A Trojan horse biomimetic delivery system using mesenchymal stem cells for HIF-1α siRNA -loaded nanoparticles on RPE cells under hypoxia environment

Abstract AIM: To demonstrate the feasibility of mesenchymal stem cell (MSC)-mediated nano drug delivery, which was characterized by the “Trojan horse”-like transport of HIF-1α siRNA between MSCs and retinal pigment epithelial cells (RPE) under hypoxia environment.METHODS: Plasmid and lentivirus targeting the human HIF-1α gene were designed and constructed by Genechem company. HIF-1α siRNA was encapsulated into Poly (lactic-co-glycolic acid)(PLGA) nanoparticles(NPs) through the water-in-oil-in-water (W/O/W) multiple emulsion technique. MSCs were transfected with the NPs and the transfection efficacy was evaluated by flow cytometry. Then a transwell co-culture system of MSCs and RPE was constructed under hypoxia environment. The effects of MSC-loaded HIF-1α siRNA PLGA-NPs on proliferation, apoptosis, and migration of RPE cells were then evaluated. The effect on HIF-1α expression of RPE cells was analyzed by using quantitative polymerase chain reaction at the time point 24 h, 3 d and 7 d.RESULTS: The average diameter of PLGA-NPs loaded with HIF siRNA was 314.1nm and the zeta potential was﹣0.36 mV. The transfection efficiency of PLGA NPs was (67.3%±5.2%) into MSCs by using flow cytometry. Compared with the lentivirus group, the PLGA-NPs loaded with HIF-1α siRNA can effectively reduce the expression of HIF-1α mRNA up to 7 days in RPE (0.63±0.05 at 7d, P < 0.001). In the transwell co-culture system of MSCs and RPE, the abilities of proliferation(2.34±0.17 vs 2.40 ± 0.28 vs2.47±0.24 at 48h, F=0.23, P=0.80), apoptosis(14.83 ± 2.43% vs 12.94 ± 2.19% vs 12.39 ± 3.21%; F= 0.70, P=0.53) and migration(124.5± 7.78 vs 119.5± 5.32 vs 130±9.89, F =1.33, P=0.33) of the RPE cells had no differences between MSC-loaded HIF-1α siRNA PLGA-NPs group and other groups. The inhibition of PLGA on the HIF-1α mRNA expression in RPE cells could continue until the 7th day, the level of HIF-1α mRNA was lower than that of other groups (F=171.98, P <0.001). CONCLUSION: The delivery of PLGA-NPs loaded with HIF-1α siRNA carried by MSCs is found to be beneficial temporally for HIF-1α mRNA inhibition in RPE cells under hypoxia environment. The MSC-based bio-mimetic delivery of HIF-1α siRNA nanoparticles is a potential method for therapy against choroidal neovascularization (CNV).