Fig. 4

Astrocytes secrete tau fibrils with maintained seeding efficiency. (a) Schematic illustration of the tau seeding assay. FRET biosensor HEK cells were exposed to astrocyte-conditioned medium (ACM) from tau-exposed astrocytic cultures at day 3 + 4, 3 + 8 and 3 + 12. (b) Representative confocal images of ACM-exposed biosensor HEK cells. Scale bar = 10 μm. (c) Quantification of FRET IntDen per cell area revealed no differences across the three time points. (d) ELISA measurements of total tau concentrations in ACM showed no differences between the different time points. (e) Tau seeding efficiency presented as FRET signal normalized to tau concentration. Bars in (c) and (d), and points in (e), represent the means and standard deviations of measurements obtained using three AD and two control parietal samples. N = 3 culture experiments, n = 3 non-overlapping fields per brain sample. ns: not significant