Effects of prenatal acetaminophen exposure at different stages, doses and courses on articular cartilage of offspring mice

Previous studies showed that chondrodysplasia has intrauterine origin. Although prenatal acetaminophen exposure (PAcE) can cause nervous and reproductive abnormalities in offspring, its effect on cartilage is uninvestigated. Herein, mice were treated with different doses and courses of acetaminophen at various gestational stages (100 or 400 mg/kg∙d on gestational days 10-12 (GD10-12), 400 mg/kg∙d on GD12 or GD15-17) based on clinical administration and conversion between humans and mice. Fetal knee joints were harvested on GD18 to analyze cartilage morphology, chondrocyte proliferation and apoptosis, and matrix content, synthesis and degradation. Results showed that 400 mg/kg∙d acetaminophen exposure during GD10-12 decreased chondrocyte numbers, safranin O staining, proliferation and matrix synthesis, without elevating matrix degradation and apoptosis. Low-dose, single-course, or late-pregnancy exposure had no effect on above indexes. Moreover, Tgfβ pathway was inhibited, showing a positive correlation with the expression of Col2a1, Acan, Ki67, and Pcna. Overall, clinical doses of PAcE can inhibit chondrocyte proliferation and matrix synthesis, causing fetal mice chondrodysplasia, especially after multi-course exposure of 400 mg/kg∙d acetaminophen during GD10-12, the mechanism of which might involve Tgfβ pathway inhibition. This study provides an experimental basis for assessing fetal developmental toxicity and standardizing the clinical use of acetaminophen during pregnancy.

Human-Based New Approach Methodologies in Developmental Toxicity Testing: A Step Ahead from the State of the Art with a Feto-Placental Organ-on-Chip Platform

Developmental toxicity testing urgently requires the implementation of human-relevant new approach methodologies (NAMs) that better recapitulate the peculiar nature of human physiology during pregnancy, especially the placenta and the maternal/fetal interface, which represent a key stage for human lifelong health. Fit-for-purpose NAMs for the placental-fetal interface are desirable to improve the biological knowledge of environmental exposure at the molecular level and to reduce the high cost, time and ethical impact of animal studies. This article reviews the state of the art on the available in vitro (placental, fetal and amniotic cell-based systems) and in silico NAMs of human relevance for developmental toxicity testing purposes; in addition, we considered available Adverse Outcome Pathways related to developmental toxicity. The OECD TG 414 for the identification and assessment of deleterious effects of prenatal exposure to chemicals on developing organisms will be discussed to delineate the regulatory context and to better debate what is missing and needed in the context of the Developmental Origins of Health and Disease hypothesis to significantly improve this sector. Starting from this analysis, the development of a novel human feto-placental organ-on-chip platform will be introduced as an innovative future alternative tool for developmental toxicity testing, considering possible implementation and validation strategies to overcome the limitation of the current animal studies and NAMs available in regulatory toxicology and in the biomedical field.

Neuronal and cardiac toxicity of pharmacological compounds identified through transcriptomic analysis of human pluripotent stem cell-derived embryoid bodies

Concurrent with the '3R' principle, the embryonic stem cell test (EST) using mouse embryonic stem cells, developed in 2000, remains the solely accepted in vitro method for embryotoxicity testing. However, the scope and implementation of EST for embryotoxicity screening, compliant with regulatory requirements, are limited. This is due to its technical complexity, long testing period, labor-intensive methodology, and limited endpoint data, leading to misclassification of embryotoxic potential. In this study, we used human induced pluripotent stem cell (hiPSC)-derived embryoid bodies (EB) as an in vitro model to investigate the embryotoxic effects of a carefully selected set of pharmacological compounds. Morphology, viability, and differentiation potential were investigated after exposing EBs to folic acid, all-trans-retinoic acid, dexamethasone, and valproic acid for 15 days. The results showed that the compounds differentially repressed cell growth, compromised morphology, and triggered apoptosis in the EBs. Further, transcriptomics was employed to compare subtle temporal changes between treated and untreated cultures. Gene ontology and pathway analysis revealed that dysregulation of a large number of genes strongly correlated with impaired neuroectoderm and cardiac mesoderm formation. This aberrant gene expression pattern was associated with several disorders of the brain like mental retardation, multiple sclerosis, stroke and of the heart like dilated cardiomyopathy, ventricular tachycardia, and ventricular arrhythmia. Lastly, these in vitro findings were validated using in ovo chick embryo model. Taken together, pharmacological compound or drug-induced defective EB development from hiPSCs could potentially be used as a suitable in vitro platform for embryotoxicity screening.

Bioinformatics analysis of biomarkers of aristolochic acid-induced early nephrotoxicity in embryonic stem cells

The present study aimed to identify key genes as potential biomarkers for early nephrotoxicity induced by aristolochic acid (AA) in embryonic stem cells (ESCs). An MTT assay was performed to determine the cytotoxicity of AA in ESCs. Differentially expressed genes (DEGs) were identified using the DNA-Chip Analyzer following microarray analysis. Gene Ontology analysis was performed to determine functional terms enriched by the DEGs in the categories biological process, cellular component and molecular function. Furthermore, the DEGs were subjected to Kyoto Encyclopedia of Genes and Genomes analysis to determine pathways they were accumulated in. Furthermore, a protein-protein interaction network was constructed using Cytoscape 3.2 software. Tumor protein 53 apoptosis effector (Perp), cation transport regulator-like 1 (Chac1), adrenoceptor β2 and Wnt6 were selected for confirmation by reverse transcription-quantitative (RT-q) PCR analysis. A total of 72 DEGs (49 upregulated and 23 downregulated) were identified. The DEGs were enriched in functional terms and pathways associated with nephrotoxicity and participated in 92 pathways. A total of two hub genes, fructose-1,6-bisphosphatase (Fbp)1 and Fbp2, were filtered out from the interaction network. Perp and phorbol-12-myristate-13-acetate-induced protein 1 were demonstrated to have vital roles in the p53 signaling pathway which was indicated in the interaction network. The results of the RT-qPCR analysis were consistent with the microarray data. Taken together, the present study suggested that hub genes involved in the p53 pathway, including Fbp1, Fbp2 and Perp, may serve as potential biomarkers for early nephrotoxicity induced by AA.

Translational mechanobiology: Designing synthetic hydrogel matrices for improved in vitro models and cell-based therapies

Synthetic hydrogels have ideal physiochemical properties to serve as reductionist mimics of the extracellular matrix (ECM) for studies on cellular mechanosensing. These studies range from basic observation of correlations between ECM mechanics and cell fate changes to molecular dissection of the underlying mechanisms. Despite intensive work on hydrogels to study mechanobiology, many fundamental questions regarding mechanosensing remain unanswered. In this review, I first discuss historical motivation for studying cellular mechanobiology, and challenges impeding this effort. I next overview recent efforts to engineer hydrogel properties to study cellular mechanosensing. Finally, I focus on in vitro modeling and cell-based therapies as applications of hydrogels that will exploit our ability to create micro-environments with physiologically relevant elasticity and viscoelasticity to control cell biology. These translational applications will not only use our current understanding of mechanobiology but will also bring new tools to study the fundamental problem of how cells sense their mechanical environment. STATEMENT OF SIGNIFICANCE: Hydrogels are an important tool for understanding how our cells can sense their mechanical environment, and to exploit that understanding in regenerative medicine. In the current review, I discuss historical work linking mechanics to cell behavior in vitro, and highlight the role hydrogels played in allowing us to understand how cells monitor mechanical cues. I then highlight potential translational applications of hydrogels with mechanical properties similar to those of the tissues where cells normally reside in our bodies, and discuss how these types of studies can provide clues to help us enhance our understanding of mechanosensing.

Using a Multi-Stage hESC Model to Characterize BDE-47 Toxicity during Neurogenesis

While the ramifications associated with polybrominated diphenyl ethers (PBDE) exposures during human pregnancy have yet to be determined, increasing evidence in humans and animal models suggests that these compounds cause neurodevelopmental toxicity. Human embryonic stem cell models (hESCs) can be used to study the effects of environmental chemicals throughout the successive stages of neuronal development. Here, using a hESC differentiation model, we investigated the effects of common PBDE congeners (BDE-47 or -99) on the successive stages of early neuronal development. First, we determined the points of vulnerability to PBDEs across four stages of in vitro neural development by using assays to assess for cytotoxicity. Differentiated neural progenitors were identified to be more sensitive to PBDEs than their less differentiated counterparts. In follow-up investigations, we observed BDE-47 to inhibit functional processes critical for neurogenesis (e.g., proliferation, expansion) in hESC-derived neural precursor cells (NPCs) at sub-lethal concentrations. Finally, to determine the mechanism(s) underlying PBDE-toxicity, we conducted global transcriptomic and methylomic analyses of BDE-47. We identified 589 genes to be differentially expressed (DE) due to BDE-47 exposure, including molecules involved in oxidative stress mediation, cell cycle, hormone signaling, steroid metabolism, and neurodevelopmental pathways. In parallel analyses, we identified a broad significant increase in CpG methylation. In summary our results suggest, on a cellular level, PBDEs induce human neurodevelopmental toxicity in a concentration-dependent manner and sensitivity to these compounds is dependent on the developmental stage of exposure. Proposed mRNA and methylomic perturbations may underlie toxicity in early embryonic neuronal populations.

Di-(2-ethylhexyl)-phthalate induces apoptosis via the PPARγ/PTEN/AKT pathway in differentiated human embryonic stem cells

[OBJECTIVE]: Di(2-ethylhexyl) phthalate (DEHP), a widely used plasticizer, may act as an endocrine disruptor and cause developmental toxicity. Differentiated human embryonic stem cells (hESCs) were used to investigate the underlying mechanism of the embryotoxicity induced by DEHP. [Materials and Methods] H9-hESCs were treated with DEHP at different concentrations for 10 days, and the cytotoxicity of DEHP on cell proliferation was determined using a cell-microelectronic sensing technique (Real-Time Cellular Analysis: RTCA). Based on the 50% inhibitory proliferation concentration (IC₅₀), differentiated H9-hESCs were treated with DEHP at 0, 50, 100, and 200 μg/ml for 120 h, followed by measurement of its toxic effects on the transcriptome by mRNA microarray and QuantiGene Plex (QGP). Proteins were detected by the iTRAQ-based proteomics method and the proteins related to the PPARγ/PTEN/Akt pathways were measured by western blotting. The progression of the cell cycle and apoptosis were characterized using flow cytometry (FCM). In other experiments, hESCs were pre-treated with GW9662 (20 μM), a specific PPARγ inhibitor, for 30 min, followed by exposure to GW9662 (20 μM) and DEHP (200 μg/ml) for 120 h to observe the underlying mechanism of DEHP's embryotoxicity. [RESULTS]: DEHP inhibited H9-hESC cell proliferation in a dose-dependent manner, with an IC₅₀ of 165.78 μg/ml. FCM results showed that DEHP could markedly induce cell cycle arrest and increase apoptosis. Gene microarray and QPG array analyses indicated that the peroxisome proliferator-activated receptor γ (PPARγ) was an apparent target for DEHP. We further demonstrated that DEHP could activate the PPARγ and upregulate the expression of PTEN downstream genes, and then play a negative role in the AKT signaling pathway. Cells pretreated with PPARγ inhibitor, GW9662, were shown to restore the effect of DEHP on the PPARγ/PTEN/AKT signaling pathway, and induce the recovery of cell cycle arrest and apoptosis. [CONCLUSION]: DEHP inhibited cell proliferation, promoted cell cycle arrest, and induced apoptosis through the PPARγ/PTEN/AKT signaling pathway in differentiated human embryonic stem cells. It suggested that DEHP exposure possibly cause reproductive or developmental toxicity in humans through the PPARγ signaling pathway.

Human-induced pluripotent stems cells as a model to dissect the selective neurotoxicity of methylmercury

Methylmercury (MeHg) is a potent neurotoxicant affecting both the developing and mature central nervous system (CNS) with apparent indiscriminate disruption of multiple homeostatic pathways. However, genetic and environmental modifiers contribute significant variability to neurotoxicity associated with human exposures. MeHg displays developmental stage and neural lineage selective neurotoxicity. To identify mechanistic-based neuroprotective strategies to mitigate human MeHg exposure risk, it will be critical to improve our understanding of the basis of MeHg neurotoxicity and of this selective neurotoxicity. Here, we propose that human-based pluripotent stem cell cellular approaches may enable mechanistic insight into genetic pathways that modify sensitivity of specific neural lineages to MeHg-induced neurotoxicity. Such studies are crucial for the development of novel disease modifying strategies impinging on MeHg exposure vulnerability.

Nanoparticle-induced neuronal toxicity across placental barriers is mediated by autophagy and dependent on astrocytes

The potential for maternal nanoparticle (NP) exposures to cause developmental toxicity in the fetus without the direct passage of NPs has previously been shown, but the mechanism remained elusive. We now demonstrate that exposure of cobalt and chromium NPs to BeWo cell barriers, an in vitro model of the human placenta, triggers impairment of the autophagic flux and release of interleukin-6. This contributes to the altered differentiation of human neural progenitor cells and DNA damage in the derived neurons and astrocytes. Crucially, neuronal DNA damage is mediated by astrocytes. Inhibiting the autophagic degradation in the BeWo barrier by overexpression of the dominant-negative human ATG4B^C74A significantly reduces the levels of DNA damage in astrocytes. In vivo, indirect NP toxicity in mice results in neurodevelopmental abnormalities with reactive astrogliosis and increased DNA damage in the fetal hippocampus. Our results demonstrate the potential importance of autophagy to elicit NP toxicity and the risk of indirect developmental neurotoxicity after maternal NP exposure.

Recommendation on test readiness criteria for new approach methods in toxicology: Exemplified for developmental neurotoxicity

Multiple non-animal-based test methods have never been formally validated. In order to use such new approach methods (NAMs) in a regulatory context, criteria to define their readiness are necessary. The field of developmental neurotoxicity (DNT) testing is used to exemplify the application of readiness criteria. The costs and number of untested chemicals are overwhelming for in vivo DNT testing. Thus, there is a need for inexpensive, high-throughput NAMs, to obtain initial information on potential hazards, and to allow prioritization for further testing. A background on the regulatory and scientific status of DNT testing is provided showing different types of test readiness levels, depending on the intended use of data from NAMs. Readiness criteria, compiled during a stakeholder workshop, uniting scientists from academia, industry and regulatory authorities are presented. An important step beyond the listing of criteria, was the suggestion for a preliminary scoring scheme. On this basis a (semi)-quantitative analysis process was assembled on test readiness of 17 NAMs with respect to various uses (e.g. prioritization/screening, risk assessment). The scoring results suggest that several assays are currently at high readiness levels. Therefore, suggestions are made on how DNT NAMs may be assembled into an integrated approach to testing and assessment (IATA). In parallel, the testing state in these assays was compiled for more than 1000 compounds. Finally, a vision is presented on how further NAM development may be guided by knowledge of signaling pathways necessary for brain development, DNT pathophysiology, and relevant adverse outcome pathways (AOP).

Stem cell toxicology: a powerful tool to assess pollution effects on human health

Environmental pollution is a global problem; the lack of comprehensive toxicological assessments may lead to increased health risks. To fully understand the health effects of pollution, it is paramount to implement fast, efficient and specific toxicity screening that relies on human models rather than on time-consuming, expensive and often inaccurate tests involving live animals. Human stem cell toxicology represents a valid alternative to traditional toxicity assays because it takes advantage of the ability of stem cells to differentiate into multiple cell types and tissues of the human body. Thus, this branch of toxicology provides a possibility to assess cellular, embryonic, developmental, reproductive and functional toxicity in vitro within a single system highly relevant to human physiology. In this review, we describe the development, performance and future perspectives of stem cell toxicology, with an emphasis on how it can meet the increasing challenges posed by environmental pollution in the modern world.

In vitro acute and developmental neurotoxicity screening: an overview of cellular platforms and high-throughput technical possibilities

Neurotoxicity and developmental neurotoxicity are important issues of chemical hazard assessment. Since the interpretation of animal data and their extrapolation to man is challenging, and the amount of substances with information gaps exceeds present animal testing capacities, there is a big demand for in vitro tests to provide initial information and to prioritize for further evaluation. During the last decade, many in vitro tests emerged. These are based on animal cells, human tumour cell lines, primary cells, immortalized cell lines, embryonic stem cells, or induced pluripotent stem cells. They differ in their read-outs and range from simple viability assays to complex functional endpoints such as neural crest cell migration. Monitoring of toxicological effects on differentiation often requires multiomics approaches, while the acute disturbance of neuronal functions may be analysed by assessing electrophysiological features. Extrapolation from in vitro data to humans requires a deep understanding of the test system biology, of the endpoints used, and of the applicability domains of the tests. Moreover, it is important that these be combined in the right way to assess toxicity. Therefore, knowledge on the advantages and disadvantages of all cellular platforms, endpoints, and analytical methods is essential when establishing in vitro test systems for different aspects of neurotoxicity. The elements of a test, and their evaluation, are discussed here in the context of comprehensive prediction of potential hazardous effects of a compound. We summarize the main cellular characteristics underlying neurotoxicity, present an overview of cellular platforms and read-out combinations assessing distinct parts of acute and developmental neurotoxicology, and highlight especially the use of stem cell-based test systems to close gaps in the available battery of tests.

Development and Validation of a Rex1-RFP Potency Activity Reporter Assay That Quantifies Stress-Forced Potency Loss in Mouse Embryonic Stem Cells

Assays for embryonic stem cells (ESCs) of the blastocyst are needed to quantify stress-induced decreases of potent subpopulations. High-throughput screens (HTSs) of stressed ESCs quantify embryonic stress, diminishing laboratory animal needs. Normal or stress-induced ESC differentiation is marked by Rex1 potency factor loss. Potency reporter ESC assays were developed, using low-stress techniques to create transgenic ESCs. Rex1 and Oct4 promoters drove RFP and green fluorescent protein (GFP) expression, respectively. Lentivirus infection and fluorescence-activated cell sorting selection of ESCs obviated the need for stressful electroporation and antibiotic selection, respectively. We showed using immunoblots, microscopic analysis, flow cytometry, and fluorescence microplate reader that the response to stress of potency-reporter ESCs is similar to parental ESCs assayed by biochemical means. Stress caused a dose-dependent decrease in bright Rex1-RFP(+) ESCs and increase in Rex1 dim ESCs. At highest stress, ∼ 20% of bright Rex1-RFP cells are lost coinciding with a 2.8-fold increase in Rex1-RFP dim cells that approach 20%. This conversion of bright to dim cells tested by flow cytometry is commensurate with about 60% loss in fluorescence measured by microplate reader. Dose-dependent stress-induced Rex1-RFP and endogenous Rex1 protein decreases are similar. The data show that Rex1 reporter ESCs accurately report stress in a microplate reader-based HTS. The increasing dim Rex1 subpopulation size is balanced by the decreasing total ESC number during culture at multiple sorbitol doses. This is consistent with previous observations that stress forces potency decrease and differentiation increase to compensate for stress-induced diminished stem cell population growth.

Integrative analysis of genes and miRNA alterations in human embryonic stem cells-derived neural cells after exposure to silver nanoparticles

Given the rapid growth of engineered and customer products made of silver nanoparticles (Ag NPs), understanding their biological and toxicological effects on humans is critically important. The molecular developmental neurotoxic effects associated with exposure to Ag NPs were analyzed at the physiological and molecular levels, using an alternative cell model: human embryonic stem cell (hESC)-derived neural stem/progenitor cells (NPCs). In this study, the cytotoxic effects of Ag NPs (10-200μg/ml) were examined in these hESC-derived NPCs, which have a capacity for neurogenesis in vitro, at 6 and 24h. The results showed that Ag NPs evoked significant toxicity in hESC-derived NPCs at 24h in a dose-dependent manner. In addition, Ag NPs induced cell cycle arrest and apoptosis following a significant increase in oxidative stress in these cells. To further clarify the molecular mechanisms of the toxicological effects of Ag NPs at the transcriptional and post-transcriptional levels, the global expression profiles of genes and miRNAs were analyzed in hESC-derived NPCs after Ag NP exposure. The results showed that Ag NPs induced oxidative stress and dysfunctional neurogenesis at the molecular level in hESC-derived NPCs. Based on this hESC-derived neural cell model, these findings have increased our understanding of the molecular events underlying developmental neurotoxicity induced by Ag NPs in humans.

HTS/HCS to screen molecules able to maintain embryonic stem cell self-renewal or to induce differentiation: overview of protocols

Embryonic stem (ES) cells, combining self-renewal ability with wide range tissue-specific cell differentiation, represent one of the most powerful model systems in basic research, drug discovery and biomedical applications. In the field of drug development, ES cells are instrumental in high-throughput/content screening (HTS/HCS) for the evaluation of large compound libraries to test biological activity and toxic properties. Since it is a high priority to test new compounds in vitro, before starting animal and human treatments, there is an increasing demand for new in vitro models that can be used in HTS/HCS to facilitate drug development. In order to achieve this objective, several methods for ES cell self-renewal or differentiation have been evaluated to assess their compatibility with HTS/HCS. This review describes protocols used to screen molecules able to maintain self-renewal or to induce differentiation in ectodermal, mesodermal, endodermal, and their derivative cell lines.

Stress-induced enzyme activation primes murine embryonic stem cells to differentiate toward the first extraembryonic lineage

Extracellular stresses influence transcription factor (TF) expression and therefore lineage identity in the peri-implantation mouse embryo and its stem cells. This potentially affects pregnancy outcome. To understand the effects of stress signaling during this critical period of pregnancy, we exposed cultured murine embryonic stem cells (mESCs) to hyperosmotic stress. We then measured stress-enzyme-dependent regulation of key pluripotency and lineage TFs. Hyperosmotic stress slowed mESC accumulation due to slowing of the cell cycle over 72 h, after a small apoptotic response within 12 h. Phosphoinositide 3-kinase (PI3K) enzymatic signaling was responsible for stem cell survival under stressed conditions. Stress initially triggered mESC differentiation after 4 h through MEK1, c-Jun N-terminal kinase (JNK), and PI3K enzymatic signaling, which led to proteasomal degradation of Oct4, Nanog, Sox2, and Rex1 TF proteins. Concurrent with this post-transcriptional effect was the decreased accumulation of potency TF mRNA transcripts. After 12-24 h of stress, cells adapted, cell cycle resumed, and Oct4 and Nanog mRNA and protein expression returned to approximately normal levels. The TF protein recovery was mediated by p38MAPK and PI3K signaling, as well as by MEK2 and/or MEK1. However, due to JNK signaling, Rex1 expression did not recover. Probing for downstream lineages revealed that although mESCs did not differentiate morphologically during 24 h of stress, they were primed to differentiate by upregulating markers of the first lineage differentiating from mESCs, extraembryonic endoderm. Thus, although two to three TFs that mark pluripotency recover expression by 24 h of stress, there is nonetheless sustained Rex1 suppression and a priming of mESCs for differentiation to the earliest lineage.

Effects of valproic acid on gene expression during human embryonic stem cell differentiation into neurons

The widely used antiepileptic drug valproic acid (VPA) is known to exhibit teratogenicity in the form of a failure of the neural tube in humans. Embryonic stem cells (ESCs) are reported to be a promising cell source for evaluating chemical teratogenicity, because they are capable of reproducing embryonic developmental model and enable reduction in the number of experimental animals used. We previously investigated 22 genes for which expressions are altered by teratogens, specifically focusing on neural differentiation of mouse ESCs. In the present study, expressions of the investigated genes were evaluated by quantitative real-time PCR and compared during differentiation of human ESCs into neurons with or without VPA. Under the conditions, almost all gene expressions significantly changed in VPA-containing culture. Specifically, in neural development-related genes such as DCX, ARX, MAP2, and NNAT, more than 2-fold expression was observed. The findings suggest that the genes focused on in this study may help to elucidate the teratogenic effects of VPA and might be a useful tool to analyze embryotoxic potential of chemicals in humans.

The effect of estrogen compounds on human embryoid bodies

Human embryonic stem cells are derived from the inner cell mass of preimplantation embryo at the blastocyst stage and their differentiation occurs through an intermediate step involving the formation of embryoid bodies (EBs), which are aggregates of embryonic stem cells. The EBs seem to be a powerful tool for investigating the development of embryos, as they can mimic the initial stages of embryonic development. In this study, we aimed to investigate the effect of estrogen compounds on the proliferation and differentiation of short-term and long-term cultured EBs in vitro. For this study, 10-day-old (short-term cultured) and 30-day-old (long-term cultured) EBs were subjected to estradiol (E2), estriol (E3), selective estrogen receptor modulator (raloxifene [RLX]), bisphenol A, and 1,3,5-tris(4-hydroxyphenyl)-4-propyl-1H-pyrazole for 7 days. To confirm the effects of estrogen treatment, ICI-182780 was added to the respective EBs for additional 7 days following estrogen treatment. Quantitative reverse transcription-polymerase chain reaction was performed to analyze the relative expression of differentiation marker genes representing the 3 germ layers. The expression of 7 marker genes, which included α-fetoprotein, hepatocyte nuclear factor (HNF)-3β, HNF-4α (endoderm), brachyury, cardiac actin ([cACT]; mesoderm), nestin (ectoderm), and Oct-4 (undifferentiated), was measured. Significantly, lower expression of HNF-4α in both short-term and long-term cultured EBs was observed after treatment of estrogen compounds compared to control. The expression of HNF-3β in short-term cultured EBs has been positively affected by E2, E3, and RLX. Regarding cACT, higher expression was observed after treatment of E2 (10(-7) mol/L) and E3 (10(-9) mol/L) in short-term cultured EBs, but opposite effects were demonstrated in long-term cultured EBs. The lower expressions of HNF-4α by E2 and RLX were negated by ICI-182780 treatment, although these findings were not statistically significant in E3-treated group. These findings suggest that estrogen compounds have effects on endodermal and mesodermal differentiation of human EBs.

Human insulin secreted from insulinogenic xenograft restores normoglycemia in type 1 diabetic mice without immunosuppression

In the present study, we examined the therapeutic potential of human amnion-derived insulin-secreting cells for type 1 diabetes. Human amniotic mesenchymal stem cells (hAMs) were isolated from amnion and cultivated to differentiate into insulin-secreting cells in vitro. After culture in vitro, the differentiated cells (hAM-ISCs) were intensively stained with dithizone and secreted insulin and c-peptide in a high-glucose-dependent manner. They expressed mRNAs of pancreatic cell-related genes, including INS, PDX1, Nkx6-1, NEUROG3, ISL1, NEUROD1, GLUT1, GLUT2, PC1/3, PC2, GCK, PPY, SST, and GC, and were positive for human insulin and c-peptide. Transplantation of hAM-ISCs into the kidneys of mice with streptozotocin-induced diabetes restored body weight and normalized the blood glucose levels, which lasted for 210 days. Only human insulin and c-peptide were detected in the blood of normalized mice after 2 months of transplantation, but little mouse insulin and c-peptide. Removal of graft-bearing kidneys from these mice resulted in causing hyperglycemia again. Human cell-specific gene, hAlu, and human pancreatic cell-specific genes, insulin, PDX1, GLUT1, GLP1R, Nkx6-1, NEUROD1, and NEUROG3, were detected in the graft-bearing kidneys. Colocalization of human insulin and human nuclei antigen was also observed. These results demonstrate that hAMs could differentiate into functional insulin-secreting cells in vitro, and human insulin secreted from hAM-ISCs following transplantation into type 1 diabetic mice could normalize hyperglycemia, overcoming immune rejection for a long period.

Developmental effects of tobacco smoke exposure during human embryonic stem cell differentiation are mediated through the transforming growth factor-β superfamily member, Nodal

While the pathologies associated with in utero smoke exposure are well established, their underlying molecular mechanisms are incompletely understood. We differentiated human embryonic stem cells in the presence of physiological concentrations of tobacco smoke and nicotine. Using post hoc microarray analysis, quantitative PCR, and immunoblot analysis, we demonstrated that tobacco smoke has lineage- and stage-specific effects on human embryonic stem cell differentiation, through both nicotine-dependent and -independent pathways. We show that three major stem cell pluripotency/differentiation pathways, Notch, canonical Wnt, and transforming growth factor-β, are affected by smoke exposure, and that Nodal signaling through SMAD2 is specifically impacted by effects on Lefty1, Nodal, and FoxH1. These events are associated with upregulation of microRNA-302a, a post-transcriptional silencer of Lefty1. The described studies provide insight into the mechanisms by which tobacco smoke influences fetal development at the cellular level, and identify specific transcriptional, post-transcriptional, and signaling pathways by which this likely occurs.

Generation and applications of human pluripotent stem cells induced into neural lineages and neural tissues

Human pluripotent stem cells (hPSCs) represent a new and exciting field in modern medicine, now the focus of many researchers and media outlets. The hype is well-earned because of the potential of stem cells to contribute to disease modeling, drug screening, and even therapeutic approaches. In this review, we focus first on neural differentiation of these cells. In a second part we compare the various cell types available and their advantages for in vitro modeling. Then we provide a “state-of-the-art” report about two major biomedical applications: (1) the drug and toxicity screening and (2) the neural tissue replacement. Finally, we made an overview about current biomedical research using differentiated hPSCs.

The potential of induced pluripotent stem cells as a translational model for neurotoxicological risk

An important goal of neurotoxicological research is to provide relevant and accurate risk assessment of environmental and pharmacological agents for populations and individuals. Owing to the challenges of human subject research and the real possibility of species specific toxicological responses, neuronal lineages derived from human embryonic stem cells (hESCs) and human neuronal precursors have been offered as a potential solution for validation of neurotoxicological data from model organism systems in humans. More recently, with the advent of induced pluripotent stem cell (iPSC) technology, there is now the possibility of personalized toxicological risk assessment, the ability to predict individual susceptibility to specific environmental agents, by this approach. This critical advance is widely expected to facilitate analysis of cellular physiological pathways in the context of human neurons and the underlying genetic factors that lead to disease. Thus this technology opens the opportunity, for the first time, to characterize the physiological, toxicological, pharmacological and molecular properties of living human neurons with identical genetic determinants as human patients. Furthermore, armed with a complete clinical history of the patients, human iPSC (hiPSC) studies can theoretically compare patients and at risk groups with distinct sensitivities to particular environmental agents, divergent clinical outcomes, differing co-morbidities, and so forth. Thus iPSCs and neuronal lineages derived from them may reflect the unique genetic blueprint of the individuals from which they are generated. Indeed, iPSC technology has the potential to revolutionize scientific approaches to human health. However, before this overarching goal can be reached a number of technical and theoretical challenges must be overcome. This review seeks to provide a realistic assessment of hiPSC technology and its application to risk assessment and mechanistic studies in the area of neurotoxicology. We seek to identify, prioritize, and detail the primary hurdles that need to be overcome if personalized toxicological risk assessment using patient-derived iPSCs is to succeed.

Diverse effects of dimethyl sulfoxide (DMSO) on the differentiation potential of human embryonic stem cells

In vitro disease modeling using pluripotent stem cells can be a fast track screening tool for toxicological testing of candidate drug molecules. Dimethyl sulfoxide (DMSO) is one of the most commonly used solvents in drug screening. In the present investigation, we exposed 14- to 21-day-old embryoid bodies (EBs) to three different concentrations of DMSO [0.01% (low dose), 0.1% (medium dose) and 1.0% (high dose)] to identify the safest dose that could effectively be used as solvent. We found that DMSO treatment substantially altered the morphology and attachment of cells in concurrence with a significant reduction in cell viability in a dose-dependent manner. Gene expression studies revealed a selective downregulation of key markers associated with stemness (Oct-4, Sox-2, Nanog and Rex-1); ectoderm (Nestin, TuJ1, NEFH and Keratin-15); mesoderm (HAND-1, MEF-2C, GATA-4 and cardiac-actin); and endoderm (SOX-17, HNF-3β, GATA-6 and albumin), indicating an aberrant and untimely differentiation trajectory. Furthermore, immunocytochemistry, flow cytometry and histological analyses demonstrated substantial decrease in the levels of albumin and CK-18 proteins coupled with a massive reduction in the number of cells positive for PAS staining, implicating reduced deposits of glycogen. Our study advocates for the first time that DMSO exposure not only affects the phenotypic characteristics but also induces significant alteration in gene expression, protein content and functionality of the differentiated hepatic cells. Overall, our experiments warrant that hESC-based assays can provide timely alerts about the outcome of widespread applications of DMSO as drug solvent, cryoprotectant and differentiating agent.

Human pluripotent stem cells in pharmacological and toxicological screening: new perspectives for personalized medicine

Human stem cells provide an important novel tool for generating in vitro pharmacological and toxicological test systems. In the development of new targeted therapies, as well as in critical safety issues, including hepato-, neuro- and cardio-toxicity, animal-based tests are mostly unsatisfactory, whereas the use of in vitro model systems is limited by the unavailability of relevant human tissues. Human embryonic stem cell lines may fill this gap and offer an advantage over primary cultures as well as tissue-derived (adult) stem cells. Human embryonic stem cells represent an unlimited source for the production of differentiated somatic progenies and allow various stable genetic manipulations. As a new opening in personalized medicine test systems, the generation of induced pluripotent stem cell lines and their derivatives can provide patient- and disease-specific cellular assays for drug development and safety assessments. This article reviews promising human stem cell applications in pharmacological and toxicological screenings, focusing on the implications for personalized medicine.