Gene therapy presents a new approach to alter the consequences of defective gene

expression and to utilize nucleic acids as therapeutic tools. Over the course of the last

decade there have been many new techniques developed for the transfer of therapeutic

genes into cells, derived from the modified viruses, or artificial non-viral liposome-based

approaches. Non-viral methods have advanced much in the last few years; however, its

efficiency remains below that achieved by virus-derived methods. Viral-derived gene

transfer vectors have become reliable tools for gene transfer.