During the past several years, particle-mediated delivery techniques have been developed as a nonviral technology for gene transfer (1 -7 ). For mammalian somatic tissues, this technology, popularly known as the gene gun method, has been shown effective for transfection of skin, liver, pancreas, muscle, spleen, and other organs in vivo (3 ,4 ), brain, mammary, and leukocyte primary cultures or tissue explants ex vivo (2 ,5 -7 ), and a wide range of cell lines in vitro (3 ,6 ,7 ). In this chapter, we describe the general principles, mechanisms, protocols, and uses of the particle-mediated gene transfer technology for in vivo gene transfer, mainly into skin tissues. Specific applications of this technology to basic studies in molecular biology as well as to gene therapy and genetic immunization against cancer are addressed.
