Figure 3: Enzyme replacement therapy with THLs in a mouse model of type VII mucopolysaccharidosis. (a) GUSB enzyme activity in GUSB null (−) fibroblasts and in fibroblasts obtained from wild type (+) mice. Fibroblasts were treated either with saline or with TfRMAb-targeted THLs encapsulated with the pCMV-GUSB expression plasmid. Data are mean ± SE (), and statistical significance was determined with ANOVA and Dunnett’s test. The difference in GUSB enzyme activity in the THL-treated cells is significantly different from the untreated cells from the GUSB null mice (). (b) GUSB enzyme activity in brain and five other organs of GUSB null mice removed at 48 h after single intravenous administration of either saline or 10 ug/mouse of pCMV-GUSB plasmid DNA encapsulated in TfRMAb-targeted THLs. Mean ± SE ( = 4-5 mice/group). The difference in GUSB enzyme activity in the THL-treated mice, as compared to the saline-treated mice, is significant (), in all organs, except the heart. From .