Endoderm and mesoderm derivatives in embryonic stem cell differentiation and their use in developmental toxicity testing

Identification of the key genes and mechanisms associated with transcatheter arterial chemoembolisation refractoriness in hepatocellular carcinoma

BACKGROUND

Transcatheter arterial embolisation (TACE) is the primary treatment for intermediate-stage hepatocellular carcinoma (HCC) patients while some HCC cases have shown resistance to TACE.

AIM

To investigate the key genes and potential mechanisms correlated with TACE refractoriness in HCC.

METHODS

The microarray datasets of TACE-treated HCC tissues, HCC and non-HCC tissues were collected by searching multiple public databases. The respective differentially expressed genes (DEGs) were attained via limma R package. Weighted gene co-expression network analysis was employed for identifying the significant modules related to TACE non-response. TACE refractoriness-related genes were obtained by intersecting up-regulated TACE-associated and HCC-associated DEGs together with the genes in significant modules related to TACE non-response. The key genes expression in the above two pairs of samples was compared respectively via Wilcoxon tests and standard mean differences model. The prognostic value of the key genes was evaluated by Kaplan-Meier curve. Multivariate analysis was utilised to investigate the independent prognostic factor in key genes. Single-cell RNA (scRNA) sequencing analysis was conducted to explore the cell types in HCC. TACE refractoriness-related genes activity was calculated via AUCell packages. The CellChat R package was used for the investigation of the cell-cell communication between the identified cell types.

RESULTS

HCC tissues of TACE non-responders (n = 66) and TACE responders (n = 81), HCC (n = 3941) and non-HCC (n = 3443) tissues were obtained. The five key genes, DLG associated protein 5 (DLGAP5), Kinesin family member 20A (KIF20A), Assembly factor for spindle microtubules (ASPM), Kinesin family member 11 (KIF11) and TPX2 microtubule nucleation factor (TPX2) in TACE refractoriness-related genes, were identified. The five key genes were all up-regulated in the TACE non-responders group and the HCC group. High expression of the five key genes predicted poor prognosis in HCC. Among the key genes, TPX2 was an independent prognostic factor. Four cell types, hepatocytes, embryonic stem cells, T cells and B cells, were identified in the HCC tissues. The TACE refractoriness-related genes expressed primarily in hepatocytes and embryonic stem cells. Hepatocytes, as the providers of ligands, had the strongest interaction with embryonic stem cells that provided receptors.

CONCLUSION

Five key genes (DLGAP5, KIF20A, ASPM, KIF11 and TPX2) were identified as promoting refractory TACE. Hepatocytes and embryonic stem cells were likely to boost TACE refractoriness.

Regeneration of Pancreatic Cells Using Optimized Nanoparticles and l-Glutamic Acid-Gelatin Scaffolds with Controlled Topography and Grafted Activin A/BMP4

Regeneration of insulin-producing cells (IPCs) from induced pluripotent stem cells (iPSCs) under controlled conditions has a lot of promise to emulate the pancreatic mechanism in vivo as a foundation of cell-based diabetic therapy. l-Glutamic acid-gelatin scaffolds with orderly pore sizes of 160 and 200 μm were grafted with activin A and bone morphogenic proteins 4 (BMP4) to differentiate iPSCs into definitive endoderm (DE) cells, which were then guided with fibroblast growth factor 7 (FGF7)-grafted retinoic acid (RA)-loaded solid lipid nanoparticles (FR-SLNs) to harvest IPCs. Response surface methodology was adopted to optimize the l-glutamic acid-to-gelatin ratio of scaffolds and to optimize surfactant concentration and lipid proportion in FR-SLNs. Experimental results of immunofluorescence, flow cytometry, and western blots revealed that activin A (100 ng/mL)-BMP4 (50 ng/mL)-l-glutamic acid (5%)-gelatin (95%) scaffolds provoked the largest number of SOX17-positive DE cells from iPSCs. Treatment with FGF7 (50 ng/mL)-RA (600 ng/mL)-SLNs elicited the highest number of PDX1-positive β-cells from differentiated DE cells. To imitate the natural pancreas, the scaffolds with controlled topography were appropriate for IPC production with sufficient insulin secretion. Hence, the current scheme using FR-SLNs and activin A-BMP4-l-glutamic acid-gelatin scaffolds in the two-stage differentiation of iPSCs can be promising for replacing impaired β-cells in diabetic management.

Developmental toxicity of remdesivir, an anti-COVID-19 drug, is implicated by in vitro assays using morphogenetic embryoid bodies of mouse and human pluripotent stem cells

BACKGROUND

Remdesivir is an antiviral drug approved for the treatment of COVID-19, whose developmental toxicity remains unclear. More information about the safety of remdesivir is urgently needed for people of childbearing potential, who are affected by the ongoing pandemic. Morphogenetic embryoid bodies (MEBs) are three-dimensional (3D) aggregates of pluripotent stem cells that recapitulate embryonic body patterning in vitro, and have been used as effective embryo models to detect the developmental toxicity of chemical exposures specifically and sensitively.

METHODS

MEBs were generated from mouse P19C5 and human H9 pluripotent stem cells, and used to examine the effects of remdesivir. The morphological effects were assessed by analyzing the morphometric parameters of MEBs after exposure to varying concentrations of remdesivir. The molecular impact of remdesivir was evaluated by measuring the transcript levels of developmental regulator genes.

RESULTS

The mouse MEB morphogenesis was impaired by remdesivir at 1-8 μM. Remdesivir affected MEBs in a manner dependent on metabolic conversion, and its potency was higher than GS-441524 and GS-621763, presumptive anti-COVID-19 drugs that act similarly to remdesivir. The expressions of developmental regulator genes, particularly those involved in axial and somite patterning, were dysregulated by remdesivir. The early stage of MEB development was more vulnerable to remdesivir exposure than the later stage. The morphogenesis and gene expression profiles of human MEBs were also impaired by remdesivir at 1-8 μM.

CONCLUSIONS

Remdesivir impaired mouse and human MEBs at concentrations that are comparable to the therapeutic plasma levels in humans, urging further investigation into the potential impact of remdesivir on developing embryos.

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.

Toward better assessments of developmental toxicity using stem cell-based in vitro embryogenesis models

In the past few decades, pluripotent stem cells have been explored as nonanimal alternatives to assess the developmental toxicity of chemicals. To date, numerous versions of stem cell-based assays have been reported that are allegedly effective. Nonetheless, none of the assays has become the gold standard in developmental toxicity assessment. Why? This article discusses several issues in the hope of facilitating the refinement of stem cell assays and their acceptance as the cornerstone in predictive developmental toxicology. Each stem cell assay is built on a limited representation of embryogenesis, so that multiple assays are needed to detect the diverse effects of various chemicals. To validate and compare the strengths and weaknesses of individual assays, standardized lists of reference chemicals should be established. Reference lists should consist of exposures defined by toxicokinetic data, namely maternal plasma concentrations that cause embryonic death or malformations, and also by the effects on the molecular machineries that control embryogenesis. Although not entirely replacing human or animal tests, carefully selected stem cell assays should serve as practical and ethical alternatives to proactively identify chemical exposures that disturb embryogenesis. To achieve this goal, unprecedented levels of coordination and conviction are required among research and regulatory communities.