Organ Model: Respiratory System

Watch the on-demand webinar “Modeling Cystic Fibrosis Through an Airway Lung-Chip” featuring data from this publication!

Organ Model: Lung (Airway)

Application: Inflammation

Abstract: Cystic fibrosis (CF) is a genetic disease caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR), which results in impaired airway mucociliary clearance, inflammation, infection, and respiratory insufficiency. The development of new therapeutics for CF are limited by the lack of reliable preclinical models that recapitulate the structural, immunological, and bioelectrical features of human CF lungs.

Webinar Abstract

Due to the rapid evolution of viruses, including influenza and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), researchers are struggling to match pace in developing antivirals and vaccines as well as in identifying which drugs can be repurposed for new uses. Furthermore, many of the models used to explore virus evolution, vaccine development, and alternative use cases for approved therapeutics involve animals or studies in culture dishes, making it difficult to faithfully model influenza infection and test whether existing drug candidates block infection from respiratory pathogens like SARS-CoV-2. Since these preclinical drug testing models are not based in human biology, the results they produce often fail to accurately depict what the human responses to a disease or therapeutic will be.

Here, we present how a human Airway Lung-Chip can be used to recapitulate influenza virus infection and evolution in vitro as well as to examine existing candidate therapeutics for both influenza and SARS-CoV-2. Studies show that the Lung-Chip can accurately recapitulate influenza viral evolution that occurs through mutation or gene reassortment. These features of the Airway Lung-Chip make it easier for researchers to keep up with continuously changing viral strains, repurpose existing drugs to fight novel diseases, and discover new therapeutics.

Organ Model: Lung (Airway)

Applications: Infectious Disease

Abstract: Human-to-human transmission of viruses, such as influenza viruses and coronaviruses, can promote virus evolution and the emergence of new strains with increased potential for creating pandemics. Clinical studies analyzing how a particular type of virus progressively evolves new traits, such as resistance to antiviral therapies, as a result of passing between different human hosts are difficult to carry out because of the complexity, scale, and cost of the challenge. Here, we demonstrate that spontaneous evolution of influenza A virus through both mutation and gene reassortment can be reconstituted in vitro by sequentially passaging infected mucus droplets between multiple human lung airway-on-a-chip microfluidic culture devices (airway chips). Modeling human-to-human transmission of influenza virus infection on chips in the continued presence of the antiviral drugs amantadine or oseltamivir led to the spontaneous emergence of clinically prevalent resistance mutations, and strains that were resistant to both drugs were identified when they were administered in combination. In contrast, we found that nafamostat, an inhibitor targeting host serine proteases, did not induce viral resistance. This human preclinical model may be useful for studying viral evolution in vitro and identifying potential influenza virus variants before they appear in human populations, thereby enabling preemptive design of new and more effective vaccines and therapeutics. IMPORTANCE The rapid evolution of viruses, such as influenza viruses and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is challenging the use and development of antivirals and vaccines. Studies of within-host viral evolution can contribute to our understanding of the evolutionary and epidemiological factors that shape viral global evolution as well as development of better antivirals and vaccines. However, little is known about how viral evolution of resistance to antivirals occurs clinically due to the lack of preclinical models that can faithfully model influenza infection in humans. Our study shows that influenza viral evolution through mutation or gene reassortment can be recapitulated in a human lung airway-on-a-chip (airway chip) microfluidic culture device that can faithfully recapitulate the influenza infection in vitro. This approach is useful for studying within-host viral evolution, evaluating viral drug resistance, and identifying potential influenza virus variants before they appear in human populations, thereby enabling the preemptive design of new and more effective vaccines and therapeutics.

eLife (2021)

Abstract

Traditional drug safety assessment often fails to predict complications in humans, especially when the drug targets the immune system. Here, we show the unprecedented capability of two human Organs-on-Chips to evaluate the safety profile of T-cell bispecific antibodies (TCBs) targeting tumor antigens. Although promising for cancer immunotherapy, TCBs are associated with an on-target, off-tumor risk due to low levels of expression of tumor antigens in healthy tissues. We leveraged in vivo target expression and toxicity data of TCBs targeting folate receptor 1 (FOLR1) or carcinoembryonic antigen (CEA) to design and validate human immunocompetent Organs-on-Chips safety platforms. We discovered that the Lung-Chip and Intestine-Chip could reproduce and predict target-dependent TCB safety liabilities, based on sensitivity to key determinants thereof, such as target expression and antibody affinity. These novel tools broaden the research options available for mechanistic understandings of engineered therapeutic antibodies and assessing safety in tissues susceptible to adverse events.

Organ Model: Lung

Application: ADME-Tox

Abstract: Microfluidic organ-on-a-chip (Organ Chip) cell culture devices are often fabricated using polydimethylsiloxane (PDMS) because it is biocompatible, transparent, elastomeric, and oxygen permeable; however, hydrophobic small molecules can absorb to PDMS, which makes it challenging to predict drug responses. Here, we describe a combined simulation and experimental approach to predict the spatial and temporal concentration profile of a drug under continuous dosing in a PDMS Organ Chip containing two parallel channels separated by a porous membrane that is lined with cultured cells, without prior knowledge of its log P value. First, a three-dimensional finite element model of drug loss into the chip was developed that incorporates absorption, adsorption, convection, and diffusion, which simulates changes in drug levels over time and space as a function of potential PDMS diffusion coefficients and log P values. By then experimentally measuring the diffusivity of the compound in PDMS and determining its partition coefficient through mass spectrometric analysis of the drug concentration in the channel outflow, it is possible to estimate the effective log P range of the compound. The diffusion and partition coefficients were experimentally derived for the antimalarial drug and potential SARS-CoV-2 therapeutic, amodiaquine, and incorporated into the model to quantitatively estimate the drug-specific concentration profile over time measured in human lung airway chips lined with bronchial epithelium interfaced with pulmonary microvascular endothelium. The same strategy can be applied to any device geometry, surface treatment, or in vitro microfluidic model to simulate the spatial and temporal gradient of a drug in 3D without prior knowledge of the partition coefficient or the rate of diffusion in PDMS. Thus, this approach may expand the use of PDMS Organ Chip devices for various forms of drug testing.

Abstract

Nature Biomedical Engineering (2021)

The rapid repurposing of antivirals is particularly pressing during pandemics. However, rapid assays for assessing candidate drugs typically involve in vitro screens and cell lines that do not recapitulate human physiology at the tissue and organ levels. Here we show that a microfluidic bronchial-airway-on-a-chip lined by highly differentiated human bronchial-airway epithelium and pulmonary endothelium can model viral infection, strain-dependent virulence, cytokine production and the recruitment of circulating immune cells. In airway chips infected with influenza A, the co-administration of nafamostat with oseltamivir doubled the treatment-time window for oseltamivir. In chips infected with pseudotyped severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), clinically relevant doses of the antimalarial drug amodiaquine inhibited infection but clinical doses of hydroxychloroquine and other antiviral drugs that inhibit the entry of pseudotyped SARS-CoV-2 in cell lines under static conditions did not. We also show that amodiaquine showed substantial prophylactic and therapeutic activities in hamsters challenged with native SARS-CoV-2. The human airway-on-a-chip may accelerate the identification of therapeutics and prophylactics with repurposing potential.

Abstract

New therapies for severe asthma, particularly treatments which can reduce exacerbations remain a great unmet medical need. Advanced pre-clinical models are needed to further elucidate complex mechanisms that underlie asthma exacerbation for the development of novel therapeutics. Recently, we have developed a 3D microphysiological human Airway Chip containing a fully differentiated mucociliary bronchiolar airway epithelium underlined by a microvascular endothelium which experiences fluid flow1. When infected with human Rhinovirus (HRV), a leading cause of asthma exacerbation in children and adults, the Airway Chip demonstrated induction of a pro-inflammatory response characterized by ciliated cells death, goblet cells hyperplasia and release of cytokines including IFN-α2, IFN-λ1, CXCL10 and CXCL11, as well as recruitment and extravasation across the endothelium of circulating human neutrophils. To recapitulate viral-induced asthma exacerbation and model molecular responses observed in severe asthma, we then infected IL-13-treated Airway Chip with HRV. HRV challenge of IL-13-treated cultures resulted in altered interferon response and increase of neutrophil recruitment when compared with IL-13 or HRV stimulation alone. Neutrophil recruitment could be pharmacologically inhibited by MK-7123, a CXCR2 antagonist (10 μM).

Webinar Overview

Infectious diseases, such as COVID-19, are challenging to study in animal models due to species differences, and conventional 2D cell-based systems lack the complexity to appropriately model the disease or immune response in humans.

Organ-Chips offer a human relevant system that can recreate key disease phenotypes in a more physiological microenvironment due to their complex 3D architecture and mechanical forces induced by flow and stretch.

In this webinar, we discuss how the Airway Lung-Chip and Alveolus Lung-Chip can be used to study viral infection and accelerate the development of new therapeutics.

Organ Model: Lung (Alveolus)

Application: Infectious Disease

Abstract: Severe cases of SARS-CoV-2 infection are characterized by hypercoagulopathies and systemic endotheliitis of the lung microvasculature. The dynamics of vascular damage, and whether it is a direct consequence of endothelial infection or an indirect consequence of an immune cell-mediated cytokine storm remain unknown. Using a vascularized lung-on-chip model, we find that infection of alveolar epithelial cells leads to limited apical release of virions, consistent with reports of monoculture infection. However, viral RNA and proteins are rapidly detected in underlying endothelial cells, which are themselves refractory to apical infection in monocultures. Although endothelial infection is unproductive, it leads to the formation of cell clusters with low CD31 expression, a progressive loss of barrier integrity and a pro-coagulatory microenvironment. Viral RNA persists in individual cells generating an inflammatory response, which is transient in epithelial cells but persistent in endothelial cells and typified by IL-6 secretion even in the absence of immune cells. Inhibition of IL-6 signalling with tocilizumab reduces but does not prevent loss of barrier integrity. SARS-CoV-2-mediated endothelial cell damage thus occurs independently of cytokine storm.

Organ Model: Lung (Alveolus)

Application: Infectious Disease

Abstract: We establish a murine lung-on-chip infection model and use time-lapse imaging to reveal the dynamics of host-Mycobacterium tuberculosis interactions at an air-liquid interface with a spatiotemporal resolution unattainable in animal models and to probe the direct role of pulmonary surfactant in early infection. Surfactant deficiency results in rapid and uncontrolled bacterial growth in both macrophages and alveolar epithelial cells. In contrast, under normal surfactant levels, a significant fraction of intracellular bacteria are non-growing. The surfactant-deficient phenotype is rescued by exogenous addition of surfactant replacement formulations, which have no effect on bacterial viability in the absence of host cells. Surfactant partially removes virulence-associated lipids and proteins from the bacterial cell surface. Consistent with this mechanism, the attenuation of bacteria lacking the ESX-1 secretion system is independent of surfactant levels. These findings may partly explain why smokers and elderly persons with compromised surfactant function are at increased risk of developing active tuberculosis.