Effective treatment of retinal neovascular leakage with fusogenic porous silicon nanoparticles delivering VEGF-siRNA.

Aim: To evaluate an intravitreally injected nanoparticle platform designed to deliver VEGF-A siRNA to inhibit retinal neovascular leakage as a new treatment for proliferative diabetic retinopathy and diabetic macular edema. Materials & methods: Fusogenic lipid-coated porous silicon nanoparticles loaded with VEGF-A siRNA, and pendant neovascular integrin-homing iRGD, were evaluated for efficacy by intravitreal injection in a rabbit model of retinal neovascularization. Results: For 12 weeks post-treatment, a reduction in vascular leakage was observed for treated diseased eyes versus control eyes (p = 0.0137), with a corresponding reduction in vitreous VEGF-A. Conclusion: Fusogenic lipid-coated porous silicon nanoparticles siRNA delivery provides persistent knockdown of VEGF-A and reduced leakage in a rabbit model of retinal neovascularization as a potential new intraocular therapeutic.

A pH-responsive prodrug delivery system of 10-HCPT for controlled release and tumor targeting.

We synthesized a pH-responsive conjugate of 10-hydroxycamptothecin-thiosemicarbazide-linear polyethylene glycol 2000 (PEG2000). The conjugate was confirmed by matrix-assisted laser desorption time of flight mass spectrometry, 1H NMR, and 13C NMR. The water solubility of the prodrug was increased by over 3,000 times; much longer body circulation time, higher tumor-targeting ability, and reduced toxicity were observed, compared with commercial 10-HCPT injection. The linker contains a pH-sensitive hydrazone bond, which breaks under low pH conditions in the tumor microenvironment. The conjugates showed good stability in phosphate-buffered saline (pH 7.4) and rat plasma. This amphiphilic conjugate could self-assemble into nanosized micelles of 80-100 nm. Cytotoxicity assay results indicate significantly higher efficacy of the conjugate (IC50 [half maximal inhibitory concentration] =0.117 µM on SW180 cells) than 10-HCPT solution (IC50 =0.241 µM on SW480 cells). Cellular uptake analysis suggested its rapid internalization and nuclear transport. Pharmacokinetic analysis of the conjugates demonstrated that the conjugate circulated for a longer time in the blood circulation system (T2/1 =10.516±1.158 h) than did 10-HCPT solution (T2/1 =1.859±1.385 h), and that it also enhanced the targeting and mean residence time (MRT0-inf =39.873±4.549 h) in the tumor site, compared with 10-HCPT (MRT0-inf =9.247±1.026 h). Finally, the conjugate demonstrated an increased tumor growth inhibition effect (TIR =82.66%±7.175%) in vivo and lower side effects than 10-HCPT (TIR =63.85%±5.233%). This prodrug holds great promise in improving therapeutic efficacy and overcoming multidrug resistance.