Cell-Mediated Release of Nanoparticles as a Preferential Option for Future Treatment of Melanoma

Targeted and immune therapies have unquestionably improved the prognosis of melanoma patients. However the treatment of this neoplasm still requires approaches with a higher therapeutic index, in order to reduce shortcomings related to toxic effects and aspecific targeting. This means developing therapeutic tools derived with high affinity molecules for tumor components differentially expressed in melanoma cells with respect to their normal counterpart. Nanomedicine has sought to address this problem owing to the high modulability of nanoparticles. This approach exploits not only the enhanced permeability and retention effect typical of the tumor microenvironment (passive targeting), but also the use of specific "molecular antennas" that recognize some tumor-overexpressed molecules (active targeting). This line of research has given rise to the so-called "smart nanoparticles," some of which have already passed the preclinical phase and are under clinical trials in melanoma patients. To further improve nanoparticles partition within tumors, for some years now a line of thought is exploiting the molecular systems that regulate the innate tumor-homing activity of platelets, granulocytes, monocytes/macrophages, stem cells, endothelial-colony-forming cells, and red blood cells loaded with nanoparticles. This new vision springs from the results obtained with some of these cells in regenerative medicine, an approach called "cell therapy." This review takes into consideration the advantages of cell therapy as the only one capable of overcoming the limits of targeting imposed by the increased interstitial pressure of tumors.