Effective delivery of siRNA needed

"The ‘revolutionary’ potency and selectivity of siRNA inhibitors of gene expression promises to enable improved targeted cancer therapeutics, but the means for systemic administration and targeted distribution to disseminated metastatic lesions are needed. "

Cancer siRNA therapy by tumor selective delivery with ligand-targeted sterically stabilized nanoparticle
Nucleic Acids Research, 2004, (19), 32
Raymond M. Schiffelers1, Aslam Ansari1, Jun Xu1, Qin Zhou, Qingquan Tang, Gert Storm, Grietje Molema, Patrick Y. Lu, Puthupparampil V. Scaria, and Martin C. Woodle

RNA interference is a recently discovered biological process with the potential to revolutionize medicine. However, effectively delivering RNAi to target cells and subsequently turning off the target gene presents a huge hurdle. This paper outlines one potential delivery system dubbed “nanoplexes”. These nanoplexes consistes of a polyethylenimine (PEI)-polyethylene glycol (PEG), siRNA inhibiting vascular endothelial growth factor receptor-2, and a peptide ligand. The nanoplexes were intravenously administered to tumor mice and showed a significant inhibition of tumor growth. However, PEI tends to be toxic at high levels so a more effective delivery complex needs to be synthesized to be used in humans.

Used Google Scholar: "siRNA therapy"