Magnetic nanoparticles navigate therapeutic genes through the body

03-09-2009: Health professionals send genes and healthy cells on their way through the bloodstream so that they can, for example, repair tissue damage to arteries. But do they reach their destination in sufficient quantities? Scientists of the PTB have developed a highly sensitive measuring method with which the efficiency of this therapy can be investigated: Small magnetic particles which are situated on the planted gene or on the planted cell can with the aid of an external magnetic field be specifically directed to the location of the damage. There the researchers determine, accurate to the picogram per cell, the quantity of the magnetic material – and thus also the quantity of the therapeutically effective genes or cells. In a joint study with the University of Bonn it became clear: By means of the magnetic method it is possible to dramatically increase the efficiency of the gene transfer in comparison to the non-magnetic method.

Magnetic nanoparticles can support or even enable gene transfer under clinically relevant experimental conditions. For the transduction of human cells, gene carriers were coupled to magnetic nanoparticles and dragged into the cells by magnetic field gradients. The efficiency of magnetic transduction turned out to be much higher than the nonmagnetic procedure. An additional welcome side effect is the "magnetization" of the cells after the incorporation of nanoparticles. This may enable the targeted transport of the cells to regions of interest. A closer look at the underlying mechanism of magnetic gene transfer was taken by the quantification of the magnetic material that was delivered to the cells. The required highly sensitive measurements in the range of a few picogramm per cell were made by PTB using magnetorelaxometry. The good correlation between measurement data and gene transfer encourages to use magnetorelaxometry for monitoring the efficiency of gene and cell transfer, possibly even in vivo.

Original publications: Combined targeting of lentiviral vectors and positioning of transduced cells by magnetic nanoparticles; PNAS 106 (1), S.44-49.