A cost-effective system for differentiation of intestinal epithelium from human induced pluripotent stem cells

Non-destructive viability assessment of cancer cell spheroids using dynamic optical coherence tomography with trypan blue validation

3D cell cultures are widely used in biomedical research for the recapitulation of in vivo microenvironments. Viability assessment and monitoring of these intricate conformations remain an open problem as standard cell viability protocols based on colorimetry or microscopy are not directly applicable to intact 3D samples. Optical coherence tomography (OCT) has been explored extensively for subsurface structural and quasi-functional analysis of 3D cell cultures and tissue. Recent studies of dynamic OCT as a source of cellular contrast have found qualitative associations with necrosis in cell spheroids, suggesting potential as a viability marker. We present empirical and validated evidence for dynamic OCT as a quantitative indicator of cell viability in 3D cultures. We analysed over 240 MCF-7 cancer cell spheroids with dynamic OCT and corresponding viability measurements using the trypan blue exclusion assay. Significant effects of common reagents dimethyl sulfoxide (DMSO) and phosphate-buffered saline (PBS) on OCT readouts were noted. We proposed a regression-based OCT brightness normalisation technique that removed reagent-induced OCT intensity biases and helped improve correspondence to the viability assay. These results offer a quantitative biological foundation for further advances of dynamic OCT as a novel non-invasive modality for 3D culture monitoring.

Interactions of SARS-CoV-2 with Human Target Cells-A Metabolic View

Viruses are obligate intracellular parasites, and they exploit the cellular pathways and resources of their respective host cells to survive and successfully multiply. The strategies of viruses concerning how to take advantage of the metabolic capabilities of host cells for their own replication can vary considerably. The most common metabolic alterations triggered by viruses affect the central carbon metabolism of infected host cells, in particular glycolysis, the pentose phosphate pathway, and the tricarboxylic acid cycle. The upregulation of these processes is aimed to increase the supply of nucleotides, amino acids, and lipids since these metabolic products are crucial for efficient viral proliferation. In detail, however, this manipulation may affect multiple sites and regulatory mechanisms of host-cell metabolism, depending not only on the specific viruses but also on the type of infected host cells. In this review, we report metabolic situations and reprogramming in different human host cells, tissues, and organs that are favorable for acute and persistent SARS-CoV-2 infection. This knowledge may be fundamental for the development of host-directed therapies.

Accessible luminal interface of bovine rectal organoids generated from cryopreserved biopsy tissues

Developing precise species-specific in vitro models that closely resemble in vivo intestinal tissues is essential for advancing our understanding of gastrointestinal physiology and associated diseases. This is especially crucial in examining host-pathogen interactions, particularly in bovines, a known reservoir for microbes and pathogens posing substantial public health threats. This research investigated the viability of producing bovine rectal organoids from cryopreserved tissues. We compared two cryopreservation methods with a traditional technique using fresh tissues, evaluating their effectiveness through growth rates, long-term viability, and comprehensive structural, cellular, and genetic analyses. These assessments utilized phase-contrast imaging, immunofluorescence imaging, and RT-qPCR assays. Additionally, the study developed a sophisticated method for forming a functional epithelial barrier from organoid-derived bovine rectal monolayers, incorporating a wide range of epithelial cells. This methodology employed transepithelial electrical resistance (TEER), parallel artificial membrane permeability assay (Papp), confocal microscopy, and advanced imaging techniques like scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Our findings decisively show that bovine rectal organoids can be effectively generated from cryopreserved biopsy tissues. Moreover, we formulated a robust and optimized protocol for creating functional rectal monolayers from these organoids. This significant progress is particularly relevant given the susceptibility of the bovine rectum to various enteric pathogens of public health concern, marking a vital step forward in veterinary and biomedical research. The creation of accurate species specific in vitro models that faithfully mimic in vivo intestinal tissues is critical for enhancing our understanding of gut physiology and related pathologies. This is particularly relevant in studying the interactions between hosts and microbes or pathogens with significant public health risks where bovine can be the major reservoir.

Utility of human induced pluripotent stem cell-derived small intestinal epithelial cells for pharmacokinetic, toxicological, and immunological studies

The small intestine, which plays a crucial role in the absorption and metabolism of drugs and foods, serves as a target organ for drug-induced toxicity and immune interactions with functional foods and intestinal bacteria. Current alternative models of the human small intestine, such as Caco-2 cells and experimental animals, have limitations due to variations in the expression levels of metabolic enzymes, transporters, and receptors. This study presents investigations into the utility of human induced pluripotent stem cell-derived small intestinal epithelial cells (hiSIECs) for pharmacokinetic, toxicological, and immunological studies, respectively. While hiSIECs displayed small intestinal epithelial cell characteristics and barrier function, they demonstrated pharmacokinetic properties such as cytochrome P450 3A4/5 activity equivalent to human primary enterocytes and stable P-glycoprotein activity. These cells also demonstrated potential for assessing two forms of intestinal toxicity caused by anticancer drugs and gamma-secretase inhibitors, displaying immune responses mediated by toll-like and fatty acid receptors while serving as an inflammatory gut model through the addition of tumor necrosis factor alpha and interferon gamma. Overall, hiSIECs hold promise as an in vitro model for assessing pharmacokinetics, toxicity, and effects on the intestinal immunity of pharmaceuticals, functional foods, supplements, and intestinal bacteria.

SARS-CoV-2 induces barrier damage and inflammatory responses in the human iPSC-derived intestinal epithelium

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has rapidly spread and led to global health crises. COVID-19 causes well-known respiratory failure and gastrointestinal symptoms, such as diarrhea, nausea, and vomiting. Thus, human gastrointestinal cell models are urgently needed for COVID-19 research; however, it is difficult to obtain primary human intestinal cells. In this study, we examined whether human induced pluripotent stem cell (iPSC)-derived small intestinal epithelial cells (iPSC-SIECs) could be used as a SARS-CoV-2 infection model. We observed that iPSC-SIECs, such as absorptive and Paneth cells, were infected with SARS-CoV-2, and remdesivir treatment decreased intracellular SARS-CoV-2 replication in iPSC-SIECs. SARS-CoV-2 infection decreased expression levels of tight junction markers, ZO-3 and CLDN1, and transepithelial electrical resistance (TEER), which evaluates the integrity of tight junction dynamics. In addition, SARS-CoV-2 infection increased expression levels of proinflammatory genes, which are elevated in patients with COVID-19. These findings suggest iPSC-SIECs as a useful in vitro model for elucidating COVID-19 pathology and drug development.

Characterization and reduction of non-endocrine cells accompanying islet-like endocrine cells differentiated from human iPSC

The differentiation of pancreatic endocrine cells from human pluripotent stem cells has been thoroughly investigated for their application in cell therapy against diabetes. Although non-endocrine cells are inevitable contaminating by-products of the differentiation process, a comprehensive profile of such cells is lacking. Therefore, we characterized non-endocrine cells in iPSC-derived pancreatic islet cells (iPIC) using single-cell transcriptomic analysis. We found that non-endocrine cells consist of (1) heterogeneous proliferating cells, and (2) cells with not only pancreatic traits but also liver or intestinal traits marked by FGB or AGR2. Non-endocrine cells specifically expressed FGFR2, PLK1, and LDHB. We demonstrated that inhibition of pathways involving these genes selectively reduced the number of non-endocrine cells in the differentiation process. These findings provide useful insights into cell purification approaches and contribute to the improvement of the mass production of endocrine cells for stem cell-derived cell therapy for diabetes.

Toward Xeno-Free Differentiation of Human Induced Pluripotent Stem Cell-Derived Small Intestinal Epithelial Cells

The small intestinal epithelium has an important role in nutrition, but also in drug absorption and metabolism. There are a few two-dimensional (2D) patient-derived induced pluripotent stem cell (iPSC)-based intestinal models enabling easy evaluation of transcellular transport. It is known that animal-derived components induce variation in the experimental outcomes. Therefore, we aimed to refine the differentiation protocol by using animal-free components. More specifically, we compared maturation of 2D-cultured iPCSs toward small intestinal epithelial cells when cultured either with or without serum, and either on Geltrex or on animal-free, recombinant laminin-based substrata. Differentiation status was characterized by qPCR, immunofluorescence imaging, and functionality assays. Our data suggest that differentiation toward definitive endoderm is more efficient without serum. Both collagen- and recombinant laminin-based coating supported differentiation of definitive endoderm, posterior definitive endoderm, and small intestinal epithelial cells from iPS-cells equally well. Small intestinal epithelial cells differentiated on recombinant laminin exhibited slightly more enterocyte specific cellular functionality than cells differentiated on Geltrex. Our data suggest that functional small intestinal epithelial cells can be generated from iPSCs in serum-free method on xeno-free substrata. This method is easily converted to an entirely xeno-free method.

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

Embryonic stem cell differentiation models have increasingly been applied in non-animal test systems for developmental toxicity. After the initial focus on cardiac differentiation, attention has also included an array of neuro-ectodermal differentiation routes. Alternative differentiation routes in the mesodermal and endodermal germ lines have received less attention. This review provides an inventory of achievements in the latter areas of embryonic stem cell differentiation, with a view to possibilities for their use in non-animal test systems in developmental toxicology. This includes murine and human stem cell differentiation models, and also gains information from the field of stem cell use in regenerative medicine. Endodermal stem cell derivatives produced in vitro include hepatocytes, pancreatic cells, lung epithelium, and intestinal epithelium, and mesodermal derivatives include cardiac muscle, osteogenic, vascular and hemopoietic cells. This inventory provides an overview of studies on the different cell types together with biomarkers and culture conditions that stimulate these differentiation routes from embryonic stem cells. These models may be used to expand the spectrum of embryonic stem cell based new approach methodologies in non-animal developmental toxicity testing.

The development of a functional human small intestinal epithelium model for drug absorption

Advanced technologies are required for generating human intestinal epithelial cells (hIECs) harboring cellular diversity and functionalities to predict oral drug absorption in humans and study normal intestinal epithelial physiology. We developed a reproducible two-step protocol to induce human pluripotent stem cells to differentiate into highly expandable hIEC progenitors and a functional hIEC monolayer exhibiting intestinal molecular features, cell type diversity, and high activities of intestinal transporters and metabolic enzymes such as cytochrome P450 3A4 (CYP3A4). Functional hIECs are more suitable for predicting compounds metabolized by CYP3A4 and absorbed in the intestine than Caco-2 cells. This system is a step toward the transition from three-dimensional (3D) intestinal organoids to 2D hIEC monolayers without compromising cellular diversity and function. A physiologically relevant hIEC model offers a novel platform for creating patient-specific assays and support translational applications, thereby bridging the gap between 3D and 2D culture models of the intestine.

An Efficient Method for the Differentiation of Human iPSC-Derived Endoderm toward Enterocytes and Hepatocytes

The endoderm, differentiated from human induced pluripotent stem cells (iPSCs), can differentiate into the small intestine and liver, which are vital for drug absorption and metabolism. The development of human iPSC-derived enterocytes (HiEnts) and hepatocytes (HiHeps) has been reported. However, pharmacokinetic function-deficiency of these cells remains to be elucidated. Here, we aimed to develop an efficient differentiation method to induce endoderm formation from human iPSCs. Cells treated with activin A for 168 h expressed higher levels of endodermal genes than those treated for 72 h. Using activin A (days 0–7), CHIR99021 and PI−103 (days 0–2), and FGF2 (days 3–7), the hiPSC-derived endoderm (HiEnd) showed 97.97% CD−117 and CD−184 double-positive cells. Moreover, HiEnts derived from the human iPSC line Windy had similar or higher expression of small intestine-specific genes than adult human small intestine. Activities of the drug transporter P-glycoprotein and drug-metabolizing enzyme cytochrome P450 (CYP) 3A4/5 were confirmed. Additionally, Windy-derived HiHeps expressed higher levels of hepatocyte- and pharmacokinetics-related genes and proteins and showed higher CYP3A4/5 activity than those derived through the conventional differentiation method. Thus, using this novel method, the differentiated HiEnts and HiHeps with pharmacokinetic functions could be used for drug development.

Vinblastine treatment decreases the undifferentiated cell contamination of human iPSC-derived intestinal epithelial-like cells

Human induced pluripotent stem cell-derived intestinal epithelial cells (hiPSC-IECs) are expected to be utilized in regenerative medicine. To perform a safe transplantation without the risk of tumor formation, residual undifferentiated hiPSCs must be removed from hiPSC-IECs. In this study, we examined whether vinblastine (a multiple drug resistance 1 [MDR1] substrate) could remove residual undifferentiated hiPSCs in hiPSC-IECs and attempted to generate hiPSC-IECs applicable to transplantation medicine. We found that the expression levels of pluripotent markers were largely decreased and those of intestinal markers were increased by vinblastine treatment. The treatment of undifferentiated hiPSCs with vinblastine significantly decreased their viability. These results suggested that undifferentiated hiPSCs can be eliminated from hiPSC-IECs by vinblastine treatment. We hypothesized that MDR1-negative cells (such as undifferentiated hiPSCs) die upon vinblastine treatment because they are unable to excrete vinblastine. As expected, the cell viability of MDR1-knockout hiPSC-IECs was significantly decreased by vinblastine treatment. Furthermore, teratomas were formed by subcutaneous transplantation of hiPSC-IECs mixed with undifferentiated hiPSCs into mice, but they were not observed when the transplanted cells were pre-treated with vinblastine. Vinblastine-treated hiPSC-IECs would be an effective cell source for safe regenerative medicine.

Coculture with hiPS-derived intestinal cells enhanced human hepatocyte functions in a pneumatic-pressure-driven two-organ microphysiological system

Examining intestine-liver interactions is important for achieving the desired physiological drug absorption and metabolism response in in vitro drug tests. Multi-organ microphysiological systems (MPSs) constitute promising tools for evaluating inter-organ interactions in vitro. For coculture on MPSs, normal cells are challenging to use because they require complex maintenance and careful handling. Herein, we demonstrated the potential of coculturing normal cells on MPSs in the evaluation of intestine-liver interactions. To this end, we cocultured human-induced pluripotent stem cell-derived intestinal cells and fresh human hepatocytes which were isolated from PXB mice with medium circulation in a pneumatic-pressure-driven MPS with pipette-friendly liquid-handling options. The cytochrome activity, albumin production, and liver-specific gene expressions in human hepatocytes freshly isolated from a PXB mouse were significantly upregulated via coculture with hiPS-intestinal cells. Our normal cell coculture shows the effects of the interactions between the intestine and liver that may occur in vivo. This study is the first to demonstrate the coculturing of hiPS-intestinal cells and fresh human hepatocytes on an MPS for examining pure inter-organ interactions. Normal-cell coculture using the multi-organ MPS could be pursued to explore unknown physiological mechanisms of inter-organ interactions in vitro and investigate the physiological response of new drugs.

Generation of Human-Induced Pluripotent Stem Cell-Derived Functional Enterocyte-Like Cells for Pharmacokinetic Studies

We aimed to establish an in vitro differentiation procedure to generate matured small intestinal cells mimicking human small intestine from human-induced pluripotent stem cells (iPSCs). We previously reported the efficient generation of CDX2-expressing intestinal progenitor cells from embryonic stem cells (ESCs) using 6-bromoindirubin-3'-oxime (BIO) and (3,5-difluorophenylacetyl)-L-alanyl-L-2-phenylglycine tert-butyl ester (DAPT) to treat definitive endodermal cells. Here, we demonstrate the generation of enterocyte-like cells by culturing human iPSC-derived intestinal progenitor cells on a collagen vitrigel membrane (CVM) and treating cells with a simple maturation medium containing BIO, DMSO, dexamethasone, and activated vitamin D3. Functional tests further confirmed that these iPSC-derived enterocyte-like cells exhibit P-gp- and BCRP-mediated efflux and cytochrome P450 3A4 (CYP3A4)-mediated metabolism. We concluded that hiPS cell-derived enterocyte-like cells can be used as a model for the evaluation of drug transport and metabolism studies in the human small intestine.

Evaluation of Barrier Functions in Human iPSC-Derived Intestinal Epithelium

The small intestine plays roles in the absorption and metabolism of orally administered drugs and chemicals. Tight junctions between intestinal epithelial cells, which form a tight barrier preventing the invasion of pathogens and toxins, are essential components of the intestinal defense system. These intestinal functions have generally been evaluated using established cell lines or primary cells in two-dimensional culture. However, these culture systems have not shown the complexity of the three-dimensional structure and diversity of cell types comprising the intestinal epithelial tissue. Here, we report the generation of intestinal organoids using human induced pluripotent stem cells subjected to sequential treatment with different cytokines and compounds. We further describe the tool for evaluating intestinal barrier functions using organoids as a physiologically relevant human platform.

Human small intestinal organotypic culture model for drug permeation, inflammation, and toxicity assays

The gastrointestinal tract (GIT), in particular, the small intestine, plays a significant role in food digestion, fluid and electrolyte transport, drug absorption and metabolism, and nutrient uptake. As the longest portion of the GIT, the small intestine also plays a vital role in protecting the host against pathogenic or opportunistic microbial invasion. However, establishing polarized intestinal tissue models in vitro that reflect the architecture and physiology of the gut has been a challenge for decades and the lack of translational models that predict human responses has impeded research in the drug absorption, metabolism, and drug-induced gastrointestinal toxicity space. Often, animals fail to recapitulate human physiology and do not predict human outcomes. Also, certain human pathogens are species specific and do not infect other hosts. Concerns such as variability of results, a low throughput format, and ethical considerations further complicate the use of animals for predicting the safety and efficacy xenobiotics in humans. These limitations necessitate the development of in vitro 3D human intestinal tissue models that recapitulate in vivo–like microenvironment and provide more physiologically relevant cellular responses so that they can better predict the safety and efficacy of pharmaceuticals and toxicants. Over the past decade, much progress has been made in the development of in vitro intestinal models (organoids and 3D-organotypic tissues) using either inducible pluripotent or adult stem cells. Among the models, the MatTek’s intestinal tissue model (EpiIntestinal™ Ashland, MA) has been used extensively by the pharmaceutical industry to study drug permeation, metabolism, drug-induced GI toxicity, pathogen infections, inflammation, wound healing, and as a predictive model for a clinical adverse outcome (diarrhea) to pharmaceutical drugs. In this paper, our review will focus on the potential of in vitro small intestinal tissues as preclinical research tool and as alternative to the use of animals.

In Vitro Human Cell-Based Experimental Models for the Evaluation of Enteric Metabolism and Drug Interaction Potential of Drugs and Natural Products

Elements of key enteric drug metabolism and disposition pathways are reviewed to aid the assessment of the applicability of current cell-based enteric experimental systems for the evaluation of enteric metabolism and drug interaction potential. Enteric nuclear receptors include vitamin D receptor, constitutive androstane receptor, pregnane X receptor, farnesoid X receptor, liver X receptor, aryl hydrocarbon receptor, and peroxisome proliferator-activated receptor. Enteric drug metabolizing enzyme pathways include both cytochrome P450 (P450) and non-P450 drug metabolizing enzymes based on gene expression, proteomics, and activity. Both uptake and efflux transporters are present in the small intestine, with P-glycoprotein found to be responsible for most drug-drug and food-drug interactions. The cell-based in vitro enteric systems reviewed are 1) immortalized cell line model: the human colon adenocarcinoma (Caco-2) cells; 2) human stem cell-derived enterocyte models: stem cell enteric systems, either from intestinal crypt cells or induced pluripotent stem cells; and 3) primary cell models: human intestinal slices, cryopreserved human enterocytes, permeabilized cofactor-supplemented (MetMax) cryopreserved human enterocytes, and cryopreserved human intestinal mucosa. The major deficiency with both immortalized cell lines and stem cell-derived enterocytes is that drug metabolizing enzyme activities, although they are detectable, are substantially lower than those for the intestinal mucosa in vivo. Human intestine slices, cryopreserved human enterocytes, MetMax cryopreserved human enterocytes, and cryopreserved human intestinal mucosa retain robust enteric drug metabolizing enzyme activity and represent appropriate models for the evaluation of metabolism and metabolism-dependent drug interaction potential of orally administered xenobiotics including drugs, botanical products, and dietary supplements. SIGNIFICANCE STATEMENT: Enteric drug metabolism plays an important role in the bioavailability and metabolic fate of orally administered drugs as well as in enteric drug-drug and food-drug interactions. The current status of key enteric drug metabolism and disposition pathways and in vitro human cell-based enteric experimental systems for the evaluation of the metabolism and drug interaction potential of orally administered substances is reviewed.

Direct On-Chip Differentiation of Intestinal Tubules from Induced Pluripotent Stem Cells

Intestinal organoids have emerged as the new paradigm for modelling the healthy and diseased intestine with patient-relevant properties. In this study, we show directed differentiation of induced pluripotent stem cells towards intestinal-like phenotype within a microfluidic device. iPSCs are cultured against a gel in microfluidic chips of the OrganoPlate, in which they undergo stepwise differentiation. Cells form a tubular structure, lose their stem cell markers and start expressing mature intestinal markers, including markers for Paneth cells, enterocytes and neuroendocrine cells. Tubes develop barrier properties as confirmed by transepithelial electrical resistance (TEER). Lastly, we show that tubules respond to pro-inflammatory cytokine triggers. The whole procedure for differentiation lasts 14 days, making it an efficient process to make patient-specific organoid tubules. We anticipate the usage of the platform for disease modelling and drug candidate screening.

Pharmacokinetic functions of human induced pluripotent stem cell-derived small intestinal epithelial cells

To develop a novel intestinal drug absorption system using intestinal epithelial cells derived from human induced pluripotent stem (iPS) cells, the cells must possess sufficient pharmacokinetic functions. However, the CYP3A4/5 activities of human iPS cell-derived small intestinal epithelial cells prepared using conventional differentiation methods is low. Further, studies of the CYP3A4/5 activities of human iPS-derived and primary small intestinal cells are not available. To fill this gap in our knowledge, here we used forskolin to develop a new differentiation protocol that activates adenosine monophosphate signaling. mRNA expressions of human iPS cell-derived small intestinal epithelial cells, such as small intestine markers, drug-metabolizing enzymes, and drug transporters, were comparable to or greater than those of the adult small intestine. The activities of CYP3A4/5 in the differentiated cells were equal to those of human primary small intestinal cells. The differentiated cells had P-glycoprotein and PEPT1 activities equivalent to those of Caco-2 cells. Differentiated cells were superior to Caco-2 cells for predicting the membrane permeability of drugs that were absorbed through a paracellular pathway and via drug transporters. In summary, here we produced human iPS cell-derived small intestinal epithelial cells with CYP3A4/5 activities equivalent to those of human primary small intestinal cells.

Establishment of a novel culture method for maintaining intestinal stem cells derived from human induced pluripotent stem cells

The small intestine plays an important role in the pharmacokinetics of orally administered drugs due to the presence of drug transporters and drug-metabolizing enzymes. However, few appropriate methods exist to investigate intestinal pharmacokinetics. Induced pluripotent stem (iPS) cells can form various types of cells and represent a potentially useful tool for drug discovery. We previously reported that differentiated enterocytes from human iPS cells are useful for pharmacokinetic studies; however, the process is time and resource intensive. Here, we established a new two-dimensional culture method for maintaining human iPS-cell-derived intestinal stem cells (ISCs) with differentiation potency and evaluated their ability to differentiate into enterocytes exhibiting appropriate pharmacokinetic function. The culture method used several factors to activate signalling pathways required for maintaining stemness, followed by differentiation into enterocytes. Functional evaluation was carried out to verify epithelial-marker expression and inducibility and activity of metabolic enzymes and transporters. Our results confirmed the establishment of an ISC culture method for maintaining stemness and verified that the differentiated enterocytes from the maintained ISCs demonstrated proper pharmacokinetic function. Thus, our findings describe a time- and cost-effective approach that can be used as a general evaluation tool for evaluating intestinal pharmacokinetics.

Generation of Human iPSC-Derived Intestinal Epithelial Cell Monolayers by CDX2 Transduction

BACKGROUND & AIMS

To develop an effective and safe orally administered drug, it is important to predict its intestinal absorption rate, intestinal first-pass effect, and drug-drug interactions of orally administered drugs. However, there is no existing model to comprehensively predict the intestinal pharmacokinetics and drug-response of orally administered drugs. In this study, we attempted to generate homogenous and functional intestinal epithelial cells from human induced pluripotent stem (iPS) cells for pharmaceutical research.

METHODS

We generated almost-homogenous Villin- and zonula occludens-1 (ZO1)-positive intestinal epithelial cells by caudal-related homeobox transcription factor 2 (CDX2) transduction into human iPS cell-derived intestinal progenitor cells.

RESULTS

The drug absorption rates in human iPS cell-derived intestinal epithelial cell monolayers (iPS-IECM) were highly correlated with those in humans (R²=0.91). The expression levels of cytochrome P450 (CYP) 3A4, a dominant drug-metabolizing enzyme in the small intestine, in human iPS-IECM were similar to those in human small intestine in vivo. In addition, intestinal availability in human iPS-IECM (the fraction passing the gut wall: Fg=0.73) was more similar to that in the human small intestine in vivo (Fg=0.57) than to that in Caco-2 cells (Fg=0.99), a human colorectal adenocarcinoma cell line. Moreover, the drug-drug interaction and drug-food interaction could be observed by using our human iPS-IECM in the presence of an inducer and inhibitor of CYP3A4, i.e., rifampicin and grape fruit juice, respectively.

CONCLUSION

Taking these results together, we succeeded in generating the human iPS-IECM that can be applied to various intestinal pharmacokinetics and drug-response tests of orally administered drugs.

STAT3 Phosphorylation Mediating DMSO's Function on Fetal Cardiomyocyte Proliferation with Developmental Changes

Endogenous cardiac regeneration has been focused for decades as a potential therapy for heart diseases with cell loss, and dimethyl sulfoxide (DMSO) has been proposed as a treatment for many diseases. In this study, we aimed to investigate the function of DMSO on fetal cardiomyocyte proliferation. By tracing BrdU⁺/α actinin⁺ cells or Ki67⁺/α actinin⁺ cells with immunohistochemical staining, we found that DMSO remarkably promoted fetal cardiomyocytes proliferation, and at the late developmental stage (LDS), such effects were more efficient than that at early developmental stage (EDS). Western blot data revealed a significant increase in STAT3 phosphorylation under DMSO treatments at LDS, while not at EDS. Consistently, STAT3 phosphorylation blocker STA21 could greatly reverse DMSO's function at LDS whereas hardly at EDS. Moreover, hearts at the EDS had less total STAT3 protein, but relatively much higher level of phosphorylated STAT3. This suggests that DMSO promote fetal cardiomyocytes proliferation, and STAT3 phosphorylation play a pivotal role in DMSO's function. With maturation, DMSO exerted a better ability to favor cardiomyocyte proliferation depending on STAT3 phosphorylation. Therefore, DMSO could serve as an effective, economic, and safe therapy for heart diseases with cell loss.

A transient DMSO treatment increases the differentiation potential of human pluripotent stem cells through the Rb family

The propensity for differentiation varies substantially across human pluripotent stem cell (hPSC) lines, greatly restricting the use of hPSCs for cell replacement therapy or disease modeling. Here, we investigate the underlying mechanisms and demonstrate that activation of the retinoblastoma (Rb) pathway in a transient manner is important for differentiation. In prior work, we demonstrated that pre-treating hPSCs with dimethylsulfoxide (DMSO) before directed differentiation enhanced differentiation potential across all three germ layers. Here, we show that exposure to DMSO improves the efficiency of hPSC differentiation through Rb and by repressing downstream E2F-target genes. While transient inactivation of the Rb family members (including Rb, p107, and p130) suppresses DMSO’s capacity to enhance differentiation across all germ layers, transient expression of a constitutively active (non-phosphorylatable) form of Rb increases the differentiation efficiency similar to DMSO. Inhibition of downstream targets of Rb, such as E2F signaling, also promotes differentiation of hPSCs. More generally, we demonstrate that the duration of Rb activation plays an important role in regulating differentiation capacity.

Efficient Generation of Small Intestinal Epithelial-like Cells from Human iPSCs for Drug Absorption and Metabolism Studies

The small intestine plays an important role in the absorption and metabolism of oral drugs. In the current evaluation system, it is difficult to predict the precise absorption and metabolism of oral drugs. In this study, we generated small intestinal epithelial-like cells from human induced pluripotent stem cells (hiPS-SIECs), which could be applied to drug absorption and metabolism studies. The small intestinal epithelial-like cells were efficiently generated from human induced pluripotent stem cell by treatment with WNT3A, R-spondin 3, Noggin, EGF, IGF-1, SB202190, and dexamethasone. The gene expression levels of small intestinal epithelial cell (SIEC) markers were similar between the hiPS-SIECs and human adult small intestine. Importantly, the gene expression levels of colonic epithelial cell markers in the hiPS-SIECs were much lower than those in human adult colon. The hiPS-SIECs generated by our protocol exerted various SIEC functions. In conclusion, the hiPS-SIECs can be utilized for evaluation of drug absorption and metabolism.

Application of Intestinal Epithelial Cells Differentiated from Human Induced Pluripotent Stem Cells for Studies of Prodrug Hydrolysis and Drug Absorption in the Small Intestine

Cell models to investigate intestinal absorption functions, such as those of transporters and metabolic enzymes, are essential for oral drug discovery and development. The purpose of this study was to generate intestinal epithelial cells from human induced pluripotent stem cells (hiPSC-IECs) and then clarify whether the functions of hydrolase and transporters in them reflect oral drug absorption in the small intestine. The hiPSC-IECs showed the transport activities of P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), and peptide transporter 1 (PEPT1), revealed by using their probe substrates ([3H]digoxin, sulfasalazine, and [14C]glycylsarcosine), and the metabolic activities of CYP3A4, CES2, and CES1, which were clarified using their probe substrates (midazolam, irinotecan, and temocapril). The intrinsic clearance by hydrolysis of six ester prodrugs into the active form in hiPSC-IECs was correlated with the plasma exposure (Cmax , AUC, and bioavailability) of the active form after oral administration of these prodrugs to rats. Also, the permeability coefficients of 14 drugs, containing two substrates of P-gp (doxorubicin and [3H]digoxin), one substrate of BCRP (sulfasalazine), and 11 nonsubstrates of transporters (ganciclovir, [14C]mannitol, famotidine, sulpiride, atenolol, furosemide, ranitidine, hydrochlorothiazide, acetaminophen, propranolol, and antipyrine) in hiPSC-IECs were correlated with their values of the fraction of intestinal absorption (Fa) in human clinical studies. These findings suggest that hiPSC-IECs would be a useful cell model to investigate the hydrolysis of ester prodrugs and to predict drug absorption in the small intestine.

Cyclic AMP Signaling Promotes the Differentiation of Human Induced Pluripotent Stem Cells into Intestinal Epithelial Cells

To develop a novel in vitro system for predicting intestinal drug absorption using human induced pluripotent stem (iPS) cell-derived intestinal epithelial cells, the cells need to have sufficient drug-metabolizing enzyme and drug transporter activities. We found that cyclic adenosine monophosphate (cAMP) signaling plays an important role in the differentiation of human iPS cells into intestinal epithelial cells. In this study, we aimed to demonstrate the effects of signaling activation in the intestinal differentiation of human iPS cells and the pharmacokinetic characteristics of human iPS cell-derived intestinal epithelial cells. Human iPS cells were differentiated into intestinal stem cells using activin A and fibroblast growth factor 2. Subsequently, the intestinal stem cells were maturated into intestinal epithelial cells by treatment with 8-bromo-cyclic adenosine monophosphate (8-Br-cAMP) and 3-isobutyl-1-methylxanthine (IBMX), which activate cAMP signaling. The expression levels of intestinal markers and pharmacokinetics-related genes in the differentiated cells were markedly increased by using 8-Br-cAMP and IBMX. In the cells differentiated with the compound we observed cytochrome P450 (CYP) 3A4 inducibility via pregnane X receptor and vitamin D receptor. The metabolic activities of CYP2C9, CYP2C19, CYP2D6, CYP3A4/5, and UDP-glucuronosyltransferase, which are expressed in the human small intestine, were also markedly increased. Furthermore, uptake of glycylsarcosine via peptide transporter 1 was markedly increased. The cells differentiated with the compounds also had drug transporter activities via organic anion transporters and P-glycoprotein. This study is the first to report that the activation of cAMP signaling promotes differentiation of human iPS cell-derived intestinal epithelial cells.

A Simple System for Differentiation of Functional Intestinal Stem Cell-like Cells from Bone Marrow Mesenchymal Stem Cells

Disruption of normal barrier function is a fundamental factor in the pathogenesis of inflammatory bowel disease, and intestinal stem cell (ISC) transplantation may be an optional treatment for patients. However, it is complicated and inefficient to isolate ISCs from the intestine, which hampers its wide application in clinic. We developed a two-step protocol in which mesenchymal stem cells (MSCs) were first induced into Sox17- or Foxa2-positive definitive endoderm cells by activin A treatment and then into Lgr5-positive ISC-like cells by miR-17 and FGF2 treatment. Furthermore, these Lgr5-positive cells could differentiate into enterocyte-like cells following induction with EGF. The results from an in vivo experiment showed that the MSC-derived Lgr5-positive cells were able to protect against dextran sulfate sodium-induced colitis. Taken together, our work might provide a new source of autologous ISCs.

Different murine-derived feeder cells alter the definitive endoderm differentiation of human induced pluripotent stem cells

The crosstalk between cells is important for differentiation of cells. Murine-derived feeder cells, SNL76/7 feeder cells (SNLs) or mouse primary embryonic fibroblast feeder cells (MEFs) are widely used for culturing undifferentiated human induced pluripotent stem cells (hiPSCs). It is still unclear whether different culture conditions affect the induction efficiency of definitive endoderm (DE) differentiation from hiPSCs. Here we show that the efficiency of DE differentiation from hiPSCs cultured on MEFs was higher than that of hiPSCs cultured on SNLs. The qPCR, immunofluorescent and flow cytometry analyses revealed that the expression levels of mRNA and/or proteins of the DE marker genes, SOX17, FOXA2 and CXCR4, in DE cells differentiated from hiPSCs cultured on MEFs were significantly higher than those cultured on SNLs. Comprehensive RNA sequencing and molecular network analyses showed the alteration of the gene expression and the signal transduction of hiPSCs cultured on SNLs and MEFs. Interestingly, the expression of non-coding hXIST exon 4 was up-regulated in hiPSCs cultured on MEFs, in comparison to that in hiPSCs cultured on SNLs. By qPCR analysis, the mRNA expression of undifferentiated stem cell markers KLF4, KLF5, OCT3/4, SOX2, NANOG, UTF1, and GRB7 were lower, while that of hXIST exon 4, LEFTY1, and LEFTY2 was higher in hiPSCs cultured on MEFs than in those cultured on SNLs. Taken together, our finding indicated that differences in murine-feeder cells used for maintenance of the undifferentiated state alter the expression of pluripotency-related genes in hiPSCs by the signaling pathways and affect DE differentiation from hiPSCs, suggesting that the feeder cells can potentiate hiPSCs for DE differentiation.

iPSC-Derived Enterocyte-like Cells for Drug Absorption and Metabolism Studies

Intestinal cell models have been widely studied and used to evaluate absorption and metabolism of drugs in the small intestine, constituting valuable tools as a first approach to evaluate the behavior of new drugs. However, such cell models might not be able to fully predict the absorption mechanisms and metabolic pathways of the tested compounds. In recent years, induced pluripotent stem cells (iPSCs) differentiated into enterocyte-like cells have been proposed as more biorelevant intestinal models. In this review, we describe mechanisms underlying the differentiation of iPSCs into enterocyte-like cells, appraise the usefulness of these cells in tridimensional intestinal models, and discuss their suitability to be used in the future for drug screening.

Conditional Reprogramming of Pediatric Human Esophageal Epithelial Cells for Use in Tissue Engineering and Disease Investigation

Identifying and expanding patient-specific cells in culture for use in tissue engineering and disease investigation can be very challenging. Utilizing various types of stem cells to derive cell types of interest is often costly, time consuming and highly inefficient. Furthermore, undesired cell types must be removed prior to using this cell source, which requires another step in the process. In order to obtain enough esophageal epithelial cells to engineer the lumen of an esophageal construct or to screen therapeutic approaches for treating esophageal disease, native esophageal epithelial cells must be expanded without altering their gene expression or phenotype. Conditional reprogramming of esophageal epithelial tissue offers a promising approach to expanding patient-specific esophageal epithelial cells. Furthermore, these cells do not need to be sorted or purified and will return to a mature epithelial state after removing them from conditional reprogramming culture. This technique has been described in many cancer screening studies and allows for indefinite expansion of these cells over multiple passages. The ability to perform esophageal screening assays would help revolutionize the treatment of pediatric esophageal diseases like eosinophilic esophagitis by identifying the trigger mechanism causing the patient's symptoms. For those patients who suffer from congenital defect, disease or injury of the esophagus, this cell source could be used as a means to seed a synthetic construct for implantation to repair or replace the affected region.

Characteristic Analysis of Intestinal Transport in Enterocyte-Like Cells Differentiated from Human Induced Pluripotent Stem Cells

We previously demonstrated that differentiated enterocytes from human induced pluripotent stem (iPS) cells exhibited drug-metabolizing activities and cytochrome P450 CYP3A4 inducibility. The aim of this study was to apply human iPS cell-derived enterocytes in pharmacokinetic studies by investigating the characteristics of drug transport into enterocyte-like cells. Human iPS cells cultured on feeder cells were differentiated into endodermal cells using activin A. These endodermal-like cells were then differentiated into intestinal stem cells by fibroblast growth factor 2. Finally, epidermal growth factor and small-molecule compounds induced the maturation of the intestinal stem cell-like cells. After differentiation, we performed transepithelial electrical resistance (TEER) measurements, immunofluorescence staining, and transport studies. TEER values increased in a time-dependent manner and reached approximately 100 Ω × cm(2) Efflux transport of Hoechst 33342, a substrate of breast cancer resistance protein (BCRP), was observed and inhibited by the BCRP inhibitor Ko143. The uptake of peptide transporter 1 substrate glycylsarcosine was also confirmed and suppressed when the temperature was lowered to 4°C. Using immunofluorescence staining, villin and Na(+)-K(+) ATPase were expressed. These results suggest that human iPS cell-derived enterocytes had loose tight junctions, polarity, as well as uptake and efflux transport functions. In addition, the rank order of apparent membrane permeability coefficient (Papp) values of these test compounds across the enterocyte-like cell membrane corresponded to the fraction absorbance (Fa) values. Therefore, differentiated enterocytes from human iPS cells may provide a useful comprehensive evaluation model of drug transport and metabolism in the small intestine.

Late stage definitive endodermal differentiation can be defined by Daf1 expression

Background

Definitive endoderm (DE) gives rise to the respiratory apparatus and digestive tract. Sox17 and Cxcr4 are useful markers of the DE. Previously, we identified a novel DE marker, Decay accelerating factor 1(Daf1/CD55), by identifying DE specific genes from the expression profile of DE derived from mouse embryonic stem cells (ESCs) by microarray analysis, and in situ hybridization of early embryos. Daf1 is expressed in a subpopulation of E-cadherin + Cxcr4+ DE cells. The characteristics of the Daf1-expressing cells during DE differentiation has not been examined.

Results

In this report, we utilized the ESC differentiation system to examine the characteristics of Daf1-expressing DE cells. We found that Daf1 expression could discriminate late DE from early DE. Early DE cells are Daf1-negative (DE-) and late DE cells are Daf1-positive (DE+). We also found that Daf1+ late DE cells show low proliferative and low cell matrix adhesive characteristics. Furthermore, the purified SOX17^low early DE cells gave rise to Daf1+ Sox17^high late DE cells.

Conclusion

Daf1-expressing late definitive endoderm proliferates slowly and show low adhesive capacity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12861-016-0120-2) contains supplementary material, which is available to authorized users.