(B) Old APPPS1 tissue was incubated with conditioned media collected from young WT slices previously treated with clodronate (old alone + young CM + Clo, grey bars ) and vehicle control (old alone + young CM + Ctr, white bars). Quantitative analysis at 7, 11 and 14 DIV reveals decreased numbers of core-only plaques upon incubation of the old APPPS1 tissue with conditioned media collected from young WT slices pre-treated with Clo. 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 < 0.001). 