two groups with regard to mean number of frozen and thawed embryos per cycle and mean endometrial thickness reached before P supplementation. More embryos were transferred per cycle in group B than group A (2.4 +/- 0.6 vs. 2.1 +/- 0.6, respectively). However, the pregnancy and clinical pregnancy rates per cycle were significantly higher in group A than in group B (39.1% and 28.3% vs. 22.8% and 13.5%, respectively). The implantation rate was also higher in group A than in group B (17.3% vs. 8.1%, respectively).

CONCLUSION(S)

FER cycles in which all embryos transferred remained fully intact at thawing achieve a better outcome than those with at least one partially damaged embryo.

Results of preimplantation genetic diagnosis in patients with Klinefelter's syndrome

With the application of preimplantation genetic diagnosis (PGD), a possible genetic contribution of spermatozoa obtained from 47,XXY non-mosaic Klinefelter patients on preimplantation embryos was analysed in eight couples. Interpretable fluorescence in-situ hybridization results were obtained for 28 out of 33 embryos biopsied (84.8%) and 23 blastomeres were analysed for chromosomes 13, 18, 21, X and Y. Nine out of 23 embryos were diagnosed as abnormal (39.1%). Five out of nine contained sex chromosome abnormalities (55.5%). Two were diagnosed as 47,XXY and three were found to have monosomy X. Besides sex chromosomal abnormalities, other abnormalities detected were haploidy, triploidy, monosomy 13, monosomy 18 and trisomy 13. Five blastomeres were analysed for sex chromosomes only and all of them were found to be normal. Overall, the rate of sex chromosome abnormality in biopsied embryos was found to be 17.8% (5/28). Moreover, among 33 embryos biopsied, five of the eight zygotes, which were classified as a poor prognosis group according to pronuclear morphology scoring, showed an impaired growth profile after biopsy and were found to be chromosomally abnormal. Elimination of abnormal embyos and transfer of normal ones resulted in four pregnancies in eight cycles (50%). Two pregnancies, one singleton and one twins resulted in healthy births. Two pregnancies, one singleton and one twins are continuing beyond the second trimester. These results show that there is in fact elevated chromosomal abnormality for both sex chromosomes and autosomes in embryos developed from Klinefelter males. Furthermore together with PGD, embryo scoring according to pronuclear morphology can give additional benefit for selecting chromosomally abnormal embryos. Therefore, PGD should be recommended in cases with Klinefelter's syndrome and this information should be discussed with the couple when genetic counselling is given.

Chromosome abnormalities identified by comparative genomic hybridization in embryos from women with repeated implantation failure

Using comparative genomic hybridization, we have detected chromosome abnormality in 76/126 (60%) single blastomeres biopsied prior to implantation from embryos from 20 women with repeated implantation failure following IVF. The abnormalities detected included aneuploidy for one or two chromosomes [32/126 (25%)] and complex chromosomal abnormality [37/126 (29%)]. Most of the chromosomes involved in single aneuploidy were those commonly found in live births or spontaneously aborted fetuses, whereas a greater range of chromosomes were involved in double aneuploidy. In blastomeres with complex abnormality, random and extensive loss and gain of all the chromosomes was observed. Further blastomeres from 25 embryos with single or double aneuploidy and 11 embryos with complex abnormality were analysed following embryo disaggregation. The specific abnormality was confirmed in the majority of cases and in some cases could be assigned as errors in meiotic or mitotic segregation. Complex abnormalities, suggestive of errors in cell cycle regulation, were present in a slightly higher proportion of these embryos than were seen in our previously studied cohort of surplus embryos. The disruption of the normal sequence of chromosome replication and segregation in early human embryos, caused either by maternal cytoplasmic factors or mutations in cell cycle control genes, may be a common cause of repeated implantation failure.

First clinical application of comparative genomic hybridization and polar body testing for preimplantation genetic diagnosis of aneuploidy

OBJECTIVE

To develop a preimplantation genetic diagnosis (PGD) protocol that allows any form of chromosome imbalance to be detected.

DESIGN

Case report employing a method based on whole-genome amplification and comparative genomic hybridization (CGH).

SETTING

Clinical IVF laboratory.

PATIENT(S)

A 40-year-old IVF patient.

INTERVENTION(S)

Polar body and blastomere biopsy.

MAIN OUTCOME MEASURE(S)

Detection of aneuploidy.

RESULT(S)

Chromosome imbalance was detected in 9 of 10 polar bodies. A variety of chromosomes were aneuploid, but chromosomal size was found to be an important predisposing factor. In three cases, the resulting embryos could be tested using fluorescence in situ hybridization, and in each case the CGH diagnosis was confirmed. A single embryo could be recommended for transfer on the basis of the CGH data, but no pregnancy ensued.

CONCLUSION(S)

Evidence suggests that preferential transfer of chromosomally normal embryos can improve IVF outcomes. However, current PGD protocols do not allow analysis of every chromosome, and therefore a proportion of abnormal embryos remains undetected. We describe a method that allows every chromosome to be assessed in polar bodies and oocytes. The technique was accurate and allowed identification of aneuploid embryos that would have been diagnosed as normal by standard PGD techniques. As well as comprehensive cytogenetic analysis, this protocol permits simultaneous testing for multiple single-gene disorders.

Laser-assisted removal of necrotic blastomeres from cryopreserved embryos that were partially damaged

OBJECTIVE

To examine whether the developmental potential of embryos that were partially damaged after freezing and thawing can be improved by removal of necrotic blastomeres before embryo transfer.

DESIGN

Prospective pilot study and observational clinical series.

SETTING

Private hospital.

PATIENT(S)

Two hundred thirty-five infertile couples undergoing frozen embryo transfer.

INTERVENTION(S)

Removal of necrotic blastomeres from frozen-thawed human embryos.

MAIN OUTCOME MEASURE(S)

Pregnancy and implantation rates.

RESULT(S)

Removal of necrotic blastomeres from partially damaged frozen-thawed embryos before transfer increased rates of pregnancy (45.7% vs. 17.1%), ongoing pregnancy (40.0% vs. 11.4%) and ongoing implantation (16.2% vs. 4.3%) compared with the control group, in which necrotic blastomeres were not removed. A similarly high implantation rate (16.7%) was seen a subsequent clinical series in which necrotic blastomeres were removed from all partially damaged embryos.

CONCLUSION(S)

The viability of partially damaged frozen-thawed embryos can be improved by removal of necrotic blastomeres before embryo transfer.

Bovine abnormal preimplantation embryos: analysis of segregated cells occurring in the subzonal space and/or blastocoele cavity for their nuclear morphology and persistence of RNA synthesis

Bovine embryos in the early blastocyst/blastocyst stage were analysed by [5-3H]uridine labelling followed by electron microscopic autoradiography. In normal control embryos an intact zona pellucida, evenly developed blastomeres and a transparent perivitelline space were seen. In this group, the blastomeres of the trophoblast and embryoblast showed high homogeneous labelling localised in the nucleoplasm and even more intense labelling in the nucleolus. On the contrary, in addition to evident cytoplasmic disintegration, a clearly different labelling pattern and a low labelling intensity were observed in the nuclei of the segregated cells in the subzonal space and in those free in the blastocoele cavity. A typical nuclear morphological feature of these blastomeres was chromatin marginalisation, similar to that observed in embryos treated with actinomycin D for transcription inhibition. It is concluded that the segregated cells are arrested in their further differentiation.

Expression of apoptosis-related genes in human oocytes and embryos

PURPOSE

The objective was to study whether apoptosis occurs in human embryogenesis.

METHODS

Human viable, arrested, and nonviable embryos and immature, and nonfertilized oocytes donated by our patients were used to detect apoptosis by Tunel labeling, annexin staining, and single-cell reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

DNA fragmentation and phosphotidylserine translocation, the two markers for apoptosis, were detected frequently in fragmented human embryos derived from in vitro fertilization-embryo transfer (IVF-ET). Using RT-PCR, apoptotic genes also were detected in these embryos. The frequencies of gene expression in viable embryos, arrested embryos, nonviable embryos, immature oocytes, and non-fertilized oocytes were: 7/8, 5/5, 5/6, 0/6, 0/3, for Bax; 8/8, 5/5, 7/7, 0/4, 0/5 for Fas; 2/8, 0/2, 0/3, 0/5, 0/3 for BCL-2; 0/8, 1/3, 0/2, 0/3, 0/2 for Fas-ligand; and 8/8, 17/17, 21/21, 24/24, 15/15 for actin, respectively.

CONCLUSIONS

Our preliminary data did not show a significant difference in the expression frequency of all studied genes between viable embryos and nonviable or arrested embryos. However, the expression of Bax and Fas was noticeably higher in nonviable embryos than in viable embryos as judged by the intensities of amplicons visualized after ethidium bromide staining. In addition, BCL-2 was only detected in viable embryos. Whether embryos quality is related to the regulation of BCL-2, Bax, and Fas expressions requires further study.

Clinical pregnancy following blastomere biopsy and PGD for a reciprocal translocation carrier: analysis of meiotic outcomes and embryo quality in two IVF cycles

A couple were referred for preimplantation genetic diagnosis (PGD) following diagnosis of a reciprocal translocation in the female partner: 46,XX,t(14;22)(q11.2;q13.3). PGD was carried out using fluorescence in situ hybridization (FISH) with probes specific for the translocated and centric segments of chromosome 22. An initial cycle was unsuccessful, producing 11 embryos for biopsy, only one of which, when followed up on day 4, yielded more than 10 nuclei (median 7.5, n=10). In addition, five of the embryos showed mosaic or chaotic chromosome constitutions; some of these embryos had fragmented or multilobed abnormal nuclei, hindering interpretation of the FISH signals. The single embryo transferred did not result in a pregnancy. A second cycle, using a revised protocol, produced 10 embryos, three of which were transferred, resulting in an ongoing singleton pregnancy. All the remaining embryos yielded 12 to 23 nuclei by day 4 (median 17, n=7). Apart from some tetraploid nuclei, only one embryo showed mosaicism. The significance of the changes in protocol leading to the successful outcome is discussed, and the pattern of meiotic segregation products is analysed and compared with other previous reports of reciprocal translocations.

Human embryos derived from in vitro and in vivo matured oocytes: analysis for chromosomal abnormalities and nuclear morphology

PURPOSE

To determine whether embryos resulting from oocytes matured in vitro have a higher incidence of nuclear and/or genetic abnormalities compared to embryos resulting from oocytes matured in vivo.

METHODS

Fluorescence in situ hybridization analysis for chromosomes X, Y, and 18 was used to compare the rates of aneuploidy, mosaicism, and nuclear abnormalities in embryos derived from oocytes that were prophase I at aspiration (immature group) to that observed in embryos resulting from oocytes that were metaphase I or II at aspiration (mature group).

RESULTS

Based on nuclear morphology, significantly more embryos in the mature group (23%) were classified as normal compared to embryos in the immature group (3%). No difference was found in the rate of aneuploidy or in the incidence of mosaicism involving these chromosomes.

CONCLUSIONS

These findings suggest that few embryos derived from prophase I oocytes collected following ovarian stimulation are morphologically normal.

The probability of abnormal preimplantation development can be predicted by a single static observation on pronuclear stage morphology

This retrospective study was undertaken to determine whether further developmental progression of two-pronucleated (2PN) zygotes can be predicted by a single, non-invasive examination of pronuclei, with the use of criteria based on the number and distribution of nucleolar precursor bodies in each pronucleus. The normal range of pronuclear variability was defined by analysis of zygotes giving rise to embryos transferred in 100%-implantation cycles (pattern 0). Morphological patterns differing from pattern 0 were classified as patterns 1-5. The frequency of developmental arrest of pattern 0 zygotes was only 8.5% as compared with 31.6, 21.9, 30.0, 20.5 and 24. 1% for patterns 1-5 respectively. Relationships of pronuclear patterns with blastomere multinucleation and cleaving embryo morphology were also noted. Clinical pregnancy was achieved in 22 of 44 (50%) treatment cycles in which at least one pattern 0 embryo was transferred, but only in two of 23 (9%) cycles in which only pattern 1-5 embryos were transferred. These data present new evaluation criteria which can be used to predict the developmental fate of human embryos as early as the pronuclear stage, without requiring repeated observations or an exact timing of pronuclear zygote inspection. Further prospective study is needed for clinical validation of these criteria.

Preimplantation diagnosis by fluorescence in situ hybridization using 13-, 16-, 18-, 21-, 22-, X-, and Y-chromosome probes

PURPOSE

Our purpose was to select the proper chromosomes for preimplantation diagnosis based on aneuploidy distribution in abortuses and to carry out a feasibility study of preimplantation diagnosis for embryos using multiple-probe fluorescence in situ hybridization (FISH) on the selected chromosomes of biopsied blastomeres.

METHODS

After determining the frequency distribution of aneuploidy found in abortuses, seven chromosomes were selected for FISH probes. Blastomeres were obtained from 33 abnormal or excess embryos. The chromosome complements of both the biopsied blastomeres and the remaining sibling blastomeres in each embryo were determined by FISH and compared to evaluate their preimplantation diagnostic potential.

RESULTS

Chromosomes (16, 22, X, Y) and (13, 18, 21) were selected on the basis of the high aneuploid prevalence in abortuses for the former group and the presence of trisomy in the newborn for the latter. Thirty-six (72%) of 50 blastomeres gave signals to permit a diagnosis. Diagnoses made from biopsied blastomeres were consistent with the diagnoses made from the remaining sibling blastomeres in 18 embryos. In only 2 of 20 cases did the biopsied blastomere diagnosis and the embryo diagnosis not match.

CONCLUSIONS

If FISH of biopsied blastomere was successful, a preimplantation diagnosis could be made with 10% error. When a combination of chromosome-13, -16, -18, -21, -22, -X, and -Y probes was used, up to 65% of the embryos destined to be aborted could be detected.

[Monozygotic pregnancy after the treatment for infertility by transfer of frozen-thawed embryos]

OBJECTIVES

It has been suggested that monozygotic pregnancies occur more frequently after in vitro fertilisation. This phenomenon is attributed to a number of factors including in vitro culture conditions, malformation of the zona pellucida due to manipulation on the oocytes and artificial opening of the zona pellucida.

DESIGN

Retrospective analysis of monozygotic pregnancies in an IVF-ET procedures and obstetrical these pregnancies outcome.

MATERIALS AND METHODS

A total of 2254 IVF-ET procedures were analysed. Three protocols were used for ovarian stimulation: short or long protocols with gonadotropins releasing hormone analogue or clomiphene citrate with hMG. In 811 cases male factor was diagnosed and intracitoplasmatic sperm injections were performed.

RESULTS

549 clinical pregnancies were achieved in analysed group. In six cases ultrasound examination 5 weeks after embryo transfer showed a greater number of foetus than the number of embryo transferred. In three of those cases the embryos were obtained after ICSI. Age and average thickness of zona pellucida were similar in group of patients with monozygotic pregnancies when compared with all pregnant patients after IVF treatment.

CONCLUSIONS

The incidence of monozygotic pregnancy is increased in group pregnancies resulting from IVF ET. No single risk factor can explain this phenomena. This type of pregnancy needs special obstetrical attention.

Laser scanning confocal imaging of abnormal or arrested human preimplantation embryos

PURPOSE

The improved resolution and optical sectioning of a confocal microscope make it an ideal instrument for extracting three-dimensional information, especially from extended biological specimens such as human embryos. The staining of actin together with chromatin allowed us to specify the architecture of the embryo and the appearance of the nucleus.

METHODS

F-Actin and chromatin distributions were visualized using laser scanning confocal microscopy in "fresh" and "cryopreserved" human preimplantation embryos obtained by in vitro fertilization.

RESULTS

The current study revealed a high rate of multinucleation in arrested or poor-quality embryos (89%, in grade IV embryos).

CONCLUSIONS

Confocal microscopy revealed high levels of multinucleated blastomeres, suggesting that the probable cause of arrested development in these embryos was due to multinucleation of blastomeres.

Preimplantation diagnosis by FISH: the Rambam experience

PURPOSE

Our purpose was to summarize our experience gained using fluorescence in situ hybridization for preimplantation diagnosis at the Rambam Medical Center.

METHODS

Seventy-three embryos (29 cycles) were analyzed for preimplantation diagnosis for the following indications: advanced maternal age (> 39 years), X-linked diseases, poor-quality embryos, repeated failure in vitro fertilization cycles and fast-dividing embryos. An additional 38 embryos with unequal pronuclei size were examined for ploidy. Biopsy of embryonic blastomeres was performed at the six- to eight-cell stage. Five fluorescence probes, for chromosomes X, Y, 13, 18, and 21, were applied for ploidy detection.

RESULTS

Eighty-four (87%) blastomeres of the 73 embryos analyzed showed clear signals. Six of the blastomeres were lost during spreading. Two of the embryos were destroyed following biopsy. No nucleus was found in five of the blastomeres, while in nine, more than one nucleus was verified. Transfer was performed in 10 patients (32 embryos). Two pregnancies were achieved. Two healthy babies were born. Fifty-seven percent of the fast-dividing embryos demonstrated normal signals. In two groups of embryos of unequal pronuclei size following conventional insemination and intracytoplasmic sperm injection, 50 and 11.4% demonstrated normal signals.

CONCLUSIONS

The efficiency of fluorescence in situ hybridization for aneuploidy detection is 87 and 97% for autosomes and gonosomes, respectively. The preimplantation genetic diagnosis is suitable for selected in vitro fertilization cases including fast-dividing embryos and embryos with unequal pronuclei size following regular in vitro fertilization.

Simultaneous detection of chromosomes X, Y, 13, 18, and 21 by fluorescence in situ hybridization in blastomeres obtained from preimplantation embryos

PURPOSE

Simultaneous fluorescence in situ hybridization (FISH) was used in a preimplantation genetic diagnosis program to determine which embryos were normal for chromosomes X, Y, 13, 18, and 21.

METHODS

Single blastomeres were disrupted and attached to glass slides using acetic acid and ethanol. Using a ratio mixture of chromosome enumeration DNA probes in combination with locus-specific identifier DNA probes, FISH was performed for the identification of chromosomes X, Y, 13, 18, and 21.

RESULTS

Fourteen couples enrolled in IVF produced 134 embryos for biopsy. Blastomeres subjected to five-color FISH revealed that 22% of embryos were normal for chromosomes X, Y, 13, 18, and 21. In addition, 52% were abnormal and no results could be detected for 25%. Twelve couples underwent embryo transfer, two couples did not receive embryos due to lack of any normal embryos, and three couples became pregnant.

CONCLUSIONS

The simultaneous detection of five-color FISH is a feasible method to detect aneuploidy in preimplantation embryos from women of advanced maternal age.

Infertile couples with Robertsonian translocations: preimplantation genetic analysis of embryos reveals chaotic cleavage divisions

Preimplantation genetic diagnosis (PGD) may provide a feasible option for some Robertsonian translocation carriers who experience severe difficulty in achieving a normal pregnancy. We report on five PGD cycles for two such couples, 45,XY,der(13;14)(q10:q10) and 45,XX,der(13;21)(q10;q10), carried out by biopsy of two cells from day 3 post-insemination embryos generated by in vitro fertilisation. Locus-specific YAC probes for chromosomes 13, 14 and 21 were used to detect the chromosomes involved in the translocation using multicolour FISH. Three embryos transfers were carried out (two single embryo transfers and one double transfer) but no clinical pregnancies were established. In two cycles no embryos were transferred as all those biopsied were chromosomally abnormal. Combined results from both couples show 13% (6/45) of embryos analysed were normal for the translocation chromosomes and 87% (39/45) were chromosomally abnormal; these were categorised as 36% aneuploid or aneuploid mosaic and 51% chaotic where the chromosome constitution varied randomly from cell to cell. This suggests two factors may be acting to reduce fertility in these couples; the aneuploid segregation of the parental Robertsonian translocation and also a post-zygotic factor leading to uncontrolled chromosome distribution in early cleavage stages in an exceptionally high proportion of embryos.

Clinical application of preimplantation diagnosis for myotonic dystrophy

Myotonic dystrophy (DM) or Steinert's disease is a progressive autosomal dominant disease characterized by increasing muscle weakness, myotonia, cataracts, and endocrine abnormalities such as diabetes and testicular atrophy. The gene for DM was cloned in 1992 and the mutation was shown to be an expanded trinucleotide (CTG) repeat. A polymerase chain reaction (PCR)-based assay was described soon after that would allow (prenatal) diagnosis of the disease. Based on these PCR assays, we have developed a method for carrying out single-cell PCR for DM. In preimplantation diagnosis, embryos obtained in vitro are checked for the presence or absence of a disease, after which only embryos shown to be free of the disease under consideration are returned to the mother. A single-cell assay was developed for preimplantation diagnosis in couples where one of the parents is afflicted with DM. Twenty intracytoplasmic sperm injection (ICSI) cycles were carried out in eight patients and between one and four embryos were replaced in 17 out of 20 cycles. Two of the patients became pregnant and have had prenatal diagnosis which has confirmed that they are unaffected.

Preimplantation development of mouse and human embryos biopsied at cleavage stages using a modified displacement technique

A modified embryo biopsy method was tested on four- and eight-cell stage mouse embryos and used on human embryos to obtain blastomeres for preimplantation genetic diagnosis. The biopsy method tested combines zona drilling and fluid displacement to force one or two cells through an opening in the zona pellucida of the cleavage-stage embryo. Rates of cell division and the percentage of mouse embryos forming blastocysts following biopsy at the eight-cell stage were not significantly different from those observed in unoperated control embryos. The percentage blastocyst formation was not significantly different in embryos biopsied at the four-cell stage and in control embryos, although cell division was significantly retarded following biopsy. 96% of the mouse blastomeres isolated at the eight-cell stage were recovered intact and 96% of those placed in culture underwent cell division. Survival and division of cells isolated at the four-cell stage were 92 and 84% respectively. Most of the cultured blastomeres cleaved several times and formed small trophoblast vesicles. Chromosomes were observed in 59% of blastomeres incubated in the presence of colcemid. In the initial use of this biopsy technique for human preimplantation genetic diagnosis, blastocyst formation was observed in 9 of 13 human embryos biopsied at the 7- to 10-cell stage. These findings support the use of this biopsy method as an alternative to aspiration techniques.

The presence of multinucleated blastomeres in human embryos is correlated with chromosomal abnormalities

The purpose of the present study was to determine whether the presence of one or more multinucleated blastomeres during early embryonic development is associated with chromosomal abnormalities in sibling blastomeres of that embryo. Embryos with multinucleated cells (n = 47) detected on day 2 or 3 or development were compared to dividing embryos without multinucleation. Arrested embryos were excluded from this study. Chromosome abnormalities were detected using fluorescent in-situ hybridization (FISH) with X, Y, 18 and 13/21 chromosome-specific probes. Of 47 embryos included in this study, 76.6% were chromosomally abnormal, compared to 50.9% in the control group (P < 0.001). Excluding aneuploidy, which is originated in the gametes and not the embryo, the differences were even higher, with 74.5% of multinucleated embryos being chromosomally abnormal compared to 32.3% of non-multinucleated embryos (P < 0.001). Day of multinucleation appearance, number of nuclei per cell, number of multinucleated cells per embryo and developmental quality of the embryos as well as the type of fertilization (intracytoplasmic sperm injection versus standard insemination) were not found to affect the rate of chromosomal abnormalities in embryos with multinucleated cells. These results suggest that embryos with multinucleated cells may not be suitable for replacement and should be excluded unless no other embryos are available.

Review: preimplantation diagnosis of inherited disease

Preimplantation diagnosis of inherited diseases has become possible with the techniques of in vitro fertilization, blastomere biopsy of the 6- to 10-cell embryo and DNA analysis of the single blastomeres. Disease-free embryos are selected for transfer to the uterus, thereby avoiding the need for termination of a fetus diagnosed as affected in prenatal diagnosis in the first or early-second trimester of pregnancy. The genetic indications for preimplantation diagnosis are theoretically the same as for prenatal diagnosis, but the defects must be detectable by the polymerase chain reaction. For X-linked recessive diseases, fluorescence in situ hybridization can be used as an alternative for the selection of female embryos. So far almost 40 healthy children have been born worldwide after preimplantation diagnosis for genetic disease. The possibilities and limitations of preimplantation diagnosis, especially in prevention of inherited disease, are discussed in this review.

Management of rhesus isoimmunization by preimplantation genetic diagnosis

A genetic assay by single blastomere analysis was developed for rhesus (RhD) blood group typing of early cleavage stage embryos. The method, which is based on the simultaneous amplification of an RhD-specific sequence and an internal control in single cells, was applied for the selective transfer of RhD-negative embryos in a family of an RhD sensitized woman and a heterozygote partner. The RhD status of two out of three biopsied embryos was determined. According to their amplified products, both were typed as RhD-negative and transferred to the uterus. Pregnancy was not achieved.