Dendrimers are very promising carriers for gene therapy due to their nanosize and strictly ordered structure, high homogeneity and the fact that, like proteins and other soluble particles from 10 to 100 nm, they may benefit from the EPR (Enhanced Permeability and Retention) effect present in the tumor microenvironment. Another advantage of dendrimers is a wide range of potential surface modifications that greatly increase their specificity for the selected cell location However, toxicity is a key problem with all non-viral carriers like dendrimers and polyethyleneimine . The toxicity is due to the overall positive charge of the carrier, which unfortunately is necessary for binding of DNA or RNA. A solution could be a labile metal complex with a neutral dendrimer, that could release the metal ions after release of the polynucleotide.