AAV9 delivery of MeCP2 reverses disease phenotypes in Tcf4+/− mice.
Tcf4+/− pups were injected at p1 with scAAV9.P546.MeCP2. Fifteen mice per treatment group were aged to p60 prior to motor and behavioral analysis. (A) After 30 min, Tcf4+/− mice showed hyperactivity in the open field and treatment with scAAV9.P546.MeCP2 significantly normalized the distance travelled compared to Tcf4+/+ littermates. Anxiety levels were quantified by number of rearing events in the open field (B) and the number of times a mouse entered the closed arm of the elevated plus maze within a 5 min period (C). Treatment with scAAV9.P546.MeCP2 significantly reduced rearing and time spent in the closed arm in Tcf4+/− treated mice. (D) Time spent self-grooming was significantly elevated in Tcf4+/− mice and rescued by scAAV9.P546.MeCP2 injection when compared to untreated controls. (E) Three chamber social interaction. Relative to littermate controls, Tcf4+/− mice spend significantly more time with the empty cylinder, and this deficit is partially rescued by the scAAV9.P546.MeCP2 construct. (F) Nesting activities were quantified by transferring mice into a test cage containing 3 g of a Nestlet and the next morning nests were scored on a scale of 1–5 (5 being normal) as described in Materials and Methods. scAAV9.P546.MeCP2-injection significantly improved nesting capabilities when compared to uninjected controls. (G) Novel Object Recognition. Tcf4+/− mice do not distinguish between familiar and novel objects, and the recognition/preference for the novel object was restored by scAAV9.P546.MeCP2-injection. (H) The number of total slips of Tcf4+/− and WT littermates was evaluated using a Beam Walk test. The number of foot faults was counted in treated and untreated animals and compared to WT (Tcf4+/+) mice. scAAV9.P546.MeCP2 treatment significantly reduced the number of foot falls when compared to untreated animals. Statistical analysis was performed using one way ANOVA followed by Sidak's (A, B, C, E, H), Dunnett's (D) or Dunn's (G, F) post hoc test. ∗p < 0.05, ∗∗p < 0.01, ∗∗∗p < 0.001, ∗∗∗∗p < 0.0001.