ABSTRACT
Gene therapy protocols have previously involved the removal of target cells from the body. These cells are then cultured in vitro to allow for gene transfer and subsequently reintroduced in vivo. Direct gene transfer techniques can be divided in three groups: direct injection of naked DNA, injection of complexed DNA, and direct injection of recombinant viruses. Direct injection of naked DNA is a simple and attractive approach for the introduction of foreign genes in vivo. Efficiency of transfection and maximal obtainable expression levels are of major importance in designing gene therapy protocols for the treatment of human inborn or acquired disorders based on the technique of naked DNA injection in skeletal muscle. Direct injection of naked DNA can be a very important gene therapy route for the production of proteins that are excreted from the muscle cells. The actual choice of the gene transfer method is a matter of the intended host tissue, required transfection efficiency, and expression level.
