Figure 4. Molecular definitions for brain perivascular and meningeal fibroblasts.

a, Anatomical reference of the human meninges (dura and arachnoid) and perivascular space, each with a resident fibroblast population.

b, UMAP of 2,985 human perivascular fibroblast-like nuclei and 428 meningeal fibroblast nuclei. Enriched biological pathways derived from respective fibroblast cell type markers (Supplemental Table 2, P value < 0.05, cumulative hypergeometric test).

c, Differentially expressed genes between perivascular (left, orange) and meningeal (right, brown) fibroblasts (MAST, Benjamini Hochberg correction; FDR < 0.01 and logFC>0.5 [log₂FC>0.72] to be colored significant).

d, Expression of all differentially expressed (from (c)) SLC and ABC family members across perivascular and meningeal fibroblasts.

e, Immunostaining validation of polarized meningeal and perivascular fibroblast transporter expression: the meningeal fibroblast-specific influx pump SLC4A4 (left, green) stains selectively in the meninges but not cortical vasculature (red); and vice versa for the perivascular-specific efflux pump ABCA8 (right, green). Scale = 50 μM.