Fig. 2

Impaired perivascular drainage and altered BM structure in Hpa-tg mice. (a-d) Vascular retention of intracortically injected fluorescent dextran in Hpa-tg and Ctrl brains. (a) Association of dextran (red) with α-SMA positive blood vessels (green) in the proximity of the injection site indicated by an asterisk (*). Cell nuclei were counterstained with DAPI (blue). (b) Confocal laser-scanning microscopy image of dextran- and α-SMA positive blood vessel. (c) Number of dextran-positive blood vessels (defined by α-SMA immunostaining) per brain section. Each point represents the data from an individual mouse brain (n = 6 Ctr mice, n = 8 Hpa-tg mice). (d) Mean dextran fluorescence associated with αSMA-positive blood vessels. Each point represents the dextran fluorescence measured from an individual blood vessel (n = 25 vessels, Ctr mice; n = 33 vessels, Hpa-tg mice). (e–g) Thickening of the VBM and swelling of the perivascular astrocyte endfeet in the cortex of Hpa-tg brain. (e) Electron micrographs of capillaries from Ctr and Hpa-tg brain sections. Enlarged views of Ctr and Hpa-tg images illustrate the positions of the basement membrane (BM), endothelial cell (EC) with tight junction (TJ), astrocyte endfoot (AF), and erythrocyte (Er) within the vessel. (f) VBM thickness analysis. (g) Size of perivascular astrocyte endfeet presented as percentage of the total capillary area. (h) Aquaporin 4 (AQP4) and glial fibrillary acidic protein (GFAP) immunostaining associated with a mouse brain vessel. (i) AQP4 Western blots of Hpa-tg and Ctrl brain homogenates. (j) Quantification of the relative AQP4 Western blot bands from Hpa-tg (n = 6) and Ctrl (n = 6) brain homogenates, corrected for β-tubulin loading controls