Magnetic Resonance Imaging and RNA Interference of Tumor with a Reducible Poly(urethane-amine) Nanocomposite System

Gadolinium-based small-molecule contrast agents are commonly utilized in clinics. However, these agents have a short retention time in vivo and possess a certain level of cytotoxicity. The reducible polymer poly(urethane-amine) can increase the relaxation rate and blood circulation time of small-molecule gadolinium chelates. Moreover, the polymer can be used as a gene carrier to bind small interfering RNAs (siRNAs). We synthesized an active targeting integrated diagnosis and treatment nanocomposite system with reducible poly(urethane-amine) as the carrier. This system incorporated functional units such as magnetic resonance imaging contrast agents Gd-diethylenetriamine pentaacetate and siRNA-vascular endothelial growth factor (siRNA-VEGF) and folic acid modified onto the surface of the polymer directed it to actively target tumor cells, thus improving the imaging effect of magnetic resonance imaging. Meanwhile, siRNA-VEGF carried by the system could reduce the expression of VEGF in tumor cells and inhibit tumor growth. The system showed good biocompatibility and was an integrated system of tumor diagnosis and treatment.

Automated summary

Gadolinium-based small-molecule contrast agents have short retention time and cytotoxicity, but poly(urethane-amine) polymer can enhance their effects and be used as a gene carrier for siRNAs. A nanocomposite system with active targeting for tumor cells was developed using this polymer, incorporating Gd-diethylenetriamine pentaacetate contrast agents and siRNA-VEGF for both imaging improvement and tumor growth inhibition. The system demonstrated good biocompatibility and integration of tumor diagnosis and treatment.