To test this hypothesis, iMGLs were transplanted into the hippocampi of xenotransplantation-compatible AD mice, previously generated and characterized in our lab (Marsh et al., 2016), to examine how iMGLs interact with AD neuropathology in vivo (Figures 7M–P and S7). Transplanted iMGLs engraft and migrate along white matter tracts, similar to microglia in development (Figure 7M). In many instances, iMGLs migrated and extended processes towards Aβ plaques to begin walling them off (Figure 7N–P, and Supplementary Video 1). A number of iMGLs also began to phagocytose fibrillar Aβ (Figures 7N–P and S7E–H). Similarly, human fetal microglia migrated towards Aβ, extended processes, and phagocytosed Aβ when transplanted in the same AD transgenic model(Figure S7A–D).
