Hepatocyte-like cells derived from human induced pluripotent stem cells using small molecules: implications of a transcriptomic study

Hepatic endoplasmic reticulum-derived nanodiscs for broad-spectrum drug detoxification

Drug overdose is a pressing global public health challenge, with current detoxification treatments often lacking the broad-spectrum efficacy needed for emergency applications. Inspired by the unique advantages of cell membrane-derived nanodiscs (CNDs), including their compact size, rapid distribution, and preservation of native cell membrane functions, we developed endoplasmic reticulum (ER)-derived nanodiscs (ER-NDs) from the ER membranes of mouse hepatic cells for broad-spectrum drug detoxification. ER-NDs retain natural cytochrome P450 (CYP) enzymes, enabling effective detoxification of three model drugs: bupropion, haloperidol, and propranolol. Cell-based assays demonstrated ER-NDs' ability to mitigate drug-induced cytotoxicity, reduce oxidative stress, and restore antioxidant defenses. In mouse models of drug intoxication, ER-ND treatment significantly improved survival rates and alleviated drug-induced oxidative damage. Importantly, ER-NDs showed no evidence of acute toxicity in vivo. These findings underscore the potential of ER-NDs as a versatile platform for broad-spectrum drug detoxification and as a promising tool for managing drug intoxication in emergency and clinical settings.

The Optimization of a Protocol for the Directed Differentiation of Induced Pluripotent Stem Cells into Liver Progenitor Cells and the Delivery of Transgenes

The liver plays a pivotal role in metabolism, detoxification, and protein synthesis and comprises several cell types, including hepatocytes and cholangiocytes. Primary human hepatocytes in 2D cultures rapidly dedifferentiate and lose their function, making their use as a reliable cell model challenging. Therefore, developing robust three-dimensional cell culture models is crucial, especially for diseases lacking reliable animal models. The aim of this study was to optimize a protocol for the directed differentiation of induced pluripotent stem cells into liver progenitor cells, achieving the high-level expression of specific markers. As a result, we established a 2D culture of liver progenitor cells capable of differentiating into three cell types: a 3D organoid culture containing hepatocyte- and cholangiocyte-like cells and a 2D cell culture comprising stellate-like cells. To evaluate gene delivery efficiency, liver progenitor cells were transduced with various rAAV serotypes carrying an eGFP reporter cassette at different multiplicities of infection (MOIs). Our results revealed that rAAV serotype 2/2 at MOI of 100,000 achieved the highest transduction efficiency of 93.6%, while electroporation demonstrated a plasmid delivery efficiency of 54.3%. These findings suggest that liver progenitor cells are a promising tissue-like cell model for regenerative medicine and demonstrate high amenability to genetic manipulation, underscoring their potential in gene therapy and genome editing studies.

Evaluating the synergistic use of advanced liver models and AI for the prediction of drug-induced liver injury

INTRODUCTION

Drug-induced liver injury (DILI) is a leading cause of acute liver failure. Hepatotoxicity typically occurs only in a subset of individuals after prolonged exposure and constitutes a major risk factor for the termination of drug development projects.

AREAS COVERED

We provide an overview of available human liver models for DILI research and discuss how they have been used to aid in early risk assessments and to mitigate the risk of project closures due to DILI in clinical stages. We summarize the different data that can be provided by such models and illustrate how these diverse data types can be interfaced with machine learning strategies to improve predictions of liver safety liabilities.

EXPERT OPINION

Advanced human liver models closely mimic human liver phenotypes and functions for many weeks, allowing for the recapitulation of hepatotoxicity events in vitro. Integration of the biochemical, histological, and toxicogenomic output data from these models with physicochemical compound properties using different machine learning architectures holds promise to enhance preclinical DILI predictions. However, to realize this aim, it is important to benchmark the available liver models on test sets of DILI positive and negative compounds and to carefully annotate and share the resulting data.

Decoding Liver Fibrosis: How Omics Technologies and Innovative Modeling Can Guide Precision Medicine

The burden of chronic liver disease (CLD) is dramatically increasing. It is estimated that 20-30% of the population worldwide is affected by CLD. Hepatic fibrosis is a symptom common to all CLDs. Although it affects liver functional activities, it is a reversible stage if diagnosed at an early stage, but no resolutive therapy to contrast liver fibrosis is currently available. Therefore, efforts are needed to study the molecular insights of the disease. Emerging cutting-edge fields in cellular and molecular biology are introducing innovative strategies. Spatial and single-cell resolution approaches are paving the way for a more detailed understanding of the mechanisms underlying liver fibrosis. Cellular models have been generated to recapitulate the in-a-dish pathophysiology of liver fibrosis, yielding remarkable results that not only uncover the underlying molecular mechanisms but also serve as patient-specific avatars for precision medicine. Induced pluripotent stem cells (iPSC) and organoids are incredible tools to reshape the modeling of liver diseases, describe their architecture, and study the residents of hepatic tissue and their heterogeneous population. The present work aims to give an overview of innovative omics technologies revolutionizing liver fibrosis research and the current tools to model this disease.

Standard Protocols for Characterising Primary and In Vitro-Generated Human Hepatocytes

Hepatocyte-like cells (HLCs) derived from pluripotent stem cells (PSCs) or direct reprogramming are an unlimited source of human hepatocytes for biomedical applications. HLCs are used to model human diseases, develop precise drugs and establish groundbreaking regenerative cell-based therapies. Primary human hepatocytes are the gold standard for studying human liver biology and pathology. However, their widespread use is limited by their rapid dedifferentiation in vitro, reliance on transplant-rejected donor organs, poor scalability and significant batch-to-batch variations. Therefore, high-quality 'off-the-shelf' HLCs are needed to overcome those limitations. Basic stepwise differentiation protocols have been developed to generate HLCs from PSCs. To evaluate the quality of the in vitro generated products, HLCs have been phenotyped using various methods. This review discusses various biological assays and methods available for the robust evaluation of HLC quality, emphasising the importance of using 24-h cultured primary human hepatocytes (PHHs) as a reference standard for comparison.

Advances in liver organoids: replicating hepatic complexity for toxicity assessment and disease modeling

The lack of in vivo accurate human liver models hinders the investigation of liver-related diseases, injuries, and drug-related toxicity, posing challenges for both basic research and clinical applications. Traditional cellular and animal models, while widely used, have significant limitations in replicating the liver's complex responses to various stressors. Liver organoids derived from human pluripotent stem cells, adult stem cells primary cells, or tissues can mimic diverse liver cell types, major physiological functions, and architectural features. Recent advancements in the field have shown that some liver organoids have sufficient accuracy to replicate specific aspects of the human liver's complexity. This review highlights recent progress in liver organoid research, with a particular emphasis on their potential for toxicity assessment and disease modeling. The intrinsic advantages of liver organoids include higher sensitivity and suitability for long-term studies, which enhance the predictive value in drug and nanomaterial toxicity testing. The integration of liver organoids with microfluidic devices enables the simulation of the liver microenvironment and facilitates high-throughput drug screening. The liver organoids also serve as ideal platforms for studying liver diseases such as hepatitis, liver fibrosis, viral liver diseases, and monogenic diseases. Additionally, this review discusses the advantages and limitations of liver organoids along with potential avenues for future research.

Small Molecule-Mediated Stage-Specific Reprogramming of MSCs to Hepatocyte-Like Cells and Hepatic Tissue for Liver Injury Treatment

BACKGROUND

Derivation of hepatocytes from stem cells has been established through various protocols involving growth factor (GF) and small molecule (SM) agents, among others. However, mesenchymal stem cell-based derivation of hepatocytes still remains expensive due to the use of a cocktail of growth factors, and a long duration of differentiation is needed, thus limiting its potential clinical application.

METHODS

In this study, we developed a chemically defined differentiation strategy that is exclusively based on SM and takes 14 days, while the GF-based protocol requires 23-28 days.

RESULTS

We optimized a stage-specific differentiation protocol for the differentiation of rat bone marrow-derived mesenchymal stem cells (MSCs) into functional hepatocyte-like cells (dHeps) that involved four stages, i.e., definitive endoderm (DE), hepatic competence (HC), hepatic specification (HS) and hepatic differentiation and growth. We further generated hepatic tissue using human decellularized liver extracellular matrix and compared it with hepatic tissue derived from the growth factor-based protocol at the transcriptional level. dHep, upon transplantation in a rat model of acute liver injury (ALI), was capable of ameliorating liver injury in rats and improving liver function and tissue damage compared to those in the ALI model.

CONCLUSIONS

In summary, this is the first study in which hepatocytes and hepatic tissue were derived from MSCs utilizing a stage-specific strategy by exclusively using SM as a differentiation factor.

Chemical approaches targeting the hurdles of hepatocyte transplantation: mechanisms, applications, and advances

Hepatocyte transplantation (HTx) has been a novel cell-based therapy for severe liver diseases, as the donor livers for orthotopic liver transplantation are of great shortage. However, HTx has been confronted with two main hurdles: limited high-quality hepatocyte sources and low cell engraftment and repopulation rate. To cope with, researchers have investigated on various strategies, including small molecule drugs with unique advantages. Small molecules are promising chemical tools to modulate cell fate and function for generating high quality hepatocyte sources. In addition, endothelial barrier, immune responses, and low proliferative efficiency of donor hepatocytes mainly contributes to low cell engraftment and repopulation rate. Interfering these biological processes with small molecules is beneficial for improving cell engraftment and repopulation. In this review, we will discuss the applications and advances of small molecules in modulating cell differentiation and reprogramming for hepatocyte resources and in improving cell engraftment and repopulation as well as its underlying mechanisms.

Metabolites in the regulatory risk assessment of pesticides in the EU

A large majority of chemicals is converted into metabolites through xenobiotic-metabolising enzymes. Metabolites may present a spectrum of characteristics varying from similar to vastly different compared with the parent compound in terms of both toxicokinetics and toxicodynamics. In the pesticide arena, the role of metabolism and metabolites is increasingly recognised as a significant factor particularly for the design and interpretation of mammalian toxicological studies and in the toxicity assessment of pesticide/metabolite-associated issues for hazard characterization and risk assessment purposes, including the role of metabolites as parts in various residues in ecotoxicological adversities. This is of particular relevance to pesticide metabolites that are unique to humans in comparison with metabolites found in in vitro or in vivo animal studies, but also to disproportionate metabolites (quantitative differences) between humans and mammalian species. Presence of unique or disproportionate metabolites may underlie potential toxicological concerns. This review aims to present the current state-of-the-art of comparative metabolism and metabolites in pesticide research for hazard and risk assessment, including One Health perspectives, and future research needs based on the experiences gained at the European Food Safety Authority.

Extracellular matrix modulates the spatial hepatic features in hepatocyte-like cells derived from human embryonic stem cells

BACKGROUND

Human pluripotent stem cell (hPSC)-derived hepatocyte-like cells (HLCs) can provide a valuable in vitro model for disease modelling and drug development. However, generating HLCs with characteristics comparable to hepatocytes in vivo is challenging. Extracellular matrix (ECM) plays an important role in supporting liver development and hepatocyte functions, but their impact on hepatocyte differentiation and maturation during hPSC differentiation remains unclear. Here, we investigate the effects of two ECM components-Matrigel and type I collagen on hepatic differentiation of human embryonic stem cells (hESCs).

METHODS

hESC-derived HLCs were generated through multistage differentiation in two-dimensional (2D) and three-dimensional (3D) cultures, incorporating either type I collagen or Matrigel during hepatic specification and maturation. The resulting HLCs was characterized for their gene expression and functionality using various molecular and cellular techniques.

RESULTS

Our results showed that HLCs cultured with collagen exhibited a significant increase in albumin and alpha-1 anti-trypsin expression with reduced AFP compared to HLCs cultured with Matrigel. They also secreted more urea than Matrigel cultures. However, these HLCs exhibited lower CYP3A4 activity and glycogen storage than those cultured with Matrigel. These functional differences in HLCs between collagen and Matrigel cultures closely resembled the hepatocytes of periportal and pericentral zones, respectively.

CONCLUSION

Our study demonstrates that Matrigel and collagen have differential effects on the differentiation and functionality of HLCs, which resemble, to an extent, hepatic zonation in the liver lobules. Our finding has an important impact on the generation of hPSC-HLCs for biomedical and medical applications.

Modeling and therapeutic targeting of inflammation-induced hepatic insulin resistance using human iPSC-derived hepatocytes and macrophages

Hepatic insulin resistance is recognized as a driver of type 2 diabetes and fatty liver disease but specific therapies are lacking. Here we explore the potential of human induced pluripotent stem cells (iPSCs) for modeling hepatic insulin resistance in vitro, with a focus on resolving the controversy about the impact of inflammation in the absence of steatosis. For this, we establish the complex insulin signaling cascade and the multiple inter-dependent functions constituting hepatic glucose metabolism in iPSC-derived hepatocytes (iPSC-Heps). Co-culture of these insulin-sensitive iPSC-Heps with isogenic iPSC-derived pro-inflammatory macrophages induces glucose output by preventing insulin from inhibiting gluconeogenesis and glycogenolysis and activating glycolysis. Screening identifies TNFα and IL1β as the mediators of insulin resistance in iPSC-Heps. Neutralizing these cytokines together restores insulin sensitivity in iPSC-Heps more effectively than individual inhibition, reflecting specific effects on insulin signaling and glucose metabolism mediated by NF-κB or JNK. These results show that inflammation is sufficient to induce hepatic insulin resistance and establish a human iPSC-based in vitro model to mechanistically dissect and therapeutically target this metabolic disease driver.

Opportunities and considerations for studying liver disease with microphysiological systems on a chip

Advances in microsystem engineering have enabled the development of highly controlled models of the liver that better recapitulate the unique in vivo biological conditions. In just a few short years, substantial progress has been made in creating complex mono- and multi-cellular models that mimic key metabolic, structural, and oxygen gradients crucial for liver function. Here we review: 1) the state-of-the-art in liver-centric microphysiological systems and 2) the array of liver diseases and pressing biological and therapeutic challenges which could be investigated with these systems. The engineering community has unique opportunities to innovate with new liver-on-a-chip devices and partner with biomedical researchers to usher in a new era of understanding of the molecular and cellular contributors to liver diseases and identify and test rational therapeutic modalities.

Liver organoids: a promising three-dimensional model for insights and innovations in tumor progression and precision medicine of liver cancer

Primary liver cancer (PLC) is one type of cancer with high incidence rate and high mortality rate in the worldwide. Systemic therapy is the major treatment for PLC, including surgical resection, immunotherapy and targeted therapy. However, mainly due to the heterogeneity of tumors, responses to the above drug therapy differ from person to person, indicating the urgent needs for personalized treatment for PLC. Organoids are 3D models derived from adult liver tissues or pluripotent stem cells. Based on the ability to recapitulate the genetic and functional features of in vivo tissues, organoids have assisted biomedical research to make tremendous progress in understanding disease origin, progression and treatment strategies since their invention and application. In liver cancer research, liver organoids contribute greatly to reflecting the heterogeneity of liver cancer and restoring tumor microenvironment (TME) by co-organizing tumor vasculature and stromal components in vitro. Therefore, they provide a promising platform for further investigation into the biology of liver cancer, drug screening and precision medicine for PLC. In this review, we discuss the recent advances of liver organoids in liver cancer, in terms of generation methods, application in precision medicine and TME modeling.

Modulation of human iPSC-derived hepatocyte phenotype via extracellular matrix microarrays

In vitro human liver models are essential for drug screening, disease modeling, and cell-based therapies. Induced pluripotent stem cell (iPSC)-derived hepatocyte-like cells (iHeps) mitigate sourcing limitations of primary human hepatocytes (PHHs) and enable precision medicine; however, current protocols yield iHeps with very low differentiated functions. The composition and stiffness of liver's extracellular matrix (ECM) cooperatively regulate hepatic phenotype in vivo, but such effects on iHeps remain unelucidated. Here, we utilized ECM microarrays and high content imaging to assess human iHep attachment and functions on ten major liver ECM proteins in single and two-way combinations robotically spotted onto polyacrylamide gels of liver-like stiffnesses; microarray findings were validated using hydrogel-conjugated multiwell plates. Collagen-IV supported higher iHep attachment than collagen-I over 2 weeks on 1 kPa, while laminin and its combinations with collagen-III, fibronectin, tenascin C, or hyaluronic acid led to both high iHep attachment and differentiated functions; laminin and its combination with tenascin or fibronectin led to similar albumin expression in iHeps and PHHs. Additionally, several collagen-IV-, laminin-, fibronectin-, and collagen-V-containing combinations on 1 kPa led to similar or higher CYP3A4 staining in iHeps than PHHs. Lastly, collagen-I or -III mixed with laminin, collagen-IV mixed with lumican, and collagen-V mixed with fibronectin led to high and stable functional output (albumin/urea secretions; CYP1A2/2C9/3A4 activities) in iHep cultures versus declining PHH numbers/functions for 3 weeks within multiwell plates containing 1 kPa hydrogels. Ultimately, these platforms can help elucidate ECM's role in liver diseases and serve as building blocks of engineered tissues for applications. STATEMENT OF SIGNIFICANCE: We utilized high-throughput extracellular matrix (ECM) microarrays and high content imaging to assess the attachment and differentiated functions of iPSC-derived human hepatocyte-like cells (iHep) on major liver ECM protein combinations spotted onto polyacrylamide gels of liver-like stiffnesses. We observed that iHep responses are regulated in unexpected ways via the cooperation between ECM stiffness and protein composition. Using this approach, we induced mature functions in iHeps on substrates of physiological stiffness and select ECM coatings at higher levels over 3+ weeks than analogous primary human hepatocyte cultures, which is useful for building platforms for drug screening, disease modeling, and regenerative medicine.

Identification of an FXR-modulated liver-intestine hybrid state in iPSC-derived hepatocyte-like cells

BACKGROUND & AIMS

Pluripotent stem cell (PSC)-derived hepatocyte-like cells (HLC) have enormous potential as a replacement for primary hepatocytes in drug screening, toxicology and cell replacement therapy, but their genome-wide expression patterns differ strongly from primary human hepatocytes (PHH).

METHODS

We differentiated human induced pluripotent stem cells (hiPSC) via definitive endoderm to HLC and characterized the cells by single-cell and bulk RNA-seq, with complementary epigenetic analyses. We then compared HLC to PHH and publicly available data on human fetal hepatocytes (FH) ex vivo; we performed bioinformatics-guided interventions to improve HLC differentiation via lentiviral transduction of the nuclear receptor FXR and agonist exposure.

RESULTS

Single-cell RNA-seq revealed that transcriptomes of individual HLC display a hybrid state, where hepatocyte-associated genes are expressed in concert with genes that are not expressed in PHH - mostly intestinal genes - within the same cell. Bulk-level overrepresentation analysis, as well as regulon analysis at the single-cell level, identified sets of regulatory factors discriminating HLC, FH, and PHH, hinting at a central role for the nuclear receptor FXR in the functional maturation of HLC. Combined FXR expression plus agonist exposure enhanced the expression of hepatocyte-associated genes and increased the ability of bile canalicular secretion as well as lipid droplet formation, thereby increasing HLCs' similarity to PHH. The undesired non-liver gene expression was reproducibly decreased, although only by a moderate degree.

CONCLUSION

In contrast to physiological hepatocyte precursor cells and mature hepatocytes, HLC co-express liver and hybrid genes in the same cell. Targeted modification of the FXR gene regulatory network improves their differentiation by suppressing intestinal traits whilst inducing hepatocyte features.

LAY SUMMARY

Generation of human hepatocytes from stem cells represents an active research field but its success is hampered by the fact that the stem cell-derived 'hepatocytes' still show major differences to hepatocytes obtained from a liver. Here, we identified an important reason for the difference, specifically that the stem cell-derived 'hepatocyte' represents a hybrid cell with features of hepatocytes and intestinal cells. We show that a specific protein (FXR) suppresses intestinal and induces liver features, thus bringing the stem cell-derived cells closer to hepatocytes derived from human livers.

Human-Origin iPSC-Based Recellularization of Decellularized Whole Rat Livers

End-stage liver diseases lead to mortality of millions of patients, as the only treatment available is liver transplantation and donor scarcity means that patients have to wait long periods before receiving a new liver. In order to minimize donor organ scarcity, a promising bioengineering approach is to decellularize livers that do not qualify for transplantation. Through decellularization, these organs can be used as scaffolds for developing new functional organs. In this process, the original cells of the organ are removed and ideally should be replaced by patient-specific cells to eliminate the risk of immune rejection. Induced pluripotent stem cells (iPSCs) are ideal candidates for developing patient-specific organs, yet the maturity and functionality of iPSC-derived cells do not match those of primary cells. In this study, we introduced iPSCs into decellularized rat liver scaffolds prior to the start of differentiation into hepatic lineages to maximize the exposure of iPSCs to native liver matrices. Through exposure to the unique composition and native 3D organization of the liver microenvironment, as well as the more efficient perfusion culture throughout the differentiation process, iPSC differentiation into hepatocyte-like cells was enhanced. The resulting cells showed significantly higher expression of mature hepatocyte markers, including important CYP450 enzymes, along with lower expression of fetal markers, such as AFP. Importantly, the gene expression profile throughout the different stages of differentiation was more similar to native development. Our study shows that the native 3D liver microenvironment has a pivotal role to play in the development of human-origin hepatocyte-like cells with more mature characteristics.

Phenotypical, functional and transcriptomic comparison of two modified methods of hepatocyte differentiation from human induced pluripotent stem cells

Directed differentiation of human induced pluripotent stem cells (iPSCs) into hepatocytes could provide an unlimited source of liver cells, and therefore holds great promise for regenerative medicine, disease modeling, drug screening and toxicology studies. Various methods have been established during the past decade to differentiate human iPSCs into hepatocyte-like cells (HLCs) using growth factors and/or small molecules. However, direct comparison of the differentiation efficiency and the quality of the final HLCs between different methods has rarely been reported. In the current study, two hepatocyte differentiation methods were devised, termed Method 1 and 2, through modifying existing well-known hepatocyte differentiation strategies, and the resultant cells were compared phenotypically and functionally at different stages of hepatocyte differentiation. Compared to Method 1, higher differentiation efficiency and reproducibility were observed in Method 2, which generated highly homogeneous functional HLCs at the end of the differentiation process. The cells exhibited morphology closely resembling primary human hepatocytes and expressed high levels of hepatic protein markers. More importantly, these HLCs demonstrated several essential characteristics of mature hepatocytes, including major serum protein (albumin, fibronectin and α-1 antitrypsin) secretion, urea release, glycogen storage and inducible cytochrome P450 activity. Further transcriptomic comparison of the HLCs derived from the two methods identified 1,481 differentially expressed genes (DEGs); 290 Gene Ontology terms in the biological process category were enriched by these genes, which were further categorized into 34 functional classes. Pathway analysis of the DEGs identified several signaling pathways closely involved in hepatocyte differentiation of pluripotent stem cells, including 'signaling pathways regulating pluripotency of stem cells', 'Wnt signaling pathway', 'TGF-beta signaling pathway' and 'PI3K-Akt signaling pathway'. These results may provide a molecular basis for the differences observed between the two differentiation methods and suggest ways to further improve hepatocyte differentiation in order to obtain more mature HLCs for biomedical applications.

Advancements in Disease Modeling and Drug Discovery Using iPSC-Derived Hepatocyte-like Cells

Serving as the metabolic hub of the human body, the liver is a vital organ that performs a variety of important physiological functions. Although known for its regenerative potential, it remains vulnerable to a variety of diseases. Despite decades of research, liver disease remains a leading cause of mortality in the United States with a multibillion-dollar-per-year economic burden. Prior research with model systems, such as primary hepatocytes and murine models, has provided many important discoveries. However, progress has been impaired by numerous obstacles associated with these models. In recent years, induced pluripotent stem cell (iPSC)-based systems have emerged as advantageous platforms for studying liver disease. Benefits, including preserved differentiation and physiological function, amenability to genetic manipulation via tools such as CRISPR/Cas9, and availability for high-throughput screening, make these systems increasingly attractive for both mechanistic studies of disease and the identification of novel therapeutics. Although limitations exist, recent studies have made progress in ameliorating these issues. In this review, we discuss recent advancements in iPSC-based models of liver disease, including improvements in model system construction as well as the use of high-throughput screens for genetic studies and drug discovery.

Elimination of Reprogramming Transgenes Facilitates the Differentiation of Induced Pluripotent Stem Cells into Hepatocyte-like Cells and Hepatic Organoids

Hepatocytes and hepatic organoids (HOs) derived from human induced pluripotent stem cells (hiPSCs) are promising cell-based therapies for liver diseases. The removal of reprogramming transgenes can affect hiPSC differentiation potential into the three germ layers but not into hepatocytes and hepatic organoids in the late developmental stage. Herein, we generated hiPSCs from normal human fibroblasts using an excisable polycistronic lentiviral vector based on the Cre recombinase-mediated removal of the loxP-flanked reprogramming cassette. Comparing the properties of transgene-carrying and transgene-free hiPSCs with the same genetic background, the pluripotent states of all hiPSCs were quite similar, as indicated by the expression of pluripotent markers, embryonic body formation, and tri-lineage differentiation in vitro. However, after in vitro differentiation into hepatocytes, transgene-free hiPSCs were superior to the transgene-residual hiPSCs. Interestingly, the generation and hepatic differentiation of human hepatic organoids (hHOs) were significantly enhanced by transgene elimination from hiPSCs, as observed by the upregulated fetal liver (CK19, SOX9, and ITGA6) and functional hepatocyte (albumin, ASGR1, HNF4α, CYP1A2, CYP3A4, and AAT) markers upon culture in differentiation media. Thus, the elimination of reprogramming transgenes facilitates hiPSC differentiation into hepatocyte-like cells and hepatic organoids with properties of liver progenitor cells. Our findings thus provide significant insights into the characteristics of iPSC-derived hepatic organoids.

Induced pluripotent stem cell-based organ-on-a-chip as personalized drug screening tools: A focus on neurodegenerative disorders

The Organ-on-a-Chip (OoC) technology shows great potential to revolutionize the drugs development pipeline by mimicking the physiological environment and functions of human organs. The translational value of OoC is further enhanced when combined with patient-specific induced pluripotent stem cells (iPSCs) to develop more realistic disease models, paving the way for the development of a new generation of patient-on-a-chip devices. iPSCs differentiation capacity leads to invaluable improvements in personalized medicine. Moreover, the connection of single-OoC into multi-OoC or body-on-a-chip allows to investigate drug pharmacodynamic and pharmacokinetics through the study of multi-organs cross-talks. The need of a breakthrough thanks to this technology is particularly relevant within the field of neurodegenerative diseases, where the number of patients is increasing and the successful rate in drug discovery is worryingly low. In this review we discuss current iPSC-based OoC as drug screening models and their implication in development of new therapies for neurodegenerative disorders.

Transcriptomic and proteomic responses of silver nanoparticles in hepatocyte-like cells derived from human induced pluripotent stem cells

Silver nanoparticles (AgNPs) have been increasingly used in a variety of consumer products over the last decades. However, their potential adverse effects have not been fully understood. In a previous study, we characterized transcriptomic changes in human induced pluripotent stem cell (iPSC)-derived hepatocyte-like cells (HLCs) in response to AgNP exposure. Here, we report findings of a follow-up proteomic study that evaluated alternations at the protein level in the same cell after being exposed to 10 μg/ml AgNPs for 24 h. In total, 6287 proteins were identified across two groups of samples (n = 3). Among these proteins, 665 were found to be differentially regulated (fold change ≥1.25, p < 0.01) between the AgNP-treated group and the untreated control group, including 264 upregulated and 401 downregulated. Bioinformatics analysis of the proteomics data, in side-by-side comparison to the transcriptomics data, confirms and substantiates previous findings on AgNP-induced alterations in metabolism, oxidative stress, inflammation, and potential association with cancer. A mechanism of action was proposed based on these results. Collectively, the findings of the current proteomic study are consistent with those of the previous transcriptomic study and further demonstrate the usefulness of iPSC-derived HLCs as an in vitro model for liver nanotoxicology.