Multifunctional drug carrier based on PEI derivatives loaded with small interfering RNA for therapy of liver cancer

Abstract Gene therapy strategies for liver cancer have broad application prospects but still lack a stable and efficient delivery vehicle. To overcome this obstacle, we designed a multifunctional gene delivery vector, sTPssOLP, which was based on oleylamine (OA)-modified disulfide-containing polyethylenimine (PEI) and incorporated into lipids to prepare a lipid nanoparticle. sTPssOLP consisted of the core of PEI derivative and cationic lipids bound to siRNA. The modified polyethylene glycol (PEG) and transferrin (Tf) were partially embedded in the phospholipid bilayer through the lipid and the other as the outer shell. The aim was to use the redox responsiveness of disulfide to trigger siRNA release in cytoplasm to enhance transfection efficiency. Pegylated lipids and Tf focus on increasing cycle life in the body and increasing accumulation at the tumor site of the carrier. In addition, two vectors were prepared as controls, one based on a PEI derivative containing no disulfide bond (POLP) and the other on the surface of the carrier not linked to Tf (PssOLP). PEI derivatives effectively avoid the toxicity problems caused by the use of PEI alone (25 kDa). Meanwhile, it was confirmed by gel retardation experiments that in the presence of dithiothreitol (DTT), the disulfide bond can indeed be reduced and the siRNA entrapped in the vector can be released. Both HepG2 and SMMC had significant uptake of sTPssOLP. The results of intracellular and lysosomal co-localization indicated that sTPssOLP achieved lysosomal escape. RT-PCR and Western blot results also confirmed that sTPssOLP had the best gene silencing activity. In vivo, the tumor inhibition rate of sTPssOLP in nude mice carrying HepG2 xenografts was 56%, which was significantly greater than that of the saline control group. In vivo imaging results showed that fluorescently labeled siRNA loaded in sTPssOLP was able to deliver more to the tumor site. At the same time, it was observed that sTPssOLP did not show significant damage to normal tissues. Therefore, this multifunctional gene delivery vector warrants further investigation.