The SARS-CoV-2 receptor ACE2 is expressed in mouse pericytes but not endothelial cells - implications for COVID-19 vascular research

Humanized mouse models and mouse-adapted SARS-CoV-2 virus are increasingly used to study COVID-19 pathogenesis, and it is therefore important to learn where the SARS-CoV-2 receptor ACE2 is expressed. Here we mapped ACE2 expression during mouse postnatal development and in adulthood. Pericytes in the central nervous system, heart and pancreas express ACE2 strongly, as do perineurial and adrenal fibroblasts, whereas endothelial cells do not at any location analyzed. In a number of other organs pericytes do not express ACE2, including in the lung where ACE2 instead is expressed in bronchial epithelium and alveolar type-II cells. The onset of ACE2 expression is organ-specific: in bronchial epithelium already at birth, in brain pericytes before and in heart pericytes after postnatal day 10.5. Establishing the vascular localization of ACE2 expression is central to correctly interpret data from modelling COVID-19 in the mouse and may shed light on the cause of vascular COVID-19 complications. single-cell transcriptomes were generated of individual cells captured from adult male mice (10-20 weeks of age) by single-cell RNA-sequencing