Immunofluorescent Staining of Mouse Intestinal Stem Cells

Organoid models: the future companions of personalized drug development

High failure rates of the current drug development process are driving exemplary changes toward methodologies centered on human diseasein-vitromodeling. Organoids are self-organized tissue sub-units resembling their organ of origin and are widely acknowledged for their unique potential in recapitulating human physio-pathological mechanisms. They are transformative for human health by becoming the platform of choice to probe disease mechanisms and advance new therapies. Furthermore, the compounds' validation as therapeutics represents another point of the drug development pipeline where organoids may provide key understandings and help pharma organizations replace or reduce animal research. In this review, we focus on gastrointestinal organoid models, which are currently the most advanced organoid models in drug development. We focus on experimental validations of their value, and we propose avenues to enhance their use in drug discovery and development, as well as precision medicine and diagnostics.

Aryl Hydrocarbon Receptor Regulates Muc2 Production Independently of IL-22 during Colitis

We previously reported that an aryl hydrocarbon receptor (AhR) ligand, indole-3-carbinol (I3C), was effective at reducing colitis severity through immune cell-mediated interleukin-22 (IL-22) production. Intestinal epithelial cells (IECs) are also involved in regulating colitis, so we investigated their AhR-mediated mechanisms in the current report. A transcriptome analysis of IECs in wildtype (WT) mice revealed that during colitis, I3C regulated select mucin proteins, which could be attributed to goblet cell development. To address this, experiments under in vivo colitis (mice) or in vitro colon organoid conditions were undertaken to determine how select mucin proteins were altered in the absence or presence of AhR in IECs during I3C treatment. Comparing WT to IEC-specific AhR knockout mice (AhRΔIEC), the results showed that AhR expression was essential in IECs for I3C-mediated protection during colitis. AhR-deficiency also impaired mucin protein expression, particularly mucin 2 (Muc2), independently of IL-22. Collectively, this report highlights the important role of AhR in direct regulation of Muc2. These results provide justification for future studies aimed at determining how AhR might regulate select mucins through mechanisms such as direct transcription binding to enhance production.

MRTF-A gain-of-function in mice impairs homeostatic renewal of the intestinal epithelium

The actin-regulated transcription factor MRTF-A represents a central relay in mechanotransduction and controls a subset of SRF-dependent target genes. However, gain-of-function studies in vivo are lacking. Here we characterize a conditional MRTF-A transgenic mouse model. While MRTF-A gain-of-function impaired embryonic development, induced expression of constitutively active MRTF-A provoked rapid hepatocyte ballooning and liver failure in adult mice. Specific expression in the intestinal epithelium caused an erosive architectural distortion, villus blunting, cryptal hyperplasia and colonic inflammation, resulting in transient weight loss. Organoids from transgenic mice repeatedly induced in vitro showed impaired self-renewal and defective cryptal compartments. Mechanistically, MRTF-A gain-of-function decreased proliferation and increased apoptosis, but did not induce fibrosis. MRTF-A targets including Acta2 and Pai-1 were induced, whereas markers of stem cells and differentiated cells were reduced. Our results suggest that activated MRTF-A in the intestinal epithelium shifts the balance between proliferation, differentiation and apoptosis.

Development of a dual-flow tissue perfusion device for modeling the gastrointestinal tract-brain axis

Despite the large number of microfluidic devices that have been described over the past decade for the study of tissues and organs, few have become widely adopted. There are many reasons for this lack of adoption, primarily that devices are constructed for a single purpose or because they are highly complex and require relatively expensive investment in facilities and training. Here, we describe a microphysiological system (MPS) that is simple to use and provides fluid channels above and below cells, or tissue biopsies, maintained on a disposable, poly(methyl methacrylate), carrier held between polycarbonate outer plates. All other fittings are standard Luer sizes for ease of adoption. The carrier can be coated with cells on both sides to generate membrane barriers, and the devices can be established in series to allow medium to flow from one cell layer to another. Furthermore, the carrier containing cells can be easily removed after treatment on the device and the cells can be visualized or recovered for additional off-chip analysis. A 0.4 μm membrane with cell monolayers proved most effective in maintaining separate fluid flows, allowing apical and basal surfaces to be perfused independently. A panel of different cell lines (Caco-2, HT29-MTX-E12, SH-SY5Y, and HUVEC) were successfully maintained in the MPS for up to 7 days, either alone or on devices connected in series. The presence of tight junctions and mucin was expressed as expected by Caco-2 and HT-29-MTX-E12, with Concanavalin A showing uniform staining. Addition of Annexin V and PI showed viability of these cells to be >80% at 7 days. Bacterial extracellular vesicles (BEVs) produced by Bacteroides thetaiotaomicron and labeled with 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbo-cyanine perchlorate (DiD) were used as a model component of the human colonic microbiota and were visualized translocating from an apical surface containing Caco-2 cells to differentiated SH-SY5Y neuronal cells cultured on the basal surface of connected devices. The newly described MPS can be easily adapted, by changing the carrier to maintain spheroids, pieces, or slices of biopsy tissue and joined in series to study a variety of cell and tissue processes. The cell layers can be made more complex through the addition of multiple cell types and/or different patterning of extracellular matrix and the ability to culture cells adjacent to one another to allow study of cell:cell transfer, e.g., passive or active drug transfer, virus or bacterial entry or BEV uptake and transfer.

The extracellular matrix controls stem cell specification and crypt morphology in the developing and adult mouse gut

The rapid renewal of the epithelial gut lining is fuelled by stem cells that reside at the base of intestinal crypts. The signal transduction pathways and morphogens that regulate intestinal stem cell self-renewal and differentiation have been extensively characterised. In contrast, although extracellular matrix (ECM) components form an integral part of the intestinal stem cell niche, their direct influence on the cellular composition is less well understood. We set out to systematically compare the effect of two ECM classes, the interstitial matrix and the basement membrane, on the intestinal epithelium. We found that both collagen I and laminin-containing cultures allow growth of small intestinal epithelial cells with all cell types present in both cultures, albeit at different ratios. The collagen cultures contained a subset of cells enriched in fetal-like markers. In contrast, laminin increased Lgr5+ stem cells and Paneth cells, and induced crypt-like morphology changes. The transition from a collagen culture to a laminin culture resembled gut development in vivo. The dramatic ECM remodelling was accompanied by a local expression of the laminin receptor ITGA6 in the crypt-forming epithelium. Importantly, deletion of laminin in the adult mouse resulted in a marked reduction of adult intestinal stem cells. Overall, our data support the hypothesis that the formation of intestinal crypts is induced by an increased laminin concentration in the ECM.

Senescent Tumor Cells in the Peritoneal Carcinomatosis Drive Immunosenescence in the Tumor Microenvironment

More than half of all patients with colorectal cancer (CRC) develop distant metastasis and, depending on the local stage of the primary tumor, up to 48% of patients present peritoneal carcinomatosis (PC). PC is often considered as a widespread metastatic disease, which is almost resistant to current systemic therapies like chemotherapeutic and immunotherapeutic regimens. Here we could show that tumor cells of PC besides being senescent also exhibit stem cell features. To investigate these surprising findings in more detail, we established a murine model based on tumor organoids that resembles the clinical setting. In this murine orthotopic transplantation model for peritoneal carcinomatosis, we could show that the metastatic site in the peritoneum is responsible for senescence and stemness induction in tumor cells and that induction of senescence is not due to oncogene activation or therapy. In both mouse and human PC, senescence is associated with a senescence-associated secretory phenotype (SASP) influencing the tumor microenvironment (TME) of PC. SASP factors are able to induce a senescence phenotype in neighbouring cells. Here we could show that SASP leads to enhanced immunosenescence in the TME of PC. Our results provide a new immunoescape mechanism in PC explaining the resistance of PC to known chemo- and immunotherapeutic approaches. Therefore, senolytic approaches may represent a novel roadmap to target this terminal stage of CRC.

Dietary fructose improves intestinal cell survival and nutrient absorption

Fructose consumption is linked to the rising incidence of obesity and cancer, which are two of the leading causes of morbidity and mortality globally1,2. Dietary fructose metabolism begins at the epithelium of the small intestine, where fructose is transported by glucose transporter type 5 (GLUT5; encoded by SLC2A5) and phosphorylated by ketohexokinase to form fructose 1-phosphate, which accumulates to high levels in the cell3,4. Although this pathway has been implicated in obesity and tumour promotion, the exact mechanism that drives these pathologies in the intestine remains unclear. Here we show that dietary fructose improves the survival of intestinal cells and increases intestinal villus length in several mouse models. The increase in villus length expands the surface area of the gut and increases nutrient absorption and adiposity in mice that are fed a high-fat diet. In hypoxic intestinal cells, fructose 1-phosphate inhibits the M2 isoform of pyruvate kinase to promote cell survival5-7. Genetic ablation of ketohexokinase or stimulation of pyruvate kinase prevents villus elongation and abolishes the nutrient absorption and tumour growth that are induced by feeding mice with high-fructose corn syrup. The ability of fructose to promote cell survival through an allosteric metabolite thus provides additional insights into the excess adiposity generated by a Western diet, and a compelling explanation for the promotion of tumour growth by high-fructose corn syrup.

From 2D to 3D Cancer Cell Models-The Enigmas of Drug Delivery Research

Over the past decades, research has made impressive breakthroughs towards drug delivery systems, resulting in a wide range of multifunctional engineered nanoparticles with biomedical applications such as cancer therapy. Despite these significant advances, well-designed nanoparticles rarely reach the clinical stage. Promising results obtained in standard 2D cell culture systems often turn into disappointing outcomes in in vivo models. Although the overall majority of in vitro nanoparticle research is still performed on 2D monolayer cultures, more and more researchers started acknowledging the importance of using 3D cell culture systems, as better models for mimicking the in vivo tumor physiology. In this review, we provide a comprehensive overview of the 3D cancer cell models currently available. We highlight their potential as a platform for drug delivery studies and pinpoint the challenges associated with their use. We discuss in which way each 3D model mimics the in vivo tumor physiology, how they can or have been used in nanomedicine research and to what extent the results obtained so far affect the progress of nanomedicine development. It is of note that the global scientific output associated with 3D models is limited, showing that the use of these systems in nanomedicine investigation is still highly challenging.

Proline-Rich Acidic Protein 1 (PRAP1) Protects the Gastrointestinal Epithelium From Irradiation-Induced Apoptosis

BACKGROUND & AIMS

The intestinal epithelium must be resilient to physiochemical stress to uphold the physiological barrier separating the systemic compartment from the microbial and antigenic components of the gut lumen. Identifying proteins that mediate protection and enhancing their expression is therefore a clear approach to promote intestinal health. We previously reported that oral ingestion of the probiotic Lactobacillus rhamnosus GG not only induced the expression of several recognized cytoprotective factors in the murine colon, but also many genes with no previously described function, including the gene encoding proline-rich acidic protein 1 (PRAP1). PRAP1 is a highly expressed protein in the epithelium of the gastrointestinal tract and we sought to define its function in this tissue.

METHODS

Purified preparations of recombinant PRAP1 were analyzed biochemically and PRAP1 antisera were used to visualize localization in tissues. Prap1-/- mice were characterized at baseline and challenged with total body irradiation, then enteroids were generated to recapitulate the irradiation challenge ex vivo.

RESULTS

PRAP1 is a 17-kilodalton intrinsically disordered protein with no recognizable sequence homology. PRAP1 expression levels were high in the epithelia of the small intestine. Although Prap1-/- mice presented only mild phenotypes at baseline, they were highly susceptible to intestinal injury upon challenge. After irradiation, the Prap1-/- mice showed accelerated death with a significant increase in apoptosis and p21 expression in the small intestinal epithelium.

CONCLUSIONS

PRAP1 is an intrinsically disordered protein highly expressed by the gastrointestinal epithelium and functions at exposed surfaces to protect the barrier from oxidative insult.

WNT and inflammatory signaling distinguish human Fallopian tube epithelial cell populations

Many high-grade serous carcinomas (HGSCs) likely originate in the distal region of the Fallopian tube’s epithelium (TE) before metastasizing to the ovary. Unfortunately, molecular mechanisms promoting malignancy in the distal TE are obfuscated, largely due to limited primary human TE gene expression data. Here we report an in depth bioinformatic characterization of 34 primary TE mRNA-seq samples. These samples were prepared from proximal and distal TE regions of 12 normal Fallopian tubes. Samples were segregated based on their aldehyde dehydrogenase (ALDH) activity. Distal cells form organoids with higher frequency and larger size during serial organoid formation assays when compared to proximal cells. Consistent with enrichment for stem/progenitor cells, ALDH+ cells have greater WNT signaling. Comparative evaluation of proximal and distal TE cell population’s shows heightened inflammatory signaling in distal differentiated (ALDH−) TE. Furthermore, comparisons of proximal and distal TE cell populations finds that the distal ALDH+ TE cells exhibit pronounced expression of gene sets characteristic of HGSC sub-types. Overall, our study indicates increased organoid forming capacity, WNT/inflammatory signaling, and HGSC signatures underlie differences between distal and proximal regions of the human TE. These findings provide the basis for further mechanistic studies of distal TE susceptibility to the malignant transformation.

Absence of neurotensin attenuates intestinal dysbiosis and inflammation by maintaining Mmp7/α-defensin axis in diet-induced obese mice

We previously reported that high levels of plasma neurotensin (NT), a gut hormone released from enteroendocrine cells of the small bowel, contribute to obesity and comorbid conditions. Gut microbiota has been implicated in the obesity development. Paneth cells are critical in maintaining gut microbiota composition and homeostasis by releasing antimicrobial proteins including α-defensins. The purpose of our current study was to determine the possible role of NT in gut microbiota composition and α-defensin gene expression associated with obesity. Here we show that the ratio of Firmicutes/Bacteroidetes (F/B ratio) and intestinal proinflammatory cytokines is significantly increased in NT+/+ mice fed with a high-fat diet (HFD) which were improved in NT-deficient mice. HFD disrupted the intestinal Mmp7/α-defensin axis, which was completely prevented in NT-/- mice. In addition, NT treatment inhibited DEFA5 expression and concurrent NF-κB activity, which was blocked by a pan PKC inhibitor (Gö6983) or an inhibitor for atypical PKCs (CRT0066854). More importantly, the shRNA-mediated knockdown of atypical PKCτ reversed NT-attenuated DEFA5 expression and increased NF-κB activity. NT contributes to the HFD-induced disruption of gut microbiota composition and α-defensin expression. PKCτ/λ plays a central role in NT-mediated α-defensin gene expression which might be mediated through the inhibition of NF-κB signaling pathways in Paneth cells.

TNFAIP8 controls murine intestinal stem cell homeostasis and regeneration by regulating microbiome-induced Akt signaling

The intestine is a highly dynamic environment that requires tight control of the various inputs to maintain homeostasis and allow for proper responses to injury. It was recently found that the stem cell niche and epithelium is regenerated after injury by de-differentiated adult cells, through a process that gives rise to Sca1+ fetal-like cells and is driven by a transient population of Clu⁺ revival stem cells (revSCs). However, the molecular mechanisms that regulate this dynamic process have not been fully defined. Here we show that TNFAIP8 (also known as TIPE0) is a regulator of intestinal homeostasis that is vital for proper regeneration. TIPE0 functions through inhibiting basal Akt activation by the commensal microbiota via modulating membrane phospholipid abundance. Loss of TIPE0 in mice results in injury-resistant enterocytes, that are hyperproliferative, yet have regenerative deficits and are shifted towards a de-differentiated state. Tipe0^-/- enterocytes show basal induction of the Clu⁺ regenerative program and a fetal gene expression signature marked by Sca1, but upon injury are unable to generate Sca-1⁺/Clu⁺ revSCs and could not regenerate the epithelium. This work demonstrates the role of TIPE0 in regulating the dynamic signaling that determines the injury response and enables intestinal epithelial cell regenerative plasticity.

Krüppel-like Factor 5 Regulates Stemness, Lineage Specification, and Regeneration of Intestinal Epithelial Stem Cells

BACKGROUND & AIMS

Self-renewal and multipotent differentiation are cardinal properties of intestinal stem cells (ISCs), mediated in part by WNT and NOTCH signaling. Although these pathways are well characterized, the molecular mechanisms that control the 'stemness' of ISCs are still not well defined. Here, we investigated the role of Krüppel-like factor 5 (KLF5) in regulating ISC functions.

METHODS

We performed studies in adult Lgr5^{EGFP-IRES-creERT2};Rosa26^LSLtdTomato (Lgr5^Ctrl) and Lgr5^{EGFP-IRES-creERT2};Klf5^fl/fl;Rosa26^LSLtdTomato (Lgr5^ΔKlf5) mice. Mice were injected with tamoxifen to activate Cre recombinase, which deletes Klf5 from the intestinal epithelium in Lgr5^ΔKlf5 but not Lgr5^Crtl mice. In experiments involving irradiation, mice were subjected to 12 Gy total body irradiation (TBI). Tissues were collected for immunofluorescence (IF) analysis and next generation sequencing. Oganoids were derived from fluoresecence activated cell sorted- (FACS-) single cells from tamoxifen-treated Lgr5^ΔKlf5 or Lgr5^Crtl mice and examined by immunofluorescence stain.

RESULTS

Lgr5⁺ ISCs lacking KLF5 proliferate faster than control ISCs but fail to self-renew, resulting in a depleted ISC compartment. Transcriptome analysis revealed that Klf5-null Lgr5⁺ cells lose ISC identity and prematurely differentiate. Following irradiation injury, which depletes Lgr5⁺ ISCs, reserve Klf5-null progenitor cells fail to dedifferentiate and regenerate the epithelium. Absence of KLF5 inactivates numerous selected enhancer elements and direct transcriptional targets including canonical WNT- and NOTCH-responsive genes. Analysis of human intestinal tissues showed increased levels of KLF5 in the regenerating epithelium as compared to those of healthy controls.

CONCLUSION

We conclude that ISC self-renewal, lineage specification, and precursor dedifferentiation require KLF5, by its ability to regulate epigenetic and transcriptional activities of ISC-specific gene sets. These findings have the potential for modulating ISC functions by targeting KLF5 in the intestinal epithelium.

Rfx6 promotes the differentiation of peptide-secreting enteroendocrine cells while repressing genetic programs controlling serotonin production

Objective

Enteroendocrine cells (EECs) of the gastro-intestinal tract sense gut luminal factors and release peptide hormones or serotonin (5-HT) to coordinate energy uptake and storage. Our goal is to decipher the gene regulatory networks controlling EECs specification from enteroendocrine progenitors. In this context, we studied the role of the transcription factor Rfx6 which had been identified as the cause of Mitchell–Riley syndrome, characterized by neonatal diabetes and congenital malabsorptive diarrhea. We previously reported that Rfx6 was essential for pancreatic beta cell development and function; however, the role of Rfx6 in EECs differentiation remained to be elucidated.

Methods

We examined the molecular, cellular, and metabolic consequences of constitutive and conditional deletion of Rfx6 in the embryonic and adult mouse intestine. We performed single cell and bulk RNA-Seq to characterize EECs diversity and identify Rfx6-regulated genes.

Results

Rfx6 is expressed in the gut endoderm; later, it is turned on in, and restricted to, enteroendocrine progenitors and persists in hormone-positive EECs. In the embryonic intestine, the constitutive lack of Rfx6 leads to gastric heterotopia, suggesting a role in the maintenance of intestinal identity. In the absence of intestinal Rfx6, EECs differentiation is severely impaired both in the embryo and adult. However, the number of serotonin-producing enterochromaffin cells and mucosal 5-HT content are increased. Concomitantly, Neurog3-positive enteroendocrine progenitors accumulate. Combined analysis of single-cell and bulk RNA-Seq data revealed that enteroendocrine progenitors differentiate in two main cell trajectories, the enterochromaffin (EC) cells and the Peptidergic Enteroendocrine (PE) cells, the differentiation programs of which are differentially regulated by Rfx6. Rfx6 operates upstream of Arx, Pax6 and Isl1 to trigger the differentiation of peptidergic EECs such as GIP-, GLP-1-, or CCK-secreting cells. On the contrary, Rfx6 represses Lmx1a and Tph1, two genes essential for serotonin biosynthesis. Finally, we identified transcriptional changes uncovering adaptive responses to the prolonged lack of enteroendocrine hormones and leading to malabsorption and lower food efficiency ratio in Rfx6-deficient mouse intestine.

Conclusion

These studies identify Rfx6 as an essential transcriptional regulator of EECs specification and shed light on the molecular mechanisms of intestinal failures in human RFX6-deficiencies such as Mitchell–Riley syndrome.

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The lack of Rfx6 impairs the differentiation of peptide-producing enteroendocrine cells.

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The number of 5-HT-expressing-cells is increased in Rfx6-deficient intestine.

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Intestinal inactivation of Rfx6 leads to lipid malabsorption and decreased food efficiency.

Distinct Colorectal Cancer-Associated APC Mutations Dictate Response to Tankyrase Inhibition

The majority of colorectal cancers show hyperactivated WNT signaling due to inactivating mutations in the adenomatous polyposis coli (APC) tumor suppressor. Genetically restoring APC suppresses WNT and induces rapid and sustained tumor regression, implying that reengaging this endogenous tumor-suppressive mechanism may be an effective therapeutic strategy. Here, using new animal models, human cell lines, and ex vivo organoid cultures, we show that tankyrase (TNKS) inhibition can control WNT hyperactivation and provide long-term tumor control in vivo, but that effective responses are critically dependent on how APC is disrupted. Mutant APC proteins truncated within the mutation cluster region physically engage the destruction complex and suppress the WNT transcriptional program, while APC variants with early truncations (e.g., Apc ^Min) show limited interaction with AXIN1 and β-catenin, and do not respond to TNKS blockade. Together, this work shows that TNKS inhibition, like APC restoration, can reestablish endogenous control of WNT/β-catenin signaling, but that APC genotype is a crucial determinant of this response. SIGNIFICANCE: This study reveals how subtle changes to the mutations in a critical colorectal tumor suppressor, APC, influence the cellular response to a targeted therapy. It underscores how investigating the specific genetic alterations that occur in human cancer can identify important biological mechanisms of drug response and resistance.This article is highlighted in the In This Issue feature, p. 1325.

Time-of-addition and Temperature-shift Assays to Determine Particular Step(s) in the Viral Life Cycle that is Blocked by Antiviral Substance(s)

Viruses infect their host cells to produce progeny virus particles through the sequential steps of the viral life cycle, such as viral attachment, entry, penetration and post-entry events. This protocol describes time-of-addition and temperature-shift assays that are employed to explore which step(s) in the viral life cycle is blocked by an antiviral substance(s).

Media from macrophages co-incubated with Enterococcus faecalis induces epithelial cell monolayer reassembly and altered cell morphology

Signal exchange between intestinal epithelial cells, microbes and local immune cells is an important mechanism of intestinal homeostasis. Given that intestinal macrophages are in close proximity to both the intestinal epithelium and the microbiota, their pathologic interactions may result in epithelial damage. The present study demonstrates that co-incubation of murine macrophages with E. faecalis strains producing gelatinase (GelE) and serine protease (SprE) leads to resultant condition media (CM) capable of inducing reassembly of primary colonic epithelial cell monolayers. Following the conditioned media (CM) exposure, some epithelial cells are shed whereas adherent cells are observed to undergo dissolution of cell-cell junctions and morphologic transformation with actin cytoskeleton reorganization resulting in flattened and elongated shapes. These cells exhibit marked filamentous filopodia and lamellipodia formation. Cellular reorganization is not observed when epithelial monolayers are exposed to: CM from macrophages co-incubated with E. faecalis GelE/SprE-deficient mutants, CM from macrophages alone, or E. faecalis (GelE/SprE) alone. Flow cytometry analysis reveals increased expression of CD24 and CD44 in cells treated with macrophage/E. faecalis CM. This finding in combination with the appearance colony formation in matrigel demonstrate that the cells treated with macrophage/E. faecalis CM contain a higher proportion progenitor cells compared to untreated control. Taken together, these findings provide evidence for a triangulated molecular dialogue between E. faecalis, macrophages and colonic epithelial cells, which may have important implications for conditions in the gut that involve inflammation, injury or tumorigenesis.

WRN conditioned media is sufficient for in vitro propagation of intestinal organoids from large farm and small companion animals

Recent years have seen significant developments in the ability to continuously propagate organoids derived from intestinal crypts. These advancements have been applied to mouse and human samples providing models for gastrointestinal tissue development and disease. We adapt these methods for the propagation of intestinal organoids (enteroids) from various large farm and small companion (LF/SC) animals, including cat, dog, cow, horse, pig, sheep and chicken. We show that LF/SC enteroids propagate and expand in L-WRN conditioned media containing signaling factors Wnt3a, R-spondin-3, and Noggin (WRN). Multiple successful isolations were achieved for each species, and the growth of LF/SC enteroids was maintained to high passage number. LF/SC enteroids expressed crypt stem cell marker LGR5 and low levels of mesenchymal marker VIM. Labeling with EdU also showed distinct regions of cell proliferation within the enteroids marking crypt-like regions. The ability to grow and maintain LF/SC enteroid cell lines provides additional models for the study of gastrointestinal developmental biology as well as platforms for the study of host-pathogen interactions between intestinal cells and zoonotic enteric pathogens of medical importance.

Summary: Culturing methods for the propagation of crypt-derived mouse and human enteroids are applicable to large farm and small companion animals, demonstrating conservation of the crypt signaling microenvironment.