Together, these results indicate that relative to either unengrafted mice or mice allografted with A2B5+/PSA-NCAM--sorted, EGFP+ murine GPCs, human glial-chimeric mice exhibit enhanced performance in 4 different learning tasks: auditory and contextual fear conditioning, Barnes maze, and novel object-location. Moreover, the analysis of auditory fear conditioning indicate that alloengraftment by mouse GPCs did not affect the learning of the recipient mice, supporting the notion that the improved learning in the humanized chimeras resulted from the presence of human glia, rather than from cell engraftment per se. As an additional control, we also noted that social interactions did not differ between human chimeras generated by engraftment in rag1 mice and their littermate controls (n=5, 6.9 ± 0.1 months; p>0.05, t test) (Figs. S5G-H), indicating that chimerization did not seen to affect their interactions with other mice.
