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ObjectiveThyroid hormone (TH) action is mediated by thyroid hormone receptor (THR) isoforms. While THR?1 is likely the main isoform expressed in liver, its role in human hepatocytes is not fully understood.MethodsTo elucidate the role of THR?1 action in human hepatocytes we used CRISPR/Cas9 editing to knock out THR?1 in induced pluripotent stem cells (iPSC). Following directed differentiation to the hepatic lineage, iPSC-derived hepatocytes were then interrogated to determine the role of THR?1 in ligand-independent and -dependent functions.ResultsWe found that the loss of THR?1 promoted alterations in proliferation rate and metabolic pathways regulated by T3, including gluconeogenesis, lipid oxidation, fatty acid synthesis, and fatty acid uptake. We observed that key genes involved in liver metabolism are regulated through both T3 ligand-dependent and -independent THR?1 signaling mechanisms. Finally, we demonstrate that following THR?1 knockout, several key metabolic genes remain T3 responsive suggesting they are THR? targets.ConclusionsThese results highlight that iPSC-derived hepatocytes are an effective platform to study mechanisms regulating TH signaling in human hepatocytes. Graphical abstractImage 1 Highlights•THR?1 is essential for T3 effects in human iPSC-derived hepatocytes (iHEPs).•THR?1 knockout reduces iPSC and progenitor cell proliferative capacity.•T3 regulates key genes involved in lipid and carbohydrate metabolism through THR?1.•THR?1 plays a strong ligand-independent role.

Background: Alzheimer's disease (AD) is characterized by progressive amyloid beta (Aβ) deposition in the brain, with eventual widespread neurodegeneration. While the cell-specific molecular signature of end-stage AD is reasonably well characterized through autopsy material, less is known about the molecular pathways in the human brain involved in the earliest exposure to Aβ. Human model systems that not only replicate the pathological features of AD but also the transcriptional landscape in neurons, astrocytes and microglia are crucial for understanding disease mechanisms and for identifying novel therapeutic targets. Methods: In this study, we used a human 3D iPSC-derived neurosphere model to explore how resident neurons, microglia and astrocytes and their interplay are modified by chronic amyloidosis induced over 3-5 weeks by supplementing media with synthetic Aβ1 - 42 oligomers. Neurospheres under chronic Aβ exposure were grown with or without microglia to investigate the functional roles of microglia. Neuronal activity and oxidative stress were monitored using genetically encoded indicators, including GCaMP6f and roGFP1, respectively. Single nuclei RNA sequencing (snRNA-seq) was performed to profile Aβ and microglia driven transcriptional changes in neurons and astrocytes, providing a comprehensive analysis of cellular responses. Results: Microglia efficiently phagocytosed Aβ inside neurospheres and significantly reduced neurotoxicity, mitigating amyloidosis-induced oxidative stress and neurodegeneration following different exposure times to Aβ. The neuroprotective effects conferred by the presence of microglia was associated with unique gene expression profiles in astrocytes and neurons, including several known AD-associated genes such as APOE. These findings reveal how microglia can directly alter the molecular landscape of AD. Conclusions: Our human 3D neurosphere culture system with chronic Aβ exposure reveals how microglia may be essential for the cellular and transcriptional responses in AD pathogenesis. Microglia are not only neuroprotective in neurospheres but also act as key drivers of Aβ-dependent APOE expression suggesting critical roles for microglia in regulating APOE in the AD brain. This novel, well characterized, functional in vitro platform offers unique opportunities to study the roles and responses of microglia to Aβ modelling key aspects of human AD. This tool will help identify new therapeutic targets, accelerating the transition from discovery to clinical applications.

Background and purpose: In this study, we applied an induced pluripotent stem cell (iPSC)-based model of inherited erythromelalgia (IEM) to screen a library of 281 small molecules, aiming to identify candidate pain-modulating compounds. Experimental approach: Human iPSC-derived sensory neuron-like cells, which exhibit action potentials in response to noxious stimulation, were evaluated using whole-cell patch-clamp and microelectrode array (MEA) techniques. Key results: Sensory neuron-like cells derived from individuals with IEM showed spontaneous electrical activity characteristic of genetic pain disorders. The drug screen identified four compounds (AZ106, AZ129, AZ037 and AZ237) that significantly decreased spontaneous firing with minimal toxicity. The calculated IC50 values indicate the potential efficacy of these compounds. Electrophysiological analysis confirmed the compounds' ability to reduce action potential generation in IEM patient-specific iPSC-derived sensory neuron-like cells. Conclusions and implications: Our screening approach demonstrates the reproducibility and effectiveness of human neuronal disease modelling offering a promising avenue for discovering new analgesics. These findings address a critical gap in current therapeutic strategies for both general and neuropathic pain, warranting further investigation. This study highlights the innovative use of patient-derived iPSC sensory neuronal models in pain research and emphasises the potential for personalised medicine in developing targeted analgesics. Key points: Utilisation of human iPSCs for efficient differentiation into sensory neuron-like cells offers a novel strategy for studying pain mechanisms. IEM sensory neuron-like cells exhibit key biomarkers and generate action potentials in response to noxious stimulation. IEM sensory neuron-like cells display spontaneous electrical activity, providing a relevant nociceptive model. Screening of 281 compounds identified four candidates that significantly reduced spontaneous firing with low cytotoxicity. Electrophysiological profiling of selected compounds revealed promising insights into their mechanisms of action, specifically modulating the NaV 1.7 channel for targeted analgesia.

The immune-modulatory effects of mesenchymal stromal cells (MSCs) are widely used to treat inflammatory disorders, with indoleamine 2,4-dioxygenase-1 (IDO-1) playing a pivotal role in suppressing stimulated T-cell proliferation. Taking that three-dimensional (3D) cultures enhance MSCs’ anti-inflammatory properties compared with two-dimensional (2D) cultures, the differentially expressed miRNAs were examined. Thus, we identified hsa-miR-4662a-5p (miR-4662a) as a key inducer of IDO-1 via its suppression of bridging integrator-1 (BIN-1), a negative regulator of the IDO-1 gene. The IDO-1-inducing potential of miR-4662a was conserved across primary MSCs from various donors and sources but exhibited variability. Notably, iPSC-derived MSCs (iMSCs) demonstrated superior IDO-1 induction and immune-modulatory efficacy compared with their donor-matched primary MSCs. Accordingly, iMSCs expressing miR-4662a (4662a/iMSC) exhibited stronger suppressive effects on T-cell proliferation and more potent suppressive effects on graft-versus-host disease (GVHD), improving survival rates and reducing tissue damage in the liver and gut. Our results point to the therapeutic potential of standardized, off-the-shelf 4662a/iMSC as a robust immune-modulating cell therapy for GVHD.

Propionic acidemia (PA) is a metabolic disorder caused by a deficiency of the mitochondrial enzyme propionyl-CoA carboxylase (PCC) due to mutations in the PCCA or PCCB genes, which encode the two PCC subunits. PA may lead to several types of cardiomyopathy and has been linked to cardiac electrical abnormalities such as QT interval prolongation, life-threatening arrhythmias, and sudden cardiac death. To gain insights into the mechanisms underlying PA-induced proarrhythmia, we recorded action potentials (APs) and ion currents using whole-cell patch-clamp in ventricular-like induced pluripotent stem cells-derived cardiomyocytes (hiPSC-CMs) from a PA patient carrying two pathogenic mutations in the PCCA gene (p.Cys616_Val633del and p.Gly477Glufs*9) (PCCA cells) and from a healthy subject (healthy cells). In cells driven at 1 Hz, PCC deficiency increased the latency and prolonged the AP duration (APD) measured at 20% of repolarization, without modifying resting membrane potential or AP amplitude. Moreover, delayed afterdepolarizations appeared at the end of the repolarization phase in unstimulated and paced PCCA cells. PCC deficiency significantly reduced peak sodium current (INa) but increased the late INa (INaL) component. In addition, L-type Ca2+ current (ICaL) density was reduced, while the inward and outward density of the Na+/Ca2+ exchanger current (INCX) was increased in PCCA cells compared to healthy ones. In conclusion, our results demonstrate that at the cellular level, PCC deficiency can modify the ion currents controlling cardiac excitability, APD, and intracellular Ca2+ handling, increasing the risk of arrhythmias independently of the progressive late-onset cardiomyopathy induced by PA disease.

The generation of retinal models from human induced pluripotent stem cells holds significant potential for advancing our understanding of retinal development, neurodegeneration, and the in vitro modeling of neurodegenerative disorders. The retina, as an accessible part of the central nervous system, offers a unique window into these processes, making it invaluable for both study and early diagnosis. This study investigates the impact of the Frontotemporal Dementia-linked IVS 10?+?16 MAPT mutation on retinal development and function using 2D and 3D retinal models derived from human induced pluripotent stem cells. Our findings reveal that the MAPT mutation leads to delayed retinal cell differentiation and maturation, with tau-mutant disease models exhibiting sustained higher expression of retinal progenitor cell markers and a reduced presence of post-mitotic neurons. Both 2D and 3D tau-mutant retinal models demonstrated an imbalance in tau isoforms, favoring 4R tau, along with increased tau phosphorylation, altered neurite morphology, and impaired cytoskeletal maturation. These changes are associated with impaired synaptic development, reduced neuronal connectivity, and enhanced cellular stress responses, including the increased formation of stress granules, markers of apoptosis and autophagy, and the presence of intracellular toxic tau aggregates. This study highlights the value of retinal models derived from human induced pluripotent stem cells in exploring the mechanisms underlying retinal pathology associated with tau mutations. These models offer essential insights into the development of therapeutic strategies for neurodegenerative diseases characterized by tau aggregation.Supplementary InformationThe online version contains supplementary material available at 10.1186/s40478-024-01920-x.

This study describes the characterization of one induced pluripotent stem cell line (iPSC) from a healthy female. It is crucial to use iPSCs derived from healthy individuals as controls in genetic disease studies. Thus, we established a human iPSC cell line derived from healthy people. The iPSC cell line was generated in our lab from the peripheral blood mononuclear cells (PBMCs) of a 28-year-old girl. The generated hiPSC line is free of episomal vectors, has a normal karyotype, expresses pluripotency markers and can differentiate into three germ layers in vivo.

BACKGROUND Thrombocytopenia leading to life-threatening excessive bleeding can be treated by platelet transfusion. Currently, such treatments are totally dependent on donor-derived platelets. To support future applications in the use of in vitro-derived platelets, we sought to identify genes whose manipulation might improve the efficiency of megakaryocyte production and resulting hemostatic effectiveness. Disruption of Lyn kinase has previously been shown to improve cell survival, megakaryocyte ploidy and TPO-mediated activation in mice, but its role in human megakaryocytes and platelets has not been examined. METHODS To analyze the role of Lyn at defined differentiation stages during human megakaryocyte differentiation, conditional Lyn-deficient cells were generated using CRISPR/Cas9 technology in iPS cells. The efficiency of Lyn-deficient megakaryocytes to differentiate and become activated in response to a range of platelet agonists was analyzed in iPSC-derived megakaryocytes. RESULTS Temporally controlled deletion of Lyn improved the in vitro differentiation of hematopoietic progenitor cells into mature megakaryocytes, as measured by the rate and extent of appearance of CD41+ CD42+ cells. Lyn-deficient megakaryocytes also demonstrated improved hemostatic effectiveness, as reported by their ability to mediate clot formation in rotational thromboelastometry. Finally, Lyn-deficient megakaryocytes produced increased numbers of platelet-like particles (PLP) in vitro. CONCLUSIONS Conditional deletion of Lyn kinase increases the hemostatic effectiveness of megakaryocytes and their progeny as well as improving their yield. Adoption of this system during generation of in vitro-derived platelets may contribute to both their efficiency of production and their ability to support hemostasis.

Idiopathic pulmonary fibrosis (IPF) is a fatal disease of unknown cause that is characterized by progressive fibrotic lung remodeling. An abnormal emergence of airway epithelial-like cells within the alveolar compartments of the lung, herein termed bronchiolization, is often observed in IPF. However, the origin of this dysfunctional distal lung epithelium remains unknown due to a lack of suitable human model systems. In this study, we established a human induced pluripotent stem cell (iPSC)-derived air-liquid interface (ALI) model of alveolar epithelial type II (ATII)-like cell differentiation that allows us to investigate alveolar epithelial progenitor cell differentiation in vitro. We treated this system with an IPF-relevant cocktail (IPF-RC) to mimic the pro-fibrotic cytokine milieu present in IPF lungs. Stimulation with IPF-RC during differentiation increases secretion of IPF biomarkers and RNA sequencing (RNA-seq) of these cultures reveals significant overlap with human IPF patient data. IPF-RC treatment further impairs ATII differentiation by driving a shift toward an airway epithelial-like expression signature, providing evidence that a pro-fibrotic cytokine environment can influence the proximo-distal differentiation pattern of human lung epithelial cells. In conclusion, we show for the first time, the establishment of a human model system that recapitulates aspects of IPF-associated bronchiolization of the lung epithelium in vitro.,reference_pmid=32297676,parent_skus=05040

Cytokine-inducible SH2-containing protein (CIS; encoded by the gene CISH) is a key negative regulator of interleukin-15 (IL-15) signaling in natural killer (NK) cells. Here, we develop human CISH-knockout (CISH-/-) NK cells using an induced pluripotent stem cell-derived NK cell (iPSC-NK cell) platform. CISH-/- iPSC-NK cells demonstrate increased IL-15-mediated JAK-STAT signaling activity. Consequently, CISH-/- iPSC-NK cells exhibit improved expansion and increased cytotoxic activity against multiple tumor cell lines when maintained at low cytokine concentrations. CISH-/- iPSC-NK cells display significantly increased in vivo persistence and inhibition of tumor progression in a leukemia xenograft model. Mechanistically, CISH-/- iPSC-NK cells display improved metabolic fitness characterized by increased basal glycolysis, glycolytic capacity, maximal mitochondrial respiration, ATP-linked respiration, and spare respiration capacity mediated by mammalian target of rapamycin (mTOR) signaling that directly contributes to enhanced NK cell function. Together, these studies demonstrate that CIS plays a key role to regulate human NK cell metabolic activity and thereby modulate anti-tumor activity.

RAG2 severe combined immune deficiency (RAG2-SCID) is a lethal disorder caused by the absence of functional T and B cells due to a differentiation block. Here, we generated induced pluripotent stem cells (iPSCs) from a RAG2-SCID patient to study the nature of the T cell developmental blockade. We observed a strongly reduced capacity to differentiate at every investigated stage of T cell development, from early CD7-CD5- to CD4+CD8+. The impaired differentiation was accompanied by an increase in CD7-CD56+CD33+ natural killer (NK) cell-like cells. T cell receptor D rearrangements were completely absent in RAG2SCID cells, whereas the rare T cell receptor B rearrangements were likely the result of illegitimate rearrangements. Repair of RAG2 restored the capacity to induce T cell receptor rearrangements, normalized T cell development, and corrected the NK cell-like phenotype. In conclusion, we succeeded in generating an iPSC-based RAG2-SCID model, which enabled the identification of previously unrecognized disorder-related T cell developmental roadblocks.

The molecular basis of the earliest neuronal changes that lead to Alzheimer's disease (AD) is unclear. Here, we analyze neural cells derived from sporadic AD (SAD), APOE4 gene-edited and control induced pluripotent stem cells (iPSCs). We observe major differences in iPSC-derived neural progenitor (NP) cells and neurons in gene networks related to neuronal differentiation, neurogenesis, and synaptic transmission. The iPSC-derived neural cells from SAD patients exhibit accelerated neural differentiation and reduced progenitor cell renewal. Moreover, a similar phenotype appears in NP cells and cerebral organoids derived from APOE4 iPSCs. Impaired function of the transcriptional repressor REST is strongly implicated in the altered transcriptome and differentiation state. SAD and APOE4 expression result in reduced REST nuclear translocation and chromatin binding, and disruption of the nuclear lamina. Thus, dysregulation of neural gene networks may set in motion the pathologic cascade that leads to AD.