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Unraveling enteroendocrine cell lineage dynamics and associated gene regulatory networks during intestinal development.
Enteroendocrine cells (EECs) are rare intestinal epithelial cells producing multiple hormones that regulate essential aspects of digestion and energy. EEC subtypes, their hormone repertoire and differentiation mechanisms from intestinal stem cells have been characterized in the adult intestine. Although EECs must be functional from birth because their absence leads to severe intestinal malabsorption in newborns, the processes that determine their subtype specification during development remain largely unknown. We used mouse embryos, human pluripotent stem cell-derived intestinal organoid models and single-cell transcriptomics to characterize EEC lineages and dynamics during development. Our findings demonstrate that in both mice and humans, the majority of EECs are specified during development through similar differentiation trajectories to those observed in the adult intestine. This suggests that EEC subtype specification occurs independently of fully organized crypt-villus structures and stimulation by diet or microbiota. However, the emergence of certain EEC subtypes depends on tissue maturation. Finally, our integrative approach infers lineage-specific regulators dynamically, identifying new candidates controlling EEC differentiation in the developing human gut.
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Differential tropisms of old and new world hantaviruses influence virulence and developing host-directed antiviral candidates.
Hantaviruses are zoonotically transmitted from rodents to humans through the respiratory route, with no currently approved antivirals or widely available vaccines. The recent discovery of interhuman-transmitted Andes virus (ANDV) necessitates the systematic identification of cell tropism, infective potential, and potent therapeutic agents. We utilized human primary lung endothelial cells, various pluripotent stem cell-derived heart and brain cell types, and established human lung organoid models to evaluate the tropisms of Old World Hantaan (HTNV) and New World ANDV and Sin Nombre (SNV) viruses. ANDV exhibited broad tropism for all cell types assessed. SNV readily infected pulmonary endothelial cells, while HTNV robustly amplified in endothelial cells, cardiomyocytes, and astrocytes. We also provide the first evidence of hantaviral infection in human 3D distal lung organoids, which effectively modeled these differential tropisms. ANDV infection transcriptionally promoted cell injury and inflammatory responses, and downregulated lipid metabolic pathways in lung epithelial cells. Evaluation of selected drug candidates and pharmacotranscriptomics revealed that the host-directed small molecule compound urolithin B inhibited ANDV infection and restored cellular metabolism with minimal changes in host transcription. Given the scarcity of academic BSL-4 facilities that enable in vivo hantaviral studies, this investigation presents advanced human cell-based model systems that closely recapitulate host cell tropism and responses to infection, thereby providing critical platforms to evaluate potential antiviral drug candidates.
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Mutations in GFAP Alter Early Lineage Commitment of Organoids.
Glial fibrillary acidic protein (GFAP) is a type-3 intermediate filament protein mainly expressed in astrocytes in the central nervous system. Mutations in GFAP cause Alexander disease (AxD), a rare and fatal neurological disorder. How exactly mutant GFAP eventually leads to white and gray matter deterioration in AxD remains unknown. GFAP is known to be expressed also in neural precursor cells in the developing brain. Here, we used AxD patient-derived induced pluripotent stem cells (iPSCs) to explore the impact of mutant GFAP during neurodifferentiation. Our results show that GFAP is already expressed in iPSCs. Moreover, we have found that mutations in GFAP can severely affect neural organoid development through altering lineage commitment in embryoid bodies. Together, these results support the notion that GFAP plays a role as an early modulator of neurodevelopment.
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Organ-Level Functional 3D Tissue Constructs with Complex Compartments and their Preclinical Applications.
There is an increasing interest in organ-level 3D tissue constructs, owing to their mirroring of in vivo-like features. This has resulted in a wide range of preclinical applications to obtain cell- or tissue-specific responses. Additionally, the development and improvement of sophisticated technologies, such as organoid generation, microfluidics, hydrogel engineering, and 3D printing, have enhanced 3D tissue constructs to become more elaborate. In particular, recent studies have focused on including complex compartments, i.e., vascular and innervation structured 3D tissue constructs, which mimic the nature of the human body in that all tissues/organs are interconnected and physiological phenomena are mediated through vascular and neural systems. Here, the strategies are categorized according to the number of dimensions (0D, 1D, 2D, and 3D) of the starting materials for scaling up, and novel approaches to introduce increased complexity in 3D tissue constructs are highlighted. Recent advances in preclinical applications are also investigated to gain insight into the future direction of 3D tissue construct research. Overcoming the challenges in improving organ-level functional 3D tissue constructs both in vitro and in vivo will ultimately become a life-saving tool in the biomedical field.
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Formation of an endometrial epithelial monolayer in a microfluidic device with human tissue-derived endometrial organoids.
The endometrium is the uterine lining that supports implantation and pregnancy. Existing in vitro systems only partly capture epithelial structure and function. We built a microfluidic model of the human endometrial epithelium using patient-derived organoids and defined a parameterized device and ECM conditions that yield a stable, polarized monolayer on chip. We specify the geometry, surface treatments, and collagen-based hydrogel or coating conditions, and we link these parameters to epithelial morphology and barrier integrity readouts. The epithelial layer maintains histologic features and endometrium-relevant markers and shows hormone-responsive transcript profiles. We quantify donor-to-donor variability across two donors and use it as a design constraint for reproducible culture. Because stromal and immune components shape the reproductive microenvironment, we will extend this platform to modular multicellular co-cultures that incorporate these elements.
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Morphogenesis and development of human telencephalic organoids in the absence and presence of exogenous extracellular matrix.
The establishment and maintenance of apical-basal polarity is a fundamental step in brain development, instructing the organization of neural progenitor cells (NPCs) and the developing cerebral cortex. Particularly, basally located extracellular matrix (ECM) is crucial for this process. In vitro, epithelial polarization can be achieved via endogenous ECM production, or exogenous ECM supplementation. While neuroepithelial development is recapitulated in neural organoids, the effects of different ECM sources in tissue morphogenesis remain underexplored. Here, we show that exposure to a solubilized basement membrane matrix substrate, Matrigel, at early neuroepithelial stages causes rapid tissue polarization and rearrangement of neuroepithelial architecture. In cultures exposed to pure ECM components or unexposed to any exogenous ECM, polarity acquisition is slower and driven by endogenous ECM production. After the onset of neurogenesis, tissue architecture and neuronal differentiation are largely independent of the initial ECM source, but Matrigel exposure has long-lasting effects on tissue patterning. These results advance the knowledge on mechanisms of exogenously and endogenously guided morphogenesis, demonstrating the self-sustainability of neuroepithelial cultures by endogenous processes.
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What (or sometimes who) are organoids? And whose are they?
In terms of ethical implications, Boers, van Delden and Bredenoord (2018) have made an interesting step forward with their model of organoids as hybrids, which seeks to find a balance between subject-like value and object-like value. Their framework aims to introduce effective procedures not to exploit donors and to increase their engagement, but it does not seem to take sufficient account of how organoids are used and how donors and society as a whole may want to act about such uses. I will concentrate my remarks on three points that I consider relevant. The first comment concerns the so-called mini-brains. The second one is related to the issue of consent and long-term 'control' over the organic material granted by donors. The last comment focuses on 'genetic minorities'.
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Effect of the mRNA decapping enzyme scavenger (DCPS) inhibitor RG3039 on glioblastoma.
BACKGROUND: Patients with glioblastoma (GBM) have a poor prognosis and limited treatment options. The mRNA decapping enzyme scavenger (DCPS) is a cap-hydrolyzing enzyme. The DCPS inhibitor RG3039 exhibited excellent central nervous system bioavailability in vivo and was safe and well tolerated in healthy volunteers in a phase 1 clinical trial. In this study, we investigated the expression of DCPS in GBM and the anti-tumor activity of RG3039 in various preclinical models of GBM. METHODS: DCPS expression was examined in human GBM and paired peritumoral tissues. Its prognostic role was evaluated together with clinicopathological characteristics of patients. The anti-GBM effect of RG3039 was determined using GBM cell lines, patient-derived organoids, and orthotopic mouse models. The therapeutic mechanisms of DCPS inhibition were explored. RESULTS: DCPS is overexpressed in GBM and is associated with poor survival of patients with GBM. The DCPS inhibitor RG3039 exhibited robust anti-GBM activities in GBM cell lines, patient-derived organoids and orthotopic mouse models, with drug exposure achievable in humans. Mechanistically, RG3039 downregulated STAT5B expression, thereby suppressing proliferation, survival and colony formation of GBM cells. CONCLUSIONS: DCPS is a promising target for GBM. Inhibition of DCPS with RG3039 at doses achievable in humans downregulates STAT5B expression and reduces proliferation, survival and colony formation of GBM cells. Given the excellent anti-cancer activity and central nervous system bioavailability in vivo and good tolerance in humans, RG3039 warrants further study as a potential GBM therapy.
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Microbiota-derived short-chain fatty acids determine stem cell characteristics of gastric chief cells.
The gastric mucosa is a highly dynamic tissue that undergoes constant self-renewal through stem cell differentiation. Chief cells maintain a quiescent state in homeostasis but are responsible for regeneration after injury. Although the role of microbiome-host interactions in the intestine is well studied, less is known about these interactions in the stomach. Using the mouse organoid and germ-free mouse models, we show that microbiota-derived short-chain fatty acids (SCFAs) suppress the proliferation of chief cells in mice. This effect is mediated by activation of G-protein-coupled receptor 43. Most importantly, through metabolomics and transplantation studies, we show butyrate-producing Lactobacillus intestinalis modulates the proliferation of chief cells in mice. Our findings identify a mechanism by which the microbiota regulates the cell characteristics of chief cells, providing insight into the complex interplay between the host and its microbial environment and the mechanisms underlying gastric homeostasis, with potential therapeutic implications for gastric diseases.
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Epithelial WNT secretion drives niche escape of developing gastric cancer.
BACKGROUND: WNT signaling plays a key role in maintaining the gastric epithelium and promoting tumorigenesis. However, how gastric tumors achieve WNT niche independence remains unclear, as mutations on APC or CTNNB1-common mechanisms of ligand-independent WNT activation in colorectal cancer-are infrequent in gastric cancer. Understanding how WNT self-sufficiency is acquired in the stomach is therefore critical. METHODS: We analyzed mouse gastric organoids harboring oncogenic KRASG12D with or without RNF43/ZNRF3 (RZ) or CDH1/TP53 (CP) mutations, along with corresponding in vivo mouse models. Niche independence was assessed through growth factor withdrawal, Porcupine and pathway-specific inhibitor treatments, and WNT rescue assays. We performed single-nucleus multiome sequencing (RNA + ATAC) to investigate transcriptional and chromatin dynamics. Findings from mouse models were validated using patient-derived gastric cancer organoids, and pan-cancer cell line datasets were analyzed to evaluate clinical and cross-tissue relevance. RESULTS: Gastric fibroblasts secreted canonical WNT2B to maintain the homeostatic gastric epithelium. Upon KRAS activation, epithelial cells were reprogrammed to secrete WNT ligands independently of additional mutations. Single-nucleus multiome analysis revealed that KRAS-driven MAPK signaling opened SMAD2/3-bound enhancers at the WNT7B locus, leading to the emergence of WNT7B-expressing subpopulations. Inhibition of SMAD2/3 phosphorylation suppressed both organoid growth and WNT7B transcription, whereas exogenous WNT restored organoid proliferation. Patient-derived organoids with HER2 amplification, KRAS amplification, or WNT2 copy-number gain exhibited Porcupine inhibitor-sensitive growth, indicating dependence on WNT secretion from the organoids. Analysis of public transcriptomic datasets further demonstrated that the KRAS-MAPK-WNT7B axis is conserved across other cancer types, including lung cancer. CONCLUSIONS: Gastric tumors can bypass niche dependence by acquiring KRAS-MAPK-SMAD2/3-driven epithelial WNT secretion. Targeting this axis-through MAPK inhibition, SMAD2/3 blockade, or suppression of WNT secretion-may represent a therapeutic vulnerability in gastric cancer and other KRAS-high malignancies.