An ABC triblock copolymer based approach for non-viral gene delivery

Gene therapy refers to the treatment of human diseases by transfer of therapeutic DNA into specific cells of a patient. It has the potential of curing inherited genetic disorders by supplying the diseased cells with functional copies of the defective genes, and also treating acquired genetic diseases like cancer. Currently one of the biggest challenges in clinical implementation of this technique is to develop a gene carrier for safe and efficient delivery of DNA to the desired locations in the body. Polymers (specifically cationic polymers) have become very popular materials for constructing gene carriers because of their safety and the relative ease with which their chemical and physical properties can be tailored to meet the different functional requirements for efficient gene delivery. In this work we have developed a novel design for polymeric gene carriers using positively-charged polymeric micelles (rather than individual polymer molecules) as the basic building blocks. The micelles are derived from the self-assembly of an ABC triblock copolymer consisting of (A) hydrophilic (poly(ethylene glycol), PEG), (B) hydrophobic (poly(n-butyl acrylate), PnBA), and (C) cationic (poly(2-(dimethylamino)ethyl methacrylate), PDMAEMA) sequence of blocks, in aqueous medium. The electrostatic complexation of these micelles with the negatively charged DNA molecules results in the formation of stable small-size DNA particles coated with a micelle monolayer (named “micelleplexes”). This dissertation presents a series of systematic studies that were conducted to evaluate the potential of the micelleplex design as a new gene delivery platform. Our results show that the micelleplexes offer several advantageous features over the state-of-the-art polymer-DNA complexes (“PEGylated polyplexes”) like greater stability in the physiologically-relevant conditions, better protection of the encapsulated from DNA enzymatic degradation and higher uptake in mammalian cells. However, these advantages come at the expense of a slightly inefficient intracellular transportation of the DNA