The factors that contribute to the long-term expression of siRNA

RNA interference (RNAi) has become a powerful tool of knocking down a specific gene in vivo. In applications of RNAi, chemically synthesized short interfering RNAs (siRNAs) are commonly used because of their easiness and simplicity. However, siRNAs are cost inhibitive and their effect is transient. DNA which encodes siRNA can overcome these problems. In this study, we compared the stability and expression efficiency of plasmid DNA vector, short and long dumbbell-shaped DNA vectors. We found that the short dumbbell-shaped DNA vector is more stable and results in long-term expression of siRNA.