Preparation And Characterization Of Polyethyleneimine Nanoparticles As Gene Delivery Systems

Recently, the methods of gene delivery are gradually developing and have made great progresses. So the gene therapy of cancer is a hot spot of the biology and clinic medical currently. The prospect of curing inherited and acquired diseases through gene therapy has engendered considerable effort toward the development of gene transfer vectors. Most ongoing human gene therapy protocols rely on recombinant retroviral and adenoviral vehicles, which risk encountering acute safety and immunological problems with large scale or repeated use, besides their limited carrier capacity. Synthetic vectors, although currently orders of magnitude less efficient than biological vectors, are increasingly being considered to be possible solutions as well.Nanoparticle is developing as a new non-viral gene delivery vector. Gene therapeutical molecules including DNA, RNA, and so on are encapsulated into or loaded on the surface of nanoparticles. At the same time, specific ligands and monoclonal antibodies are linked onto the surface of nanoparticles. The nanoparticles/DNA complexes can be taken into target cells by receptor-mediated endocytosis, so the effective target gene therapy is achieved.It is vital for nanoparticle-mediated gene delivery and gene therapy to select proper materials. The nanoparticle materials must have very good biodegradability and biocompatibility and be non-immunogenic. The biodegradable polymer nanoparticles have some advantages, such as stabilization, non-toxicity, non-immunogenicity and good biocompatibility. In addition, they can protect the loaded DNA from degradation. Polyethylenimine(PEI)is the most common used polycation gene delivery vector, which can condense plasmids DNA into the particles of hundreds of nanometer or so. PEI/DNA particles abundant with positive charge adhere to negative charged mucoproteins on the surface of the cells, then passively pinocytized into the cells. PEI can not be decomposed by enzymes in the endosome,has a " protons pong effect" which make endosome osmotic swelling to rupture, and help DNA escape into the cytosol from the endosome. Receptor targeted PEI can enhance PEI's transfection eficiency.We used polyethylenimine (PEI) to prepare PEI NPs by a Emulsion-evaporation method. They are biodegradable, biocompatible and non-immunogenic. The surface of PEI NPs was positive that make the nanoparticles could bind DNA. At the same time, we found that PEI/DNA complexes could protect the DNA from degradation of DNaseI. We found that PEI NPs had no obvious cell toxicity to L-02 and HepG3 cells when concentration of PEI<10mg/ml, but cell toxicity could be showed when concentration of PEI>25mg/ml. The EGFP expression plasmid could be transfected effectively into NIH3T3 cells by PEI NPs in vitro. The transfection efficiency was about 33%, which was higher than that of SuperFect^TM. In conclusion, PEI NPs is a versatile gene carrier with minimal cytotoxicity and has great potential for gene therapy.