Redox-Responsive and Electrically Neutral PLGA Nanoparticles for siRNA Delivery in Human Cervical Carcinoma Cells.

Purpose: Many non-viral vectors with positive charge and physical encapsulation of siRNA have been reported. However, the studies of non-viral vectors with chemical conjugation of siRNA and neutral charge were rarely reported. Methods: A redox-responsive and neutral nanoparticle (NP) was designed using poly(d,l-lactide-co-glycolide) (PLGA)-conjugated siRNA, PLGA, and Chitosan oligosaccharide. The physicochemical properties, stability, permeation ability, redox responsiveness, and in vitro free siRNA release of the NPs were evaluated. In vitro cellular uptake and gene silencing activity of the NPs were also investigated in four cervical cancer cell lines (SiHa, CaSki, HeLa, and c33a). Results: Redox-responsive and electrically neutral PLGA NPs encapsulating siRNA targeting the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene were formulated. The NPs were modified with chitosan oligosaccharide in order to achieve a neutral surface charge, at a nitrogen/phosphate (N/P) ratio of 20:1, and they had the desired size of ~ 90 nm. They were characterized by a high encapsulation efficiency (approximately 70%), in vitro stability in physiologic conditions, long-term shelf-life stability (> 18 months), and rapid permeation ability through mucus. NP disassembly in reducing environments was rapid. A sustained release phenomenon was observed, which contributed to higher concentrations and prolonged activity of the NPs. The GAPDH silencing efficiency of the NPs was both N/P ratio- and cell type-dependent, and it was as efficient as lipofectamine 2000 in SiHa, CaSki, HeLa, and c33a cells at an N/P ratio of 20:1. Conclusion: Our findings indicate that redox-responsive and electrically neutral NPs are promising nanocarriers for siRNA delivery to potentially treat human cervical carcinoma. [ABSTRACT FROM AUTHOR]