An attractive application of RGD-coated DNA particles would be targeting of the neovasculature of metastases by way of systemic delivery [16]. Indeed, resting endothelial cells of normal blood vessels precisely
express matrix-binding molecules at their basolateral face, whereas growing and less differentiated blood vessel cells of metastases express them also on the luminal side, hence the targeting. Intravenous injection experiments we did with RGD-PEI/DNA complexes, however, did not target tumors better than the passive accumulation of PEI/DNA or transferrin-PEI /DNA complexes through the leaky vasculature [20].