ε-Caprolactone-Modified Polyethylenimine as Efficient Nanocarriers for siRNA Delivery in Vivo

RNA interference (RNAi) therapy is a promising treatment for various diseases. However, its application is still restricted by the lack of efficient and safe delivery systems. A novel siRNA delivery vehicle based on ε-caprolactone-modified polyethylenimine (PEI-CL) is presented here. The PEI-CL macromolecules with different grafting degrees were synthesized via a simple ring-opening reaction. This macromolecule strongly protects the siRNA from degradation in serum and promotes the cellular uptake and endosomal escape detected via chemical exchange saturation transfer magnetic resonance analysis and fluorescence imaging. The in vivo measurement was performed with HCT-116 colon tumor xenograft that stably expressed luciferase. The data showed that the PEI-CL/siRNA nanocomplexes elicited strong RNAi response. More interestingly, enhanced gene transfection efficiency was achieved by simultaneous cotransfection with siRNA and DNA plasmid via this novel nanosystem. Overall, our study suggests the PEI-CL macromolecule with great promise for siRNA delivery.