Generation of a bank of clinical-grade, HLA-homozygous iPSC lines with high coverage of the Spanish population

BACKGROUND

Induced pluripotent stem cell (iPSC)-derived cell therapies are an interesting new area in the field of regenerative medicine. One of the approaches to decrease the costs of iPSC-derived therapies is the use of allogenic homozygous human leukocyte antigen (HLA)-matched donors to generate iPSC lines and to build a clinical-grade iPSC bank covering a high percentage of the Spanish population.

METHODS

The Spanish Stem Cell Transplantation Registry was screened for cord blood units (CBUs) homozygous for the most common HLA-A, HLA-B and HLA-DRB1 haplotypes. Seven donors were selected with haplotypes covering 21.37% of the haplotypes of the Spanish population. CD34-positive hematopoietic progenitors were isolated from the mononuclear cell fraction of frozen cord blood units from each donor by density gradient centrifugation and further by immune magnetic labeling and separation using purification columns. Purified CD34 + cells were reprogrammed to iPSCs by transduction with the CTS CytoTune-iPS 2.1 Sendai Reprogramming Kit.

RESULTS

The iPSCs generated from the 7 donors were expanded, characterized, banked and registered. Master cell banks (MCBs) and working cell banks (WCBs) from the iPSCs of each donor were produced under GMP conditions in qualified clean rooms.

CONCLUSIONS

Here, we present the first clinical-grade, iPSC haplobank in Spain made from CD34 + cells from seven cord blood units homozygous for the most common HLA-A, HLA-B and HLA-DRB1 haplotypes within the Spanish population. We describe their generation by transduction with Sendai viral vectors and their GMP-compliant expansion and banking. These haplolines will constitute starting materials for advanced therapy medicinal product development (ATMP).

About the relationship of the processing conditions, mechanical properties, and microstructure of a co-precipitated Fe/Cu prealloyed powder

The sinterability of a commercial Fe-Cu pre-alloyed powder, designed to be used as a metallic bond in diamond impregnated tools, has been greatly analyzed by combining dilatometry, computational thermodynamic calculations, and microstructural analysis. The effect of sintering temperature and alloying elements such as graphite and iron phosphide have been taken into consideration in order to demonstrate the capability of tailoring final properties through different strategies, and dilatometry and microstructural analysis have been used to understand the densification process of the alloys. Solid phase sintering was the mechanism taking place during thermal cycle. In fact, a liquid phase appears but because of the high densification level at that time mechanisms associated with LPS do not contribute to densification. Discussion about mechanical properties has been related to key microstructural phenomena, i.e., grain growth, phase transformation, precipitation, and solid solution. Obtained hardness ranged from 83 HRB to 106 HRB with yield stresses between 450 MPa and 700 MPa and elongations above 3%, while final tensile properties similar to those obtained by cobalt-based powders processed by hot pressing were also obtained.

P-412 3D live-imaging reconstruction of the human embryo implantation ex vivo

Study question

How do human embryos implant in physiological conditions and develop beyond blastocyst stage?

Summary answer

Human embryos apply forces during invasion of the matrix, the mural trophectoderm undergoes a quick compaction leading to a fast radial expansion of polar side

What is known already

Human embryos can be cultured beyond blastocyst stage using supplements of animal origin, such as fetal bovine serum. However, two main issues limit our understanding of the implantation of the human embryo. First, human embryos do not express fluorescent proteins, severely limiting the access to advanced live-imaging tools. Second, the animal serums may not represent the physiological peri-implantation conditions of the human embryo, thus limiting the reproducibility of the in vitro experiments. Here we combine label-free multiphoton imaging with media formulations including clinical-grade protein supplements from human plasma unlocking the observation of the human embryo in 3D and physiological conditions

Study design, size, duration

We have cultured 150 human embryos from D3 until blastocyst stage and also more than 600 mouse embryos from zygote until blastocyst stage and then transferred them into a 3D implantation platform. All embryos were supplemented with clinical-grade human-derived serum, which is rich in globulins and growth factors, and commercial basal media. The implantation was monitored for 3-to-5 days up until day 11. Traction-force microscopy and molecular imaging was employed to quantify implantation markers.

Participants/materials, setting, methods

Implantation was measured using our novel version of traction-force microscopy, which reveals the force applied by entire embryos during live-imaging experiments. Multiphoton illumination of autofluorescent molecules allows to reconstruct images of live human embryos on 3D at unprecedented resolution. Key molecular markers for the formation of the epiblast rosette (OCT4), extra-embryonic visceral endoderm (GATA4), extra-embryonic ectoderm and trophoblast (CDX2) and primary yolk sac and pre-amniotic cavity were reconstructed in 3D using high resolution confocal imaging.

Main results and the role of chance

The implantation of human embryos was visualized in 3D movies at high resolution, during time-resolved experiments and compared to implantation in mouse embryos. Human embryos undergo a remarkable compaction upon attachment of the polar trophectoderm and thereafter they implant by engaging the matrix through many different points (>8). The post-implantation compaction leads to a strong invasion of the polar trophectoderm, digging large holes in the matrix and expanding radially. Some trophoblast cells escape the embryo colonizing the matrix. Human embryos expressed the correct pattern of molecular markers by day 11 of culture. Actin staining and OCT4 expression revealed the formation of a central rosette defining the pre-amniotic cavity. GATA6 expression defined the visceral endoderm and the formation of a primordial yolk sac. Mouse embryos conversely, compact upon implantation of the mural trophectoderm and are less invasive, typically anchoring to the matrix through 2-to-3 points. Post-implantation culture of mouse embryos starting at zygote was possible until the formation and large expansion of the amniotic cavity, which constituted 2/3 of the whole embryo size, corresponding with the initial steps of gastrulation, longer than any previous protocol Transfer of mouse blastocysts back to receptive mothers resulted in birth of viable litter.

Limitations, reasons for caution

This study has been performed with human embryos ex vivo using bioengineering technology to implant embryos outside the mother uterus. The bio-compatibility of our serum supplements was validated by live birth of transferred embryos in animal models, but would require further evaluation in clinical trials.

Wider implications of the findings

Our work stresses the safety and efficiency of supplementing embryo culture and particularly embryo transfer, with human plasma-derived serums of clinical-grade. The correct expression of main molecular markers indicates that this type of supplementation promotes implantation physiologically, which opens the possibility to employ these serums in the IVF laboratory.

Trial registration number

Not applicable

O-053 ART treatment and pregnancy during covid 19 pandemia: what we learned

In 2020, SARS-CoV-2 and the COVID-19 pandemic had a huge impact on the access to and provision of ART treatments. Gradually, knowledge about the virus and its transmission has become available and has allowed ART activities to resume with certain restrictions. Still, questions on the impact of the virus on fertility and ART treatments remain.

Regarding the possible consequences of COVID-19 in men, ACE2 and TMPRSS2, the receptors required for the viral penetration into cells, are highly expressed in the testis and the presence of SARS-CoV-2 has been demonstrated in the testicular tissue and the ejaculate in a small percentage of males with active and severe COVID-19 infection. Impairment of the sperm quality has been described during the acute and recovery phase of infection.

In the female scenario, low levels of ACE2 have been reported in ovarian tissue and co-expression of ACE2 and TMPRSS2 has been demonstrated in oocytes, zygotes and blastocysts that are thus potentially susceptible to SARS-CoV-2 infection upon exposure to the virus. The endometrium has been shown to be at a low risk of infection. Although infrequent, vertical transmission of SARS-CoV-2 has been reported in cases of severe maternal infection.

The effects of SARS-CoV-2 infection have been analysed in ART patients. Certain studies suggest that ovarian function might be altered and that IVF results could be poorer in patients that have recovered from COVID-19 while others show no evidence of compromised follicular function. The possible effects of vaccination in male and in female patients have also been explored. Neither the ovarian response nor the sperm quality is affected by the administration of COVID-19 vaccines, which are highly recommended in couples planning a pregnancy, either spontaneous or through ART.

During the different waves of the COVID-19 pandemic, the ESHRE COVID-19 Working Group has produced recommendations and publications to guide patients and professionals in their journey through ART during these difficult times.

P–561 Male and female blastocyst: any difference other than the sex?

Study question

Is there any imbalance in the sex ratio (SR) and in the aneuploidy rate of male and female human blastocysts from a PGT-A programme?

Summary answer

Although SR in human blastocysts is significantly male-biased, more aneuploidies are observed among male blastocysts, resulting in comparable euploid male and female embryos available.

What is known already

More boys than girls are born worldwide, meaning that the SR at birth is biased towards males. Differences in the SR of children born after ART have been also reported. Factors such as the insemination technique or the day of embryo transfer have been shown to be related to the SR at birth, but whether the SR is shifted during the preimplantation and/or postimplantation development remains unknown. Study design, size, duration: Embryos from patients undergoing 921 PGT-A cycles from September 2017 to February 2020 were included in the study. Data from the chromosomal constitution of 2637 biopsied blastocysts was retrospectively analysed.

Participants/materials, setting, methods

Embryos were cultured in time-lapse incubators with low oxygen tension (5%) (Embryoscope®; Geri®) using single-step medium (Global®, LifeGlobal®; GTL™, Vitrolife). Blastocyst biopsy was performed between D5-D7 followed by immediate vitrification (Cryotop®, Kitazato). Trophectoderm samples were analysed by NGS. Embryos were categorized as euploid, aneuploid or mosaic. Embryos were called as mosaic when the deviation from the normal copy number was ≥30% and <70%.

Main results and the role of chance

Overall biopsies from 2637 blastocysts were analysed, 1320 on day 5 (50.1%), 1169 on day 6 (44.3%) and 148 on day 7 (5.6%). Sex distribution among the embryos analysed was skewed in favor of male sex with 1401 diagnosed as male (53.1%) and 1236 were female (46.9%), [OR (95%CI):1.13(1.05–1.22)]. As a consequence of this biased SR, more male embryos reached the blastocyst stage and were biopsied both on day 5/6 (708/1320, 53.6% on day 5 and 619/1169, 53% on day 6). Embryos biopsied on day 7 were balanced between sexes with 50% being male and 50% being female. Following biopsy and PGT-A, 1086 (41.2%) of the embryos were classified as euploid, 1349 (51.16%) as aneuploid, and 202 (7.7%) as mosaic embryos. More chromosomal anomalies were observed among male blastocysts when compared to the female ones, 738 (52.7%) vs 611 (49.4%). Similarly, mosaicism was more frequents in male as compared with female blastocysts, 123 (8.8%) vs 79 (6.4%). (P = 0.000). As more aneuploidies are observed among male blastocysts, the final number of available euploid blastocysts for embryo transfer was comparable between sexes (540 male/546 female), [OR (95%CI): 0.99 (0.87–1.11)].

Limitations, reasons for caution

This is a retrospective study. Only embryos at the blastocyst stage have been analyzed. Potential confounding factors such as sperm quality or the female age have not been analyzed. No data regarding the SR at birth have been analyzed in these study.

Wider implications of the findings: In our study, more male embryos develop to the blastocyst when compared to female ones. It can be hypothesized that female embryos can be more affected by an early arrest at cleavage stages. SR at birth would be expected to be similar as more aneuploidy is observed in male embryos.

Trial registration number

Not applicable

Electrocardiographic markers of incident atrial fibrillation in patients with cryptogenic stroke

Funding Acknowledgements

Type of funding sources: None.

Introduction

Prolonged screening of AF in patients (pts) with cryptogenic stroke (CS) is recommended and electrocardiographic markers of atrial remodeling, like p-wave dispersion, have been described in literature. Electrocardiographic changes in pts with CS to predict AF in the follow up are not well-established.

Purpose

To identify ECG predictors of AF in a subset of pts with cryptogenic stroke.

Methods

We prospectively included consecutive pts admitted with CS. A surface 12-lead ECG was performed at admission, recorded at 25 mm/second and 10 mV/cm with commercially available imaging system. P-wave analysis of maximum (P max) and minimum (P min) duration, p-wave dispersion (PWD, defined as the difference between the P max and P min, being abnormal if > 40 msec) and amplitude were evaluated by a two independent operator. P-wave axis was determined by an automated mode available in the equipment. ROC curve was analyzed to determine the optimal cut-off values.

Results

We enrolled 105 pts (55.2% males), with mean age of 68.18 ± 8.83 years, 79% had hypertension, 18.1% had diabetes, 44.8% with dyslipidemia, 21% current smokers.

During follow up period, 18 pts (17.1%) developed AF. We found that only PWD (AUC 0.706, IC95%: 0.564-0.848, p = 0.006) and P-wave axis (AUC 0.715, IC95%: 0.870-0.860, p = 0.004) were strong predictors of AF. PWD cut-off of 47.50 presented a sensitivity of 77.8% and specificity of 59.8% and P-wave axis cut off value of 75.50 had a specificity of 95.4%. Age (p = 0.032) and current smoking (p = 0.014) were associated with occurrence of AF during the follow up.

  Conclusion: PWD and P-wave axis predicted incident AF in this subset of pts with cryptogenic stroke. The ECG may be a toll to identify pts at risk of developing AF, although larger studies are needed to confirm these results. Abstract Figure.

Derivation of induced pluripotent stem cells (iPSCs) by retroviral transduction of skin fibroblasts from four patients suffering 7q11.23 microduplication syndrome

Skin fibroblasts were obtained from four patients with 7q11.23 microduplication syndrome carrying the reciprocal rearrangement of Williams-Beuren syndrome at the 7q11.23 genomic region. Induced pluripotent stem cells (iPSCs) were generated by retroviral infection of fibroblasts with polycystronic vectors. The generated iPSC clones ESi058B, ESi057B, ESi070A and ESi071A had the 7q11.23 duplication with no additional genomic alterations, a stable karyotype, expressed pluripotency markers and could differentiate towards the three germ layers in vitro via embryoid body formation and in vivo by teratoma formation. Patient's derived iPSCs are a valuable resource for in vitro modeling of 7q11.23 microduplication syndrome. Resource Table.

Microgravity effects on frozen human sperm samples

PURPOSE

Microgravity has severe effects on cellular and molecular structures as well as on metabolic interactions. The aim of this study is to investigate the effects of microgravity (μg) exposure on human frozen sperm samples.

METHODS

Sibling samples from 15 normozoospermic healthy donors were frozen using glycerol as cryoprotectant and analyzed under microgravity and ground conditions. Microgravity was obtained by parabolic flights using a CAP10B plane. The plane executed 20 parabolic maneuvers with a mean of 8.5 s of microgravity for each parabola.

RESULTS

Frozen sperm samples preserved in cryostraws and stored in a secure and specific nitrogen vapor cryoshipper do not suffer significant alterations after μg exposure. Comparing the study group (μg) and the control group (1 g), similar results were obtained in the main parameters studied: sperm motility (M/ml) 13.72 ± 12.57 vs 13.03 ± 12.13 (- 0.69 95% CI [- 2.9; 1.52]), progressive a + b sperm motility (%) 21.83 ± 11.69 vs 22.54 ± 12.83 (0.03 95% CI [- 0.08; 0.15]), sperm vitality (%) 46.42 ± 10.81 vs 44.62 ± 9.34 (- 0.04 95% CI [- 0.13; 0.05]), morphologically normal spermatozoa (%) 7.03 ± 2.61 vs 8.09 ± 3.61 (0.12 95% CI [0.01; 0.24]), DNA sperm fragmentation by SCD (%) 13.33 ± 5.12 vs 13.88 ± 6.14 (0.03 95% CI [- 0.09; 0.16]), and apoptotic spermatozoa by MACS (%) 15.47 ± 15.04 vs 23.80 ± 23.63 (- 0.20 95% CI [- 0.66; 1.05]).

CONCLUSION

The lack of differences obtained between frozen samples exposed to μg and those maintained in ground conditions provides the possibility of considering the safe transport of human male gametes to space. Nevertheless, further research is needed to validate the results and to consider the possibility of creating a human sperm bank outside the Earth.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov: NCT03760783.

Two decades of embryonic stem cells: a historical overview

STUDY QUESTION

How did the field of stem cell research develop in the years following the derivation of the first human embryonic stem cell (hESC) line?

SUMMARY ANSWER

Supported by the increasing number of clinical trials to date, significant technological advances in the past two decades have brought us ever closer to clinical therapies derived from pluripotent cells.

WHAT IS KNOWN ALREADY

Since their discovery 20 years ago, the use of human pluripotent stem cells has progressed tremendously from bench to bedside. Here, we provide a concise review of the main keystones of this journey and focus on ongoing clinical trials, while indicating the most relevant future research directions.

STUDY DESIGN, SIZE, DURATION

This is a historical narrative, including relevant publications in the field of pluripotent stem cells (PSC) derivation and differentiation, recounted both through scholarly research of published evidence and interviews of six pioneers who participated in some of the most relevant discoveries in the field.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The authors all contributed by researching the literature and agreed upon body of works. Portions of the interviews of the field pioneers have been integrated into the review and have also been included in full for advanced reader interest.

MAIN RESULTS AND THE ROLE OF CHANCE

The stem cell field is ever expanding. We find that in the 20 years since the derivation of the first hESC lines, several relevant developments have shaped the pluripotent cell field, from the discovery of different states of pluripotency, the derivation of induced PSC, the refinement of differentiation protocols with several clinical trials underway, as well as the recent development of organoids. The challenge for the years to come will be to validate and refine PSCs for clinical use, from the production of highly defined cell populations in clinical grade conditions to the possibility of creating replacement organoids for functional, if not anatomical, function restoration.

LIMITATIONS, REASONS FOR CAUTION

This is a non-systematic review of current literature. Some references may have escaped the experts’ analysis due to the exceedingly diverse nature of the field. As the field of regenerative medicine is rapidly advancing, some of the most recent developments may have not been captured entirely.

WIDER IMPLICATIONS OF THE FINDINGS

The multi-disciplinary nature and tremendous potential of the stem cell field has important implications for basic as well as translational research. Recounting these activities will serve to provide an in-depth overview of the field, fostering a further understanding of human stem cell and developmental biology. The comprehensive overview of clinical trials and expert opinions included in this narrative may serve as a valuable scientific resource, supporting future efforts in translational approaches.

STUDY FUNDING/COMPETING INTEREST(S)

ESHRE provided funding for the authors’ on-site meeting and discussion during the preparation of this manuscript. S.M.C.S.L. is funded by the European Research Council Consolidator (ERC-CoG-725722-OVOGROWTH). M.P. is supported by the Special Research Fund, Bijzonder Onderzoeksfonds (BOF01D08114). M.G. is supported by the Methusalem grant of Vrije Universiteit Brussel, in the name of Prof. Karen Sermon and by Innovation by Science and Technology in Flanders (IWT, Project Number: 150042). A.V. and B.A. are supported by the Plataforma de Proteomica, Genotipado y Líneas Celulares (PT1770019/0015) (PRB3), Instituto de Salud Carlos III. Research grant to B.H. by the Research Foundation—Flanders (FWO) (FWO.KAN.2016.0005.01 and FWO.Project G051516N). There are no conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

Not applicable.

ESHRE Pages are not externally peer reviewed. This article has been approved by the Executive Committee of ESHRE.

Nanoclusters of crystallographically aligned nanoparticles for magnetic thermotherapy: aqueous ferrofluid, agarose phantoms and ex vivo melanoma tumour assessment

Magnetic hyperthermia is an oncological therapy where magnetic nanostructures, under a radiofrequency field, act as heat transducers increasing tumour temperature and killing cancerous cells. Nanostructure heating efficiency depends both on the field conditions and on the nanostructure properties and mobility inside the tumour. Such nanostructures are often incorrectly bench-marketed in the colloidal state and using field settings far off from the recommended therapeutic values. Here, we prepared nanoclusters composed of iron oxide magnetite nanoparticles crystallographically aligned and their specific absorption rate (SAR) values were calorimetrically determined in physiological fluids, agarose-gel-phantoms and ex vivo tumours extracted from mice challenged with B16-F0 melanoma cells. A portable, multipurpose applicator using medical field settings; 100 kHz and 9.3 kA m^-1, was developed and the results were fully analysed in terms of nanoclusters' structural and magnetic properties. A careful evaluation of the nanoclusters' heating capacity in the three milieus clearly indicates that the SAR values of fluid suspensions or agarose-gel-phantoms are not adequate to predict the real tissue temperature increase or the dosage needed to heat a tumour. Our results show that besides nanostructure mobility, perfusion and local thermoregulation, the nanostructure distribution inside the tumour plays a key role in effective heating. A suppression of the magnetic material effective heating efficiency appears in tumour tissue. In fact, dosage had to be increased considerably, from the SAR values predicted from fluid or agarose, to achieve the desired temperature increase. These results represent an important contribution towards the design of more efficient nanostructures and towards the clinical translation of hyperthermia.

Recent developments in genetics and medically assisted reproduction: from research to clinical applications

Two leading European professional societies, the European Society of Human Genetics and the European Society for Human Reproduction and Embryology, have worked together since 2004 to evaluate the impact of fast research advances at the interface of assisted reproduction and genetics, including their application into clinical practice. In September 2016, the expert panel met for the third time. The topics discussed highlighted important issues covering the impacts of expanded carrier screening, direct-to-consumer genetic testing, voiding of the presumed anonymity of gamete donors by advanced genetic testing, advances in the research of genetic causes underlying male and female infertility, utilisation of massively parallel sequencing in preimplantation genetic testing and non-invasive prenatal screening, mitochondrial replacement in human oocytes, and additionally, issues related to cross-generational epigenetic inheritance following IVF and germline genome editing. The resulting paper represents a consensus of both professional societies involved.

Recent developments in genetics and medically-assisted reproduction: from research to clinical applications†‡

Two leading European professional societies, the European Society of Human Genetics and the European Society for Human Reproduction and Embryology, have worked together since 2004 to evaluate the impact of fast research advances at the interface of assisted reproduction and genetics, including their application into clinical practice. In September 2016, the expert panel met for the third time. The topics discussed highlighted important issues covering the impacts of expanded carrier screening, direct-to-consumer genetic testing, voiding of the presumed anonymity of gamete donors by advanced genetic testing, advances in the research of genetic causes underlying male and female infertility, utilisation of massively-parallel sequencing in preimplantation genetic testing and non-invasive prenatal screening, mitochondrial replacement in human oocytes, and additionally, issues related to cross-generational epigenetic inheritance following IVF and germline genome editing. The resulting paper represents a consensus of both professional societies involved.

Generation of six multiple sclerosis patient-derived induced pluripotent stem cell lines

Multiple sclerosis (MS) is considered a chronic autoimmune disease of the central nervous system that leads to gliosis, demyelination, axonal damage and neuronal death. The MS disease aetiology is unknown, though a polymorphism of the TNFRSF1A gene, rs1800693, is known to confer an increased risk for MS. Using retroviral delivery of reprogramming transgenes, we generated six MS patient-specific iPSC lines with two distinct genotypes, CC or TT, of the polymorphism rs1800693. iPSC lines had normal karyotype, expressed pluripotency genes and differentiated into the three germ layers. These lines offer a good tool to study MS pathomechanisms and for drug testing.

Molecular markers of putative spermatogonial stem cells in the domestic cat

Spermatogonial stem cells (SSCs) are an important tool for fertility preservation and species conservation. The ability to expand SSCs by in vitro culture is a crucial premise for their use in assisted reproduction. Because SSCs represent a small proportion of the germ cells in the adult testis, culture success is aided by pre-enrichment through sorting techniques based on cell surface-specific markers. Given the importance of the domestic cat as a model for conservation of endangered wild felids, herein we sought to examine culture conditions as well as molecular markers for cat SSCs. Using a cell culture medium for mouse SSCs supplemented with glial cell-derived neurotrophic factor (GDNF), germ cells from prepuberal cat testes remained viable in culture for up to 43 days. Immunohistochemistry for promyelocytic leukaemia zinc finger (PLZF) protein on foetal, prepuberal and adult testis sections revealed a pattern of expression consistent with the labelling of undifferentiated spermatogonia. Fluorescence-activated cell sorting (FACS) with an antibody against epithelial cell adhesion molecule (EPCAM) was used to sort live cells. Then, the gene expression profile of EPCAM-sorted cells was investigated through RT-qPCR. Notably, EPCAM (+) cells expressed relatively high levels of CKIT (CD117), a surface protein typically expressed in differentiating germ cells but not SSCs. Conversely, EPCAM (-) cells expressed relatively high levels of POU domain class 5 transcription factor 1 (POU1F5 or OCT4), clearly a germ line stem cell marker. These results suggest that cat SSCs would probably be found within the population of EPCAM (-) cells. Future studies should identify additional surface markers that alone or in combination can be used to further enrich SSCs from cat germ cells.

The quantum CP-violating kaon system reproduced in the electronic laboratory

The equivalence between the Schrödinger dynamics of a quantum system with a finite number of basis states and a classical dynamics is realized in terms of electric networks. The isomorphism that connects in a univocal way both dynamical systems was applied to the case of neutral mesons, kaons in particular, and the class of electric networks univocally related to the quantum system was analysed. Moreover, under CPT invariance, the relevant ϵ parameter that measures CP violation in the kaon system is reinterpreted in terms of network parameters. All these results were explicitly shown by means of both a numerical simulation of the implied networks and by constructing the corresponding circuits.

Genome engineering through CRISPR/Cas9 technology in the human germline and pluripotent stem cells

BACKGROUND

With the recent development of CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 genome editing technology, the possibility to genetically manipulate the human germline (gametes and embryos) has become a distinct technical possibility. Although many technical challenges still need to be overcome in order to achieve adequate efficiency and precision of the technology in human embryos, the path leading to genome editing has never been simpler, more affordable, and widespread.

OBJECTIVE AND RATIONALE

In this narrative review we seek to understand the possible impact of CRISR/Cas9 technology on human reproduction from the technical and ethical point of view, and suggest a course of action for the scientific community.

SEARCH METHODS

This non-systematic review was carried out using Medline articles in English, as well as technical documents from the Human Fertilisation and Embryology Authority and reports in the media. The technical possibilities of the CRISPR/Cas9 technology with regard to human reproduction are analysed based on results obtained in model systems such as large animals and laboratory rodents. Further, the possibility of CRISPR/Cas9 use in the context of human reproduction, to modify embryos, germline cells, and pluripotent stem cells is reviewed based on the authors' expert opinion. Finally, the possible uses and consequences of CRISPR/cas9 gene editing in reproduction are analysed from the ethical point of view.

OUTCOMES

We identify critical technical and ethical issues that should deter from employing CRISPR/Cas9 based technologies in human reproduction until they are clarified.

WIDER IMPLICATIONS

Overcoming the numerous technical limitations currently associated with CRISPR/Cas9 mediated editing of the human germline will depend on intensive research that needs to be transparent and widely disseminated. Rather than a call to a generalized moratorium, or banning, of this type of research, efforts should be placed on establishing an open, international, collaborative and regulated research framework. Equally important, a societal discussion on the risks, benefits, and preferred applications of the new technology, including all relevant stakeholders, is urgently needed and should be promoted, and ultimately guide research priorities in this area.

Stem cells in reproductive medicine: ready for the patient?

STUDY QUESTION

Are there effective and clinically validated stem cell-based therapies for reproductive diseases?

SUMMARY ANSWER

At the moment, clinically validated stem cell treatments for reproductive diseases and alterations are not available.

WHAT IS KNOWN ALREADY

Research in stem cells and regenerative medicine is growing in scope, and its translation to the clinic is heralded by the recent initiation of controlled clinical trials with pluripotent derived cells. Unfortunately, stem cell 'treatments' are currently offered to patients outside of the controlled framework of scientifically sound research and regulated clinical trials. Both physicians and patients in reproductive medicine are often unsure about stem cells therapeutic options.

STUDY DESIGN, SIZE, DURATION

An international working group was assembled to review critically the available scientific literature in both the human species and animal models.

PARTICIPANTS/MATERIALS, SETTING, METHODS

This review includes work published in English until December 2014, and available through Pubmed.

MAIN RESULTS AND THE ROLE OF CHANCE

A few areas of research in stem cell and reproductive medicine were identified: in vitro gamete production, endometrial regeneration, erectile dysfunction amelioration, vaginal reconstruction. The stem cells studied range from pluripotent (embryonic stem cells and induced pluripotent stem cells) to monopotent stem cells, such as spermatogonial stem cells or mesenchymal stem cells. The vast majority of studies have been carried out in animal models, with data that are preliminary at best.

LIMITATIONS, REASONS FOR CAUTION

This review was not conducted in a systematic fashion, and reports in publications not indexed in Pubmed were not analyzed.

WIDER IMPLICATIONS OF THE FINDINGS

A much broader clinical knowledge will have to be acquired before translation to the clinic of stem cell therapies in reproductive medicine; patients and physicians should be wary of unfounded claims of improvement of existing medical conditions; at the moment, effective stem cell treatment for reproductive diseases and alterations is not available.

STUDY FUNDING/COMPETING INTERESTS

None.

TRIAL REGISTRATION NUMBER

NA.

Complete meiosis from human induced pluripotent stem cells

Gamete failure-derived infertility affects millions of people worldwide; for many patients, gamete donation by unrelated donors is the only available treatment. Embryonic stem cells (ESCs) can differentiate in vitro into germ-like cells, but they are genetically unrelated to the patient. Using an in vitro protocol that aims at recapitulating development, we have achieved, for the first time, complete differentiation of human induced pluripotent stem cells (hiPSCs) to postmeiotic cells. Unlike previous reports using human ESCs, postmeiotic cells arose without the over-expression of germline related transcription factors. Moreover, we consistently obtained haploid cells from hiPSCs of different origin (keratinocytes and cord blood), produced with a different number of transcription factors, and of both genetic sexes, suggesting the independence of our approach from the epigenetic memory of the reprogrammed somatic cells. Our work brings us closer to the production of personalized human gametes in vitro.

[Last morphological selection]

Selection criteria for embryo transfer is an essential step in ART. Evaluation of pronuclear morphology, evaluation of zygote, embryo cleavage, quality of blastomeres predict the viability of embryos. Multinucleation in cleavage stage embryos is associated with a lower implantation and pregnancy rate.

A physiological replacement for polyvinylpyrrolidone (PVP) in assisted reproductive technology

The technique of intracytoplasmic sperm injection (ICSI) requires mechanical immobilization of the sperm that are to be injected; damage thus caused to the sperm membrane is considered to be necessary to activate the sperm for fertilization. Mechanical immobilization and the injection procedure are facilitated by introducing the sperm into a viscous medium that will hinder motility: a solution of polyvinylpyrrolidone (PVP) has been used successfully for this purpose. PVP is an artificial polymer, which has been regarded as chemically inert, although adverse effects have been reported as a result of its use both in vivo and in vitro. Therefore, the use of hyaluronate, the natural component of the extracellular matrix of the cumulus-oocyte complex, was investigated as a replacement for PVP during ICSI. A solution of hyaluronate was found to be as effective as PVP in facilitating the injection procedure, its effect on sperm motility was readily reversible, and its use did not affect the outcome of the treatment cycles in terms of fertilization, pregnancy and live birth rates. Every attempt should be made to eliminate artificial factors in assisted reproductive procedures. Hyaluronate, a natural and readily degradable glycosaminoglycan can be used as a substitute for the artificial PVP polymer without jeopardising the outcome of the treatment cycle.

Creation of a registry for human embryonic stem cells carrying an inherited defect: joint collaboration between ESHRE and hESCreg

Human embryonic stem cells (hESCs), derived from human blastocysts, hold a great promise for regenerative medicine, drug development and basic research in developmental biology. Moreover, hESC lines that carry a clinically relevant inherited defect, monogenic or chromosomal, present an important tool for research into the pathophysiology of these diseases. The hESC registry (hESCreg) was started up in 2007 in order to register all stem cell lines derived in Europe (www.hescreg.eu). Because of the special nature of the hESC lines that carry an inherited disease, they are of particular interest to researchers outside the assisted reproductive technologies or stem cell fields, for instance, those involved in regenerative medicine and in medical and human genetics. To reach these researchers, and to better disseminate the information on the cell lines, a concerted action of the hESCreg together with ESHRE's Special Interest Groups in Reproductive Genetics and Stem Cells was initiated. This mini-review is a first report that will be followed by yearly reports of new lines, not unlike the reports from the Preimplantation Genetic Diagnosis Consortium or the European IVF Monitoring.