Strategies to achieve targeted gene delivery via the receptor-mediated endocytosis pathway

Gene transfer to eukaryotic cells may be accomplished by capitalizing on endogenous cellular pathways of macromolecular transport. In this regard, molecular conjugate vectors have been developed which deliver DNA via the receptor-mediated endocytosis pathway. An attractive feature of this vector system is the potential to achieve targeted gene delivery based upon flexible incorporation of a targeting ligand. In this review we describe steps that have been taken to optimize this vector system. Specific strategies include the incorporation of mechanisms to achieve conjugate escape from the endosome and the derivation of methods to eliminate sources of nonspecificity. These developments have demonstrated the potential to construct a vector system in which multiple independent components may function in a concerted manner to accomplish targeted high efficiency gene delivery. In their present state of development, molecular conjugate vectors may have many potential applications for in vitro use.