Delivery of oligoribonucleotides to human hepatoma cells using cationic lipid particles conjugated to ferric protoporphyrin IX (heme)

Abstract

The receptor-ligand interaction between hepatocyte heme receptors and heme was evaluated as a basis for developing a targeted cationic lipid delivery reagent for nucleic acids. Heme (ferric protoporphyrin IX) was conjugated to the aminolipid dioleoyl phosphatidylethanolamine (DOPE) and used to form cationic lipid particles with dioleoyl trimethylammonium propane (DOTAP). These lipids particles (DDH) protect oligoribonucleotides from degradation in human serum and increase oligoribonucleotide uptake into 2.2.15 human hepatoma cells (to a level of 50-60 ng oligo/10(4) cells) when compared with the same lipid particles (DD) prepared identically without heme. The DDH heme level that was optimal for oligoribonucleotide delivery was also optimal for maximum expression of plasmid-encoded luciferase. The enhancing effect of heme was evident only at net particle negative charge. Fluorescence microscopy showed that DDH delivered oligoribonucleotides into both the 2.2.15 cell cytoplasm and nucleus. DDH may thus be a potentially useful delivery vehicle for oligonucleotide-based therapeutics and transgenes, appropriate for use in such liver diseases as viral hepatitis, hepatoma, and hypercholesterolemia.