Read to see why Organ-Chips can help prevent medicines causing drug-induced liver injury from reaching patients

In the beginning, it’s just nausea. But soon, abdominal pain sets in with general fatigue and a growing sense that something has gone wrong. These seemingly innocuous symptoms can be early indications of drug-induced liver injury (DILI). Without quick action, patients developing DILI may progress to multi-organ failure and potentially death.

Bringing harm to a patient is the worst-case scenario that looms large as new drugs transition from preclinical to clinical studies. For more than half a century, DILI has been a frequent cause of post-market drug withdrawal and a common cause of clinical trial failure1,2. It is unfortunately easy to find examples of this. In January of 2020, the development of inarigavir was halted after the tragic death of patient who presented with clear signs of DILI. This year alone, both Pfizer and Aligos Therapeutics halted production of promising therapeutics as a result of unforeseen DILI in clinical trial patients. It is no exaggeration to say that DILI is a leading patient safety concern.

An insidious condition, DILI develops when a therapeutic turns toxic in a patient’s liver, leading to a decline in liver function and ultimately death. It’s a difficult condition to detect and even harder to predict1. A battery of preclinical models are used to screen prospective compounds for toxicity before they reach patients, with animal models often viewed as the ultimate predictor of drug safety. Though animal models have undoubtedly played an important role in the evolution of modern drug development, many statistics suggest they are unreliable2-7:

  • 90% of drugs entering clinical trials fail, with approximately 30% failing due to toxicity8;
  • Toxicity is the primary reason for post-approval drug withdrawal, despite each drug having been declared safe in preclinical animal studies1,6;
  • One study found that, of 43 post-approval drugs with serious toxicity effects, only 19% of them showed direct correlates of toxicity in animal studies, echoing numerous other such studies5.

In reviewing the literature, it becomes clear that relying on animal models to predict toxicity generally, and DILI specifically, is unlikely to prevent many toxic compounds from entering clinical trials and causing harm to patients. Such grave errors can be avoided, though, if the right preclinical models are used. 

In a recent study published to BioRxiv, Emulate researchers provided strong evidence indicating that Organ-on-a-Chip technology can be a far more reliable predictor of drug toxicity.

The predictive power of Organ-on-a-Chip technology

Organ-on-a-Chip technology is a type of microphysiological system in which cells can be cultured in a highly controlled, physiologically relevant microenvironment. These microengineered culture systems combine organ-specific cell types, a tissue-specific extracellular matrix, and biophysical forces to mimic in vivo microenvironments. Multiple studies have shown that cells grown in Organ-Chips closely mimic in vivo cells both in behavior and in gene expression profiles9-12.

Many studies had previously suggested that Organ-Chips may be superior to conventional preclinical models when predicting drug toxicity13,14. However, the limited scale of these studies left some doubt about the robustness of Organ-Chips. To truly evaluate the potential of Organ-Chips, a large study was needed.

In December of 2021, such a study was completed by researchers at Emulate9.

The research team used 780 liver-chips to analyze the model’s ability to predict DILI caused by 27 known hepatotoxic and non-hepatotoxic small molecule drugs. Importantly, these molecules were not chosen at random, but were selected based on guidance from the Innovation and Quality (IQ) consortium—a collaboration of pharmaceutical and biotechnology companies that aim to advance science and technology to enhance drug discovery programs. Towards this goal, the IQ consortium have released guidance stipulating basic expectations of preclinical models of liver toxicity. The model should:

  • Replicate key histological structures and functions of the liver
  • Be able to distinguish between seven pairs of preselected small molecule toxic drugs and their non-toxic analogs
  • Demonstrate its ability to predict the clinical responses of six additional selected drugs

Before this study, no microphysiological system had met these standards.

The Emulate Liver-Chip showed close resemblance to the human liver, accurately identified toxic from non-toxic drugs, and correctly predicted toxicity for the tested drugs.

In going beyond the IQ consortium’s standards, Emulate researchers expanded the study to include an additional 8 known hepatotoxic compounds to evaluate the model’s utility in predictive toxicology.

The Emulate Liver-Chip showed an 87% sensitivity and 100% specificity in predicting drug toxicity, far outperforming liver spheroids (a common preclinical model) which showed a sensitivity of only 47%. Here, it’s worth noting that each of these drugs had been found to be safe in animal models but ultimately proved toxic when given to patients.

The Liver-Chip could save lives and billions of dollars

The mere fact that the Liver-Chip showed an 87% sensitivity and 100% specificity in identifying these toxic drugs is impressive on its own, but set against the history of these drugs, the significance of this improvement falls into sharp relief. The 22 toxic drugs in this study had previously advanced to human use, and collectively are responsible for more than 200 patient deaths and 10 liver transplants15. Were the Liver-Chip available when these drugs were being developed, many of these deaths could have been avoided.

The benefits of Organ-Chips go beyond improved patient safety. Roughly 75% of costs in drug development are lost to drug candidates that ultimately fail due to efficacy or safety issues16. A major contributing factor in drug failure is poor model validity. It’s been argued that even small improvements in the predictive validity of preclinical models could have a significant impact on drug development success rates17.

In the study of the Liver-Chip, Emulate researchers modeled the potential impact that routine use of the Liver-Chip could have on drug development productivity. By simply improving our ability to detect hepatotoxicity with 87% sensitivity, it’s estimated that the Liver-Chip could increase research and development productivity by $3 billion dollars on an annual basis.

Bottom line: The Liver-Chip should be integrated into preclinical development

Emulate’s results provide strong evidence for the use of the Liver-Chip in preclinical drug development. Not only do they faithfully recreate the liver microenvironment, but they’ve proven to be a robust, sensitive, and specific model for assessing a drug’s likelihood of inducing DILI. This means fewer toxic drugs advancing to clinical trials, saving billions of dollars that can be reinvested in other drug candidates, and most importantly, saving patients from the devastating effects of drug induced liver toxicity.

References

  1. Guidance for Industry Drug-Induced Liver Injury: Premarketing Clinical Evaluation Drug Safety. 2009.
  2. Babai, Samy, et al. “Safety Data and Withdrawal of Hepatotoxic Drugs.” Thérapie, Feb. 2018, 10.1016/j.therap.2018.02.004. Accessed 18 Mar. 2020.
  3. Van Norman GA. Limitations of animal studies for predicting toxicity in clinical trials: Is it time to rethink our current approach? JACC Basic Transl Sci. 2019;4(7):845-854. 2019. doi: 10.1016/j.jacbts.2019.10.008
  4. Matthews RA. Medical progress depends on animal models – doesn’t it? J R Soc Med. 2008;101(2):95-98. doi: 10.1258/jrsm.2007.070164
  5. Bailey J, Thew M, Balls M. An analysis of the use of animal models in predicting human toxicology and Drug Safety. Altern Lab Anim. 2014;42(3):181-199. doi: 10.1177/026119291404200306
  6. Siramshetty VB, Nickel J, Omieczynski C, Gohlke BO, Drwal MN, Preissner R. WITHDRAWN–a resource for withdrawn and discontinued drugs. Nucleic Acids Res. 2016;44(D1):D1080-D1086. doi: 10.1093/nar/gkv1192
  7. van Meer PJK, Kooijman M, Gispen-de Wied CC, Moors EHM, Schellekens H. The ability of animal studies to detect serious post marketing adverse events is limited. Regul Toxicol Pharmacol. 2012;64(3):345-349. doi: 10.1016/j.yrtph.2012.09.002
  8. Sun, Duxin, et al. “Why 90% of Clinical Drug Development Fails and How to Improve It?” Acta Pharmaceutica Sinica B, Feb. 2022, 10.1016/j.apsb.2022.02.002.
  9. Apostolou, Athanasia, et al. “A Novel Microphysiological Colon Platform to Decipher Mechanisms Driving Human Intestinal Permeability.” Cellular and Molecular Gastroenterology and Hepatology, vol. 12, no. 5, 2021, pp. 1719–1741, 10.1016/j.jcmgh.2021.07.004. Accessed 13 Apr. 2022.
  10. Si, Longlong, et al. “A Human-Airway-On-a-Chip for the Rapid Identification of Candidate Antiviral Therapeutics and Prophylactics.” Nature Biomedical Engineering, 3 May 2021, pp. 1–15, www.nature.com/articles/s41551-021-00718-9, 10.1038/s41551-021-00718-9.
  11. Kasendra, Magdalena, et al. “Duodenum Intestine-Chip for Preclinical Drug Assessment in a Human Relevant Model.” ELife, vol. 9, 14 Jan. 2020, p. e50135, elifesciences.org/articles/50135, 10.7554/eLife.50135. Accessed 17 Feb. 2022.
  12. Sheyn, Dmitriy, et al. “Bone-Chip System to Monitor Osteogenic Differentiation Using Optical Imaging.” Microfluidics and Nanofluidics, vol. 23, no. 8, 6 July 2019, 10.1007/s10404-019-2261-7. Accessed 13 Apr. 2022.
  13. Danku, Alex Ede, et al. “Organ-On-A-Chip: A Survey of Technical Results and Problems.” Frontiers in Bioengineering and Biotechnology, vol. 10, 10 Feb. 2022, 10.3389/fbioe.2022.840674.
  14. Bovard, David, et al. “Organs-On-a-Chip.” Toxicology Research and Application, vol. 1, Jan. 2017, p. 239784731772635, 10.1177/2397847317726351. Accessed 11 Sept. 2019.
  15. Emulate’s unpublished internal data
  16. Paul, Steven M., et al. “How to Improve R&D Productivity: The Pharmaceutical Industry’s Grand Challenge.” Nature Reviews Drug Discovery, vol. 9, no. 3, 19 Feb. 2010, pp. 203–214, www.nature.com/articles/nrd3078, 10.1038/nrd3078.
  17. Scannell, Jack W., and Jim Bosley. “When Quality Beats Quantity: Decision Theory, Drug Discovery, and the Reproducibility Crisis.” PLOS ONE, vol. 11, no. 2, 10 Feb. 2016, p. e0147215, 10.1371/journal.pone.0147215.

For far too long, a 90% drug failure rate has been the status quo. With Organ-on-a-Chip technology, researchers are leveraging human-relevant science and technology to redefine how we develop life-changing therapies for those that need them most. And we are just getting started. 

Ground-breaking science takes courage, bravery, and a relentless pursuit of a healthier tomorrow. It takes a community. It takes Moxi.  

Introducing Moxi: The Social Network for Organ-on-a-Chip Technology

Moxi is made for trailblazers. For the researcher never satisfied with the status quo. For the scientist who prizes progress over past achievements. For you and everyone around the world using, or interested in using, Organ-on-a-Chip technology. It is a platform dedicated to connecting with peers, keeping up with the latest news, and collaborating to accelerate science into a new era.  

While Moxi is powered by Emulate, it is not an Emulate Technical Support forum. Above all, Moxi is a community for researchers, by researchers.  

To celebrate the launch of Moxi, we’re offering members two competitions: 

iPad Air® Drawing

The first 500 Moxi registrants will be entered to win an iPad Air®. One lucky winner will be randomly selected and notified via email. We will also share the winner’s name and institution on LinkedIn and Twitter.  

Organ-Chip Image Competition 

Registered members of Moxi will be eligible to submit up to one image from their Organ-Chip research, view the submissions, and vote for their favorite. The participant whose entry receives the most votes will win a paid trip to the 2023 MPS World Summit in Berlin, Germany. We look forward to seeing your beautiful images.

Who can participate? 

  • Anyone who wishes to enter the Organ-Chip Image Competition must be a registered user of moxicentral.com. If you are not currently a member, you can join here

how to submit images

Entry Requirements 

  • Each participant must be a registered user of moxicentral.com
  • Each participant may only submit one photo. 
  • Each participant must agree to the terms and conditions of entry (listed below).  

Voting 

  • The winner will be chosen by the Moxi Community. Voting will be available from May 31, 2022, to August 31, 2022. Each participant is allowed one vote. 

Prizes 

  • The participant whose entry received the most votes will win a trip to the 2023 MPS World Summit in Berlin, Germany.  

Submission Requirements 

  • Organ-Chip Vendor 
  • Cell Type 
  • Microscope Type & Details 
  • Image Title 
  • Image Description 

Terms and Conditions of Entry 

  1. Participants must be the original creator of image entries. 
  1. By entering an image into this competition, participants give consent for Emulate, Inc to use their work on emulatebio.com, moxicentral.com, and promotional materials (e.g., social media, promotional brochures). 
  1. When using images of people where any individual(s) feature prominently or are clearly identifiable, the entrant must obtain consent from any such individual before entering the competition. 
  1. Submissions may not include any copyrighted material. 
  1. Entrant names will appear with the image as a credit. 

Eligibility: 

  • Employment: The applicant must be an active employee or enrollee at a company or institution, and they must hold a position that requires them to perform cell biology research. Applicants are subject to certain further eligibility requirements set forth below. 

Grant Award Scope: 

  • 1 winner will be selected and receive the following: 
  • Roundtrip airfare to and from Berlin, Germany 
  • Hotel accommodation for the duration of the 2023 MPS World Summit conference 
  • 1 full conference registration badge  

Additional Terms & Conditions: 

  • Applications must be entered via the online submission form between 12:00 am ET on May 31, 2022, and 11:59:59 pm ET on July 31, 2022. 
  • Voting via Woobox will conclude on August 31, 2022. Once the social voting has concluded, the winner will be notified via email by an Emulate representative. 
  • The award winner is responsible for any city, state, or federal tax liability incurred by accepting the award. 
  • Emulate reserves the right to select the winner in its sole discretion. 
  • Employees of Emulate and their immediate family members are not eligible to participate. Emulate reserves the right to disqualify participants who work for organizations that are direct competitors. 
  • No substitution or transfer of the awarded prize is permitted, except as allowed by Emulate. 
  • Participants agree that Emulate may process the personal data provided with the application in accordance with Emulate privacy policies. See https://emulatebio.com/legal for more information. 
  • Emulate may require the winner to sign and return an affidavit of eligibility, a release of liability, a publicity release, and other appropriate legal documentation reasonably requested by Emulate. 
  • These terms and conditions as well as any action related to this program will be governed by the laws of The Commonwealth of Massachusetts without regard to, or application of, its conflict of law provisions or your state/country of residence. 
  • All claims, legal proceedings, or litigation arising in connection with these terms and conditions, or with this photo contest will be brought solely in front of the federal or state courts located in The Commonwealth of Massachusetts. All participants consent to the jurisdiction of and venue in such courts and waive any objection as to inconvenient forum. By participating in this grant program, each participant unconditionally accepts and agrees to comply with and abide by these terms and conditions. 
  • By applying, you acknowledge that you are not prohibited from participating by employment, law, regulation, funding source, industry code of conduct, or the policies or practices of your institution or employer. This Program is void wherever prohibited. 
  • Please submit any questions about the Organ-Chip Image Competition to askmoxi@moxicentral.com 

To get started, visit moxicentral.com and register your free account.

It’s time to join the movement.
It’s time to progress science, together.

Organ-Chips & Organoids: Better Together

Learn how these two complementary technologies can be combined for improved physiological relevance

In recent years, organoids—tiny, self-organized, three-dimensional cell models—have emerged as a promising technology for researching human physiology and disease. A major advantage of organoids is that they can be developed from induced pluripotent stem cells (iPSCs) or stem cells from primary human biopsies. As a result, they are able to differentiate into a variety of cell types to contain a greater range of cellular diversity than conventional models such as immortalized Caco-2 cell lines. 

However, organoids lack some critical elements of the in vivo intestinal microenvironment, which limits their physiological relevance, such as the presence of vasculature and the mechanical forces caused by fluid flow and peristalsis. Additionally, their spherical structure results in several experimental challenges, including inconsistencies in size and shape, poor experimental control of key variables, and access to only one side of the epithelium.   

Fortunately, researchers can unlock the full potential of organoids by using them as a robust cell source for Organ-Chips, enabling the creation of more accurate human biological models such as the Colon Intestine-Chip and Duodenum Intestine-Chip. Combining these technologies improves the organoids’ cellular morphology and functionality, results in more in vivo-like gene expression, and opens the door for new experimental designs—from simple drug permeability assays to more complex studies of colon inflammation, immune cell recruitment, and colorectal cancer tumor cell invasion. 

Combining Organ-Chips and Organoids

Each Emulate Organ-Chip contains a top (epithelial) channel and a bottom (endothelial) channel separated by a thin, flexible, porous membrane that enables cell-cell interaction. This membrane is coated with tissue-specific extracellular matrix (ECM) on top of which human cells can be cultured. To create the Intestine-Chip, intestinal epithelial organoids are first established from endoscopic biopsies of healthy adults.

They are then dissociated into fragments and seeded onto the ECM-coated porous membrane in the top channel. Meanwhile, primary microvascular endothelial cells are seeded on the other side of the ECM-coated porous membrane in the endothelial channel. Importantly, both the organoids and microvascular endothelial cells are intestine-specific, meaning researchers can model particular sections of the intestine, such as the duodenum, jejunum, ileum, or colon.

Colon Intestine-Chip Cross Section

Distinct media flows through each channel to promote cellular differentiation, and stretch can be applied at different amplitudes and frequencies to create intestinal peristalsis-like motions. Over several days, the epithelial cells form a confluent monolayer in the top channel, and the endothelial cells form a complete blood vessel in the bottom channel. 

 

The advantages of Organ-on-a-Chip technology

Using organoids as a cell source for Organ-Chips enables researchers to create more physiologically relevant models and allows for a greater range of study possibilities. Some of the advantages include: 

Endothelial co-culture and tissue-tissue interactions 

Epithelial Morphology with or without Endothelial Co-Culture

Organ-Chips allow for the inclusion of tissue-specific endothelial cells to recreate the epithelial-endothelial interface of the intestinal barrier and support tissue-tissue interactions—critical drivers of cellular function that organoids lack. This endothelial co-culture was shown to result in several distinct advantages in a study using the Colon Intestine-Chip, including enhanced epithelial polarity, correct localization of tight junction markers, a tight epithelial barrier with low permeability, and the formation of a mature brush border with densely packed and elongated microvilli. In addition, researchers can administer their drug candidate of interest through the vascular channel of Organ-Chips, recapitulating how many therapeutics reach the intended tissue in vivo

Cell interactions and cytoarchitecture 

Although the cells in organoids are in a 3D structure, their organization does not resemble what it would be in vivo. The lack of directional cues results in somewhat random tissue organization, and the spherical shape results in reduced oxygen exposure in their center, often resulting in necrotic cores. In contrast, Organ-Chips provide the appropriate microenvironmental conditions for epithelial cells to spontaneously organize into physiological cytoarchitecture, including correct polarity and the formation of microvilli.

Dynamic media flow

Unlike organoids in static culture, Emulate Organ-Chips are designed to allow for continuous, unidirectional media flow, enabling steady-state nutrient levels and recreating the dynamic shear forces cells experience in the body. In the Duodenum Intestine-Chip, this media flow was shown to positively affect tissue architecture, resulting in increased cell height, cobblestone-like morphology, well-defined cell-cell junction formation, and dense microvilli.  

Peristalsic-like stretching 

With the Zoë Culture Module, researchers can fine-tune the frequency and strain of the chip’s flexible membrane to create peristalsis-like mechanical forces, enabling studies not possible with animals or alternative in vitro models. Recently, researchers at the Ellison Institute of USC applied this unique functionality to study the role of peristalsis in colorectal cancer tumor cell invasion. The Pasteur Institute has also leveraged this capability to study the impact of mechanical forces on Shigella infection and found that peristalsis is critical for specific stages of the infection process.  

Improved gene expression 

Multiple RNA-Seq analyses have shown that organoid-derived epithelial cells cultured in Emulate Organ-Chips have a transcriptome profile significantly closer to in vivo tissue than those same organoids in suspension. Analysis of specific pathways revealed differences in epithelial differentiation and key metabolic enzymes and pathways, indicating enhanced cell differentiation. This reinforces the advanced functionality of endothelial co-culture and the dynamic chip microenvironment. Given the closer in vivo gene expression, Organ-Chip models with organoids are more likely to express drug targets than organoids alone.  

Immune cell incorporation 

The fluidic nature of Emulate Organ-on-a-Chip technology allows users to introduce circulating immune cells through the chip channels, which is critical for modeling some aspects of disease. Additionally, research published in eLife used this approach to evaluate the safety of T-cell bispecific antibodies, a cancer immunotherapy difficult to study in animals due to fundamental species differences in immunological response.

Increase the physiological complexity of your organoid studies

Creating the next generation of effective therapeutics requires more human-relevant models of health and disease. While organoids offer several advantages over traditional monolayers, it is only when they are combined with Organ-on-a-Chip technology that their full potential can be realized, with improvements to cell morphology, functionality, and gene expression. By leveraging these advanced in vitro models, researchers can model more complex human biological mechanisms—including peristalsis, tumor cell migration, and immune cell interaction—enabling studies not possible with conventional models.  

Contact us to learn more about how Organ-on-a-Chip technology can help you improve the physiological relevance of your research. 

Not ready to chat? Check out our resources below to see data generated on the organoid-based Duodenum Intestine-Chip and Colon Intestine-Chip

Related Resources:

See how the Colon Intestine-Chip has been used to model cytokine-mediated intestine inflammation and barrier disruption.

Bacteria, viruses, and potential toxins all transit through the human intestines. In healthy conditions, the intestinal barrier serves as a protective wall, helping to prevent the engagement of these would-be biological agents. However, when this protective barrier breaks down, problems arise. Intestinal barrier dysfunction is often associated with chronic inflammation and is increasingly linked to pathological conditions ranging from inflammatory bowel disease (IBD) to Parkinson’s Disease. These observations suggest that intestinal barrier deterioration may influence pathogenesis of some diseases and have value as a therapeutic target.

understanding of the processes that lead to intestinal barrier deterioration is limited, due in part to a lack of human-relevant models. The intestine is a dynamic organ consisting of many diverse cell types whose behaviors are influenced by the complex milieu of cell-cell interactions, peristaltic contractions, and various environmental factors. Normally, it is exceedingly difficult for single-model systems to capture this complexity. However, recent evidence suggests Organ–a-Chip technology can provide a strong approximation of in vivo conditions, making it an invaluable tool for studying intestinal biology.  

In a paper published in Cellular and Molecular Gastroenterology and Hepatology, researchers from Emulate characterize a colon intestine model in which patient-derived colonic organoids are cultured in a dynamic Organ-on-a-Chip platform. Unlike conventional models, this “gut-on-a-chip” includes primary human cells that are subject to biomechanical forces and co-cultured with intestine-specific endothelial cells, closely resembling the phenotypic characteristics of in vivo tissue.  

Collectively, the data presented in this paper highlights the Colon Intestine-Chip’s ability to provide detailed insights into the human intestine barrier in health and disease settings.  

Experimental Overview

Research Area: Gastroenterology, Disease pathology 
Organisms: Human 
Sample Types: Colon Intestine-Chip 
Research Question: Can this “gut-on-a-chip” be used to model the effects of cytokines, therapeutics, and other agents on intestinal barrier integrity? 

Results:  

  • Co-culture of colonoids with endothelial cells in the Colon Intestine-Chip results in improved epithelial cell phenotypic and transcriptomic profiles that more accurately represent in vivo observations compared to immortalized epithelial cell monolayers or colonoids cultured in suspension. 
  • Perfusion of the Colon Intestine-Chip vascular chamber with IFN-γ promotes inflammatory phenotypes in epithelial cells, breakdown of tight junctions in the epithelial cell barrier, and subsequent increased barrier permeability. 
  • Treatment of the Colon Intestine-Chip with Interleukin-22 (IL-22) promotes inflammatory signaling and tight junction breakdown, shedding light on the potential role of IL-22 in the pathogenesis of intestinal barrier deterioration. 

Conclusion: The Colon Intestine-Chip represents an improved model of the human colon that contains a heterogeneous epithelial cell layer displaying phenotypic and transcriptomic profiles similar to those observed in vivo. Using this model, researchers can effectively investigate the mechanisms behind cytokine-mediated inflammation and the efficacy of therapeutic candidates on human colonic barrier integrity. Because of this, the Colon Intestine-Chip can help shed light on the complex relationship between intestinal barrier integrity and disease pathogenesis.  

Modeling a dynamic organ 

Researchers aiming to study gastrointestinal physiology and disease primarily rely on three types of models: animals, organoids, and conventional monolayer cultures of immortalized cell-lines. Each of these has been invaluable in advancing our understanding of gut physiology; however, none are able to recreate the critical features of the human intestine that influence cellular response to stressors and—in turn—disease pathogenesis. Because of this, it has been challenging to translate results from these models into effective disease modifying therapies. 

Organ-on-a-Chip technology presents a promising alternative. Emulate Organ-Chips are three-dimensional, dynamic systems that co-culture tissue-specific cell types—such as epithelial cells and immune cells—alongside endothelial cells under fluid flow and in the presence of tissue-specific extracellular matrix proteins. Selectively seeding cells into the chip’s two channels enables the formation of a vascular chamber consisting of endothelial cells and a tissue chamber containing the remaining cell types. These two channels are separated by a thin, porous membrane to enable communication between cell chambers while maintaining distinct microenvironments. 

To improve on current models of the intestines, researchers from Emulate leveraged Organ-Chip technology to develop a Colon Intestine-Chip. 

Colon Intestine-Chip: an improved model of gastrointestinal physiology

To create the Colon Intestine-Chip, Apostolou et al., made use of Emulate’s Organ-on-a-Chip technology, which enables multiple cell types to be co-cultured in a dynamic environment.  Colonic organoids (colonoids), which came from healthy patient biopsies and were mechanically dissociated, served as the basis for the chip’s intestinal chamber. In parallel, colonic human intestinal microvascular endothelial cells were seeded in the vascular chamber. When exposed to unidirectional media flow as well as cyclic 10% stretch to emulate peristalsis, the model closely resembles the microenvironment intestinal cells would experience in vivo. 

Colon Intestine-Chip Cross-Section

Characterization of the Colon Intestine-Chips revealed a close phenotypic resemblance to healthy colonic barriers, including: The formation of a confluent, highly polarized epithelial cell barrier with low permeability (0.89 x 10-6 cm / s); the localization of tight junction proteins at intercellular junctions; the asymmetric distribution of ion channels; and the formation of a mature brush border with densely packed microvilli.

Notably, the epithelial cells’ mature phenotype was dependent on the presence of endothelial cells within the chip’s vascular chamber. Exclusion of endothelial cells from the Colon Intestine-Chip led to increased barrier permeability, decreased tight junction formation, and decreased epithelial cell polarization, collectively demonstrating the importance of endothelial co-culture with epithelial cells in modeling the intestinal barrier.  

Given these findings, it’s unlikely that colonoids or conventional monolayer culture models could mimic in vivo conditions as well as the Colon Intestine-Chips. This claim is reinforced by transcriptomic data collected from Colon Intestine-Chips and colonoid cells grown in suspension, which showed that the presence of endothelial cells and periodic stretching in Colon Intestine-Chips produced superior gene expression profiles. 

Using the Colon Intestine-Chip to model gut barrier breakdown

To study To study the pathophysiology of gut barrier dysfunction, the team perfused the vascular chamber with interferon gamma (IFN-γ), a cytokine known to affect the pathogenesis of inflammatory bowel disease.  

Within two days of treatment, the epithelial cell barrier showed clear signs of distress. Epithelial barrier permeability increased in an IFN-γ-concentration-dependent manner, tight junction proteins were sequestered to the cellular cytoplasm, and F-actin staining revealed cell deformations and poorly defined cell borders. Collectively, these findings indicate that the presence of IFN-γ was driving a breakdown in the epithelial cell barrier—a conclusion that was strongly reinforced by an increase in epithelial cell death (as indicated by elevated levels of cleaved caspase).

What’s more, treatment with IFN-γ prompted an increase in the cytokine IL-6 and vascular adhesion molecule-1—both of which have been found in the sera of patients with inflammatory bowel disease—reinforcing that this model is able to accurately recreate aspects of an IBD-like clinical phenotype.

Barrier Disruption Visual Abstract
Advancing our understanding of gut barrier physiology and pathophysiology

Interleukin-22 (IL-22) is a cytokine released by various immune cells in response to pathogens. To date, our understanding of IL-22’s role in intestinal health and disease is incomplete. Various ulcerative colitis studies using mice have found conflicting results, with some results suggesting IL-22 has pro-inflammatory effects and others suggesting it has anti-inflammatory effects.  

After showing that the Colon Intestine-Chip model can accurately recreate a mature intestinal epithelial cell barrier phenotype and model the effect of well-characterized, barrier-disrupting cytokine IFN-γ, the authors evaluated whether the model could shed light on the true role of IL-22 in intestinal barrier function.  

Before administering IL-22, the team first confirmed the expression of the IL-22 receptor and found that expression was higher in the Colon Intestine-Chip compared with organoids in suspension. These results suggest that our incomplete understanding of IL-22’s role in barrier homeostasis may be due in part to limited gene expression in other models.

Perfusing IL-22 through the vascular chamber negatively affected epithelial cell barrier function in the Colon Intestine-Chip model. Barrier permeability increased, cell morphology became aberrant, and transcriptomic profiles and immunofluorescent staining revealed a marked increase in apoptosis. Taken together, these results suggest that IL-22 drives barrier dysfunction.  

Conclusion

ln total, this study showed that the Colon Intestine-Chip can be a powerful model for studying intestinal barrier dysfunction. Immunofluorescent staining, scanning electron microscopy, and RNA sequencing data show that the Colon Intestine-Chip model produces a mature epithelial cell phenotype that responds to inflammatory cytokines, such as IFN-γ, in ways that reflect observations from patients with inflammatory bowel disease. 

Importantly, this study showed that endothelial co-culture is critical to promote a mature, functional epithelial phenotype, driving positive effects on cell morphology, polarization, and barrier formation. This insight highlights an advantage Organ-Chips have over intestinal models without endothelial co-culture, such as organoids in suspension.

The team’s use of the Colon Intestine-Chip to study IL-22’s effects on intestinal barrier integrity demonstrates the potential to apply this model in studying mechanisms of intestinal barrier dysfunction. Collectively, this study shows how the Colon Intestine-Chip is a more physiologically relevant model of the human colon that researchers can use to study gastrointestinal disease pathogenesis and the efficacy or safety of preclinical drug candidates in preclinical stages.