  The discovery in the early 2000's that magnetic nanoparticles (MNPs)
complexed to nonviral or viral vectors can, in the presence of an external
magnetic field, greatly enhance gene transfer into cells has raised much
interest. This technique, called magnetofection, was initially developed mainly
to improve gene transfer in cell cultures, a simpler and more easily
controllable scenario than in vivo models. These studies provided evidence for
some unique capabilities of magnetofection. Progressively, the interest in
magnetofection expanded to its application in animal models and led to the
association of this technique with another technology, magnetic drug targeting
(MDT). This combination offers the possibility to develop more efficient and
less invasive gene therapy strategies for a number of major pathologies like
cancer, neurodegeneration and myocardial infarction. The goal of MDT is to
concentrate MNPs functionalized with therapeutic drugs, in target areas of the
body by means of properly focused external magnetic fields. The availability of
stable, nontoxic MNP-gene vector complexes now offers the opportunity to
develop magnetic gene targeting (MGT), a variant of MDT in which the gene
coding for a therapeutic molecule, rather than the molecule itself, is
delivered to a therapeutic target area in the body. This article will first
outline the principle of magnetofection, subsequently describing the properties
of the magnetic fields and MNPs used in this technique. Next, it will review
the results achieved by magnetofection in cell cultures. Last, the potential of
MGT for implementing minimally invasive gene therapy will be discussed.
