Fig. 5

In tissue sections, ACE2 immunostaining is predominantly observed in neurons in the human brain and in the cerebrovasculature in mice. A–E Representative immunostaining of ACE2 (green in IF or red in IHC) in fresh frozen human hippocampus A, B, formalin-fixed paraffin-embedded parietal cortex C–E, and in murine fresh frozen hippocampal F and cerebellar G–H sections. Inlaid in G, the primary mAb was preblocked with its immunogenic peptide, preventing epitope binding. For immunofluorescence, NeuN (neuronal marker) A, B, collagen IV (endothelial marker) F or PDGFRβ (a marker of mural cells including pericytes) H are in red, and DAPI (nuclei) is in blue A–C, F–H. For immunohistochemistry, sections were counterstained with hematoxylin (nuclei) D, E, and negative control is inserted in E. In human samples, strong ACE2 staining is observed in large and small neurons, whereas in mice, neuronal signal is moderate and vascular ACE2 staining is strong and colocalizes well with PDGFRβ. Red arrows point to ACE2 + /NeuN + cells and green arrows to erythrocytes; dashed white line highlights small ACE2 + /NeuN + cells that stain strongly for DAPI. ACE2 antibodies: rabbit mAb #ab108252 C, G, rabbit pAb #HPA000288 A, B, E, F and #35–1875 D or goat pAb #AF3437. Scale bars: 200 µm A, F, G, H, 20 µm B, D, E and 10 µm C. ACE2 Angiotensin-Converting Enzyme 2, Coll IV Collagen IV, Coloc Colocalization, NeuN Neuronal nuclear protein, PDGFRβ Platelet Derived Growth Factor Receptor Beta mAb monoclonal antibody, pAb polyclonal antibody