Fig. 2
Measurement of Aβ in TgCRND8 slice culture medium and slice tissue. a Aβ1-42 concentration in the culture medium was measured over time in vitro. Samples were first taken 4 days after plating, when medium was completely replaced (thick dashed line). At 7 div a further sample was taken before a 50 % feed (thin dashed line). Samples were then taken at weekly intervals, shortly before each 50 % medium exchange. There is a rapid rise in Aβ1-42 in the first 2 weeks in culture (shown by the gradient of the line between feeds), which slows after this point. Between 14 and 42 div production rate and removal are fairly well balanced, such that concentration lies between 5, 000 and 10,000 pg/ml between feeds. This corresponds to 1.1-2.2nM Aβ1-42. (n = 5 membranes, each from a different mouse (biological replicates)) (b) Comparison of Aβ1-40 and Aβ1-42 in the culture medium and slices homogenised in 5 M guanidine. Whilst Aβ1-40 is the predominant species in both sample types, Aβ1-42: Aβ1-40 ratio is significantly higher in slice tissue than in the medium throughout the culture period (2 way ANOVA p < 0.0001) indicating a greater proportion of Aβ1-42 is retained within the slice. There is a trend to this ratio difference increasing with age (2 way ANOVA p = 0.055). Star values comparing slice tissue and culture medium represent multiple comparisons from the ANOVA analysis. (n = 4 membranes per timepoint/sample type. Membranes in each timepoint were from different mice)