ACE2 and COVID-19: Endothelial ACE2 expression has been reported based on immunodetection (Hamming et al., 2004; Lovren et al., 2008; Sluimer et al., 2008) or single-cell RNA sequencing (scRNA-seq) studies (Muus et al., 2021), and the presence of SARS-CoV-2 virus particles in ECs in COVID-19 patients has been proposed (Ackermann et al., 2020; Varga et al., 2020), although the data interpretation has also been questioned (Goldsmith et al., 2020).