EPIREGULIN creates a developmental niche for spatially organized human intestinal enteroids

A robust ingredient makes human gut stem cell niches on a dish

Human intestinal organoids (HIOs) generated from induced pluripotent stem cells (iPSCs) are utilized for disease modeling but they lack a full complement of niche components. Childs et al.1 demonstrate that EPIREGULIN-driven HIOs mature into functional, neuromuscular, and vascularized niches, establishing a powerful platform for human gut physiology and disease research.

Coordinated differentiation of human intestinal organoids with functional enteric neurons and vasculature

Human intestinal organoids (HIOs) derived from human pluripotent stem cells co-differentiate both epithelial and mesenchymal lineages in vitro but lack important cell types such as neurons, endothelial cells, and smooth muscle, which limits translational potential. Here, we demonstrate that the intestinal stem cell niche factor, EPIREGULIN (EREG), enhances HIO differentiation with epithelium, mesenchyme, enteric neuroglial populations, endothelial cells, and organized smooth muscle in a single differentiation, without the need for co-culture. When transplanted into a murine host, HIOs mature and demonstrate enteric nervous system function, undergoing peristaltic-like contractions indicative of a functional neuromuscular unit. HIOs also form functional vasculature, demonstrated in vitro using microfluidic devices and in vivo following transplantation, where HIO endothelial cells anastomose with host vasculature. These complex HIOs represent a transformative tool for translational research in the human gut and can be used to interrogate complex diseases as well as for testing therapeutic interventions with high fidelity to human pathophysiology.

Functional maturation of preterm intestinal epithelium through CFTR activation

Preterm birth disrupts intestinal epithelial maturation, impairing digestive and absorptive functions. This study integrates analysis of single-cell RNA sequencing datasets, spanning fetal to adult stages, with human preterm intestinal models derived from the ileal tissue of preterm infants. We investigate the potential of extracellular vesicles (EVs) derived from human Wharton's jelly mesenchymal stem cells to promote intestinal maturation. Distinct enterocyte differentiation trajectories are identified during the transition from immature to mature stages of human intestinal development. EV treatment, particularly with the EV39 line, significantly upregulates maturation-specific gene expression related to enterocyte function. Gene set enrichment analysis reveals an enrichment of TGFβ1 signaling pathways, and proteomic analysis identifies TGFβ1 and FGF2 as key mediators of EV39's effects. These treatments enhance cell proliferation, epithelial barrier integrity, and fatty acid uptake, primarily through CFTR-dependent mechanisms-unique to human preterm models, not observed in mouse intestinal organoids. This highlights the translational potential of EV39 and CFTR activation in promoting the functional maturation of the premature human intestine.

Intestinal organoids: The path towards clinical application

Organoids have revolutionized the whole field of biology with their ability to model complex three-dimensional human organs in vitro. Intestinal organoids were especially consequential as the first successful long-term culture of intestinal stem cells, which raised hopes for translational medical applications. Despite significant contributions to basic research, challenges remain to develop intestinal organoids into clinical tools for diagnosis, prognosis, and therapy. In this review, we outline the current state of translational research involving adult stem cell and pluripotent stem cell derived intestinal organoids, highlighting the advances and limitations in disease modeling, drug-screening, personalized medicine, and stem cell therapy. Preclinical studies have demonstrated a remarkable functional recapitulation of infectious and genetic diseases, and there is mounting evidence for the reliability of intestinal organoids as a patient-specific avatar. Breakthroughs now allow the generation of structurally and cellularly complex intestinal models to better capture a wider range of intestinal pathophysiology. As the field develops and evolves, there is a need for standardized frameworks for generation, culture, storage, and analysis of intestinal organoids to ensure reproducibility, comparability, and interpretability of these preclinical and clinical studies to ultimately enable clinical translation.

Harnessing 3D models to uncover the mechanisms driving infectious and inflammatory disease in the intestine

Representative models of intestinal diseases are transforming our knowledge of the molecular mechanisms of disease, facilitating effective drug screening and avenues for personalised medicine. Despite the emergence of 3D in vitro intestinal organoid culture systems that replicate the genetic and functional characteristics of the epithelial tissue of origin, there are still challenges in reproducing the human physiological tissue environment in a format that enables functional readouts. Here, we describe the latest platforms engineered to investigate environmental tissue impacts, host-microbe interactions and enable drug discovery. This highlights the potential to revolutionise knowledge on the impact of intestinal infection and inflammation and enable personalised disease modelling and clinical translation.

Paneth Cells: Dispensable yet Irreplaceable for the Intestinal Stem Cell Niche

Intestinal stem cells replenish the epithelium throughout life by continuously generating intestinal epithelial cell types, including absorptive enterocytes, and secretory goblet, endocrine, and Paneth cells. This process is orchestrated by a symphony of niche factors required to maintain intestinal stem cells and to direct their proliferation and differentiation. Among the various mature intestinal epithelial cell types, Paneth cells are unique in their location in the stem cell zone, directly adjacent to intestinal stem cells. Although Paneth cells were first described as an epithelial cell component of the innate immune system due to their expression of anti-microbial peptides, they have been proposed to be niche cells due to their close proximity to intestinal stem cells and expression of niche factors. However, function as a niche cell has been debated since mice lacking Paneth cells retain functional stem cells that continue to replenish the intestinal epithelium. In this review, we summarize the intestinal stem cell niche, including the Notch, Wnt, growth factor, mechanical, and metabolic niche, and discuss how Paneth cells might contribute to these various components. We also present a nuanced view of the Paneth cell as a niche cell. Although not required, Paneth cells enhance stem cell function, particularly during intestinal development and regeneration. Furthermore, we suggest that Paneth cell loss induces intestinal stem cell remodeling to adjust their niche demands.

Structure and organization of full-length Epidermal Growth Factor Receptor in extracellular vesicles by cryo-electron tomography

We report here transport of the Epidermal Growth Factor Receptor (EGFR), Insulin Receptor, 7-pass transmembrane receptor Smoothened, and 13-pass Sodium-iodide symporter to extracellular vesicles (EVs) for structural and functional studies. Mass spectrometry confirmed the transported proteins as the most abundant in EV membranes, and the presence of many receptor-interacting proteins demonstrates the utility of EVs for characterizing membrane protein interactomes. Cryo-electron tomography of EGFR-containing EVs reveals that EGFR forms clusters in the presence of EGF with a ∼3 nm gap between the inner membrane and cytoplasmic density. EGFR extracellular regions do not form regular arrays, suggesting that clustering is mediated by the intracellular region. Subtomogram averaging of the EGFR extracellular region (ECR) yielded a 15 Å map into which the crystal structure of the ligand-bound EGFR ECR dimer fits well. These findings refine our understanding of EGFR activation, clustering, and signaling, and they establish EVs as a versatile platform for structural and functional characterization of human membrane proteins in a native-like environment.

Significance Statement

Atomic or near-atomic resolution structural studies of proteins embedded in cell membranes have proven challenging. We show that transporting integral membrane proteins to cell-derived extracellular vesicles enables structural and functional studies of human membrane proteins in a native membrane environment. We have used this approach to visualize an active form of full-length Epidermal Growth Factor Receptor (EGFR) and show that it forms clusters in the membrane and projects its cytoplasmic signaling domains ∼3 nm away from the membrane surface. EGFR is essential for normal development, but abnormal EGFR activity is associated with several human cancers and is the target of many anticancer therapies. Our studies refine current models of how ligand binding to EGFR transmits signals across cell membranes.

An iPSC-derived small intestine-on-chip with self-organizing epithelial, mesenchymal, and neural cells

Human induced pluripotent stem cell (hiPSC)-derived intestinal organoids are valuable tools for researching developmental biology and personalized therapies, but their closed topology and relative immature state limit applications. Here, we use organ-on-chip technology to develop a hiPSC-derived intestinal barrier with apical and basolateral access in a more physiological in vitro microenvironment. To replicate growth factor gradients along the crypt-villus axis, we locally expose the cells to expansion and differentiation media. In these conditions, intestinal epithelial cells self-organize into villus-like folds with physiological barrier integrity, and myofibroblasts and neurons emerge and form a subepithelial tissue in the bottom channel. The growth factor gradients efficiently balance dividing and mature cell types and induce an intestinal epithelial composition, including absorptive and secretory lineages, resembling the composition of the human small intestine. This well-characterized hiPSC-derived intestine-on-chip system can facilitate personalized studies on physiological processes and therapy development in the human small intestine.

BEST4+ cells in the intestinal epithelium

The recent development of single-cell transcriptomics highlighted the existence of a new lineage of mature absorptive cells in the human intestinal epithelium. This subpopulation is characterized by the specific expression of Bestrophin 4 (BEST4) and of other marker genes including OTOP2, CA7, GUCA2A, GUCA2B, and SPIB. BEST4+ cells appear early in development and are present in all regions of the small and large intestine at a low abundance (<5% of all epithelial cells). Location-specific gene expression profiles in BEST4+ cells suggest their functional specialization in each gut region, as exemplified by the small intestine-specific expression of the ion channel CFTR. The putative roles of BEST4+ cells include sensing and regulation of luminal pH, tuning of guanylyl cyclase-C signaling, transport of electrolytes, hydration of mucus, and secretion of antimicrobial peptides. However, most of these hypotheses lack functional validation, notably because BEST4+ cells are absent in mice. The presence of BEST4+ cells in human intestinal organoids indicates that this in vitro model should be suitable to study their role. Recent studies showed that BEST4+ cells are also present in the intestinal epithelium of macaque, pig, and zebrafish and, here, we report their presence in rabbits, which suggests that these species could be appropriate animal models to study BEST4+ cells during the development of diseases and their interactions with environmental factors such as diet or the microbiota. In this review, we summarize the existing literature regarding BEST4+ cells and emphasize the description of their predicted roles in the intestinal epithelium in health and disease.NEW & NOTEWORTHY BEST4+ cells are a novel subtype of mature absorptive cells in the human intestinal epithelium highlighted by single-cell transcriptomics. The gene expression profile of BEST4+ cells suggests their role in pH regulation, electrolyte secretion, mucus hydration, and innate immune defense. The absence of BEST4+ cells in mice requires the use of alternative animal models or organoids to decipher the role of this novel type of intestinal epithelial cells.

RTK signalling promotes epithelial columnar cell shape and apical junction maintenance in human lung progenitor cells

Multipotent epithelial progenitor cells can be expanded from human embryonic lungs as organoids and maintained in a self-renewing state using a defined medium. The organoid cells are columnar, resembling the cell morphology of the developing lung tip epithelium in vivo. Cell shape dynamics and fate are tightly coordinated during development. We therefore used the organoid system to identify signalling pathways that maintain the columnar shape of human lung tip progenitors. We found that EGF, FGF7 and FGF10 have distinct functions in lung tip progenitors. FGF7 activates MAPK/ERK and PI3K/AKT signalling, and is sufficient to promote columnar cell shape in primary tip progenitors. Inhibitor experiments show that MAPK/ERK and PI3K/AKT signalling are key downstream pathways, regulating cell proliferation, columnar cell shape and cell junctions. We identified integrin signalling as a key pathway downstream of MAPK/ERK in the tip progenitors; disrupting integrin alters polarity, cell adhesion and tight junction assembly. By contrast, stimulation with FGF10 or EGF alone is not sufficient to maintain organoid columnar cell shape. This study employs organoids to provide insight into the cellular mechanisms regulating human lung development.