Polyethylenimine Conjugated Stearic Acid-g-chitosan Oligosaccharide Micelles For Antitumor Gene Therapy

Chitosan is playing an important role of non-viral gene delivery vector because of low cytotoxicity, high biocompatibility and biodegradation. In this study, Chitosan derivate based gene delivery system was investigated to obtain high gene transfection and effective gene therapy.Chitosan oligosaccharide (CSO) with the molecular weight of 17.5 KDa was prepared by enzymatic degradation. Chitosan oligosaccharide grafted stearic acid (CSOSA) with 3.46%and 20.7%amino-substituted degree were synthesized in the presence of 1-Ethyl-3-(3-dimethy laminopropyl) carbodiimide (EDC), and the critical micellar concentration were 0.120 g/L and 0.091 g/L, respectively. The CSOSA micelles could compact the plasmid DNA (pDNA) to form nanoparticles, and protect pDNA from enzymatic degradation by ribozyme. The mean diameter and zeta potential of CSOSA/pDNA complex nanoparticles were measured. The in vitro transfection efficiency of CSOSA/pDNA was investigated by using LipofectamineTM 2000 as a positive control. The results revealed that the transfection of CSOSA/pDNA was enhanced in the presence of serum or arginine, and the cytotoxicity of CSOSA/pDNA was much lower than that of LipofectamineTM 2000/pDNA.Non-viral vesicle composed of low molecular weight polyethylenimine (PEI) conjugated CSOSA (polyethylenimine conjugated stearic acid-g-chitosan oligosaccharide, CSOSA-g-PEI) was synthesized in the presence of sodium periodate. CSOSA-g-PEI could form positively charged nano-sized particles (100-150 nm) with pDNA, and both CSOSA-g-PEI had similar strong ion-buffer capabilities. In vitro gene transfection tests demonstrated that CSOSA-g-PEI showed much lower cytotoxicity and matched transfection efficiency in comparison with LipofectamineTM 2000 in both human uterine cervix cancer (Hela) cells and human breast carcinoma (MCF-7) cells. The gene transfection of CSOSA-g-PEI/pDNA could be further enhanced in the presence of serum or by adding arginine during incubation of CSOSA-g-PEI micelles with plasmid DNA. In vivo antitumor activity results showed that CSOSA-g-PEI/plasmid pigment epithelium derived factor (pPEDF) formulation effectively suppressed the tumor growth with little systematic toxicity against animal body. These results suggested that CSOSA-g-PEI would be a promising non-viral vector for gene delivery system.