(A) Old APPPS1 tissue was cultured alone (old alone, white bars) or incubated with conditioned media (CM) collected from young WT slices (old alone + young CM, grey bars). Analysis included co-culture of old APPPS1 and young WT brain slices (old co-culture, black bars) as a positive control and old APPPS1 tissue incubated with conditioned media collected from old APPPS1 slices (old alone + old CM, white squared bars) as a negative control. Quantitative analysis at 7, 11 and 14 DIV reveals increased numbers of core-only plaques upon incubation of the old APPPS1 tissue with conditioned media collected from young WT slices, fully recapitulating core-only plaque numbers observed in the co-culture. The values are expressed as percentages of core-only plaques from the total number of amyloid plaques and represent mean ± SEM from 3 independent experiments, each experiment including at least 2 independent slice culture dishes (n.s.= not significant, **P <0.01, ***P < 0.001). 