Researchers from the University of North Carolina and Duke University have developed lab-grown mini lungs, who have exposed to the virus SARS-CoV-2 to see how they behave to help better understand the current pandemic.

The study, published in Cell Stem Cell, explains how they have created these small organs through human stem cells. Despite not being as complex as a human lung, the authors note, this experiment gives an idea on a molecular scale of how Covid-19 works.

To do this, each mini organ has only one type of lung stem cell, known as alveolar epithelial cell type 2 (which scientists have called AT2), with the ability to self-renew, differentiate from other lung cells, keep the alveolus open with surfactants and bind directly to the virus.

By introducing SARS-CoV-2, the cause of the Covid-19 disease, scientists point out that the virus rapidly infected AT2 cells and spread throughout the structure similar to the alveoli. Likewise, they state, this infection triggered a inflammatory answer in the organoid: reduced surfactant production and proliferation and induced cell death, sometimes in surrounding areas that had not yet been touched by the virus.

By analyzing the gene expression of these miniature organs, the researchers discovered that the inflammatory state triggered by the SARS-CoV-2 infection led to production of interferons, cytokines, chemokines and the activation of genes related to cell death.

The authors point out in their study that this reaction saves a “striking similarity” with what is seen in severe Covid-19 patients, and further coincides with growing evidence suggesting that severe Covid cases trigger a cytokine storm that can leave lungs damaged.

“The cytokine storm was thought to be due to the large influx of immune cells, but we can see that it also occurs in the lung stem cells themselves“said the cell biologist Purushothama Rao Tata, from the Duke university and one of the study authors. “Now we have a way to discover how to energize cells to fight this deadly virus,” he added.