[Show abstract][Hide abstract] ABSTRACT: Gene delivery is an essential research tool for elucidating gene structure, regulation, and function in biomedical research and is the technological basis for gene therapy. However, the application of nonviral vectors in mammalian cell transfection and gene therapy is limited in that current methods require large amounts of exogenous DNA and/or exhibit high cytotoxicity and low transfection efficiency in primary cells. Here we describe the development of a novel, noninvasive gene delivery protocol using plasmid DNA vectors, based on the principle of electric field-induced molecular vibration. This method enables foreign DNA molecules to penetrate the plasma membrane and enter the cytoplasm of both primary mesenchymal progenitor cells and established cell lines of various species, at high efficiency and with low cell mortality. This procedure requires no special reagents, allows stable expression of transduced DNA, and does not interfere with the normal cellular differentiation activities of human and chick mesenchymal progenitors.