Fig. 9: GLAST-expressing perivascular cells reside in the human CNS vasculature.

Representative images of post-mortem human tissue from the healthy spinal cord (a) and occipital cortex (e) labeled with antibodies recognizing PDGFRβ and podocalyxin (Pdx). Insets show magnified boxed regions and reveal PDGFRβ-expressing perivascular cells enveloping the endothelial tube. Example of a pericyte (labeled with an antibody against PDGFRβ) with characteristic protruding ovoid cell body and processes encircling the endothelial wall of a small caliber blood vessel in the healthy human spinal cord (b). Example of a pericyte (PDGFRβ⁺) extending its processes around the endothelial wall of a small caliber blood vessel in the healthy human occipital cortex (f). Human endothelial cells were labeled with Ulex Europaeus-I (UEA-1) lectin. Arrowheads points at the pericyte soma. Detection of SLC1A3 (GLAST) and PDGFRB mRNA in the healthy human spinal cord (c, d) and occipital cortex (g, h) by RNAscope in situ hybridization combined with immunofluorescence for the UEA-1. White arrowheads point at blood vessel-associated cells positive for PDGFRB and SLC1A3 mRNA signals, representing GLAST⁺PDGFRβ⁺ perivascular cells; yellow arrowheads identify blood vessel-associated cells positive for PDGFRB mRNA signals with low/undetectable levels of SLC1A3 mRNA, representing GLAST⁻ PDGFRβ⁺ perivascular cells; white arrows point at parenchymal (non-blood vessel-associated) cells positive for SLC1A3 mRNA signals with low/undetectable levels of PDGFRB mRNA, likely representing GLAST⁺PDGFRβ⁺ astrocytes. Cell nuclei are labeled with DAPI. Scale bars: 100 μm (a, e), 50 μm (c), 20 μm (g, insets in a, e), 10 μm (d, h) and 5 μm (b, f). All images show coronal sections. Images are representative of four independent individuals.