Chapter 18 The advantages of liposome-based gene therapy: A comparison of viral versus liposome-based gene delivery

Viruses have evolved in such a way they are able to efficiently introduce and express exogenous genes in eukaryotic cells. Most viruses need to maintain high-level expression of their proteins for only a short time and need not be concerned with the viability of the host cell after infection. Attempts to modify a virus into a gene therapy vector can be hampered by this conflict. Virus-based methods of gene therapy are likely to be most useful in applications that require a burst of high-level expression in many of the patient's cells, such as in cancer therapy. Liposomal methods of gene therapy are flexible in that all the components of the system are controlled by designers. As these systems have become more sophisticated, they have begun to take on several characteristics of the viruses that they are intended to replace. The use of basic substances to condense DNA has increased the efficiency of encapsulation. The addition of nucleophilic proteins raises the efficiency of transfection. By adding antibodies or other targeting molecules to the surface of liposomes, preferential binding of vesicles to a desired cell type has been increased.