Papers by Author: Myung Haing Cho

Abstract: Novel, biodegradable poly(ester amine)s (PEAs) were synthesized using hydrophobic polycaprolactone diacrylate (PCLDA) and highly cationic polyethylenimine (PEI). This novel gene carrier can form stable DNA complexes with particle sizes around 200 nm, and showing excellent transfection efficiency and relatively low cytotoxicity compared with PEI 25K. Effect of hydrophobicity on transfection efficiency and cytotoxicity was profound and was relatively important parameter for the success of gene delivery.

Abstract: Polypropylenimine (PPI) dendrimers have been used by many researchers as gene delivery carriers due to their high functionality. Glucose as a kind of carbohydrate is biocompatible and hydrophilic. In this study, we synthesized glucosylated PPI (G-PPI) dendrimers to reduce cytotoxicity. Glucose substitution of G-PPI dendrimers was determined by the sulfuric acid micromethod. The G-PPI dendrimer was complexed with plasmid DNA in various N/P ratios, and the complex was characterized. G-PPI dendrimers showed good DNA binding ability and high protection of DNA from nuclease attack. The G-PPI dendrimer had low cytotoxicity compared to PPI dendrimer by cytotoxicity assay. Also, transfection efficiency was influenced by glucosylation degree and the transfection efficiency for the G-PPI-5 was slightly higher than that of PPI dendrimer in HeLa cell line.

Abstract: The key strategy for the advancement of gene therapy is the development of an efficient targeted gene delivery system into cells. The targeted gene delivery system is especially important in non-viral gene transfer which shows the relatively low transfection efficiency. It also opens the possibility of selective delivery of therapeutic plasmids to specific tissues. Chitosan has been considered to be a good candidate for gene delivery system, since it is already known as a biocompatible, biodegradable, and low toxic material with high cationic potential. However, low specificity and low transfection efficiency of chitosan need to be overcome prior to clinical trial. In this study, we focused on the chemical modification of chitosan for enhancement of cell specificity and transfection efficiency. Also, the potential of clinical application was investigated.

Abstract: Vectors are vital aspect of gene delivery system which decides the success of gene therapy. Efficient transfection with minimum or no toxicity, are two principal aims of any gene delivery system. In this our study, we rationally developed biodegradable water soluble poly(ßamino ester) (PAE) based on spermine (SPR) and poly (ethylene glycol) (PEG), by Michael-type addition reaction and further studied for its potential as a gene carrier. Confirmation of synthesized PAE was done by proton NMR spectroscopy. In gel retardation assay, the PAEs have shown good DNA binding ability over wide range of polyplexes. The addition of PEG over SPR resulted in a novel PAE with higher degree of safety and transfection efficiency as compared with polyethylenimine 25K (PEI) when studied in 293T human kidney carcinoma cells.

Abstract: The development of an efficient targeted gene delivery system into cells is an important strategy for the advancement of gene therapy. The targeted gene delivery system is especially important in non-viral gene transfer which shows the relative low transfection efficiency. And it also opens the possibility of selective delivery of therapeutic plasmids to specific tissues. Chitosan has been considered to be a good candidate for gene delivery system, since it is already known as a biocompatible, biodegradable, and low toxic material with high cationic potential. However, low specificity and low transfection efficiency of chitosan need to be overcome prior to clinical trial. In this study, we focused on the chemical modification of chitosan for enhancement of cell specificity and transfection efficiency.