Christina Bergh

Derivation, Characterization, and Differentiation of Human Embryonic Stem Cells

The derivation of human embryonic stem (hES) cells establishes a new avenue to approach many issues in human biology and medicine for the first time. To meet the increased demand for characterized hES cell lines, we present the derivation and characterization of six hES cell lines. In addition to the previously described immunosurgery procedure, we were able to propagate the inner cell mass and establish hES cell lines from pronase‐treated and hatched blastocysts. The cell lines were extensively characterized by expression analysis of markers characteristic for undifferentiated and differentiated hES cells, karyotyping, telomerase activity measurement, and pluripotency assays in vitro and in vivo. Whereas three of the cell lines expressed all the characteristics of undifferentiated pluripotent hES cells, one cell line carried a chromosome 13 trisomy while maintaining an undifferentiated pluripotent state, and two cell lines, one of which carried a triploid karyotype, exhibited limited pluripotency in vivo. Furthermore, we clonally derived one cell line, which could be propagated in an undifferentiated pluripotent state.

Children born after cryopreservation of embryos or oocytes: a systematic review of outcome data

BACKGROUND An estimated 3.5 million children have been born to date using assisted reproduction technologies. We reviewed the data in order to evaluate current knowledge of medical outcome for IVF/ICSI children born after cryopreservation, slow freezing and vitrification of early cleavage stage embryos, blastocysts and oocytes. METHODS A systematic review was performed. We searched the PubMed, Cochrane and Embase databases from 1984 to September 2008. Inclusion criteria for slow freezing of early cleavage stage embryos were controlled studies reporting perinatal or child outcomes. For slow freezing and vitrification of blastocysts and oocytes, and vitrification of early cleavage stage embryos, case reports on perinatal or child outcomes were also included. Three reviewers independently read and evaluated all selected studies. RESULTS For early cleavage embryos, data from controlled studies indicated a better or at least as good obstetric outcome, measured as preterm birth and low birthweight for children born after cryopreservation, as compared with children born after fresh cycles. Most studies found comparable malformation rates between frozen and fresh IVF/ICSI. For slow freezing of blastocysts and for vitrification of early cleavage stage embryos, blastocysts and oocytes, limited neonatal data was reported. We found no long-term child follow-up data for any cryopreservation technique. CONCLUSION Data concerning infant outcome after slow freezing of embryos was reassuring. Properly controlled follow-up studies of neonatal outcome are needed after slow freezing of blastocysts and after vitrification of early cleavage stage embryos, blastocysts and oocytes. In addition, child long-term follow-up studies for all cryopreservation techniques are essential.

Preimplantation genetic screening in women of advanced maternal age caused a decrease in clinical pregnancy rate: a randomized controlled trial

BACKGROUND Advanced maternal age (AMA) is an important parameter that negatively influences the clinical pregnancy rate in IVF, in particular owing to the increased embryo aneuploidy rate. It has thus been suggested that only transferring euploid embryos in this patient group would improve the pregnancy rate. The purpose of this study was to test whether employing preimplantation genetic screening (PGS) in AMA patients would increase the clinical pregnancy rate. METHODS We conducted a two-center, randomized controlled trial (RCT) to analyze the outcome of embryo transfers in AMA patients (>or=38 years of age) after PGS using FISH analysis for chromosomes X, Y, 13, 16, 18, 21 and 22. The PGS group was compared with a control group. The primary outcome measure was clinical pregnancy rate after 6-7 weeks of gestation per randomized patient. RESULTS The study was terminated early as an interim analysis showed a very low conditional power of superiority for the primary outcome. Of the 320 patients calculated to be included in the study, 56 and 53 patients were randomized into the PGS and control groups, respectively. The clinical pregnancy rate in the PGS group was 8.9% (95% CI, 2.9-19.6%) compared with 24.5% (95% CI, 13.8-38.3%) in the control group, giving a difference of 15.6% (95% CI, 1.8-29.4%, P = 0.039). CONCLUSIONS Although the study was terminated early, this RCT study provides evidence against the use of PGS for AMA patients when performing IVF. TRIAL REGISTRATION NUMBER ISRCTN38014610.

Derivation of a Xeno‐Free Human Embryonic Stem Cell Line

Elimination of all animal material during both the derivation and long‐term culture of human embryonic stem cells (hESCs) is necessary prior to future application of hESCs in clinical cell therapy. The potential consequences of transplanting xeno‐contaminated hESCs into patients, such as an increased risk of graft rejection [Stem Cells 2006;24:221–229] and the potential transfer of nonhuman pathogens, make existing hESC lines unsuitable for clinical applications. To avoid xeno‐contamination during derivation and culture of hESCs, we first developed a xeno‐free medium supplemented with human serum, which supports long‐term (>50 passages) culture of hESCs in an undifferentiated state. To enable derivation of new xeno‐free hESCs, we also established xeno‐free human foreskin fibroblast feeders and replaced immunosurgery, which involves the use of guinea pig complement, with a modified animal‐product‐free derivation procedure. Here, we report the establishment and characterization (>20 passages) of a xeno‐free pluripotent diploid normal hESC line, SA611.

Perinatal outcomes of children born after frozen-thawed embryo transfer: a Nordic cohort study from the CoNARTaS group

STUDY QUESTIONS What are the risks of adverse outcomes in singletons born after frozen-thawed embryo transfer (FET)? SUMMARY ANSWER Singletons born after FET have a better perinatal outcome compared with singletons born after fresh IVF and ICSI as regards low birthweight (LBW) and preterm birth (PTB), but a worse perinatal outcome compared with singletons born after spontaneous conception. WHAT IS KNOWN ALREADY Previous studies have shown a worse perinatal outcome in children born after IVF in general compared with children born after spontaneous conception. In singletons born after FET, a lower rate of PTB and LBW and a higher rate of large for gestational age (LGA) compared with singletons born after fresh IVF have been shown. STUDY DESIGN A retrospective Nordic population-based cohort study of all singletons conceived after FET in Denmark, Norway and Sweden until December 2007 was performed. PARTICIPANTS/MATERIALS, SETTING AND METHODS Singletons born after FET (n = 6647) were compared with a control group of singletons born after fresh IVF and ICSI (n = 42 242) and singletons born after spontaneous conception (n = 288 542). Data on perinatal outcomes were obtained by linkage to the national Medical Birth Registries. Odds ratios were calculated for several perinatal outcomes and adjustments were made for maternal age, parity, year of birth, offspring sex and country of origin. MAIN RESULTS AND THE ROLE OF CHANCE Singletons born after FET had a lower risk of LBW (adjusted odds ratio (aOR) 0.81, 95% confidence interval (CI) 0.71-0.91), PTB (aOR 0.84, 95% CI 0.76-0.92), very PTB (VPTB; aOR 0.79, 95% CI 0.66-0.95) and small for gestational age (SGA; aOR 0.72, 95% CI 0.62-0.83), but a higher risk of post-term birth (aOR 1.40, 95% CI 1.27-1.55), LGA (aOR 1.45, 95% CI 1.27-1.64), macrosomia (aOR 1.58, 95% CI 1.39-1.80) and perinatal mortality (aOR 1.49, 95% CI 1.07-2.07) compared with singletons born after fresh IVF and ICSI. Compared with children conceived after spontaneous conception, singletons born after FET had a higher risk of LBW (aOR 1.27, 95% CI 1.13-1.43), very LBW (aOR 1.69, 95% CI 1.33-2.15), PTB (aOR 1.49, 95% CI 1.35-1.63), VPTB (aOR 2.68, 95% CI 2.24-3.22), SGA (aOR 1.18, 95% CI 1.03-1.35), LGA (aOR 1.29, 95% CI 1.15-1.45), macrosomia (aOR 1.29, 95% CI 1.15-1.45) and perinatal (aOR 1.39, 95% CI 1.03-1.87) neonatal (aOR 1.87, 95% CI 1.23-2.84) and infant mortality (aOR 1.92, 95% CI 1.36-2.72). When analyzing trends over time, the risk of being born LGA increased over time for singletons born after FET compared with singletons born after fresh IVF and ICSI (P = 0.04). LIMITATIONS, REASONS FOR CAUTION As in all observational studies, the possible role of residual confounding factors and bias should be considered. In this study, we were not able to control for confounding factors, such as BMI, smoking and reason for, or length of, infertility. WIDER IMPLICATIONS OF THE FINDINGS Perinatal outcomes in this large population-based cohort of children born after FET from three Nordic countries compared with fresh IVF and ICSI and spontaneous conception were in agreement with the literature.

Postnatal growth and health in children born after cryopreservation as embryos

BACKGROUND There is uncertainty about the health of children born from in-vitro fertilisation (IVF) with cryopreserved embryos. We investigated the postnatal growth and health (up to 18 months) of these children compared with those born after standard IVF with fresh embryos and those from spontaneous pregnancies. METHODS 255 children from cryopreserved embryos were matched by maternal age, parity, single or twin pregnancy, and date of delivery with 255 children born after IVF with fresh embryos, and 252 children from spontaneous pregnancies. The main endpoint was growth; secondary endpoints were the prevalence of chronic illness, major malformations, cumulative incidence of common diseases, and development during the first 18 months. Growth was assessed by comparison with standard Swedish growth charts and by standard deviation scores. FINDINGS Growth features were similar for both singletons and twins in the three groups. There were 6 (2.4%) of 255, 9 (3.5%) of 255, and 8 (3.2%) of 252 major malformations in the cryopreserved group, standard IVF, and spontaneous groups, respectively (p=0.6 between the cryopreserved and standard IVF group). The prevalence of chronic diseases did not differ between the three groups, with 18.0%, 15.3%, and 16.7% of children with a chronic illness in the cryopreserved group, standard IVF, and spontaneous groups, respectively. INTERPRETATION The cryopreservation process does not adversely affect the growth and health of children during infancy and early childhood. Minor handicaps, behavioural disturbances, learning difficulties, and dysfunction of attention and perception cannot be ruled out at this age.

Assisted reproductive technology in Europe, 2012: results generated from European registers by ESHRE.

STUDY QUESTION The 16th European IVF-monitoring (EIM) report presents the data of the treatments involving assisted reproductive technology (ART) and intrauterine insemination (IUI) initiated in Europe during 2012: are there any changes compared with previous years? SUMMARY ANSWER Despite some fluctuations in the number of countries reporting data, the overall number of ART cycles has continued to increase year by year, the pregnancy rates (PRs) in 2012 remained stable compared with those reported in 2011, and the number of transfers with multiple embryos (3+) and the multiple delivery rates were lower than ever before. WHAT IS KNOWN ALREADY Since 1997, ART data in Europe have been collected and re-ported in 15 manuscripts, published in Human Reproduction. STUDY DESIGN, SIZE, DURATION Retrospective data collection of European ART data by the EIM Consortium for the European Society of Human Reproduction and Embryology (ESHRE). Data for cycles between 1 January and 31 December 2012 were collected from National Registers, when existing, or on a voluntary basis by personal information. PARTICIPANTS/MATERIALS, SETTING, METHODS From 34 countries (+1 compared with 2011), 1111 clinics reported 640 144 treatment cycles including 139 978 of IVF, 312 600 of ICSI, 139 558 of frozen embryo replacement (FER), 33 605 of egg donation (ED), 421 of in vitro maturation, 8433 of preimplantation genetic diagnosis/preimplantation genetic screening and 5549 of frozen oocyte replacements (FOR). European data on intrauterine insemination using husband/partners semen (IUI-H) and donor semen (IUI-D) were reported from 1126 IUI labs in 24 countries. A total of 175 028 IUI-H and 43 497 IUI-D cycles were included. MAIN RESULTS AND THE ROLE OF CHANCE In 18 countries where all clinics reported to their ART register, a total of 369 081 ART cycles were performed in a population of around 295 million inhabitants, corresponding to 1252 cycles per million inhabitants (range 325-2732 cycles per million inhabitants). For all IVF cycles, the clinical PRs per aspiration and per transfer were stable with 29.4 (29.1% in 2011) and 33.8% (33.2% in 2011), respectively. For ICSI, the corresponding rates also were stable with 27.8 (27.9% in 2011) and 32.3% (31.8% in 2011). In FER cycles, the PR per thawing/warming increased to 23.1% (21.3% in 2011). In ED cycles, the PR per fresh transfer increased to 48.4% (45.8% in 2011) and to 35.9% (33.6% in 2011) per thawed transfer, while it was 45.1% for transfers after FOR. The delivery rate after IUI remained stable, at 8.5% (8.3% in 2011) after IUI-H and 12.0% (12.2% in 2011) after IUI-D. In IVF and ICSI cycles, 1, 2, 3 and 4+ embryos were transferred in 30.2, 55.4, 13.3 and 1.1% of the cycles, respectively. The proportions of singleton, twin and triplet deliveries after IVF and ICSI (added together) were 82.1, 17.3 and 0.6%, respectively, resulting in a total multiple delivery rate of 17.9% compared with 19.2% in 2011 and 20.6% in 2010. In FER cycles, the multiple delivery rate was 12.5% (12.2% twins and 0.3% triplets). Twin and triplet delivery rates associated with IUI cycles were 9.0%/0.4% and 7.2%/0.5%, following treatment with husband and donor semen, respectively. LIMITATIONS, REASONS FOR CAUTION The method of reporting varies among countries, and registers from a number of countries have been unable to provide some of the relevant data such as initiated cycles and deliveries. As long as data are incomplete and generated through different methods of collection, results should be interpreted with caution. WIDER IMPLICATIONS OF THE FINDINGS The 16th ESHRE report on ART shows a continuing expansion of the number of treatment cycles in Europe, with more than 640 000 cycles reported in 2012 with an increasing contribution to birthrate in many countries. However, the need to improve and standardize the national registries, and to establish validation methodologies remains manifest. STUDY FUNDING/COMPETING INTERESTS The study has no external funding; all costs are covered by ESHRE. There are no competing interests.

Obstetric outcome in singletons after in vitro fertilization with cryopreserved/thawed embryos

BACKGROUND There is increasing use of cryopreservation in IVF. This study compared singletons born after cryopreservation with singletons born after fresh IVF cycles and singletons born to women in the general population. METHODS Data were collected for Swedish IVF treatments during the years 2002-2006. All singletons from single embryo transfer (SET) and double embryo transfer (DET) after cryopreserved (n = 2348) and fresh cycles (n = 8944) were included and cross-linked with the Swedish Medical Birth Registry and compared with all singletons born after spontaneous conception (n = 571 914). Main outcomes were preterm and very preterm birth and low and very low birthweight (VLBW). Other outcomes were small for gestational age, large for gestational age (LGA), perinatal mortality and maternal outcomes. RESULTS Singletons from cryopreserved SET/DET or cryopreserved SET had increased rates of extreme preterm birth compared with singletons from the general population. A lower rate of LBW was found for cryopreserved SET/DET singletons compared with singletons from fresh cycles; however, a higher rate of perinatal mortality was detected. The rates of LGA and macrosomia were increased for cryopreserved SET/DET singletons when compared with those from fresh cycles and the general population. For maternal outcomes, a higher rate of pre-eclampsia was noted for pregnancies from cryopreserved cycles compared with those from fresh cycles or the general population, but the rate of placenta praevia was lower in pregnancies from cryopreserved cycles compared with those from fresh cycles. CONCLUSIONS The obstetric outcome of singletons after cryopreservation was slightly poorer when compared with the general population. In comparison with fresh cycles, the outcome varied. The finding of an increased rate of LGA after cryopreservation requires further study.

Medical follow-up study of 5-year-old ICSI children

Children born after intracytoplasmic sperm injection (ICSI) are still a matter of concern. The purposes of the present study were to investigate the physical outcome in 5-year-old children born after ICSI and compare them with children born after spontaneous conception. Three hundred singleton children from Belgium, Sweden and the USA, born after ICSI, were matched by maternal age, child age and gender. In one centre, matching was also performed for maternal education. The main end-point was growth. Secondary end-points were general health, e.g. common diseases, chronic illnesses, surgical interventions and physical/neurological examinations. Standard deviation scores assessed growth. Growth assessed as stature at follow-up was similar in the two groups, despite a higher rate of preterm birth and low birth weight in the ICSI children. Common diseases and chronic illnesses occurred at similar rates in both groups. More ICSI children underwent surgical interventions and required other therapy e. g. physiotherapy and dietary therapy. Physical/neurological examinations revealed few abnormalities in either group. In conclusion, infertility treatment by ICSI does not adversely affect growth during childhood. The childrens general health seems satisfactory.

Chromosomal integrity maintained in five human embryonic stem cell lines after prolonged in vitro culture

There have been recent reports of human embryonic stem cell (hESC) lines developing chromosomal aberrations after long-term culture, indicating an unstable genomic status due to the in vitro milieu. This raises concern, since it would limit their use in therapeutics. In this study the chromosomal status of five well-characterized hESC lines, SA002, SA002.5, AS034.1.1, SA121 and SA461, was monitored during long-term in vitro culture. The criteria of defined hESCs were met by all of the five hESC lines (four diploid and one trisomic for chromosome 13). The genomes were screened for chromosomal aberrations and rearrangements using comparative genomic hybridization (CGH), interphase fluorescence in situ hybridization (FISH) and traditional karyotyping on several occasions while in culture. The genomic integrity was shown to be maintained after repeated freeze-thaw procedures and continuous culture in vitro for up to 22 months (148 passages). We discuss the most common de novo chromosomal aberrations reported in hESCs, as well as their possible origin.