ACE2 and COVID-19: SARS-CoV-2 was depicted as a neurotropic virus, in line with the evidence such as the capacity of SARS-CoV-2 to infect and replicate in neuro cells [8], and COVID-19 was also thought as an endothelial but not an epithelial disease[9], consistent with the pieces of evidence that ACE2 is broadly expressed on the membrane of the endothelium and pericytes which are composed of the capillaries of vascular microcirculation of all organs, including the cerebrum [10].