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Drug-induced liver injury (DILI) remains a persistent challenge in drug development, endangering patient safety and delaying the availability of critical therapies. Just days ago, the FDA issued a warning about Ocaliva (obeticholic acid), a treatment for primary biliary cholangitis, after reports of severe liver injury in patients without pre-existing cirrhosis. Among 81 patients treated with Ocaliva, seven required liver transplants compared to just one in the placebo group, and four patients died versus one death in the placebo group.  

Unfortunately, Ocaliva is far from an isolated case. On December 6^th, BioAge Labs announced the discontinuation of its STRIDES Phase I trial for Azelaprag, a promising obesity drug candidate, due to unexpected liver safety concerns. While Azelaprag initially showed potential to improve patient outcomes, concerns arose after 11 individuals in the treatment groups experienced elevated liver enzyme levels. 

These recent incidents add to the growing list of drugs derailed or delayed due to liver toxicity concerns, underscoring the persistent shortcomings of traditional preclinical models—such as animal studies and 2D cell cultures—which often fail to predict human liver toxicity with the accuracy needed to ensure patient safety. 

Together, these cases emphasize the urgent need for more predictive preclinical models. More human-relevant approaches, like Organ-on-a-Chip technology, can help bridge the gap, offering a more accurate, human-centered approach to mitigate the risks of DILI and support safer drug development. 

Unpredicted DILI: A Persistent Patient Safety Concern 

Unexpected cases of DILI continue to pose significant risks to patients and disrupt drug development. Since January 2022, at least eleven clinical trials or marketed drugs have reported DILI, with some resulting in patient deaths. 

Recent examples include: 

• TNG348 (2024): Development of this USP1 inhibitor for cancer was halted after a Phase I/II study revealed grade 3 and life-threatening grade 4 liver function abnormalities after eight weeks of treatment. 

• Evobrutinib (2023): This Bruton tyrosine kinase (BTK) inhibitor for multiple sclerosis had its Phase III trials partially paused due to two cases of liver injury markers indicative of DILI. 

• Tolebrutinib (2022): Another BTK inhibitor for multiple sclerosis faced a partial clinical hold following DILI reports, including a case where a patient required a liver transplant and later died from complications. 

• Lumakras (sotorasib) in combination therapy (2022): In Phase Ib trials, combining this KRAS G12C inhibitor with immune checkpoint inhibitors like Keytruda or Tecentriq led to severe liver toxicity in 50% of patients, halting further combination studies. 

These examples highlight the pressing need for predictive models that better replicate human liver biology, reducing the risk of such severe outcomes. 

Why conventional models fall short in predicting liver injury 

Traditional preclinical models fail to emulate the complexity of the human liver, limiting their ability to predict toxicity effectively, leaving patients vulnerable to unanticipated adverse events, and delaying the development of life-saving therapies. 

Conventional model limitations include: 

• Animal Models: Differences in metabolism, immune responses, and drug transport mechanisms between species result in poor translation to human biology. Key contributors to DILI, like cytochrome P450 variability and immune-mediated hepatotoxicity, are often misrepresented in animals. 

• 2D hepatocyte cultures: These static systems lack cell-cell interactions, media flow, and mechanical forces, leading to a rapid loss of liver-specific functions and poor sensitivity in predicting DILI. 

• 3D Organoids and Spheroids: While these technologies improve cellular organization, they lack essential features like vascularization and mechanical forces, making it challenging to model the biological complexity of the human liver sinusoid. 

A paradigm shift toward more human-relevant preclinical models is urgently needed to bridge these gaps and ensure better outcomes for patients. 

The Emulate Liver-Chip: A Human-Relevant Solution 

To address the persistent challenge of drug-induced liver injury (DILI) and the limitations of traditional preclinical models, the Emulate Liver-Chip provides a human-relevant platform for assessing hepatotoxicity. By incorporating primary human liver cells in a dynamic Organ-Chip microenvironment, the Liver-Chip enables researchers to generate predictive and mechanistic insights that can improve drug safety assessments, helping to mitigate risks like those recently observed with Ocaliva, Azelaprag, and other therapies. 

High Predictive Accuracy 

In a study published in Communications Medicine, the Liver-Chip S1 demonstrated exceptional predictive accuracy, achieving a sensitivity of 77% and specificity of 100% across 27 small molecule drugs tested on a single donor. It effectively distinguished all seven pairs of hepatotoxic drugs and their non-toxic structural analogs, such as trovafloxacin and levofloxacin. When an additional donor was tested on 18 small molecule drugs, combining both datasets improved sensitivity to 87% while maintaining 100% specificity. These results are nearly double the sensitivity of 3D hepatic spheroids (47%) for the same drugs, emphasizing the Liver-Chip’s superior predictivity. 

Mechanistic Insights 

The Liver-Chip goes beyond prediction, providing insights into the mechanisms of liver injury. Its design includes hepatocytes, Kupffer cells, stellate cells, and endothelial cells, enabling cell-cell interactions that reveal pathways of damage. Researchers can measure albumin production and ALT release to track functionality and injury, while imaging highlights morphological changes, apoptosis, mitochondrial dysfunction, and lipid accumulation. These mechanistic insights empower researchers to understand how drugs cause liver toxicity, enabling earlier and more targeted design updates to improve drug safety. 

Regulatory Alignment 

In September 2024, the Liver-Chip S1 became the first Organ-on-a-Chip technology accepted into the FDA ISTAND Pilot Program. While not yet fully qualified, this milestone underscores the potential of the Liver-Chip S1 as a future standard for liver toxicity assessment in regulatory submissions, providing a more reliable basis for evaluating drug safety. 

Why the Liver-Chip Matters 

The ongoing issues with drug-induced liver injury, exemplified by Ocaliva, Azelaprag, and other recent cases, highlight the critical need for innovative tools that prioritize patient safety. The Emulate Liver-Chip directly addresses these challenges, offering a human-relevant platform that bridges the gap between preclinical testing and clinical outcomes. By enhancing the prediction of hepatotoxicity, providing detailed mechanistic insights, and aligning with evolving regulatory frameworks, the Liver-Chip supports safer and more efficient drug development. 

With this technology, the pharmaceutical industry can move beyond the limitations of outdated models, helping to prevent future DILI-related incidents, reduce patient risks, and accelerate the availability of life-saving therapies. 

Learn More 

For more information on how the Liver-Chip can enhance preclinical workflows and improve drug safety, download the Liver Toxicology White Paper. This resource demonstrates how Emulate Organ-Chips can advance toxicity prediction to support the development of safer therapies and better protect patients. 

Introduction

In recent years, the pharmaceutical and biotechnology industries have increasingly turned to complex in vitro models (CIVMs) to improve the predictability of preclinical studies. These models offer a more physiologically relevant environment for cells compared to traditional 2D cell cultures and avoid the species-translation issues of animal models. Because of this, their potential use in Investigational New Drug (IND) submissions to the U.S. Food and Drug Administration (FDA) has become a topic of significant interest. 

What are Complex In Vitro Models?

In vitro models are laboratory-based systems that use isolated cells, tissues, or biological molecules to study biological processes and drug effects outside of a living organism. CIVMs take it one step further—they are advanced laboratory cell culture tools designed to simulate the structure and function of human tissues and organs. The IQ MPS—an affiliate of the International Consortium for Innovation and Quality in Drug Development—classifies CIVMs into three major categories:

1. Static Models – Traditional in vitro cell culture systems that lack dynamic environmental factors found in vivo, such as fluid flow or mechanical forces. They include 2D cell cultures, such as transwells and co-cultures, and 3D models, such as spheroids or organoids. 

2. Static MPS Models – A subset of microphysiological systems (MPS) that incorporate advanced engineering features such as electrical sensors but lack dynamic environmental features such as continuous fluid flow or mechanical forces. 

3. Dynamic MPS Models – Advanced platforms designed to replicate the functional and mechanical aspects of human tissues and organs by integrating dynamic environmental conditions such as fluid flow, mechanical forces, and tissue-tissue interactions. The most prominent example is Organ-Chips. 

Each model aims to close the gap between conventional 2D in vitro testing and human biology. By doing so, they can offer improved predictability over traditional preclinical methods. 

Challenges in Preclinical Drug Development

In the preclinical stages of drug development, researchers assess the pharmacokinetics (PK) and pharmacodynamics (PD) of a drug candidate to evaluate its safety and efficacy. They rely on two main types of models to do so: 

2D Cell Cultures: These static models are simple and cost effective, but they lack the biological complexity of humans, meaning they often fail predict human response. 

Animal Models: Animals have long been integral to preclinical drug testing, largely because their biological complexity is similar to that of humans. However, there are still significant differences between human and animal physiology, leading to inaccurate predictions of drug responses in humans. 

The limitations of these model types contribute to the high failure rate of drug candidates in clinical trials, with some estimates suggesting that up to 90% of drugs fail in clinical stages due to unforeseen toxicity or lack of efficacy¹. 

How Complex In Vitro Models Enhance Preclinical Studies

Since CIVMs are designed to recreate the microphysiological environments of human organs, they address many of the limitations of conventional 2D cell culture and animal models: 

1. Physiological Relevance 

CIVMs are designed to more accurately mimic human tissue structure and function. For example, a key feature of Organ-Chips is that researchers can easily control and finely tune the mechanical forces cells experience. When Organ-Chips are placed under media flow and cyclic mechanical strain, cells experience the mechanical forces they would in the body—such as peristalsis in the intestines, breathing in lungs, and blood flow through vessels. All of these features combined—multicellular complexity, cell-cell interactions, tissue-specific ECM, and mechanical forces—result in more in vivo-relevant gene expression, morphology, and functionality than is possible with conventional cell culture methods. 

2. Better Prediction of Human Responses 

Because CIVMs can replicate human organ systems with high fidelity, they can often offer better predictive value compared to animal models. In fact, a 2022 survey conducted by the Linus Group on behalf of Emulate found that researchers who have used Organ-Chips in their experiments overwhelmingly agree—70% of experienced users rated the technology as more predictive than animal models, and an additional 21% said the technology is similarly predictive. 

3. Reduced Animal Use 

In recent years, there has been growing pressure to reduce the use of animals in preclinical testing. CIVMs offer a viable alternative, allowing researchers to perform toxicity and efficacy testing without relying solely on animal models. This not only allows researchers to avoid lengthy and rigid animal experiments, but it also aligns with the FDA’s ongoing efforts to promote alternatives to animal testing, as outlined in their Advancing Alternative Methods (AAM) initiative². 

CIVMs in IND Submissions to the FDA

The FDA requires extensive safety and efficacy data before approving an Investigational New Drug (IND) application, which is the first step towards clinical trials. CIVMs offer several ways to enhance the quality of the data submitted, potentially reducing the risk of delays or rejections. 

1. Safety Assessment 

The primary focus of an IND submission is to determine the safety of a drug candidate; CIVMs can provide highly predictive toxicology data. For example, Liver-Chips are increasingly used to study drug metabolism and liver toxicity, helping to identify adverse effects that might not be evident in standard in vitro assays. 

In a landmark study published in Communications Medicine, Emulate researchers showed that the Liver-Chip S1 outperformed conventional animal and hepatic spheroid models in predicting drug-induced liver injury (DILI), correctly identifying 87% of a set of 18 drugs that caused DILI in humans, despite passing through animal testing.​ Applied across the pharmaceutical development pipeline, widespread adoption of Organ-Chips in preclinical testing could create productivity gains of up to $3 billion through its increased predictive power. Perhaps most importantly, however, is that the Liver-Chip could have prevented 242 deaths in the clinic due to its predictive power in safety assessments.​ 

2. Pharmacokinetics and Pharmacodynamics 

In addition to safety, PK and PD data are essential components of an IND submission. Scientists can create CIVMs that simulate multiple organ systems to assess how a drug is absorbed, distributed, metabolized, and excreted (ADME) in the human body. For instance, a Kidney-Chip model can be used to predict renal clearance and drug-drug interactions, while a gut-on-chip system can study drug absorption³. 

These models can offer more accurate data on drug behavior in humans compared to animal models, leading to more confident dosing strategies in early-phase clinical trials. 

3. Improved Disease Modeling 

CIVMs can also be used to model specific disease states more accurately than animal models. For instance, researchers can create disease-specific Organ-Chip models (e.g., Lung-Chips for studying cystic fibrosis or asthma) to test how drug candidates perform in a human-relevant disease environment. This can provide additional support for an IND submission, demonstrating that a drug is not only safe but also effective in a human-specific disease context. 

4. Regulatory Acceptance and FDA Guidelines 

The FDA has shown increasing interest in the use of CIVMs for IND submissions, particularly in the context of toxicology and disease modeling. While these models are not yet required in IND submissions, they are becoming an accepted method to supplement traditional data. In 2020, the FDA launched the Innovative Science and Technology Approaches for New Drugs (ISTAND) pilot program, which aims to qualify novel approaches like Organ-Chips for regulatory use. In September 2024, the Liver-Chip S1 became the first Organ-Chip model to be accepted into the program, marking a significant step forward in the regulatory acceptance of CIVMs. 

Drug developers must work closely with the FDA during the pre-IND phase to ensure that any data generated using CIVMs aligns with regulatory expectations. The agency’s guidance on the use of alternative methods is evolving, and incorporating CIVMs could improve the chances of a successful IND application. 

Real-World Examples of CIVMs in Drug Development

Several high-profile pharmaceutical companies are already leveraging CIVMs to improve their drug development pipelines. Take for example Moderna: 

Samantha Atkins, PhD, is a scientist in the Investigative Pathology division at Moderna. Her goal is to de-risk their lipid nanoparticle (LNP) candidates to make them safer before they progress into NHP studies. To increase the efficiency of her research program, Dr. Atkins has started using the Emulate human Liver-Chip to screen for LNP-mediated toxicity instead of relying solely on NHPs. 

In a simple cost analysis, Dr. Atkins found that she was able to screen 35 novel LNPs in the Liver-Chip during a course of experiments that took 18 months at a total cost of $325,000. If she were to screen the same number of LNPs using traditional NHP studies, it would have cost Moderna over $5,000,000 and taken over 60 months to complete. 

Simply by incorporating Liver-Chips into her workflow, she is able to down-select LNPs over 4x faster and at a fraction of the cost of NHP studies. 

Another pharmaceutical company using CIVMs to improve their R&D programs is GlaxoSmithKline. Dr. Josie McAuliffe, the Lab Head of Cell Biology & In Vitro Models, has started incorporating Lymph Node-Chips into her preclinical assessment of vaccines to bridge gaps between in vitro models, animal studies, and clinical outcomes. Dr. McAuliffe’s goals are to test the chip’s capacity with RNA vaccines of varying effectiveness to evaluate the dynamic range of the chip, as well as to better correlate in vitro model outcomes with clinical efficacy to improve the overall translation of vaccine candidates. 

These real-world applications demonstrate how CIVMs are making their way into the regulatory landscape, offering valuable data to support IND submissions. 

Conclusion

CIVMs represent a significant leap forward in drug development. By providing more physiologically relevant data, reducing reliance on animal models, and offering better predictions of human responses, CIVMs are poised to play an increasingly important role in IND submissions to the FDA. As the regulatory landscape continues to evolve, companies that adopt these models early may have a competitive advantage, reducing the risk of late-stage clinical failures and improving the overall efficiency of their drug development process. 

By integrating CIVMs into their preclinical programs, pharmaceutical and biotechnology companies can enhance the quality of their IND submissions, ultimately leading to safer, more effective drugs reaching the market faster.

Continue Learning: 

• eBook: An Introduction to Organ-on-a-Chip Technology

• Blog: Microphysiological Systems: The Future of Research and Drug Development 

• Blog: Are Non-Human Primates a Research Dead End? 

• Webinar: Organ-Chips 101: Bridging the Gap Between Traditional Models and Human Biology

Sources: 

1. Sun D, Gao W, Hu H, Zhou S. Why 90% of clinical drug development fails and how to improve it? Acta Pharm Sin B. 2022 Jul;12(7):3049-3062. doi: 10.1016/j.apsb.2022.02.002. Epub 2022 Feb 11. PMID: 35865092; PMCID: PMC9293739. 

2. Commissioner, Office of the. “Advancing Alternative Methods at FDA.” FDA, 5 Jan. 2022, www.fda.gov/science-research/about-science-research-fda/advancing-alternative-methods-fda. 

3. Center for Drug Evaluation and Research. “Drug Development and Drug Interactions.” U.S. Food and Drug Administration, 2019, www.fda.gov/drugs/drug-interactions-labeling/drug-interactions-relevant-regulatory-guidance-and-policy-documents. 

Recently, we announced that the Emulate Liver-Chip S1 was accepted into the FDA’s ISTAND pilot program. To learn more, we sat down with Dr. Lorna Ewart, Chief Scientific Officer at Emulate, for a conversation about what this acceptance means for the company, the drug development industry, and the future of drug safety assessment. 

Q: What exactly is the FDA ISTAND program, and why is it relevant to drug development? 

Lorna Ewart: The ISTAND program—which stands for Innovative Science and Technology Approaches for New Drugs—is a pilot initiative introduced by the FDA to qualify innovative tools and technologies for use in regulatory submissions. Essentially, it provides a pathway for new methodologies, like our Organ-Chips, to be recognized by the FDA as a reliable and robust drug development tool in drug development. 

When sponsors include data from a  qualified drug development tool in their regulatory submissions, FDA reviewers can have confidence in that data’s quality and reproducibility. This allows them to focus on the experiment outcome and how the data support the sponsor’s proposal, such as initiating a clinical trial, without focusing on how the data was generated.  

Q: How does this acceptance impact Emulate and the broader pharmaceutical industry? 

LE: For Emulate, being accepted into the ISTAND program is an important milestone that represents the Liver-Chip S1’s potential applicability in regulatory contexts. For the pharmaceutical industry, it indicates the increasing interest in using more human-relevant models earlier in the drug development process. Ultimately, full qualification could mean more accurate prediction of drug-induced liver injury (DILI) for drugs whose structural analogs have previously shown a DILI response in the clinic. This could improve patient safety by reducing the risk of adverse effects that traditional models may miss. 

Q: Can you walk us through the process of gaining acceptance into the ISTAND program? 

LE: Certainly. The ISTAND program involves a three-stage process, the first of which is the Letter of Intent (LOI). For this, we submitted a detailed proposal outlining the unmet need in drug development that our technology addresses. In this stage, establishing a narrow context of use is paramount, and we focused on demonstrating how the Liver-Chip S1 can better predict small-molecule DILI compared to traditional models—specifically in cases comparing structurally similar compounds, where one is known to cause clinical DILI. 

With the LOI accepted, we’re moving into the second stage of the ISTAND program, the Qualification Plan. In this phase, we will work with the FDA to design a study plan aimed at demonstrating reproducibility and repeatability of our Liver-Chip S1 in predicting DILI in the approved context of use. More specifically, when carrying out these studies, we’ll be showing that our technology produces consistent results across different laboratories and with various hepatocyte donors. We’ll also be working closely with the FDA to ensure our Qualification Plan meets all regulatory expectations. This partnership is crucial for addressing any questions and aligning the data requirements. 

The third and final stage is Full Qualification. Here, we will present the data from our Qualification Plan to the FDA. If successful, our Liver-Chip S1 would be fully qualified for use in regulatory submissions within the stated context of use. 

Q: What were some key findings from your studies that supported your submission? 

LE: Our submission was underpinned by robust data from our study published in Communications Medicine, part of the Nature Portfolio, where we evaluated 27 small-molecule drugs using the Liver-Chip S1 on a single donor. The drugs were categorized into five levels of severity based on their Garside DILI rank and included seven pairs of toxic drugs and their non-toxic structural analogs for direct comparison. The Liver-Chip S1 achieved an impressive 77% sensitivity and 100% specificity for all 27 compounds tested. We then a subset of 18 drugs on an additional donor and combed the data from both donors, where we found that the sensitivity increased to 87%, while specificity was maintained at 100%.  Importantly, the Liver-Chip S1 also successfully distinguished between all seven pairs of the drugs and their structural analogs—a result that proved crucial to our submission. Altogether, these results mean that the Liver-Chip S1 was highly effective in correctly identifying both toxic and non-toxic compounds. 

The Liver-Chip S1 was able to detect liver toxicity that conventional models, including spheroids and animal models, failed to predict. This highlights the potential of our technology to improve drug safety assessments. In a follow-up study, we developed the Liver-Chip S1 DILI Score, which quantifies the severity of liver injury on a scale of 1 to 5. This score aligns with clinical outcomes and provides a nuanced understanding of a compound’s hepatotoxic potential. 

Q: How might the Liver-Chip S1 change the way companies assess drug safety, particularly regarding liver toxicity? 

LE: Once the Liver-Chip S1 has passed each of the qualification stages, it could help to significantly enhance how pharmaceutical companies evaluate liver toxicity within the context-of-use defined for the submission. By providing a more human-relevant model, companies can better predict the potential liver toxicity of drugs whose structural analogs have previously shown a toxic response, reducing the risk of late-stage failures. Data from the Liver-Chip S1 can inform go/no-go decisions and guide modifications to chemical structures to improve safety profiles. 

Q: Are there other applications for the Liver-Chip S1 beyond the scope of the ISTAND program? 

LE: Absolutely. While our ISTAND submission focuses on a very specific context of use, researchers around the world have leveraged the Liver-Chip for various applications. Beyond small molecule toxicity testing, Liver-Chips have been used to assess the safety of monoclonal antibodies, cannabinoids, and gene therapy delivery vehicles. One particularly impactful example is its use in early drug development: Scientists at Moderna leveraged the Liver-Chip to screen 35 novel lipid nanoparticles (LNPs), allowing them to identify the most promising candidates before advancing to costly and lengthy non-human primate studies. Additionally, the Liver-Chip can model liver diseases, providing unique insights into disease progression and potential therapeutic approaches. For example, in a 2021 Cell paper, researchers used a Liver-Chip to model alcohol-associated liver disease (ALD) using human-relevant blood alcohol levels and clinically meaningful endpoints. The Liver-Chip exhibited key markers of ALD, such as lipid accumulation, oxidative stress, and bile canalicular remodeling, after ethanol exposure. These findings indicate that the Liver-Chip could provide more human-relevant assessments of ALD and aid in the development of novel therapies. 

Q: Any final thoughts you’d like to share about this milestone? 

LE: We’re excited about this significant step forward. The Liver-Chip S1’s acceptance into the ISTAND program is not only a promising development for our technology but also marks progress towards widespread incorporation of more predictive and human-relevant models in drug development. We look forward to working with the FDA in the next phase and are enthusiastic about the potential our technology has in helping the broader scientific community enhance drug safety and efficacy.

From July 3^rd–5^th, 2024, Emulate joined the European Organ-on-Chip society (EUROoCS) annual conference hosted at the historical Leonardo Campus of Politecnico di Milano in the splendid city of Milan, Italy.

What is EUROoCS?

EUROoCS is an independent, not-for-profit organization established to encourage and develop research into Organ-Chips and provide opportunities to share knowledge and advance the field with the ultimate goal of creating a healthier future. EUROoCS holds an annual conference fostering worldwide delegates active in the field of Organ-on-a-Chip technology and microphysiological systems to showcase the latest scientific breakthroughs and engage in meaningful discussions on the field’s cutting-edge advancements. The conference brings together a broad audience of Organ-Chip experts and enthusiasts from government, academia, pharma, medicine, and other institutions.

Learn how you can join EUROoCS here.

EUROoCS in Review

This exciting event started with the plenary talk from Prof Andries D. van der Meer, EUROoCS Chair, highlighting the “Official publication of the international Roadmap for Organ-on-Chip Standardization.” This was followed by a keynote talk titled, “Building a roadmap towards Regulatory Acceptance of NAMs in the Development and Approval of Pharmaceuticals,” delivered by Sonja Beken, PhD, Coordinator of the Unit of non-clinical evaluators at the Belgian Federal Agency for Medicines and Health Products (FAMHP), which highlighted the vision of the 3Rs Working Party and Member of the Non-Clinical Working Party at the European Medicines Agency. There was also a consecutive regulatory industrial round table discussion on Organ-Chip-based test methods for the authorization of medicinal products. Another interesting keynote was delivered by Kimberly Homan, PhD, where she discussed how combining organoids with Organ-Chips opens new doors in drug research and development.

Another interesting keynote was delivered by Genentech’s Kimberly Homan, PhD, where she discussed how combining organoids with Organ-Chips allows researchers to unlock new possibilities in drug research and development.

At the conference, Emulate provided attendees an opportunity to gain hands-on experience in our Organ-Chip wet lab and explore cutting-edge innovations, including the Chip-A1 Accessible Chip and our new CAR T Organ-Chip application.

Our customers also showcased their latest scientific breakthroughs in presentations and poster sessions.

Talks:

• “Comparison of Spheroids and a Microfluidic Chip Model as Advanced in Vitro Liver Models” by Heidrun Ellinger-Ziegelbauer, PhD, Principal Scientist, Bayer AG Pharmaceuticals
• “Recapitulating memory B cell responses in a Lymphoid Organ-Chip to evaluate mRNA vaccine boosting strategies” by Lisa Chakrabarti, PhD, Control of Chronic Viral Infections Group, Virus and Immunity Unit, Institute Pasteur, Université de Paris
• “Development and validation of an organ-chip model of breast cancer bone metastasis” by Stefaan Verbruggen PhD, Centre for Predictive in vitro Models, Engineering and Materials Science, Queen Mary University of London, London, United Kingdom

Posters:

• “Impact of tissue microenvironment and mechanical forces of the human gut on pathogens invasion” by Samy Gobaa, PhD, Head of Organ-on-Chip Center, Institute Pasteur
• “Lung organoid-on-chip models to study respiratory infections” by Barbara Fonseca, PhD, Researcher, Institut Pasteur
• “Evaluation of Cell-Type Specific miRNA Secretion in a Liver-Chip Model” by Nicole Reisinger, DSM-Firmenich, ANH R&D Center, Tulln, Austria

EUROoCS2024 was an amazing opportunity to connect with fellow Organ-Chip enthusiasts and see how scientists are using Emulate Organ-on-a-Chip technology to advance research across a wide variety of areas. The field of Organ-Chips is in a better place than it’s ever been, and we’re excited to see what new achievements will be made over the next year. See you at EUROoCS2025!

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In this Emulate guest blog, Vivek Thacker, PhD, Group Leader at University Hospital Heidelberg, explains how he and his team at his previous organization, École Polytechnique Fédérale de Lausanne, used the Emulate Lung-Chip to study how bacterial “cords” contribute to the pathogenesis of Mycobacterium tuberculosis.

What is tuberculosis, and what makes it so interesting to study?

Tuberculosis (TB), an infectious bacterial disease, is humankind’s oldest and deadliest foe, still responsible for roughly 1.5 million deaths per year globally. The causative bacterium, Mycobacterium tuberculosis (Mtb), has co-evolved with humans over thousands of years, making TB a chronic disease with a wide spectrum of manifestations. Today, the most common treatment is a multi-drug antibiotic regimen that needs to be administered for several months, leading to poor treatment compliance and an increasing profile of drug resistance.

Interestingly, many individuals in high-risk countries are frequently exposed to Mtb but do not go on to develop TB or adaptive immune responses to Mtb antigens. This suggests that it is important to understand how the human innate immune system effectively halts disease progression. As such, my team and I wanted to characterize Mtb’s earliest interactions with epithelial cells and macrophages in the lung, study how Mtb adapts to the lung microenvironment, and investigate what causes tissue resident immune cells to succeed or fail in their quest to contain infection.

What makes tuberculosis so challenging to study?

TB is spread by aerosols, meaning that the earliest host-pathogen interactions should be single-cell interactions in the vast alveolar spaces of the lung. However, early TB activity in these alveolar spaces is relatively understudied, as it is difficult to isolate a few hundred bacteria in the lungs of any animal model, and it is even more challenging to study the spatiotemporal dynamics of host-pathogen interactions, particularly in BSL-3 conditions.

How did Organ-Chips allow you to overcome these challenges?

These challenges are perfectly suited to Organ-Chips, which fit into the large space in the “middle”—that is, they recapitulate complex cellular interactions that do not occur in simple model systems, allowing us to study the mechanisms of early-stage bacterial exposure and response with high spatiotemporal resolution. As you can imagine, this opens many new research avenues.

Organ-Chips are invaluable for discovery research, allowing us to identify new phenomena or roles for certain cell types in specific host niches. On top of this, the modular nature of this technology allows us to perturb only specific cells in a co-culture for targeted studies. Many “traditional” assays can also be made more precise and quantitative—e.g., fast and accurate measurements of bacterial killing and regrowth after antibiotic treatment. Organ-Chips also enable new kinds of measurements, such as in situ electron microscopy.

Can you describe the model you developed and the insights it yielded?

The Lung-Chip recreates the physiological air-liquid interface seen in alveolar biology while being accessible to long-term live-cell imaging. Using this model, we found that pulmonary surfactant secreted by epithelial cells protected the host from Mtb infection, rendering many Mtb unable to grow in host cells. However, exposure to surfactant in turn stimulated the bacteria to produce lipids that survived this first interaction, leading to the formation of biofilm-like cords in host cells that help Mtb bacteria evade clearance by antibiotics.

The consistent growth of Mtb cords in the Lung-Chip led us to search for these structures in the early stages of infection. To do this, we designed an experimental strategy wherein we imaged thick tissue slices with confocal microscopy in order to search for these cords in situ. We were then able to identify cords in an animal model, not only providing crucial validation but also expanding the predictive reach of the Organ-Chips. This provides a roadmap for future iterative development of the Lung-Chip to explore more aspects of Mtb pathogenesis.

How have these findings changed your research, and what does the future look like for you?

Clearly demonstrating that cords play a role in Mtb pathogenesis opens several new research avenues. In future studies, we will seek to understand how the mechanical rigidity of these structures affects immune function as well as focus on dissecting this complex host-pathogen interaction, with the aim to develop better protective strategies. We will also focus on gaining a better understanding of antibiotic responses within specific tissue microenvironments. Using Organ-Chips, we can study how specific tissue niches and barriers change the “effective” antibiotic concentrations that bacteria may experience and how these antibiotics may be processed differently within these bacteria (e.g., restricted access due to tight packing in cords).

Learn more in the full article published in Cell.

The Origins of Modern Cell Culture

The tone of Robert Hooke’s writing in 1665 was one of unmistakable glee. Hooke, having recently constructed a rudimentary but powerful microscope, was now able to document in detail the underlying components that afforded plants, rocks, and animals their functional properties. To Hooke, this newfound world held the key to understanding the nature of life.  

“And could we so easily and certainly discover the [design] and texture even of these films and of several other bodies…we might as readily render the true reason of all their phenomena.”  

Driven by this potential, Hooke proceeded to catalogue the microscopic world around him. His work, documented in Micrographia, not only introduced the term ‘cell’, but also demonstrated the benefits of meticulously studying the cellular world, thus laying the groundwork for modern cell biology.  

Today, cell culture, which involves growing cells outside of their native organism, is a foundational tool in the molecular sciences. Cells that have been isolated from a patient or immortalized long ago allow researchers to study various aspects of the human body, using the cells as proxies for the larger organs they hail from. However, deriving valuable information about an organism from its cells is far from simple. Cells isolated from the human body (in vitro) are unlikely to behave naturally, and those within the body (in vivo) are often difficult to observe. There have been significant strides towards understanding the mechanics of life and disease at the cellular level, and recent advances in the technology used to study cells are opening up even newer possibilities.  

In vitro cell culture involves growing living cells in a highly controlled, non-living environment. In vitro is Latin for “in the glass,” and as the name suggests, this kind of cell culture is most often carried out by growing cells in a two-dimensional (2D) plane on glass or plastic petri dishes. These cells may be sourced directly from patients (known as patient-derived cells) or collected from a patient long ago and subsequently engineered to enable long-term propagation (so called immortalized cell lines).  

In Vitro Cell Culture Advantages and Disadvantages

Advantages 

• Growing and maintaining cells is relatively inexpensive. 

• Researchers gain a high degree of control over the cell’s environment, maintaining control over the nutrients, temperature, and other variables that cells are exposed to.  
• These cells are often far easier to observe through a microscope, enabling high-content studies of the cell’s behavior. 
• This approach is often amenable to high-throughput applications, such as drug or functional screening. 

Disadvantages 

• The in vitro environment is far removed from the cell’s natural environment in the human body, where cells experience three-dimensional contact with proteins and other cells, biomechanical forces, as well as dynamic nutrient and waste gradients. Each of these factors can influence how the cell behaves. By removing cells from a complex environment to a far more simplified one, the translational value of in vitro cell culture diminishes.  
• In vitro cell culture may result in artificial mutations that cause cells to behave abnormally. 

In Vivo Studies: Advantages and Disadvantages

In vivo, meaning “within the living,” involves studying cells within their native organism. This method provides the most accurate representation of how cells behave in their physiological context. In vivo studies have long been viewed as the gold standard for understanding complex interactions within tissues, organs, and systems, as well as for assessing the real-world effects of drugs and treatments. This is largely because of the aforementioned drawbacks of traditional in vitro cell culture systems.  

However, in vivo studies come with a significant cost. The in vivo environment is inherently more complex, making it difficult to isolate the effects of specific variables on cell and organismal behavior. Additionally, many in vivo studies are performed in model organisms, such as rats and dogs, to predict how the human body will respond to disease or therapeutics. The genetic and physiological differences between animals and humans can erode the accuracy of these models. This is particularly hazardous in preclinical drug safety testing, where inaccurate predictions can lead to dangerous compounds advancing into the clinic.  

Bridging the gap with more advanced in vitro systems  

Recent advances to in vitro cell culture are helping to alleviate the challenges researchers have faced historically, particularly by incorporating more complex, in vivo-relevant environments. The most powerful example of this comes from Organ-on-a-Chip technology, also known as “Organ-Chips.” 

Organ-Chips are advanced, three-dimensional in vitro culture systems that closely mimic the natural environment of a cell. Specifically, these systems expose cells to biomechanical forces, dynamic fluid flow, and heterogenous cell populations while providing three-dimensional contact with proteins or other cells. Collectively, these features encourage the cells to behave as they would in a living organism, thus greatly improving researchers’ ability to accurately study the behavior of cells in vitro. And, unlike many in vivo model systems, Organ-Chips can be constructed with human cells, thus circumventing the interspecies differences that plague many in vivo systems. As such, Organ-Chips are now being used in a variety of applications to help researchers study cell behavior with increasing accuracy. 

Cell biology has evolved considerably since Hooke’s discovery, progressing in ways that allow researchers to study the cellular world with ever greater accuracy. That progression has often been catalyzed by technological development, from Hooke’s microscope to the advent of Organ-on-a-Chip technology. 

Commonly Asked Questions About Modern Cell Culture 

What is Ex Vivo Cell Culture?

Ex vivo cell culture is a form of in vitro cell culture that uses cells or tissue freshly collected from a living organism. Ex vivo cell culture may be particularly valuable when studying patient-specific conditions or when working with mature, terminally differentiated cell types that are difficult to produce with stem cells.  

Are in vitro studies reliable? 

Yes, to an extent. In vitro studies can be extremely valuable tools for studying cell biology and human physiology. While the traditional in vitro cell culture environment is very different from an in vivo environment—and thus cells are less likely to behave as they would in vivo—many cellular phenotypes are quite robust. This means that some cell behaviors in vitro do accurately represent how cells in vivo would behave. However, the reliability of in vitro studies can be greatly improved by using more complex culture systems, such as Organ-Chips, that faithfully emulate the cells’ natural environment.  

What is a typical in vitro study design? 

In vitro studies can be vastly different in design and scale; therefore, there is no single template for an in vitro study. However, there are common elements within subdisciplines. For example, in vitro studies for pharmaceutical development often use human cell lines (for larger scale studies, immortalized cells are common early in the drug development process). These cells may be grown in 96-well plates that allow for automated handling. Candidate drugs may then be added, one to each well of cells, followed by a period of observation. The cell’s ability to survive, proliferate, or release various signaling factors may be measured (among many potential response mechanisms).  

In March 2020, I was fortunate to join Emulate, intrigued by one of those rare opportunities to bring truly game-changing technology to healthcare. 

Five days later, the world shut down.  

Every day since has been motivated by a vital mission to leverage human biology and technology to ignite a new era in human health, driven by a team of people with an unwavering commitment to bring a human-centric approach to biological innovation.

As we were coming to terms with our new normal, our team’s focus and action were nothing short of miraculous. Undaunted, and united under a single vision, the team persevered. We found new ways to move forward with a collective strength to overcome challenges. We embraced new processes to shatter unexpected roadblocks. And we responded to the needs of our customers to ensure their science could keep moving forward.  

We grew our team, adding deep commercial and functional expertise to implement structure and processes in order to rapidly scale. The scientific team has grown to include researchers focused on our application roadmap areas such as immunology and microbiome. We expanded our leadership team with Donald Ingber, MD, PhD, a scientific founder of Emulate and Chairman of its Scientific Advisory Board – and arguably one of the great pioneers in the field of biologically inspired engineering – joining our Board of Directors. Also, Scott Kantor accepted the role of Chief Financial Officer and Larry Weiss came on as Chief Legal Officer.  

Over the past 18 months, we announced our roadmap for expanding Organ-Chip applications with a focus on developing targeted and advanced biologics. Additionally, we released a series of breakthrough applications and organ-models, such as the Brain-Chip and the Colon Intestine-Chip, deepening our portfolio of the human-relevant Organ-Chips that helped solidify our commitment to scientific excellence. 

We have bolstered our leadership team, accelerated product development goals, and seen healthy growth in demand for our products. Several leading indicators validate our belief that organ-on-a-chip technology will dramatically transform the entire drug discovery and development pipeline and ultimately eliminate unnecessary animal testing.

Jim Corbett, Emulate CEO

Aside from our product and commercial developments, we have taken a stronger stance against animal testing, as there is scientific proof that it has significant  limitations in effectiveness – particularly for today’s novel drugs and vaccines. In response to a New York Times article, we championed legislation reducing the use of primates for drug testing. More recently, the FDA Modernization Act and the Humane Research Act have been introduced to Congress to rally support for alternatives to animal testing, citing scientific inadequacies and ethical concerns associated with it. Our team also joined the North American 3Rs collaborative and believe that moving in the right direction means encouraging the use of more accurate and humane technologies. We truly believe that organ-chips will become an integral part of drug development and has the potential to ultimately eliminate animal testing.

This level of achievement would be astonishing in normal times and no doubt helped propel our fundraising efforts. Today, we announced the close of an $82 million dollar round of financing, which will enable Emulate to expand research and development efforts to new heights. We will scale-up R&D activities to facilitate the creation of new human-relevant organ-on-a-chip models in immunology, neuroinflammation, tumor modeling, and more. To help meet growing global demand, we will extend operations in the Asia Pacific region with new distributor relationships. 

I am excited to see what this team will accomplish as we set out into a changed world, continuing to scale and meet global demand as well as allow researchers to predict human response better than conventional cell culture and animal-based experimental testing. This biological revolution is just getting started. Let’s go! 

A summary of the paper published in Nature Biomedical Engineering: On-chip recapitulation of clinical bone marrow toxicities and patient-specific pathophysiology.

Human bone marrow is the body’s major site of hematopoiesis, the proliferation and differentiation of all blood cellular components from hematopoietic stem cells. These actively dividing and maturing cells are highly sensitive to toxic stimuli and, thus, bone marrow is one of the major targets of unwanted toxicity caused by drugs or therapeutic agents. Predicting drug-related hematotoxicity with clinically relevant pharmacokinetics would be extremely valuable for designing safety assessments and human trials. 

Studying bone marrow tissue is particularly difficult due to its inaccessibility and the limited number of physiologically relevant in vitro models that can support growth and maintenance of bone marrow cultures. Current hematopoietic toxicity studies are performed using methylcellulose colony cultures in which cells are suspended and can be exposed to higher-than-usual concentrations of drugs for extended periods of time. To address the unmet need for a predictive model to study hematopoietic dysfunction and pathophysiology of bone marrow, the authors created a Bone Marrow-Chip (BM-Chip) to recapitulate relevant hematopoietic cell types in a three-dimensional (3D), mechanically active next-generation in vitro model. This model possesses relevant levels of complexity to closely mimic the in vivo environment to examine the effects of known myelotoxic stressors and to investigate a genetic condition resulting in bone marrow failure.

• Research Area: Drug development, Toxicity testing, Rare Disease
• Organisms: Human
• Sample Types: Human bone marrow-derived mesenchymal stromal cells, hematopoietic stem/progenitor (CD34+) cells, umbilical cord vascular endothelial cells
• Research Question: Can a Bone Marrow-Chip recapitulate the features of human hematopoiesis and dysfunction resulting from genetic mutations and exposure to drugs and radiation?

 

Experimental Overview

Characterizing the Bone Marrow-Chip

Researchers created the BM-Chip using human bone marrow-derived stromal cells (BMSC) and CD34+ cells co-cultured in a fibrin gel in the upper channel of the chip. The lower channel of the chip contained human umbilical vein endothelial cells (HUVEC) with unidirectional continuous flow of culture medium containing cytokines that support cell growth (stem cell factor, Flt3 ligand and thrombopoietin) as well as factors that encourage multilineage differentiation (granulocyte colony stimulating factor and erythropoietin). Compared to the same cells grown in static models in suspension and in 3D gel, the BM-Chip increased the numbers of proliferating myeloerythroid and neutrophil progenitors, demonstrating increased cell survival and robust hematopoiesis in vitro over prolonged culture time (28 days).  

Schematic of bone and insert micrograph showing normal human bone marrow histology. Left middle: schematic of the cross-sectional view of the human BM-Chip on day 0 after seeding, showing singly dispersed CD34+ progenitors and BMSCs in a gel in the top channel and an incomplete vascular lining (seeded on either day 0 or day 8) in the bottom channel. Right middle: within 2 weeks of culture initiation, endothelial cells grow to cover all four sides of the lower channel and create a vascular lumen, while CD34+ cells undergo expansion and multilineage differentiation. Right: immunofluorescence image of a vertical cross-section through the gel in the upper channel of the BM-Chip taken at day 14 (magenta: erythroid lineage; yellow: megakaryocyte lineage; blue: neutrophil and other hematopoietic lineages). 

Modeling Drug-Induced Hematotoxicity in the Bone Marrow-Chip

To determine if the BM-Chip could be used to model human bone marrow pathophysiology, the researchers exposed the chips to 5-fluorouracil (5-FU) at dosage-appropriate plasma concentrations to observe toxic effects. BM-Chips from six different CD34+ donors infused with 5-FU through the vascular (bottom) channel consistently showed hematotoxicity at clinically relevant concentrations, whereas suspension and static gel co-cultures did not.

In the next set of experiments, the researchers challenged the BM-Chip with AZD2811, a small-molecule inhibitor of Aurora B kinase that is critical for proper cell division and is currently in phase II clinical development as a cancer therapeutic drug. In earlier phases of clinical trials, AZD2811 has been shown to selectively target dividing neutrophil and erythroid cells with varying effects in a time and dose-dependent manner. The authors used the BM-Chip to explore these effects on both mature and progenitor cell types and provide insight into the drug’s mechanisms of action. 2- and 48-hour AZD2811 infusions resulted in dose-dependent toxicities of the erythroid lineage, with much greater effect following the 2-hour infusion regimen than the 48-hour regimen. In the neutrophil lineage, dose-dependent toxicity in the BM-Chip was greater with the 48-hour infusion. Importantly, both regimens revealed maturation-dependent sensitivity to the treatment via selective decrease in immature cells of both lineages compared to mature cells.

Suspension cultures of CD34+ cells failed to replicate the dose-dependent erythroid toxicity that was successfully modeled by the human BM-Chip, suggesting that it can more accurately predict hematological effects at clinically relevant drug exposures than static culture models.

Radiation and Bone Marrow Recovery

Building on the observation that immature, proliferating cell types were selectively affected by AZD2811 treatment, the authors tested maturation-dependent toxicity caused by ionizing radiation. Radiation treatments are widely used as a cancer therapy, and they commonly cause bone marrow depletion – a reduced production of blood cells from all lineages. The authors noted that the BM-Chips showed decreased numbers in all cell types studied that correlated with increasing doses of radiation. These experiments show that the BM-Chip is a useful model of human-specific radiosensitivity, inviting more detailed analyses of radiation-associated cell death.

The researchers went on to demonstrate that the BM-Chip can also be used as an in vitro model to examine bone marrow recovery and response to potential therapeutics using human-relevant pharmacokinetic profiles during preclinical drug evaluation, development, and regulatory assessment, which cannot be done using animal models.

Modeling Rare Conditions: Shwachman-Diamond Syndrome

Shwachman–Diamond syndrome (SDS) is a genetic condition that causes bone marrow depletion and failure, resulting in neutropenia. The extent of hematological dysfunction may involve other cell lineages as well, leading to myeloid malignancies in some SDS patients. Understanding SDS has been limited by a lack of animal models that faithfully recapitulate the condition. In this study, the authors cultured CD34+ cells from two patients with SDS alongside normal BMSCs and endothelial cells to understand the clinical manifestations of the syndrome using this disease model.

The researchers noted that the cells in the SDS BM-Chips exhibited defective hematopoiesis, with fewer numbers of neutrophils and erythroid cells, as well as impaired maturation of neutrophils. The blunted maturation of neutrophils, denoted by their pattern of CD16/CD13 expression, matched retrospective patterns found in bone marrow aspirates of other SDS patients, suggesting that the BM-Chip can replicate the phenotype and some features of the disease. Further studies on the mechanisms of bone marrow failure, anemia, and neutropenia should be possible using the SDS BM-Chip.

Conclusions

This study provides evidence that the human BM-Chip is an effective preclinical model of human BM pathophysiology, enabling analysis of human responses to clinically relevant drug pharmacokinetics profiles and radiation dose exposures. The data show that the BM-Chip supports erythroid differentiation as well as myeloid development and mobilization over four weeks of culture while improving the maintenance of CD34+ progenitors compared to traditional culture methods. Additionally, the BM-Chips were able to better recapitulate the toxicity responses of human bone marrow to clinically relevant dose exposures of AZD2811 and 5-FU and showed an improved ability to recover after injury. 

BM-Chips derived from patients with Shwachman-Diamond syndrome showed dysfunctions that parallel key hematological abnormalities observed in vivo and led to the discovery of a neutrophil maturation abnormality that exists in a significant subset of SDS patients. Taken together, next-generation in vitro modeling of human bone marrow using Emulate’s microfluidic organ-chips has great potential to facilitate drug development, disease modeling, and translational studies for a range of hematopoietic disorders and toxicities – all while offering a human-specific alternative to animal testing for regulatory assessment. 

Testing new vaccines against seasonally emerging influenza strains is a necessary process, due to frequent changes in the virus’s immunogenic surface proteins. Vaccines and other drugs, such as immunotherapies, are evaluated for efficacy and safety in vitro using cultured human immune cells and in animal models. However, these assessments often fail to fully predict human responses, because they lack the biologically relevant microenvironment in which to develop an adaptive immune response. 

Modeling a true human immune response is a complex undertaking. Primary lymphoid organs, like the thymus and bone marrow, allow immune stem cells to proliferate, differentiate, and mature. Secondary lymphoid organs like the lymph nodes, spleen, and tonsils maintain mature but naïve cells ready to be activated by contact with antigen presenting cells, leading to clonal expansion and affinity maturation for the adaptive immune response. Lymphoid follicles (LFs) that are present within lymph nodes or form ectopically within other secondary lymphoid organs contain germinal centers that support the development of plasma cells that secrete high affinity antibodies. 

A human model of the LF would provide a better understanding as to why these organ structures are critical for developing adaptive immune responses and would be extremely useful for preclinical assessment of vaccine efficacy. This study represents the first-of-its-kind human LF-Chip containing B, T, plasma and antigen-presenting cells to test functional immunization responses to vaccines and adjuvants in vitro. 

• Research Area: Vaccine and adjuvant testing
• Organisms: Human
• Sample Types: Peripheral blood-derived immune cells
• Research Question: Can the LF-Chip be a useful human-relevant preclinical tool for assessing the efficacy and safety of influenza vaccines and adjuvants?

 

 

Experimental Overview

Characterizing the LF-Chip

Researchers created the LF Organ-Chip by using peripheral blood mononuclear cells (PBMC) isolated from donor blood and culturing the cells at a high density within the extracellular matrix (ECM) in the lower chamber of the chip, with culture medium flow supplied in the upper chamber. The researchers observed self-aggregation of lymphocytes within the ECM resembling which resembled germinal centers. They did not see autoactivation of B cells (determined by levels of IgG or IgM in the Organ-Chip cultures), overcoming a key challenge seen in static 2D cultures. 

Within the LF-like structures formed in the chip, the researchers detected molecules that indicate immune reaction, including the chemokine CXCL13, which recruits T cells, and activation-induced cytidine deaminase (AID) expression, which is required for the critical antibody class switching step. Class switching and plasma cell formation were observed, and, when exposed to an antigen that mimics the presence of dead bacteria, a robust IgG response was generated, suggesting that the model faithfully recapitulated a functional adaptive immune response.

Vaccination Testing on the LF-Chip 

Protective immunity induced by vaccination requires plasma cell production of antigen-specific antibodies. To see if the model could simulate an immune response to vaccination with viral antigens with or without an immune stimulating adjuvant, the authors added patient monocyte-derived dendritic cells in a 3D ECM gel within the Organ-Chip and tested it with influenza virions and adjuvant. The germinal centers showed plasma cell formation, expression of AID by resident B cells, and production of cytokines, and robust production of antibodies to influenza virus hemagglutinin – similar to vaccinated humans. Notably, these results were not replicated within a 2D static cell culture model. A commercial influenza vaccine was used to induce a clinically relevant immune response in the chip, showing important features like cytokine response and donor variability. 

Towards a Better Preclinical Assessment of Vaccines and Adjuvants

This is the first reported in vitro model that supports formation of human LFs with functional germinal centers similar to those found in secondary lymphoid organs in vivo using cells isolated from peripheral blood. Within the LF-Chip, B and T cells support plasma cell differentiation and antibody secretion while spontaneously forming LFs that express the correct cytokines and chemokines. These Organ-Chip microphysiological systems are also patient-specific and can recapitulate donor variability in response to vaccination. 

Previous attempts at recreating cell culture models of the lymph node for preclinical vaccine testing are not as useful for modeling the human adaptive immune response. These experimental models do not result in the appropriate biomarkers, de novo lymphoid follicle formation, or survival of plasma cells. In addition to ethical concerns and shortages of non-human primates due to the current COVID-19 pandemic, animal models do not usually replicate an intact human immune response. Taken together, these findings suggest that the LF-Chip may be a useful human-relevant tool for assessing the efficacy and safety of vaccines and adjuvants in a patient-specific manner. 

Future Uses for the LF-Chip 

Using primary human blood cells collected non-invasively, the LF-Chip can also be used to study the basic biology of immune organ formation as well as antigen-induced immunological responses. Specifically, results obtained in this study suggest that the presence of dynamic fluid flow promotes LF formation and reduces autoactivation of B cells, possibly facilitated by the ECM to promote proper cell interactions. Future work with the chip could explore how mechanical forces work to support organ formation at the cellular level. The LF-Chip may also be used to understand control of genes encoding cytokines and chemokines that govern the microenvironment critical for formation of germinal centers and immune cell activation. Using high-resolution imaging, many of the cellular and molecular processes occurring in the LF-Chip can be observed over time, enabling valuable longitudinal studies of human immune responses. 

Drug candidates are usually discovered or developed with a specific purpose in mind: to stop infections, to target and kill cancer cells, or to repair a faulty cellular pathway. Sometimes, once these approved treatments are taken by large groups of people, clinicians may observe unexpected and exciting benefits. For example, the drug Raloxifene was developed to prevent and treat osteoporosis by mimicking the effects of estrogen to increase bone density. Through retrospective clinical analysis, the drug was also shown to decrease the risk of developing invasive breast cancer by blocking estrogen’s effect on breast tissue.  

Drugs that inhibit viral infection have been successfully developed and in use for decades, and with the current SARS-CoV-2 crisis, speeding up testing of potential preventive therapies is an urgent priority. One of the fastest ways to respond to a global challenge like a pandemic is to repurpose existing, approved drugs as treatments for emerging pathogens. 

Organ-Chips Identify Potential Prophylactic Treatment for COVID-19

During the past year, many research groups around the world have focused on drug repurposing for COVID-19 using established cell lines, primary tissue-derived human cells, organoids, and explanted human lung tissue cultures. However, it is well known that cells grown in a two-dimensional dish do not behave like the cells in a living human body, and many drugs that appear effective in pre-clinical lab studies do not work well in patients. 

In a collaborative effort to test whether existing drug candidates block infection from respiratory pathogens like SARS-CoV-2, researchers from the Wyss Institute for Biologically Inspired Engineering at Harvard University, the University of Maryland School of Medicine, the Icahn School of Medicine at Mount Sinai and others used Emulate technology to develop an Airway Lung-Chip to examine eight existing candidate therapeutics for SARS-CoV-2, including hydroxychloroquine and chloroquine, that they and others had previously observed in conventional cell culture assays. The study is reported in Nature Biomedical Engineering.  

The Emulate Airway Lung-Chip used for these studies is a small microfluidic culture system device with two parallel channels separated by a porous membrane. Human lung airway cells are grown in one channel exposed to air, while human blood vessel cells are grown in the other channel exposed to cell culture medium to mimic blood flow. Cells in the Airway Lung-Chip differentiate into specific types similar to those in the human airway and develop lung-specific traits such as cilia and the ability to produce and move mucus. The cells also express angiotensin-converting enzyme-2 (ACE2) receptors on their surface, which is co-opted by the virus to gain entry into cells. 

When the cells in the Airway Lung-Chip were infected with a non-infectious SARS-CoV-2 virus, most of these drugs, including hydroxychloroquine and chloroquine, were not effective at stopping infection. However, one antimalarial drug called amodiaquine reduced infection by 60 percent by preventing viral entry. 

Subsequent Research Suggests Drug’s Potential Therapeutic Effects 

Despite the promise of amodiaquine, the team still needed to demonstrate that it worked against the infectious SARS-CoV-2 virus. Virologists Matthew Frieman, PhD at the University of Maryland School of Medicine and Benjamin tenOever, PhD at the Icahn School of Medicine at Mount Sinai, had both the expertise and laboratories designed to study infectious pathogens and were eager to collaborate with the Wyss Institute. The Frieman lab tested amodiaquine and its active metabolite, desethylamodiaquine, against native SARS-CoV-2 via high-throughput assays in cells in vitro and confirmed that the drug inhibited viral infection. 

In parallel, the tenOever lab tested amodiaquine and hydroxychloroquine against native SARS-CoV-2 in a head-to-head comparison in a small animal COVID-19 model and saw that prophylactic treatment with amodiaquine resulted in an approximately 70 percent reduction in viral load upon exposure, while hydroxychloroquine was ineffective. They also saw that amodiaquine prevented the transmission of the virus more than 90 percent of the time, and that it was also effective in reducing viral load when administered after introduction of the virus. Thus, their results suggest that amodiaquine could work in both treatment and prevention modes. 

“Seeing how beautifully amodiaquine inhibited infection in the Airway Lung-Chip was extremely exciting,” said Frieman. “The fact that it seems to work both before and after exposure to SARS-CoV-2 means that it could potentially be effective in a wide variety of settings.” 

“This collaboration has allowed us to do things that we never would have had the resources to do otherwise, including recently setting up Organ-Chips in our own lab so that we can now use them to study the interactions between infectious viruses and their hosts. While we’re proud of what we’ve accomplished so far for COVID-19, we’re also looking forward to studying additional virus-host dynamics using the Organ-Chips in the hopes that we’ll be able to prevent or address future pandemics,” said tenOever, who is a Professor of Microbiology. 

The Organ-Chip-based testing ecosystem greatly streamlines the process of evaluating the safety and efficacy of existing drugs for new medical applications and provides a proof-of-concept for the use of Organ-Chips to rapidly repurpose existing drugs for new medical applications, including future pandemics. Amodiaquine is now in clinical trials for COVID-19 at multiple sites in Africa, where this drug is inexpensive and widely available. 

“The collaboration with the Wyss Institute and the Frieman and tenOever labs has created a preclinical drug development pipeline that produced clinically significant results with incredible speed,” said Lorna Ewart, EVP of Science at Emulate. “With customizable Organ-Chip technology in the hands of researchers, preclinical testing of new drug candidates or repurposed drugs can be further accelerated with more human-relevant models, allowing us to be better prepared to confront this and future pandemics.” 

For more information on how Emulate products are being used to study COVID-19, read our blog post titled How Organs-on-Chips Technology is being used to Provide Scientific Insights into COVID-19.