GALA-Modified Lipid Nanoparticles for the Targeted Delivery of Plasmid DNA to the Lungs.

This study describes the development of lipid nanoparticles (LNPs) for the efficient and selective delivery of plasmid DNA (pDNA) to the lungs. The GALA peptide was used as a ligand to target the lung endothelium and as an endosomal escape device. Transfection activity in the lungs was significantly improved when pDNA was encapsulated in double-coated LNPs. The inner coat was composed of dioleoylphsophoethanolamine and a stearylated octaarginine (STR-R8) peptide, while the outer coat was largely a cationic lipid, di-octadecenyl-trimethylammonium propane, mixed with YSK05, a pH-sensitive lipid, and cholesterol. Optimized amounts of YSK05 and GALA were used to achieve an efficient and lung-selective system. The optimized system produced a high gene expression level in the lungs (>107 RLU/mg protein) with high lung/liver and lung/spleen ratios. GALA/R8 modification and the double-coating design were indispensable for efficient gene expression in the lungs. Despite the fact that NPs prepared with 1-step or 2-step coating have the same lipid amount and composition and the same pDNA dose, the transfection activity was dramatically higher in the lungs in the case of 2-step coating. Surprisingly, 1-step or 2-step coatings had no effect on the amount of nanoparticles that were delivered to the lungs, suggesting that the double-coating strategy substantially improved the efficiency of gene expression at the intracellular level.

Effective Therapy Using a Liposomal siRNA that Targets the Tumor Vasculature in a Model Murine Breast Cancer with Lung Metastasis.

Although metastatic cancer is a major cause of death for cancer patients, no efficacious treatment for metastasis is available. We previously showed that the growth of a primary tumor could be inhibited by the administration of an anti-angiogenic small interfering RNA (siRNA) that is encapsulated in an RGD peptide-modified lipid nanoparticle (RGD-LNP). We herein report on the delivery of siRNA by an RGD-LNP to the vasculature is also effective for treating metastatic tumors. We compared the RGD-LNP with the polyethylene glycol (PEG)ylated LNP (PEG-LNP) in terms of accumulation in a lung-metastasized model. Despite malformed structure of vasculature in the metastasized lung, the accumulation of the PEG-LNP in the metastasized lung was lower than that for the RGD-LNP, which suggests that the delivery strategy based on vascular permeability is not completely effective for targeting metastasis tumors. The systemic injection of the RGD-LNP induced a significant silencing in the metastasized vasculature, but not in the normal lung. In addition, the continuous injection of the RGD-LNP encapsulating siRNA against a delta-like ligand 4 (DLL4) drastically prolonged the overall survival of metastasized model mice. Accordingly, our current findings suggest that vasculature targeting would be more effective than enhanced permeability and retention effect-based therapy for the treatment of metastatic cancer.