Figure 1.

Twenty-one-Nucleotide shRNA Directed to Muscles Can Cause Toxicity in Mice

(A) Schematic of experimental design. (B) Histological muscle sections from 19-and 21-nt injected mice at 6 weeks post-injection. Left panels are H&E-stained sections, and the right panels are stained with human placental alkaline phosphatase (hPLAP). Sections shown are quadriceps (Quad), gastrocnemius (Gas), diaphragm (Dia), heart (Hrt), and tibialis anterior (TA). (C) Serum ALT and AST levels in 19-and 21-nt injected mice. ALT and AST levels are significantly higher in 21-nt injected mice as compared with 19-nt injected mice at 2 weeks post-injection (Welch’s t test, p = 0.0201 and p = 0.0122, respectively), and resolve by 12 weeks post-injection. n = 3–4 mice per group. (D) qRT-PCR for lacZ and hPLAP levels in heart and quadriceps tissues of 19- and 21-nt injected mice at 6 weeks post-injection. LacZ expression is significantly reduced in tissues of treated animals to 5%–11% of untreated levels, and hPLAP levels are not significantly different. n = 3 mice per group. One-way ANOVA followed by Tukey’s multiple comparisons. Data are mean ± SD.