Fig. 3

Aβ₄₂ are stored in astrocytes for a very long time. To follow degradation of intracellular Aβ₄₂-555 in astrocytes following Aβ₄₂-555 protofibril removal, cells were divided into four categories; cells with no detectable levels of Aβ₄₂-555 (–), cells with only small amounts of Aβ₄₂-555 (+), cells containing medium sized Aβ₄₂-555 deposits (++) and cells with large Aβ₄₂-555 inclusions (+++) (a). Astrocytes degrade Aβ₄₂-555 protofibrils very slowly and much Aβ₄₂ remains in the cells 12 days after Aβ₄₂-555 protofibril removal (b). Neurons contain almost no Aβ₄₂ (c). The few oligodendrocytes in the culture also degrade the Aβ₄₂-555 protofibrils slowly (d). Although the glial cells degrade the Aβ₄₂-555 protofibrils slowly, the total number of 555-stained inclusions (24 h: 10.4 ± 7.7; 24 h + 6 days: 7.9 ± 7.1; 24 h + 12 days: 6.2 ± 7.1) in the culture decline significantly from 24 h to 24 h + 6 days (P = 0.013) and 24 h + 12 days (P < 0.001) (e). In line with these results, the total 555-intensity (24 h: 1.7 × 10⁷ ± 8.5 × 10⁶; 24 h + 6 days: 8.3 × 10⁶ ± 5.1 × 10⁶; 24 h + 12 days: 5.9 × 10⁶ ± 4.3 × 10⁶) (f) and total 555-positive area (24 h: 9.6 ± 2.3 μm²; 24 h + 6 days: 6.7 ± 3.5 μm²; 24 h + 12 days: 6.8 ± 2.5 μm²) (g) also decline significantly over time (P < 0.001 already from 24 h to 24 h + 6 days). Aβ inclusions are marked with white arrow heads. Scale bars: 10 μm. The experiments were performed in triplicates with independent cell cultures and 10 images/experiment were analyzed. Mann–Whitney U-test ***P < 0.001