Use of synthetic peptides for non-viral gene delivery

The development of non-viral gene delivery systems is an important key to solving several problems occurring in viral gene delivery, such as endogenous virus recombination, oncogenic effects and unexpected immune responses.As discussed in other chapters of this book, most of the basic techniques of non-viral gene delivery systems have relied on liposome and polymer chemistries; however, peptide chemistry has also contributed strongly to this field. Peptides can be synthesized automatically or manually and their chemistry allows the design and synthesis of complicated structures, e.g. ligand-modified peptides recognizable by specific cells, dye-modified peptides to trace their locations in cells and tissues, and other "intelligent" peptides to achieve functional gene delivery. It is expected that the relative ease of peptide construction will provide researchers with a wide range of molecules as well as important information about the structural requirements for functional gene delivery. Peptides play many roles in gene delivery, such as providing a simple cationic moiety to bind DNA, acting as a ligand or facilitating the release of DNA into the cytosol, carrying a signal for transport to the nucleus, or functioning as a sensor for the regulation of gene expression in cells. In this chapter, some examples of the use of peptides in gene delivery are described, and the prospects of utilizing such peptides in gene therapy are discussed.