MAPT and Alzheimer disease: To evaluate the effect of AD BDEVs on tau pathology development in vivo, we next stereotaxically injected APOE4/4 and 3/3 BDEVs (containing 300 pg tau in one μL) into the outer molecular layer (OML) of the dentate gyrus (DG) of human MAPT (Tau KI) and APPNL-G-F : MAPT double knock-in (APP/Tau KI) mouse brains at 10 month-old (Fig. 1d, e, respectively).