Recent progress in non-viral nucleic acids delivery.

A major goal of nucleic acid based therapies is to treat inherted and acquired disorders by adding, correcting, suppressing or eplacing genes (Abbas et al., 2008). Advantages of non-viral vectors or delivering nucleic acid based therapies include ease of scale-up, torage stability and improved quality control. The most promisng non-viral vectors have been liposomes and cationic polymers hich complex with nucleic acids such as siRNA and plasmid DNA o form lipoplexes or polyplexes (Wang et al., 2011). Advances in he development of this technology have included pegylation to ncrease circulation times and impart stealth-like properties to the ector and attachment of cell targeting or cell binding ligands to ncrease nucleic acid delivery efficiency. Other improvements have ncluded new formulation strategies to enhance protection of the ucleic acids against enzymatic degradation, to improve stability in he presence of serum and to optimize eventual release capabilities. n additional major goal of researchers has been to design non-viral ectors with desirable cytotoxicity and reduced immunogenicity haracteristics. In this special theme issue, we have assembled manuscripts rom an outstanding group of researchers that are leaders in the ffort to optimize non-viral vectors and overcome several chalenges and barriers to translating use of non-viral vectors into the linic. This theme issue includes comprehensive reviews by Amiji Xu et al., 2011), Torchilin (Wang et al., 2011) and Patil (Kapoor et al., 011) that present recent progress in non-condensing polymeric anoparticles, condensing cationic polymer based nanoplexes and he physico-chemical characterization of lipid based delivery sysems for siRNA. Original research articles in this theme issue focus n the development and testing of nucleic acid delivery systems. or example, Pun and colleagues discuss the development of a educible HPMA-co-oligolysine copolymer for nucleic acid delivery Shi et al., 2011). Mallapragada and colleagues discuss the develpment a temperature-responsive pentablock copolymer that is esigned to deliver DNA and prolong gene expression by forming thermogelling release depot after subcutaneous or intratumoral njection (Zhang et al., 2011). Kwon and colleagues present a iodegradable hybrid recombinant block copolymer for non-viral ene delivery that is capable of appreciable transfections with ow toxicity (Chen et al., 2011). Ghandehari and colleagues carry ut a comparative study between silk-elastin like protein polymer ydrogels and poloxamer gels for matrix-mediated viral gene delivry (Price et al., 2011). Berkland and colleagues demonstrate the tility of calcium condensed cell penetrating peptide (TAT) comlexes for efficient gene silencing with reduced toxicity (Baoum t al., 2011). Salem and colleagues describe the development of a annosylated pegylated polyethylenimine for siRNA delivery and he development of optimized dextran–polyethylenimine conjuates for plasmid DNA delivery (Jiang and Salem, 2011; Kim et al.,