a, Vector design showing the neprilysin, inactive neprilysin (NepX), and green fluorescent protein (GFP) expressing lentiviral constructs. The internal promoters driving the transgenes are indicated by arrows (human CMV). LTR sequences are shown on the ends (packaging signal, Ψ). b, 293T cells transduced with Lenti-Nep (10 nl per well, or 0.015 pg p24 gag-antigen per cell) were immunostained for neprilysin expression and analyzed by flow cytometry.c, Immunoblot on 293T cells and differentiated rat neural progenitors (HCN) transduced with the Lenti-Nep or Lenti-GFP vector. d, 293T cells transduced with serial dilutions of Lenti-Nep could degrade Aβ_1–42 in a dose-dependent manner. Lenti-GFP transduced cells were used as a negative control (GFP), whereas medium alone was used to determine the baseline (Medium). e, Differentiated neural progenitors (HCN) infected with Lenti-Nep (Nep; n = 2), Lenti-NepX (NepX; n = 2) or Lenti-GFP (GFP; n = 2) were used to degrade Aβ_1–42 (as above). Values are presented as the percentage of the average value from the GFP samples. Thiorphan was also used as a negative control (Nep + Thior.;n = 1).