Chemical Methods for DNA Delivery: An Overview

Introduction of DNA into mammalian cells is a powerful tool for studying the function of various DNA sequences, and for gene therapy. The process of introducing DNA into cells for the purpose of gene expression is called transfection or gene delivery. Synthetic compounds used to facilitate DNA transfer are often named synthetic vectors or transfection reagents. Compared with biological (viral vectors) and physical methods that are covered elsewhere in this volume and in the next volume, the major advantages of synthetic vectors (or chemical methods) are their simplicity, ease of production, and relatively low toxicity. Many synthetic compounds have been developed since DEAE-dextran was first used in transfection experiments more than 35 years ago. Rapid progress in developing more efficient synthetic vectors has led to successful DNA delivery into a variety of cell types in vitro and in vivo. More importantly, in the last few years, we have witnessed significant efforts and progress in elucidating the mechanisms underlying synthetic vector-mediated DNA delivery. With the continuous effort to meet the need for safe and efficient gene-delivery methods for human gene therapy, it is foreseeable that significant advances will be made in the future. This article concentrates on four major types of chemical reagents that are available to most investigators: calcium phosphate, DEAE-dextran, cationic lipid, and cationic polymer. Each of these types of reagents has its advantages and disadvantages, some of which we briefly outline in this overview chapter.