Early human development and stem cell-based human embryo models.

The use of stem cells to model the early human embryo promises to transform our understanding of developmental biology and human reproduction. In this review, we present our current knowledge of the first 2 weeks of human embryo development. We first focus on the distinct cell lineages of the embryo and the derivation of stem cell lines.

Human iPSC-derived liver co-culture spheroids to model liver fibrosis.

The lack of adequate humanmodels that recapitulate the cellular composition and response of the human liver to injury hampers the development of anti-fibrotic drugs. The goal of this study was to develop a human spheroid culture model to study liver fibrosis by using induced pluripotent stem cell (iPSC)-derived liver cells. iPSCs were independently differentiated towards hepatoblasts (iHepatoblasts), hepatic stellate cells (iHSCs), endothelial cells (iECs) and macrophages (iMΦ), before assembly into free floating spheroids by culturing cells in 96-well U-bottom plates and orbital shaking for up to 21 days to allow further maturation.

Spatially Self-Organized Three-Dimensional Neural Concentroid as a Novel Reductionist Humanized Model to Study Neurovascular Development.

Although human pluripotent stem cell (PSC)-derived brain organoids have enabled researchers to gain insight into human brain development and disease, these organoids contain solely ectodermal cells and are not vascularized as occurs during brain development. Here it is created less complex and more homogenous large neural constructs starting from PSC-derived neuroprogenitor cells (NPC), by fusing small NPC spheroids into so-called concentroids. Such concentroids consisted of a pro-angiogenic core, containing neuronal and outer radial glia cells, surrounded by an astroglia-dense outer layer.

VEGF overexpressed mesoangioblasts enhance urethral and vaginal recovery following simulated vaginal birth in rats.

Vaginal birth causes pelvic floor injury which may lead to urinary incontinence. Cell therapy has been proposed to assist in functional recovery. We aim to assess if intra-arterial injection of rat mesoangioblasts (MABs) and stable Vascular Endothelial Growth Factor (VEGF)-expressing MABs, improve recovery of urethral and vaginal function following simulated vaginal delivery (SVD).

Large-scale perfused tissues via synthetic 3D soft microfluidics.

The vascularization of engineered tissues and organoids has remained a major unresolved challenge in regenerative medicine. While multiple approaches have been developed to vascularize in vitro tissues, it has thus far not been possible to generate sufficiently dense networks of small-scale vessels to perfuse large de novo tissues. Here, we achieve the perfusion of multi-mm tissue constructs by generating networks of synthetic capillary-scale 3D vessels.

High Acetate Concentration Protects Intestinal Barrier and Exerts Anti-Inflammatory Effects in Organoid-Derived Epithelial Monolayer Cultures from Patients with Ulcerative Colitis.

Short-chain fatty acids as well as their bacterial producers are of increasing interest in inflammatory bowel diseases. Although less studied compared to butyrate, acetate might also be of interest as it may be less toxic to epithelial cells, stimulate butyrate-producing bacteria by cross-feeding, and have anti-inflammatory and barrier-protective properties. Moreover, one of the causative factors of the probiotic potency of var.

Microbiota, not host origin drives intestinal epithelial responses.

Microbial dysbiosis is an established finding in patients with inflammatory bowel disease (IBD), but host-microbial interactions are poorly understood. We aimed to unravel the effect of microbiota exposure on intestinal epithelial cells. Confluent Transwell® organoid monolayers of eight UC patients and eight non-IBD controls were co-cultured for six hours with microbiota (3x10 cells) of UC patients or a healthy volunteer (HV), in the presence or absence of an inflammatory cytokine mix.

Severity of the S1251N allele in cystic fibrosis is affected by the presence of the F508C variant in cis.

Background: In cystic fibrosis (CF), genotype-phenotype correlation is complicated by the large number of CFTR variants, the influence of modifier genes, environmental effects, and the existence of complex alleles. We document the importance of complex alleles, in particular the F508C variant present in cis with the S1251N disease-causing variant, by detailed analysis of a patient with CF, with the [S1251N;F508]/G542X genotype and a very mild phenotype, contrasting it to that of four subjects with the [S1251N;F508C]/F508del genotype and classical CF presentation.

Methods: Genetic differences were identified by Sanger sequencing and CFTR function was quantified using rectal organoids in rectal organoid morphology analysis (ROMA) and forskolin-induced swelling (FIS) assays.

Human iPSC model reveals a central role for NOX4 and oxidative stress in Duchenne cardiomyopathy.

Duchenne muscular dystrophy (DMD) is a progressive muscle disorder caused by mutations in the Dystrophin gene. Cardiomyopathy is a major cause of early death. We used DMD-patient-specific human induced pluripotent stem cells (hiPSCs) to model cardiomyopathic features and unravel novel pathologic insights.

Fetal hematopoietic stem cell homing is controlled by VEGF regulating the integrity and oxidative status of the stromal-vascular bone marrow niches.

Hematopoietic stem and progenitor cell (HSPC) engraftment after transplantation during anticancer treatment depends on support from the recipient bone marrow (BM) microenvironment. Here, by studying physiological homing of fetal HSPCs, we show the critical requirement of balanced local crosstalk within the skeletal niche for successful HSPC settlement in BM. Transgene-induced overproduction of vascular endothelial growth factor (VEGF) by osteoprogenitor cells elicits stromal and endothelial hyperactivation, profoundly impacting the stromal-vessel interface and vascular architecture.

Upregulation of miR181a/miR212 Improves Myogenic Commitment in Murine Fusion-Negative Rhabdomyosarcoma.

Fusion-negative rhabdomyosarcoma (FN-RMS) is the most common soft tissue sarcoma of childhood arising from undifferentiated skeletal muscle cells from uncertain origin. Currently used therapies are poorly tumor-specific and fail to tackle the molecular machinery underlying the tumorigenicity and uncontrolled proliferation of FN-RMS. We and other groups recently found that microRNAs (miRNA) network contributes to myogenic epigenetic memory and can influence pluripotent stem cell commitments.

A modular approach for modeling the cell cycle based on functional response curves.

Modeling biochemical reactions by means of differential equations often results in systems with a large number of variables and parameters. As this might complicate the interpretation and generalization of the obtained results, it is often desirable to reduce the complexity of the model. One way to accomplish this is by replacing the detailed reaction mechanisms of certain modules in the model by a mathematical expression that qualitatively describes the dynamical behavior of these modules.

Directed differentiation of human induced pluripotent stem cells to hepatic stellate cells.

Hepatic stellate cells (HSCs) are nonparenchymal liver cells responsible for extracellular matrix homeostasis and are the main cells involved in the development of liver fibrosis following injury. The lack of reliable sources of HSCs has hence limited the development of complex in vitro systems to model liver diseases and toxicity. Here we describe a protocol to differentiate human induced pluripotent stem cells (iPSCs) into hepatic stellate cells (iPSC-HSCs).

Rectal organoid morphology analysis (ROMA) as a promising diagnostic tool in cystic fibrosis.

Diagnosing cystic fibrosis (CF) when sweat chloride is not in the CF range and less than 2 disease-causing mutations are found requires physiological CFTR assays, which are not always feasible or available. We developed a new physiological CFTR assay based on the morphological differences between rectal organoids from subjects with and without CF. In organoids from 167 subjects with and 22 without CF, two parameters derived from a semi-automated image analysis protocol (rectal organoid morphology analysis, ROMA) fully discriminated CF subjects with two disease-causing mutations from non-CF subjects (p<0.

Organoid-based Models to Study the Role of Host-microbiota Interactions in IBD.

The gut microbiota appears to play a central role in health, and alterations in the gut microbiota are observed in both forms of inflammatory bowel disease [IBD], namely Crohn's disease and ulcerative colitis. Yet, the mechanisms behind host-microbiota interactions in IBD, especially at the intestinal epithelial cell level, are not yet fully understood. Dissecting the role of host-microbiota interactions in disease onset and progression is pivotal, and requires representative models mimicking the gastrointestinal ecosystem, including the intestinal epithelium, the gut microbiota, and immune cells.

Intestinal Receptor of SARS-CoV-2 in Inflamed IBD Tissue Seems Downregulated by HNF4A in Ileum and Upregulated by Interferon Regulating Factors in Colon.

Background: Patients with inflammatory bowel disease [IBD] are considered immunosuppressed, but do not seem more vulnerable for COVID-19. Nevertheless, intestinal inflammation has shown to be an important risk factor for SARS-CoV-2 infection and prognosis. Therefore, we investigated the role of intestinal inflammation on the viral intestinal entry mechanisms, including ACE2, in IBD.

The EU-ToxRisk method documentation, data processing and chemical testing pipeline for the regulatory use of new approach methods.

Hazard assessment, based on new approach methods (NAM), requires the use of batteries of assays, where individual tests may be contributed by different laboratories. A unified strategy for such collaborative testing is presented. It details all procedures required to allow test information to be usable for integrated hazard assessment, strategic project decisions and/or for regulatory purposes.

Alternative Cell Sources for Liver Parenchyma Repopulation: Where Do We Stand?

Acute and chronic liver failure is a highly prevalent medical condition with high morbidity and mortality. Currently, the therapy is orthotopic liver transplantation. However, in some instances, chiefly in the setting of metabolic diseases, transplantation of individual cells, specifically functional hepatocytes, can be an acceptable alternative.

Controlled ploidy reduction of pluripotent 4n cells generates 2n cells during mouse embryo development.

Cells with high ploidy content are common in mammalian extraembryonic and adult tissues. Cell-to-cell fusion generates polyploid cells during mammalian development and tissue regeneration. However, whether increased ploidy can be occasionally tolerated in embryonic lineages still remains largely unknown.

Expression Levels of 4 Genes in Colon Tissue Might Be Used to Predict Which Patients Will Enter Endoscopic Remission After Vedolizumab Therapy for Inflammatory Bowel Diseases.

Background & Aims: We aimed to identify biomarkers that might be used to predict responses of patients with inflammatory bowel diseases (IBD) to vedolizumab therapy.

Methods: We obtained biopsies from inflamed colon of patients with IBD who began treatment with vedolizumab (n = 31) or tumor necrosis factor (TNF) antagonists (n = 20) and performed RNA-sequencing analyses. We compared gene expression patterns between patients who did and did not enter endoscopic remission (absence of ulcerations at month 6 for patients with Crohn's disease or Mayo endoscopic subscore ≤1 at week 14 for patients with ulcerative colitis) and performed pathway analysis and cell deconvolution for training (n = 20) and validation (n = 11) datasets.

Dystrophin deficiency leads to dysfunctional glutamate clearance in iPSC derived astrocytes.

Duchenne muscular dystrophy (DMD) results, beside muscle degeneration in cognitive defects. As neuronal function is supported by astrocytes, which express dystrophin, we hypothesized that loss of dystrophin from DMD astrocytes might contribute to these cognitive defects. We generated cortical neuronal and astrocytic progeny from induced pluripotent stem cells (PSC) from six DMD subjects carrying different mutations and several unaffected PSC lines.