Polycation-Based Ternary Gene Delivery System

Recent progress in gene therapy has opened the door for various human diseases. The greatest challenge that gene vectors still face is the ability to sufficiently deliver nucleic acid into target cells. To overcome various barriers, plenty of researches have been undertaken utilizing diverse strategies, among which a wide variety of polycation/pDNA vectors have been developed and explored frequently. For enhanced transfection efficiency, polycations are constantly utilized with covalent modifications, which however lead to reduced positive charge density and changed properties of polycation/pDNA complexes. Accordingly, non-covalent or ternary strategy is proposed. The cationic properties of polycations can be retained and the transfection efficiency can be enhanced by introducing additional polymers with functional groups via non-covalent assembly. This review will discuss the construction and advantages of ternary complexes gene delivery system, including low toxicity and enhanced gene expression both in vitro and in vivo. Recent progress and expectations with promising results that may have some reference for clinical application are also discussed.