Combined Self-Assembled iRGD Polymersomes for Effective Targeted siRNA Anti-Tumor Therapy

Introduction: iRGD is usually used as a motif to modify siRNA-nanodelivery vectors to improve tumor-targeting and penetration. However, most of the modifications are realized by covalent conjugation, which normally requires complex preparation processes possibly with low conjugation efficiency and yield, and might lower its bioactivity. To avoid this, here, we presented an alternative physical method to decorate iRGD on nanopolymersomes via facile self-assembly in water. Methods: siVEGF was chosen as a siRNA model, and lipopolysaccharide-amine nanopolymersomes (NPs), an efficient cytosolic delivery vector developed by our group, was used as an original vector. By successively incubating siVEGF with NPs, followed by adding iRGD, a siVEGF-loaded NPs functionalized with iRGD (siRNA/iRGD-NPs) was obtained. The properties of iRGD-NPs or siRNA/iRGD-NPs were evaluated in vitro and in vivo. Results: iRGD is efficiently introduced onto NPs with different amounts, which can be precisely controlled by the feeding ratio. The introduced iRGD keeps tumor-targeting and-penetrating bioactivity, which endows iRGD-NPs with similar to 100% of tumor-cell uptake and excellent tumor spheroid-penetration, and thus iRGD-NPs can efficiently deliver siVEGF to significantly inhibit angiogenesis in zebrafish and tumor growth in nude mice bearing breast cancer without obvious toxicity. Conclusion: This study provides a facile physical method to decorate nanodelivery vectors with iRGD for effective targeted siRNA anti-tumor therapy.