Lipid-based emulsion system as non-viral gene carriers

The genetic materials for systemic administration meet a number of hurdles before they reach the nucleus of the target cells, such as enzymatic degradation in the bloodstream, extravascularization around the target tissue, endocytosis by the target cells, and endosomal escape of the genes. Therefore, there have been tremendous needs of effective gene carriers that can deliver the genetic materials to the target site. Of numerous approaches, recent studies have demonstrated that the lipid-based emulsion systems have the high potential as non-viral gene carriers: 1 lipid emulsions are biocompatible because their major constituents are composed of the non-toxic oils and amphiphilic lipids; 2 the cationic lipid emulsions can form nano-sized complexes with negatively charged DNAs, through which the genetic materials can be protected from the enzymatic degradation in the body fluids; 3 The emulsion/DNA complexes are shown to be stable in the bloodstream since their surfaces are rarely recognized by the immune-related cells and serum proteins; and 4 the surfaces of the emulsion complexes are readily modified by varying the lipid composition. In this review, highlighted are the recent advances in the emulsion-based gene carriers.