Fig. 7.

Rat primary astrocytes readily take up tau in an HPSG-dependent manner. A The amount of VPR-0N4R labeled with AlexaFluor488 (+ VPR, green) internalized by primary astrocytes increases over time from 1 to 6 h, while the presence of heparin has attenuated the tau uptake rate in astrocytes, as observed by fluorescence microscopy. Scale bar = 100 μm B Representative fluorescent images of GFAP (red) and Hoechst (blue) for primary astrocytes under different conditions, as indicated, where VPR indicates the addition of VPR-488 with (middle panel) or without (bottom panel) heparin to the cell as observed via fluorescence microscopy. Scale bar = 100 μm. C To determine population behavior, VPR-AF488 endocytosed by primary astrocytes was determined by flow cytometry with and without heparin addition. Grey filled line: negative control, black line: cells without heparin, red line: cells with heparin. D The propensity of VPR-0N4R uptake was quantified in primary astrocytes by flow cytometry (n = 2) E An RT-qPCR analysis was performed to detect the expression levels of IL-1β (lightly shaded bars), IL-6 (open bars), and TNF-α (filled bars) in primary astrocytes affected by incubation with VPR and heparin, as indicated. β-Actin was used as an internal control. *p < 0.05 between different test conditions; n = 2