Direct derivation of human alveolospheres for SARS-CoV-2 infection modeling and drug screening

Abstract

Although the main cellular target of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is thought to be alveolar cells, the absence of their tractable culture system has precluded the development of a clinically-relevant SARS-CoV-2 infection model. Here, we established an efficient human alveolosphere culture method and sphere-based drug testing platform for SARS-CoV-2. Alveolospheres exhibited indolent growth in a Wnt and R-spondin dependent manner. Gene expression, immunofluorescence and electron microscopy analyses revealed the presence of alveolar cells in alveolospheres. Alveolospheres expressed ACE2 and allowed SARS-CoV-2 to propagate nearly 100,000- fold in three days of infection. While lopinavir and nelfinavir, protease inhibitors used for the treatment of HIV infection, had a modest anti-viral effect on SARS-CoV-2, remdesivir, a nucleotide prodrug, showed anti-viral effect at the concentration comparable to the circulating drug level. These results demonstrated the validity of alveolosphere culture system for the development of therapeutic agents to combat SARS-CoV-2.

Nasal delivery of single-domain antibody improves symptoms of SARS-CoV-2 infection in an animal model

“…Because SARS-CoV-2 targets lung tissues and induces severe respiratory disease, we evaluated K-874A VHH in a human lung–derived alveolar organoid that is susceptible to SARS-CoV-2 and releases high levels of progeny virus into the culture supernatant [ 19 , 20 ]. To determine if K-874A blocks production of virus progeny in infected alveolar organoids, we incubated the organoid cells with SARS-CoV-2 for 1 hr before treating the infected cells with K-874A-containing medium for 3 days.…”

“…SARS-CoV-2, 2019-nCoV JPN/TY/WK-521, B1.1.7 (Alpha), B.1.351(Beta), P.1 (Gamma) and B.1.617.2 (Delta) were provided from National Institute of Infectious Diseases (NIID, Japan). KUH003 (Accession number LC630936) [ 20 ] is isolated from nasal swab of COVID-19 patients in Tokyo. KUH003 has D614G.…”

“…Human alveolar-derived organoids were established [ 20 ]. Briefly, 3D cultured organoid compound in Matrigel was treated with cell recovery solution to remove the cells from the Matrigel.…”

Scientific Validation and Clinical Application of Lung Cancer Organoids

“…Lung organoids can be divided into airway and alveolar organoids [ 13 , 14 , 15 ]. Airway organoids originate from basal cells [ 8 , 16 ], which proliferate and differentiate to ciliated, goblet, and club cells in cyst-like structures.…”

“…WNT-conditioned medium from L-Wnt3A cells can show significant inter-batch differences in WNT activity. R-spondin1 conditioned medium supports WNT signaling by stabilizing the cytosolic β-catenin level [ 15 , 16 , 27 ]. Ebisudani et al introduced serum-free Afamin-Wnt 3A containing culture medium for the long-term culture of alveolospheres [ 15 ].…”