A Human Alveolus-on-Chip Recapitulates SARS-CoV-2-mediated Lung Injury in an Organ-relevant Context for Pre-clinical Applications

Respiratory viruses pose a constant threat to public health as highlighted by the pandemic outbreak of COVID-19. The most severe manifestation of COVID-19 is observed in the distal lung, where SARS-CoV-2 infection can result in massive inflammation and barrier breakdown. To date, few therapies are approved for clinical use in COVID-19 patients partially due to the lack of highly translational pre-clinical models of the alveoli. Human-derived microphysiological systems pose a promising new class of in vitro models to study viral infection in a relevant context. Therefore, we aimed to develop a Lung-on-Chip (LOC) model for studying SARS-CoV-2 infection at the alveolar barrier.

Using an immortalized alveolar epithelial cell line, ^AX iAEC, and human lung microvascular endothelial cells (hLMVEC) we established a SARS-CoV-2 infection model on a LOC system. The LOC models the alveolar epithelial/endothelial barrier under physiological breathing motion.

Our results demonstrated that ^AX iAEC maturation at the air-liquid interface (ALI) is essential for SARS-CoV-2 infection. SARS-CoV-2 infected the breathing LOC model and induced breakdown of the air-blood barrier. Finally, we evaluated the application of the LOC SARS-CoV-2 infection model for efficacy testing and demonstrated the antiviral effect of remdesivir. Drug treatment not only inhibited viral replication but also protected the alveolar barrier from damage and partially reverted SARS-CoV-2-mediated transcriptional dysregulation in ^AX iAEC.

This novel LOC infection model recapitulates aspects of COVID-19. Our results highlight the importance of physiological cues such as ALI and stretch to accurately model host-pathogen interactions in the distal lung. Application of LOC models in pre-clinical drug testing may facilitate candidate compound selection at an early stage, allowing the allocation of resources to a few promising candidate compounds raising the potential to accelerate drug development and reduce costs and animal testing.