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Magnetic field-assisted gene delivery
Casalini M.B.1, Schwerdt J. I.1, Mykhaylyk O.2, Morel G.R.1, Sánchez F.3, Goya R.G.1
1
INIBIOLP-Histology B, University of La Plata (UNLP), Argentina; 2 Klinikum rechts
der Isar der TUM, München, Germany; 3 Institute of Physics, UNLP, Argentina
Gene therapy has undergone a remarkable development in the last 20 years with
important advances having been made in the improvement of gene transfer and
expression technology.
The association of viral vector-based gene delivery with nanotechnology now
offers the possibility to develop more efficient and less invasive gene therapy strategies
for a number of major pathologies like Parkinson´s and Alzheimer´s disease. This
approach combines Magnetic Drug Targeting (MDT) and magnetofection, two novel
methodologies based on the use of magnetic nanoparticles (MNP). The concept of MDT
was introduced in 1978 by the group led by K. J. Widder and its goal is to concentrate
magnetically responsive therapeutic complexes in target areas of the body by means of
external magnetic fields. So far, the main application of MDT has been cancer therapy.
Typically, magnetic microparticles (µm sized) or MNP (nm sized) associated to a
therapeutic drug are intravascularly injected near the tumor blood supply and are
concentrated into the tumor by means of an external magnetic field. This strategy has
shown promising results in clinical trials. Magnetofection is a methodology developed
in the early 2000’s by the group led by C. Plank in Munich. It is based on the
association of MNP with nonviral or viral vectors in order to optimize gene delivery in
the presence of a magnetic field.
In order to implement magnetofection in the brain we have constructed two
adenoviral vectors, RAd-DsRed2 which expresses DsRed2, a red fluorescent protein
from Discosoma, and RAd-GFP a vector expressing green fluorescent protein (GFP).
The vectors were constructed by the two-plasmid method. These vectors were or are to
be complexed with four types of magnetic nanoparticles (MNP) termed, PEI-Mag2
(S9), SO-Mag6-125, PB Mag1-4 and AdenoMag, all possessing a magnetite core and
different polymeric coatings. Non complexed vectors were tested at varying
multiplicities of infection (MOI) in different cell lines (HEK 293, B92, N2a and A549
cells) and showed pancellular expression of the corresponding reporter gene. In the rat
brain, the vectors showed appropriate levels of expression in the hypothalamus,
substantia nigra and the ependymal cell layer. Subsequently, MNP-RAd complexes
were generated and tested on the above cell lines under the influence of an external
magnetic field. Magnetic field-assisted reporter gene delivery (magnetotransduction) led
to a MNP-dose dependent enhancement of gene expression. We conclude that our
MNP-RAd complexes are suitable for magnetotransduction in vitro. These magnetic
adenovectors are to be used in in vivo magnetotransduction studies in the rat brain.
Keywords: nanotechnology –magnetic nanoparticles – gene delivery - magnetofection
Email: [email protected]