Fig. 1

Seeding profile of cases (Experiment I). Punch biopsies were taken from 25 brain regions in 20 individuals (NFT stages I, III and V), homogenized, and transduced into v2H biosensor cells. Seeding was quantified by determining the percentage of FRET positive cells on a flow cytometer. Each sample was tested in biological/technical triplicate, and the average is reported. a Negative controls included cells that were treated with: (1) lipofectamine (+ buffer); (2) buffer only; (3) tau negative human brain tissue (from individual number 21 in Table 1; 4) brain tissue from tau knockout mice. The average seeding for each condition is shown as percentage of FRET positive cells ± standard deviation. We used the average of all negative samples and 3 × their respective standard deviations to determine the seeding threshold at 0.35% (in red). Only samples with seeding above 0.35% were scored positive. b The FRET average for each sample in experiment 1 was plotted on a log scale against the coefficient of variation (measure of assay precision defined as the standard deviation divided by the FRET average). The coefficient of variation is low for samples with seeding above the threshold of ~ 0.35%. For samples with seeding below this threshold, the coefficient of variation is significantly larger. c The FRET average for controls with standard deviation was plotted on a linear scale against the coefficient of variation. For lipofectamine and buffer controls, the average and standard deviation were derived from all 97 respectively 12 wells in this experiment. For tau negative human tissue and tau knockout mouse tissue, averages and standard deviation were calculated for each of 2 triplicates and plotted separately. Note that all controls ± standard deviation are below the seeding threshold of 0.35%. Color code: lipofectamine (yellow), buffer (pink), tau negative human brain tissue (blue), tau knockout mouse brain tissue (green), samples from individuals 1–20 (black)