Walid E. Maalouf

Trichostatin A treatment of cloned mouse embryos improves constitutive heterochromatin remodeling as well as developmental potential to term

BackgroundGenome reprogramming in early mouse embryos is associated with nuclear reorganization and particular features such as the peculiar distribution of centromeric and pericentric heterochromatin during the first developmental stage. This zygote-specific heterochromatin organization could be observed both in maternal and paternal pronuclei after natural fertilization as well as in embryonic stem (ES) cell nuclei after nuclear transfer suggesting that this particular type of nuclear organization was essential for embryonic reprogramming and subsequent development.ResultsHere, we show that remodeling into a zygotic-like organization also occurs after somatic cell nuclear transfer (SCNT), supporting the hypothesis that reorganization of constitutive heterochromatin occurs regardless of the source and differentiation state of the starting material. However, abnormal nuclear remodeling was frequently observed after SCNT, in association with low developmental efficiency. When transient treatment with the histone deacetylase inhibitor trichostatin A (TSA) was tested, we observed improved nuclear remodeling in 1-cell SCNT embryos that correlated with improved rates of embryonic development at subsequent stages.ConclusionTogether, the results suggest that proper organization of constitutive heterochromatin in early embryos is involved in the initial developmental steps and might have long term consequences, especially in cloning procedures.

Differential acetylation of histone H4 lysine during development of in vitro fertilized, cloned and parthenogenetically activated bovine embryos.

The oocyte is remarkable in its ability to remodel parental genomes following fertilization and to reprogram somatic nuclei after nuclear transfer (NT). To characterise the patterns of histone H4 acetylation and DNA methylation during development of bovine gametogenesis and embryogenesis, specific antibodies for histone H4 acetylated at lysine 5 (K5), K8, K12 and K16 residues and for methylated cytosine of CpG dinucleotides were used. Oocytes and sperm lacked the staining for histone acetylation, when DNA methylation staining was intense. In IVF zygotes, both pronuclei were transiently hyper-acetylated. However, the male pronucleus was faster in acquiring acetylated histones, and concurrently it was rapidly demethylated. Both pronuclei were equally acetylated during the S to G2-phase transition, while methylation staining was only still observed in the female pronucleus. In parthenogenetically activated oocytes, acetylation of the female pronucleus was enriched faster, while DNA remained methylated. A transient de-acetylation was observed in NT embryos reconstructed using a non-activated ooplast of a metaphase second arrested oocyte. Remarkably, the intensity of acetylation staining of most H4 lysine residues peaked at the 8-cell stage in IVF embryos, which coincided with zygotic genome activation and with lowest DNA methylation staining. At the blastocyst stage, trophectodermal cells of IVF and parthenogenetic embryos generally demonstrated more intense staining for most acetylated H4 lysine, whilst ICM cells stained very weakly. In contrast methylation of the DNA stained more intensely in ICM. NT blastocysts showed differential acetylation of blastomeres but not methylation. The inverse association of histone lysine acetylation and DNA methylation at different vital embryo stages suggests a mechanistically significant relationship. The complexities of these epigenetic interactions are discussed.

Efficacy of dehydroepiandrosterone to improve ovarian response in women with diminished ovarian reserve: a meta-analysis

Women with diminished ovarian reserve often respond poorly to controlled ovarian stimulation resulting in retrieval of fewer oocytes and reduced pregnancy rates. It has been proposed that pre-IVF Dehydroepiandrosterone (DHEA) adjuvant therapy may improve ovarian response and pregnancy rates in women with diminished ovarian reserve. This meta-analysis aims to investigate efficacy of DHEA as an adjuvant to improve ovarian response and IVF outcome in women with diminished ovarian reserve. Electronic databases were searched under the following terms: (DHEA) and (diminished ovarian reserve) and/or (poor response). Studies were included if they reported at least one of the following outcomes; clinical pregnancy rate, number of oocytes retrieved, miscarriage rate. We identified 22 publications determining effects of DHEA in clinical trials. Only 3 controlled studies were eligible for meta-analysis. There was no significant difference in the clinical pregnancy rate and miscarriage rates between women pre-treated with DHEA compared to those without DHEA pre-treatment (RR 1.87, 95% CI 0.96-3.64; and RR 0.59, 95% CI 0.21-1.65, respectively). The number of oocytes retrieved (WMD -1.88, 95% CI -2.08, 1.67; P < 0.001) was significantly lower in the DHEA group. In conclusion, based on the limited available evidence from a total of approximately 200 IVF cycles, there are insufficient data to support a beneficial role of DHEA as an adjuvant to controlled ovarian stimulation in IVF cycle. Well-designed, randomised controlled trials as well as more exact knowledge about DHEA mechanisms of action are needed to support use of DHEA in standard practice for poor-responders.

Effects of dehydroepiandrosterone on in vivo ovine follicular development

STUDY QUESTION What are the effects of exposure of ovarian tissue to dehydroepiandrosterone (DHEA) supplementation in vivo? SUMMARY ANSWER DHEA exposure stimulates initiation of primordial follicles and development of gonadotrophin-responsive preantral/early antral follicles possibly mediated through promoting granulosa cell proliferation and enhancing anti-Mullerian hormone (AMH) expression. WHAT IS KNOWN ALREADY?: Ovarian ageing is a cause of subfertility and is associated with poor outcomes of IVF treatment and premature menopause. A few clinical studies have shown that DHEA can improve ovarian response and increase the chances of pregnancy after IVF treatment in women with a diminished ovarian reserve (DOR) suggesting DHEA may help to overcome the effect of ovarian ageing. However, there are no data about how DHEA acts on ovarian folliculogenesis. STUDY DESIGN, SIZE AND DURATION A cortical autograft experimental model was conducted in six female sheep aged at least 24 months. The period of DHEA treatment in the animals lasted for 10 weeks. PARTICIPANTS/MATERIALS, SETTING, METHODS All the animals were subjected to unilateral oophorectomy. Half of the ovary was fixed for histological analysis as a time-zero control. The remaining tissue was used to isolate patches of ovarian cortex which were autografted back onto the ovarian pedicle. The grafting procedure eradicated all growing follicles and synchronized early follicular development. After a 10-week treatment period with DHEA implants, the ewes were sacrificed and the graft and remaining ovary were harvested. Histological and immunohistochemistry (IHC) findings, accompanied with serum hormonal profiles were compared to determine the effect on the follicle population. MAIN RESULTS AND THE ROLE OF CHANCE Higher proportions of the follicle population in the remaining ovary were observed to be in the antral stage after DHEA treatment. The observation coincided with an increase in the rate of primordial follicle initiation and preantral follicle development in cortical grafts and the remaining ovarian tissue, respectively. The IHC results indicated that DHEA increased the expression of both the proliferation marker (KI-67) in granulosa cells and the follicular AMH expression at the preantral and early antral follicle stages. LIMITATIONS, REASONS FOR CAUTION The experimental design compared follicle populations before and after DHEA treatment within individual animals to allow changes over time to be detected against a background of high inter-animal variation. However, since no controls without DHEA were included, we cannot say what would have happened over time in its absence, and it is possible that other factors may have resulted in the changes in follicle development observed during the experiment. WIDER IMPLICATIONS OF THE FINDING Our data supports the idea that DHEA might be a useful therapy to delay the effects of ovarian ageing. Therefore, it may have a role as an adjunct during IVF to improve ovarian response in women with DOR and as a treatment for premature ovarian insufficiency. STUDY FUNDING/COMPETING INTEREST(S) The research received finance support from the University of Nottingham. The authors declare no conflict of interest in this study.

Effects of assisted reproductive technologies on human sex ratio at birth

OBJECTIVE To investigate the effect of assisted reproductive technology (ART) treatments on the sex ratio of babies born. DESIGN Assessment of direct effects of assisted conception through retrospective data analysis on the progeny sex ratio of treated women in the United Kingdom. SETTING The study uses the anonymized register of the Human Fertilisation and Embryology Authority. PATIENT(S) A total of 106,066 babies of known gender born to 76,994 treated mothers and 85,511 treatment cycles between 2000 and 2010 in the United Kingdom. INTERVENTION(S) Intrauterine insemination, IVF, or intracytoplasmic sperm injection (ICSI). MAIN OUTCOME MEASURE(S) Sex ratio of babies born. RESULT(S) Intrauterine insemination, IVF, and ICSI lead to different sex ratios, highest after IVF (proportion male = mean 0.521 ± confidence interval 0.0056) and lowest under ICSI embryo transfer (0.493 ± 0.0031). In addition, for both ICSI and IVF, transferring embryos at a later stage (blastocyst) results in approximately 6% more males than after early cleavage-stage ET. CONCLUSION(S) Because the cumulative number of IVF babies born is increasing significantly in Britain and elsewhere, more research is needed into the causes of gender bias after ART and into the public health impact of such gender bias of offspring born observed on the rest of the population.

Effects of caffeine, cumulus cell removal and aging on polyspermy and embryo development on in vitro matured and fertilized ovine oocytes.

The objectives of these studies were to determine the effects of cumulus cell removal and caffeine treatment on the development of in vitro matured ovine oocytes aged in vitro until until fertilization. Oocytes were denuded (DO) at 24h post-onset of maturation (hpm), control cumulus oocyte complexes (COCs) and DO groups were fertilized at 24 hpm or returned to culture in the presence or absence of 10mM caffeine and fertilized at 30 hpm. Removal of cumulus cells and aging both increased polyspermy, caffeine reduced this increase, however, with the exception of DOs (30 hpm) vs. COCs (24 hpm) the differences were not statistically significant. Aging significantly decreased cleavage between COC groups at 24 hpm and 30 hpm and caffeine did not affect this (68.4%, 73.4%, 74.0% respectively). In contrast, the frequency of cleavage was significantly reduced in the DO (24 hpm) group as compared to COC controls (45.6% vs. 68.4% (P<0.05)), however, cleavage increased in the DO group on aging (73.4%) and this was not affected by caffeine (73.0%). The percentage of COCs and DOs developing to the blastocyst stage significantly decreased on aging, caffeine treatment of DOs prevented this (31.3%, 12.7% and 29.4% respectively (P<0.05)) but had no effect on COCs (4.2% vs. 3.9%). Total cell numbers in blastocysts were not statistically different (92.4+/-5.2, 84.7+/-3.7 and 80.4+/-5.8 (P>0.05)). In summary caffeine treatment of aged COCs had no significant effect on the frequency of development, however, in aged DOs caffeine treatment statistically increased development to blastocyst and lowered the frequency of polyspermy.

Effect of ethnicity on live birth rates after in vitro fertilisation or intracytoplasmic sperm injection treatment.

To assess the relationship between the ethnicity of women and the clinical success of in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI) treatment.

Early epigenetic reprogramming in fertilized, cloned, and parthenogenetic embryos.

Despite ongoing research in a number of species, the efficiency of embryo production by nuclear transfer remains low. Incomplete epigenetic reprogramming of the nucleus introduced in the recipient oocyte is one factor proposed to limit the success of this technique. Nonetheless, knowledge of reprogramming factors has increased-thanks to comparative studies on reprogramming of the paternal genome brought by sperm on fertilization-and will be reviewed here. Another valuable model of reprogramming is the one obtained in the absence of sperm fertilization through artificial activation-the parthenote-and will also be introduced. Altogether the objective of this review is to have a better understanding on the mechanisms responsible for the resistance to reprogramming, not only because it could improve embryonic development but also as it could benefit therapeutic reprogramming research.

Efficacy of dehydroepiandrosterone to overcome the effect of ovarian ageing (DITTO): a proof of principle randomised controlled trial protocol

Introduction Dehydroepiandrosterone (DHEA) has been proposed to improve pregnancy rates in women with diminished ovarian reserve undergoing in vitro fertilisation (IVF) treatment. However, evidence regarding its efficacy is supported by a limited number of randomised controlled trials (RCTs). This double-blinded RCT aims to measure the effect of DHEA supplementation prior to and during controlled ovarian hyperstimulation on ovarian response prior to IVF treatment in women predicted to have poor ovarian reserve. Methods and analysis Sixty women with ovarian antral follicle count ≤10 and serum anti-Mullerian hormone ≤5 pmol/L undergoing IVF/intracytoplasmic sperm injection (ICSI) treatment at the Nurture fertility clinic, Nottingham will be recruited. They will be randomised to either receive DHEA capsule 75 mg/day or placebo for at least 12 weeks before egg collection. All participants will undergo standard long down regulation protocol using human menopausal gonadotropin 300 IU/day. Serum samples and follicular fluids at the time of egg collection will be collected for hormonal immunoassays. For ICSI participants, cumulus cells stripped from oocyte will be collected for cumulus gene expression analyses regarding oocyte competence. Microdrops of oocyte culture media before the time of ICSI will be assessed for glucose, pyruvate and lactate utilisation. Embryo transfer will be performed on day 2, 3 or 5 based on the number and quality of the embryos available. Pregnancy will be defined as urine pregnancy test positive (biochemical pregnancy) and 6–8 weeks ultrasound scan with fetal heart beat (clinical pregnancy) and live birth. It is planned to perform the molecular and nutritional fingerprint analyses in batches after finishing the clinical phase of the study. Ethics and dissemination The approval of the study was granted by the NHS Research Ethics Committee (Ref number NRES 12/EM/0002), the Medicines and Healthcare products Regulatory Agency (MHRA), and the Nottingham University Hospitals Trust Research and Development department. All participants shall provide written informed consent before being randomised into allocated treatment groups. Trial registration number Protocol V.2.0; EudraCT number: 2011-002425-21; http://www.clinicaltrials.gov; NCT01572025; CTA reference: 03057/0053/001-0002

Nuclear dynamics of histone H3 trimethylated on lysine 9 and/or phosphorylated on serine 10 in mouse cloned embryos as new markers of reprogramming?

Somatic cell nuclear transfer (SCNT) is the injection of a donor nucleus into an enucleated egg. Despite the use of this technology for many years in research, it is still quite inefficient. One of the causes for this is thought to be incorrect or incomplete genome reprogramming. Embryos produced by nuclear transfer (cloned embryos) very often present abnormal epigenetic signatures and irregular chromatin reorganization. Of these two issues, the issue of chromatin rearrangements within the nuclei after transfer is the least studied. It is known that cloned embryos often present pericentromeric heterochromatin clumps very similar to the chromocenters structures present in the donor nuclei. Therefore, it is believed that the somatic nuclear configuration of donor nuclei, especially that of the chromocenters, is not completely lost after nuclear transfer, in other words, not well reprogrammed. To further investigate pericentromeric heterochromatin reorganization after nuclear transfer, we decided to study its rearrangements in cumulus-derived clones using several related epigenetic markers such as H3S10P, H3K9me3, and the double marker H3K9me3S10P. We observed that two of these markers, H3S10P and H3K9me3S10P, are the ones found on the part of the pericentromeric heterochromatin that is remodeled correctly, resembling exactly the embryonic heterochromatin configuration of naturally fertilized embryos. Conversely, H3K9me3 and heterochromatin protein 1 beta (HP1β)-associated protein were also detected in the perinuclear clumps of heterochromatin, making obvious the maintenance of the somatic epigenetic signature within these nuclear regions. Our results demonstrate that H3S10P and H3K9me3S10P could be good candidates for evaluating heterochromatin reorganization following nuclear reprogramming.