CONICET | Buscador de Institutos y Recursos Humanos

It has been shown that magnetically-assisted gene transfer (magnetofection) dramatically improves transfection effi ciency[1]. In order to characterize the dependence of magnetofection on magnetic force, we used an adenoviral-vector expressing the gene for green fuorescent protein, electrostatically complexed to iron oxide polyethyleneimine-coated magnetic nanoparticles (NPs). Typically, NP/virus complexes consist of a single viral particle surrounded by a multilayer shell of NPs [2]. NP mean moment ~mu (~H ) = ~M (~H )Vp, depends on NP magnetization ~M and magnetic volume Vp. The force on the complex due to the energy E = -mu*H under the magnetic field H , is ~F = mu0*Np*V*(H*(dM/dH)+M(H))*GradH To evaluate ~F, M and dM/dH were obtained from the complex M vs H curve at room temperture, while ~H and GradH were measured on and over an ad hoc magnetic field applicator, and a commercial applicator. From experimental values found in the literature [2], the number of NPs per viral particle in the complex was estimated to be 5e10^3. In vitro magnetofection experiments with both applicators were performed on glial B92 cells using the above mentioned NPviral vector complex. We determined that under our experimental conditions, the NP/virus optimal ratio was 0.41 fg Fe/ physical viral particle. Naked viral particles were used as a baseline reference. At all ratios tested, gene transfer efficiency (fuorescence) was about 3-fold higher when a magnetic field was applied. Gene transfer effi ciency for the complexes in the absence of a magnetic field was comparable of that of the naked vector. A preliminary determination of the dependence of magnetofection on the magnetic force was performed. Our results show that our adenovector-based magnetofection system is e ffective to enhance gene transfer effi ciency in cell cultures.