The ultimate aim of somatic gene therapy is to alter the genetic material of living cells which involves transfer of DNA. Genetic material is transferred by various methods like use of viral or non viral vectors. The choice of an appropriate vector depends on several factors like ability of stimulating immune response, duration for which the transgene is expressed, efficiency in targeting the dividing or quiescent cells, efficiency of integration with the host genome without producing safety issues, the length of trangene which can be transported etc (Gould and Favorov, 2003).