Three-Dimensional Human Alveolar Stem Cell Culture Models Reveal Infection Response to SARS-CoV-2

Abstract

Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2), which is the cause of a present global pandemic, infects human lung alveolar type 2 (hAT2) cells. Characterizing pathogenesis is crucial for developing vaccines and therapeutics. However, the lack of models mirroring the cellular physiology and pathology of hAT2 cells limits the study. Here, we develop a feeder-free, long-term three-dimensional (3D) culture technique for hAT2 cells derived from primary human lung tissue, and investigate infection response to SARS-CoV-2. By imaging-based analysis and single-cell transcriptome profiling, we reveal rapid viral replication and the increased expression of interferon-associated genes and pro-inflammatory genes in infected hAT2 cells, indicating robust endogenous innate immune response. Further tracing of viral mutations acquired during transmission identifies full infection of individual cells effectively from a single viral entry. Our study provides deep insights into the pathogenesis of SARS-CoV-2, and the application of defined 3D hAT2 cultures as models for respiratory diseases.

Repurposing A549 Adenocarcinoma Cells: New Options for Drug Discovery

“…Organotypic 3D cultures, organon-a-chip, and precision-cut lung slices are now reliable tools that provide the environment required to maintain and study AT2 cells and other epithelial progenitor cells. They can be used in various settings, from understanding developmental processes to disease modeling and drug testing (13)(14)(15)(16)(17). These new tools offer great promise for broad applications.…”

Progress towards non-small-cell lung cancer models that represent clinical evolutionary trajectories

“…Similar to 2D cultures, most reported alveolar organoid systems have not allowed serial passaging [ 67 , 101 ], limiting their utility for cancer modelling. Recently, long-term culture methods for human organoids containing AT2 cells that are capable of AT1-like differentiation have been described [ 102 , 103 ], further expanding the repertoire of models available.…”

Halting SARS‐CoV‐2: lung organoids step up to the plate

“…Cigarette smoke exposure led to goblet cell metaplasia and a higher infection rate (Purkayastha et al , 2020). Primary lung‐derived alveolospheres were infected and mirrored features of COVID‐19 lungs including increased interferon, pro‐inflammatory, and apoptotic pathway genes and decreased surfactants (Katsura et al , 2020; Youk et al , 2020). iPSC‐derived alveolar type 2 cells adapted to air–liquid interface culture were infected and showed an inflammatory phenotype with upregulation of NFkB signalling and loss of mature alveolar program (Huang et al , 2020).…”