Figure 1

Spatial and contextual memory impairments are similar in APP_Swe/PS1 mice transplanted with CCR2-deficient BMCs and APP_Swe/PS1/CCR2^−/− mice. The numbers of trials and latency to accomplish the water T-maze task were determined in mice harboring WT GFP or CCR2^−/− cells in the bloodstream at 6 months of age for the acquisition (A, C) and reversal learning phases (B, D). The transplantation of GFP cells significantly prevented the apparition of mnesic impairment in APP_Swe/PS1 and APP_Swe/PS1/CCR2^−/− mice. In contrast, APP_Swe/PS1 mice harboring CCR2^−/− cells in their bloodstream exhibited memory impairment, comparable to that observed in APP_Swe/PS1/CCR2^−/− mice. To assess contextual memory using the passive avoidance test, the latency to enter the dark box was measured during the acquisition phase (E) and 24 h after the conditioning test (F). APP_Swe/PS1 mice harboring CCR2^−/− cells in their bloodstream exhibited contextual deficit similar to that of APP_Swe/PS1/CCR2^−/− mice, which was rescued by the transplantation of WT GFP cells. Results are expressed as the mean ± SEM; n = 8−15; *P < 0.05, **P < 0.01 and ***P < 0.001 versus WT; ^◆P < 0.05 versus APP_Swe/PS1; ^#P < 0.05 and ^###P < 0.001 versus GFP → APP_Swe/PS1; °P < 0.05 and °°°P < 0.001 versus APP_Swe/PS1/CCR2^−/−. One-way ANOVA was performed using a Tamhane post hoc test. □, WT; ■, APP_Swe/PS1; , GFP → APP_Swe/PS1; , CCR2^−/− → APP_Swe/PS1; , APP_Swe/PS1/CCR2^−/−; , GFP → APP_Swe/PS1/CCR2^−/−.