A new pathway for developing in vitro nanostructured non-viral gene carriers

Extracellular and intracellular barriers typically prevent the efficient transfection of non-viral gene vectors. The formulation of a gene delivery carrier that can overcome the barriers would be a key for successful gene therapy. We have developed a novel pathway for the preparation of core-shelled DNA nanoparticles by invoking solvent-induced condensation of plasmid DNA (beta-galactosidase) in a poor solvent mixture and subsequent encapsulation of the condensed DNA globule in a tri-block copolymer (e.g. polylactide-poly( ethylene glycol)-polylactide, L8E78L8). The polylactide shell can protect the encapsulated DNA from degradation during electrospinning of a mixture of encapsulated DNA nanoparticles and biodegradable PLGA ( a random copolymer of lactide and glycolide) to form a non-woven nanofibrous DNA-containing scaffold. The bioactive plasmid DNA can then be released in an intact form and in sufficient quantity from the scaffold with a controlled release rate and to transfect cells in vitro. Further consideration of the stability of the DNA in extracellular and intracellular environments is proposed. In particular, the use of block copolymers with a positively charged block and a hydrophilic block, as well as tri-arm block copolymers with an additional hydrophobic, biodegradable block to stabilize the DNA chain of interest, is discussed.