Bioreducible Cationic Polymers for Gene Transfection

Gene therapy holds substantial promise for the treatment of a broad class of overwhelming human diseases such as cancer and AIDS (Verma & Somia, 1997). An essential procedure in gene therapy program involves the delivery of encoded plasmid genes into the patient’s somatic cells so as to express therapeutic proteins. An ideal strategy for successful gene delivery depends on safe and efficient gene delivery vectors (El-Aneed, 2004). Generally, gene delivery vectors are classified into two categories: viral vectors and non-viral vectors. Viral vectors are derived from natural viruses such as adenovirus and retrovirus with eliminated pathogenicity. Because of their unique capability in cell infection, viral vectors are most popular for gene delivery in vitro and in vivo. Unfortunately, clinical practice of viral vectors is seriously hampered by a few inherent issues including random insertion into the host genomes, immunogenicity, gene-carrying capacity limitation, and small-scale production (C.E. Thomas et al., 2003). In the past decades, these safety concerns on viral vectors have led to accelerated advancement in non-viral vectors (S. Li & Huang, 2000). Non-viral vectors such as lipids and polymers take more advantages over conventional viral vectors, including low immunogenicity after repeated administration, easy manufacture, large-scale production and low cost. However, current non-viral systems typically fail to give rise to as efficient gene transfection as powerful viral vectors (Pack et al., 2005). Thus, the availability of highly potent non-viral gene delivery vectors still remains a big challenge.