Begoña Aran

Waves of early transcriptional activation and pluripotency program initiation during human preimplantation development.

The events regulating human preimplantation development are still largely unknown owing to a scarcity of material, ethical and legal limitations and a lack of reliable techniques to faithfully amplify the transcriptome of a single cell. Nonetheless, human embryology is gathering renewed interest due to its close relationship with both stem cell biology and epigenetic reprogramming to pluripotency and their importance in regenerative medicine. Carefully timed genome-wide transcript analyses of single oocytes and embryos uncovered a series of successive waves of embryonic transcriptional initiation that start as early as the 2-cell stage. In addition, we identified the hierarchical activation of genes involved in the regulation of pluripotency. Finally, we developed HumER, a database of human preimplantation gene expression, to serve the scientific community. Importantly, our work links early transcription in the human embryo with the correct execution of the pluripotency program later in development and paves the way for the identification of factors to improve epigenetic reprogramming.

Screening for abnormalities of chromosomes X, Y, and 18 and for diploidy in spermatozoa from infertile men participating in an in vitro fertilization-intracytoplasmic sperm injection program

OBJECTIVE To evaluate the frequency of disomy (for chromosomes X, Y, and 18) and of diploidy in the spermatozoa of infertile men undergoing intracytoplasmic sperm injection (ICSI). DESIGN Prospective analysis of sperm nuclei by fluorescence in situ hybridization (FISH). SETTING University-affiliated IVF-ICSI program. PATIENT(S) Semen samples from 19 patients participating in an IVF-ICSI program. INTERVENTION(S) Semen samples were analyzed and prepared for FISH. MAIN OUTCOME MEASURE(S) Semen parameters were evaluated. The frequency of disomy for chromosomes X, Y, and 18 and the frequency of diploidy were analyzed by FISH. RESULT(S) A total of 9,373 spermatozoa from 19 infertile patients were analyzed and compared with spermatozoa from a control group of 5 healthy men. No differences in the frequency of disomy 18 were found, but statistically significant differences in the incidence of sex chromosome disomy and of diploidy were observed. CONCLUSION(S) The study of sperm nuclei by FISH is useful to improve genetic counseling in infertile patients selected for ICSI.

Generation of Cardiomyocytes from New Human Embryonic Stem Cell Lines Derived from Poor-quality Blastocysts

Human embryonic stem (hES) cells represent a potential source for cell replacement therapy of many degenerative diseases. Most frequently, hES cell lines are derived from surplus embryos from assisted reproduction cycles, independent of their quality or morphology. Here, we show that hES cell lines can be obtained from poor-quality blastocysts with the same efficiency as that obtained from good- or intermediate-quality blastocysts. Furthermore, we show that the self-renewal, pluripotency, and differentiation ability of hES cell lines derived from either source are comparable. Finally, we present a simple and reproducible embryoid body-based protocol for the differentiation of hES cells into functional cardiomyocytes. The five new hES cell lines derived here should widen the spectrum of available resources for investigating the biology of hES cells and advancing toward efficient strategies of regenerative medicine.

Increased Incidence of Meiotic Anomalies in Oligoasthenozoospermic Males Preselected for Intracytoplasmic Sperm Injection

AbstractPurpose: Based on data from the literature, to detect thepossible presence of an increased frequency of meiotic anomaliesin oligoasthenozoospermic (OA) patients preselectedfor intracytoplasmic sperm injection. Methods: Meiotic studies in as many successive patientswith a clinical indication for a diagnostic testicular biopsyas needed to complete at least 100 cases with a severe OA(motile sperm concentration ≤1.5 × 106/ml). Results: An increased incidence of meiotic anomalies wasfound in 102 patients with a severe OA (17.6%) comparedto the mean for 105 patients with other etiologies in theseries (5.7%) or the mean for patients reviewed in the literature(6.5%). Conclusions: Patients with a severe OA have a higher incidenceof synaptic anomalies. This may result in themalsegregation of chromosomes at meiosis I, producingabnormal sperm, and could explain the high incidence ofsterility and some cases of abortion (in two thirds of thecouples with abortions the husband had meiotic anomalies)in this group.

The changing landscape of European and international regulation on embryonic stem cell research.

Legislation in individual member states of the European Union on human embryonic stem cell (hESC) research is as divergent as the different cultural, ethical, and religious views on the issue. On the occasion of the public launch of the European Human Embryonic Stem Cell Registry (hESCreg: www.hescreg.eu), a two-day symposium was held on 18 and 19 January 2008 in Berlin to offer participants an overview of state-of-the-art hESC research and legislation throughout Europe and in selected regions of the world. Thirty leading scientists from Europe as well as from the United States, Japan, and Australia reported on a range of aspects related to research on hESC and reviewed the key elements of the newly established hESCreg database of hESC lines. In this article we summarize and complete the information on the current status of international hESC regulation.

Preimplantation genetic diagnosis in patients with male meiotic abnormalities.

Indications and candidates for preimplantation genetic diagnosis (PGD) have increased in recent years. This study evaluates whether IVF-intracytoplasmic sperm injection (ICSI) results could be improved by selecting embryos through PGD-AS (aneuploidy screening) in couples in whom the male partner presents meiotic abnormalities. Two hundred and fifty-six embryos were biopsied and 183 were suitable for analysis (73.2%). Ninety-two embryos showed normal chromosomal analysis (50.3% of the analysed embryos and 57.5% of the diagnosed embryos). Pregnancy, abortion and implantation rates were compared with 66 IVF-ICSI cycles performed in 44 patients with meiotic abnormalities without PGD (control group). No statistically significant differences in the pregnancy rate (52 versus 43.9%), implantation rate (32.1 versus 23.5%) and miscarriage rate (15.4 versus 10.3%) were observed between the groups. Although the embryos obtained from men with meiotic abnormalities showed a high frequency of chromosome abnormalities, no improvements in pregnancy and implantation rates were obtained after PGD-AS in the series analysed.

International stem cell registries

Rapid advances in stem cell research have led to the derivation of hundreds of human embryonic stem (hES) cell lines in centers throughout the world, as well as the development of new technologies for producing pluripotent stem cells. These cell lines have unique characteristics and were derived using a variety of ethical guidelines. Stem cell registries have been developed in order to collect, organize, and disseminate cell line-specific information. In this review, we describe the current state of the field by providing an overview of the unique qualities and mandates of the three major stem cell registries: the European hES Cell Registry, the Registry of hES Cell Line Provenance developed by the International Society for Stem Cell Research, and the International Stem Cell Registry of hES and induced pluripotent stem cell lines established at the University of Massachusetts Medical School. While each registry has its own unique mandate and features, there is some overlap in the goals and information provided. This review discusses the challenges and prospects for an integrated approach in which all three registries effectively collaborate to minimize duplication and facilitate information exchange within the stem cell community.

Influence of spermatogenic profile and meiotic abnormalities on reproductive outcome of infertile patients

Genetic aspects of male infertility and the possible risks of new assisted reproduction and their influence on the development of zygotes and children born after intracytoplasmic sperm injection (ICSI) need further research. These patients have an increased risk of diploidy, and disomies are frequent in their spermatozoa. Meiotic disorders are more common in testicular biopsies of patients with severe oligoasthenozoospermia. For these reasons, a detailed andrological study is absolutely mandatory before accepting a couple with these characteristics into an IVF-ICSI programme. When an andrological patient has plasma FSH values >10 IU/l and/or very low total motile sperm count <1 x 10(6), despite a normal karyotype, they clearly need a testicular biopsy and a meiotic study in order to rule out meiotic arrest or synaptic anomalies. Another important aspect to be considered is the possible benefit of applying preimplantation genetic diagnosis in these cases because they normally have a high percentage of chromosomally abnormal embryos, although in the present study this was not evident. All studies agree on the necessity of conducting follow-up studies in the population of children born after IVF-ICSI. In this way, it will be possible to find out if these infertile patients and their offspring have a higher risk of suffering epigenetic errors and imprinting disorders.

First evaluation of the European hESCreg

859 (Fig. 1) allows independent visualization of data entry completeness levels and has five categories, which are represented by graphical bars that can be ‘on’ or ‘off ’. The first bar indicates the availability of a line for independent review, which proved to be a practicable criterion. The second bar requires completed registration information such as cell line provider contact data, the source of the line, karyotype, genetic modifications, differentiation potential and expression of molecular human embryonic stem cell markers. At least the expression of any four hES cell markers established by one of five measurement methods, as well as proof of differentiation into cells of all three germ layers, should be included. The third bar requires information on the ‘core set’ of six hES cell markers as proposed by the ISCI consortium (that is, DNMT3B, GABRB3, GDF3, NANOG, POU5F1 and TDGF1). For further bars, researchers are requested to complete additional information, at least on culture conditions but also on further hES cell markers, detailed derivation information, extended characterization data (e.g., human leukocyte antigen (HLA) typing) and to upload regulatory documents, such as material transfer agreements. An additional bar to indicate the availability of regulatory and ethical information is still under discussion. This bar would indicate whether or not the line is eligible for EU funding7. We propose to turn the bar ‘on’ after all provided data of the cell line has been independently reviewed by hESCreg’s scientific advisory board and ethics committee. As of last month, of the 307 hES cell lines listed in the registry, 123 are available, which means that a provider or bank has entered information about these lines and indicated that the lines are available for independent review. Of the 123 available PO Box 750 Sentrum, NO-0106 Oslo, Norway. e-mail: arne.holst-jensen@vetinst.no

Couples' opinions regarding the fate of surplus frozen embryos

With the passing of Act 45/2003, research with viable human embryos became legal in Spain. Since then, Institut Universitari Dexeus has been in contact with couples whose embryos had been frozen for more than 2 years to inform them about the new legal options and gather their opinions. A reply was received from 35.9% of the couples contacted, with the following results: 33.3% wished to preserve the embryos for their own use, 30.0% wished to donate the embryos for embryonic stem cell research, 20.2% wished to donate the embryos to third parties for reproductive purposes and 10.3% wished to terminate the cryopreservation process without further use. The couples who chose to donate the embryos for research were asked to give written informed consent to the donation of their embryos for a specific project. The possibility of donating embryos for research has been well received by the couples, and offers a solution to those who wish to make neither a further attempt for pregnancy nor a donation with reproductive goals. Donation for research purposes is considered a preferable alternative to disposal.