ABSTRACT
Polyethylenimine (PEI) is well known in the chemical industry as a polymer with high positive charge density. It has been used in water purification, the paper industry, biotechnology (to remove nucleic acids from protein solutions), and also in the food industry. In 1995, the group of Jean-Paul Behr made the first use of this polymer for the delivery of DNA and oligonucleotides.1 Since then, over 300 publications (as of June 2003) have appeared describing the use of PEI as a gene transfer agent. This chapter will give an overview of PEI and its functional derivatives in gene delivery, from its chemistry and transfection properties to its use in preclinical gene therapy protocols.
