Suicide-gene transfection of tumor-tropic placental stem cells employing ultrasound-responsive nanoparticles.

A Trojan-horse strategy for cancer therapy employing tumor-tropic mesenchymal stem cells transfected with a non-viral nanovector is here presented. In this sense, ultrasound-responsive mesoporous silica nanoparticles were coated with a polycation (using two different molecular weights), providing them with gene transfection capabilities that were evaluated using two different plasmids. First, the expression of Green Fluorescent Protein was analyzed in Decidua-derived Mesenchymal Stem Cells after incubation with the silica nanoparticles. The most successful nanoparticle was then employed to induce the expression of two suicide genes: cytosine deaminase and uracil phosphoribosyl transferase, which allow the cells to convert a non-toxic pro-drug (5-fluorocytosine) into a toxic drug (5-Fluorouridine monophosphate). The effect of the production of the toxic final product was also evaluated in a cancer cell line (NMU cells) co-cultured with the transfected vehicle cells, Decidua-derived Mesenchymal Stem Cells. STATEMENT OF SIGNIFICANCE: Cell-mediated cancer therapy has recently attracted great interest. Tumor-homing cells can exert anticancer effects through innate capacities, via transfection with a therapeutic gene or acting as vehicles of therapeutic nanoparticles. In this work, an ultrasound-responsive mesoporous silica nanoparticle (capable of carrying an anticancer drug) is engineered to act as a non-viral transfection agent for tumor-tropic human placental mesenchymal stem cells. The successful transfection of the vehicle cells is evaluated employing different expression plasmids. After transfection with two suicide genes, the vehicle cells are capable of converting a non-toxic pro-drug into a highly toxic molecule, which can also kill surrounding cancer cells in an in vitro co-culture model. This work opens the gate for a plethora of strategies in which both genes and drug-loaded nanoparticles can be transported towards tumor tissues by easily available human mesenchymal stem cells.