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.

Productive transfection and gene transfer require not simply the entry of DNA into cells and subsequent transcription from an appropriate promoter, but also a number of intracellular events that allow the DNA to move from the extracellular surface of the cell into and through the cytoplasm, and ultimately across the nuclear envelope and into the nucleus before any transcription can initiate. Immediately upon entry into the cytoplasm, naked DNA, either delivered through physical techniques or after disassembly of DNA–carrier complexes, associates with a large number of cellular proteins that mediate subsequent interactions with the microtubule network for movement toward the microtubule organizing center and the nuclear envelope. Plasmids then enter the nucleus either upon the mitotic disassembly of the nuclear envelope or through nuclear pore complexes in the absence of cell division, using a different set of proteins. This review will discuss our current understanding of these pathways used by naked DNA during the transfection process. While much has been elucidated on these processes, much remains to be discerned, but with the development of a number of model systems and approaches, great progress is being made.

Mechanical breathing motions have a fundamental function in lung development and disease, but little is known about how they contribute to host innate immunity. Here we use a human lung alveolus chip that experiences cyclic breathing-like deformations to investigate whether physical forces influence innate immune responses to viral infection. Influenza H3N2 infection of mechanically active chips induces a cascade of host responses including increased lung permeability, apoptosis, cell regeneration, cytokines production, and recruitment of circulating immune cells. Comparison with static chips reveals that breathing motions suppress viral replication by activating protective innate immune responses in epithelial and endothelial cells, which are mediated in part through activation of the mechanosensitive ion channel TRPV4 and signaling via receptor for advanced glycation end products (RAGE). RAGE inhibitors suppress cytokines induction, while TRPV4 inhibition attenuates both inflammation and viral burden, in infected chips with breathing motions. Therefore, TRPV4 and RAGE may serve as new targets for therapeutic intervention in patients infected with influenza and other potential pandemic viruses that cause life-threatening lung inflammation.

Rapidly spreading viral pandemics, such as those caused by influenza and SAR-CoV-2 (COVID19), require rapid action and the fastest way to combat this challenge is by repurposing existing drugs as anti-viral therapeutics. Here we first show that human organ-on-a-chip (Organ Chip) microfluidic culture devices lined by a highly differentiated, primary, human lung airway epithelium cultured under an air-liquid interface and fed by continuous medium flow can be used to model virus entry, replication, strain-dependent virulence, host cytokine production, and recruitment of circulating immune cells in response to infection by influenza, as well as effects of existing and novel therapeutics. These Airway was not certified by peer review) Chips, which contain human lung epithelial cells that express high levels of ACE2 and TMPRSS2, were then used to assess the inhibitory activities of 7 clinically approved drugs (chloroquine, arbidol, toremifene, clomiphene, amodiaquine, verapamil, and amiodarone) that we found inhibit infection by viral pseudoparticles expressing SARS-CoV-2 spike protein in human Huh-7 cells, and others recently showed suppress infection by native SARS-CoV-2 in Vero cells. However, when these drugs were administered under flow at the maximal concentration in blood reported in clinical studies in human Airway Chips, only two of these drugs  amodiaquine and toremifene  significantly inhibited entry of the pseudotyped SARS-CoV-2 virus. This work suggests that human Organ Chip technology may be used in conjunction with existing rapid cell-based screening assays to study human disease pathogenesis and expedite drug repurposing in biothreat crises caused by pandemic viruses. ______________________________________________________________________The increasing incidence of potentially pandemic viruses, such as influenza, MERS, SARS, and now SARS-CoV-2, requires development of new preclinical approaches that can accelerate development of effective therapeutics and prophylactics. The most rapid way to confront a pandemic challenge would be to repurpose existing drugs that are approved for other medical applications as anti-viral therapeutics. While clinicians around the world are attempting to do this for the COVID19 pandemic, the current approaches have been haphazard, which have resulted in equivocal results regarding drug efficacies and possible toxicity risks as in the case of chloroquine 1-3 ; thus, there is a great need to attack this problem in a was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission.

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