Gene Delivery Systems

Thanks to the changes in medicine, pharmacological treatment rapidly progresses into new fields. There is an emphasis on the development of treatment methods to eliminate underlying factors rather than to treat the symptoms of a disease. Therefore, research is increasingly utilizing knowledge from the field of genetics. Genetic mutation and deletion lead to many genetic disorders. Genetic disorders in metabolic pathways, regulation of cell cycle, ligand/receptor function, cell skeleton and extracellular proteins cause serious diseases. Both genetic and acquired diseases may be treated using gene therapy. Genetic diseases are generally caused by deletion or mutation of a single cell. Conversely, in acquired diseases, a single gene cannot be defined as the sole cause of a disease. Gene therapy has increased in prominence, and has shown great potential in treating acquired and genetic diseases. Gene delivery systems are categorized as: viral-based, non-viral-based and combined hybrid systems. Viral-mediated gene delivery systems consist of viruses that are modified to be replication-deficient, but which can deliver DNA for expression. Adenoviruses, retroviruses, and lentiviruses are used as viral gene-delivery vectors. Non-viral gene delivery systems were introduced as an alternative to viral-based systems. One of the most important advantages of these systems is improved transfection. Non-viral systems are categorized according to preparation, as physical or chemical types. The most common physical methods are microinjection, electroporation, ultrasound, gene gun, and hydrodynamic applications. In general terms, physical methods refer to delivery of the gene via the application of physical force to increase permeability of the cell membrane. In contrast, chemical methods utilize natural or synthetic carriers to deliver genes into cells. In this session polymers, liposomes, dendrimers, and cationic lipid systems are described as gene delivery systems.