Airway-on-a-chip technology enables COVID-19 drug repurposing

An airway on a chip was used to show that amodiaquine inhibits SARS-CoV-2 infection, making it a potential COVID-19 therapeutic.

COVID-19 and SARS-CoV-2

Researchers have used organ-on-a-chip (organ-chip) technology to identify the anti-malarial drug amodiaquine as an effective inhibitor of infection SARS-CoV-2, the virus that causes COVID-19, as in their in Natural biomedical engineering.

According to the researchers, the organ chip-based drug testing ecosystem streamlines the process of evaluating the safety and effectiveness of existing drugs for new medical uses and provides a proof-of-concept for using organ chips to quickly reuse existing drugs for new medical uses, including future ones Pandemics.

The team at the Wyss Institute in Harvard, USA that developed the organ chip examined eight existing drugs, including hydroxychloroquine and chloroquine, which showed antiviral activity against SARS-CoV-2 in conventional cell culture tests. However, the researchers highlight that cells grown in a dish do not behave like cells in a living human body, which means that many drugs that appear to be effective in laboratory studies do not work in patients – hence the organ chip required.

Development of chip technology

Over three years ago, the Wyss Institute received funding from the Defense Advanced Research Projects Agency (DARPA) and the US National Institutes of Health (NIH) to investigate whether its microfluidic culture technology for human organ chips mimicked the function of human organs in vitrocould be used to address potential biothreat challenges, including pandemic respiratory viruses.

Amodiaquine prevented the transmission of the virus from sick to healthy animals in more than 90 percent of cases. “

The human airway chip developed by the team is a microfluidic device roughly the size of a USB memory stick and containing two parallel channels separated by a porous membrane. Human pulmonary airway cells are grown in one channel that is perfused with air, while human blood vessel cells are grown in the other channel that is perfused with liquid culture medium to replicate blood flow. Cells grown in this device naturally differentiate into multiple airway-specific cell types in proportions similar to those found in the human airway, and develop traits observed in living lungs such as cilia and the ability to produce and move mucus become.

Two years after the start of the project, the team refined its pulmonary airway chip to study drugs that can be used to treat influenza virus infections. Then, in January 2020, the direction changed for the group when the news of the spread of SARS-CoV-2 became widespread.

“We have been following the updates closely because we believed our airway chip model could be an important tool in studying this virus,” said Dr. Longlong Si, one of the study’s earliest authors.

Use against SARS-CoV-2

According to the team, airway chip cells have higher levels of angiotensin converting enzyme-2 (ACE2) receptor protein, which plays a central role in lung physiology and in which COVID-19 can infect human cells.

“Our biggest challenge in shifting our focus to SARS-CoV-2 was that we did not have laboratory facilities with the necessary infrastructure to safely examine dangerous pathogens. To get around this problem, we developed a SARS-CoV-2 pseudovirus that expresses the SARS-CoV-2 spike (S) protein so that we can identify drugs that affect the S protein’s ability to act the ACE2 of human lung cells to bind receptors, “said Dr. Haiqing Bai, another of the first authors. “A secondary goal was to show that these types of studies can be done by other organ-chip researchers who have this technology but do not have access to laboratory facilities necessary to study highly infectious viruses.”


The human airway chip re-establishes the interface between the airways and blood vessels in the human lungs, allowing researchers to study how various drugs and pathogens such as viruses affect lung function [credit: Wyss Institute at Harvard University].

Using the pseudovirus, the team first perfused the chips’ blood vessel canal with several approved drugs, including amodiaquine, toremifene, clomiphene, chloroquine, hydroxychloroquine, arbidol, verapamil, and amiodarone, all of which showed antiviral activity in previous studies. Unlike static culture studies, however, the researchers were able to perfuse the drug through the channels of the chip at a clinically relevant dose to mimic how the drug would be distributed to tissues in the body. After 24 hours, they inserted the SARS-CoV-2 pseudovirus into the air duct of the airway chips to mimic infection from airborne viruses such as coughing or sneezing.

Only three of these drugs significantly prevented the entry of viruses without causing cell damage in the airway chips: amodiaquine, toremifene, and clomiphene. The most effective drug, amodiaquine, reduced infection by about 60 percent.

The team also performed spectrometric measurements to determine how the drugs affected the airway cells. These studies showed that amodiaquine produced marked and broader protein changes than the other antimalarial drugs.

Lead optimization

Despite the promise of amodiaquine, the team still had to prove that it was effective against the real infectious SARS-CoV-2 virus. The researchers contacted Dr. Matthew Frieman of the University of Maryland School of Medicine and Dr. Benjamin TenOever of the Icahn School of Medicine on Mount Sinai, USA.

The Frieman laboratory tested amodiaquine and its active metabolite desethylamodiaquine against native SARS-CoV-2 using high-throughput assays in cells in vitro and confirmed that the drug inhibited the viral infection.

In parallel, the tenOever laboratory tested amodiaquine and hydroxychloroquine against native SARS-CoV-2 in a comparison in a COVID-19 model for small animals and found that prophylactic treatment with amodiaquine upon exposure reduced the viral load by about 70 percent while this was the case with hydroxychloroquine, ineffective. They also saw that amodiaquine prevented the virus from being transmitted from sick to healthy animals more than 90 percent of the time, and that it was also effective in reducing viral loads when given after the virus was introduced.

“It was extremely exciting to see how beautifully amodiaquine inhibits the infection of the airway chip,” said Frieman. “And the fact that it appears to work both before and after exposure to SARS-CoV-2 means it could potentially be effective in a variety of settings.”

Next Steps

Since amodiaquine was identified as a potential candidate to fight COVID-19, it has been enrolled in a clinical trial in collaboration with the University of Witwatersrand, South Africa, and Shin Poong Pharmaceutical in South Korea. The Drugs for Neglected Diseases Initiative (DNDI) also added amodiaquine to the ANTICOV clinical trial for COVID-19, which includes 19 sites in over 13 different countries in Africa.

Lungs and COVID-19In addition to SARS-CoV-2, the team is now also focusing on the use of the respiratory chip to develop drugs against other viral pathogens.

“With our experience with this drug development pipeline to validate amodiaquine for COVID-19, we are now applying what we have learned to influenza and other pandemic-causing pathogens,” said co-author Dr. Ken Carlson. “This process has given us confidence that organ chips will predict what we will see in more complex living models of viral infections.”

In addition to influenza, the team is currently researching drugs that could be used against the new SARS-CoV-2 mutant strains to suppress the dangerous cytokine storm that leads to many hospital admissions and to alleviate the symptoms of what is known as long COVID.