Nucleic acid delivery with α-tocopherol-polyethyleneimine-polyethylene glycol nanocarrier system

Purpose: Nucleic acid-based therapies are a promising therapeutic tool. The major obstacle in their clinical translation is their efficient delivery to the desired tissue. We developed a novel nanosized delivery system composed of conjugates of α-tocopherol, polyethylenei-mine, and polyethylene glycol (TPP) to deliver nucleic acids. Methods: We synthesized a panel of TPP molecules using different molecular weights of PEG and PEI and analyzed with various analytical approaches. The optimized version of TPP (TPP₁₁₁-the 1:1:1 molecular ratio) was self-assembled in water to produce nanostructures and then evaluated in diversified in vitro and in vivo studies. Results: Through a panel of synthesized molecules, TPP₁₁₁ conjugate components self-assembled in water, forming globular shaped nanostructures of ~90 nm, with high nucleic acid entrapment efficiency. The polymer had low cytotoxicity in vitro and protected nucleic acids from nucleases. Using a luciferase-expressing plasmid, TPP₁₁₁-plasmid nano-complexes were rapidly up-taken by cancer cells in vitro and induced strong transfection, comparable to PEI. Colocalization of the nano-complexes and endosomes/lysosomes sug-gested an endosome-mediated uptake. Using a subcutaneous tumor model, intravenously injected nano-complexes preferentially accumulated to the tumor area over 24 h. Conclusion: These results indicate that we successfully synthesized the TPP₁₁₁ nanocarrier system, which can deliver nucleic acids in vitro and in vivo and merits further evaluation.