Direct Derivation of Human Alveolospheres for SARS-CoV-2 Infection Modeling and Drug Screening

Ebisudani, Toshiki; Sugimoto, Shinya; Haga, Kei; Mitsuishi, Akifumi; Takai-Todaka, Reiko; Fujii, Masayuki; Toshimitsu, Kohta; Hamamoto, Junko; Sugihara, Kai; Hishida, Tomoyuki; Asamura, Hisao; Fukunaga, Koichi; Yasuda, Hiroyuki; Katayama, Kazuhiko; Sato, Toshiro

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.