Engineering silica-polymer hybrid nanosystems for dual drug and gene delivery

In recent years, it has been shown that a combination of different antitumour strategies involving distinct therapeutic agents, such as chemical compounds and genetic material, could result in an effective therapeutic activity that is much higher than that obtained by conventionally used individual approaches. Therefore, the main goal of this work was to develop a new hybrid nanosystem based on mesoporous silica nanoparticles and polymers to efficiently transport and deliver drug and plasmid DNA into cancer cells. Moreover, its potential to mediate a combinatorial antitumour strategy involving epirubicin and herpes simplex virus thymidine kinase/ganciclovir (HSV-TK/GCV) gene therapy was evaluated. For this purpose, various cationic polymers were assessed, including poly(β-amino ester) homopolymer, gelatine type A, gelatine type B, and poly(ethylene glycol)-b-poly(2-aminoethyl methacrylate hydrochloride) block copolymer. The obtained results show that using different polymers leads to nanosystems with different physicochemical properties and, consequently, different biological activities. The best formulation was obtained for hybrid nanosystems coated with PEG-b-PAMA. They demonstrated the ability to cotransport and codeliver an anticancer drug and plasmid DNA and effectively mediate the combined antitumour strategy in 2D and 3D tumour cell culture models. In summary, we developed a novel silica- and polymer-based nanosystem able to mediate a dual chemotherapeutic and suicide gene therapy strategy with a much higher therapeutic effect than that obtained through the use of individual approaches, showing its potential for cancer treatment.