Core Role of Hydrophobic Core of Polymeric Nanomicelle in Endosomal Escape of siRNA

Abstract

Efficient endosomal escape is the most essential but challenging issue for siRNA drug development. Herein, a series of quaternary ammonium-based amphiphilic triblock polymers harnessing an elaborately tailored pH-sensitive hydrophobic core were synthesized and screened. Upon incubating in an endosomal pH environment (pH 6.5–6.8), mPEG45-P­(DPA50-co-DMAEMA56)-PT53 (PDDT, the optimized polymer) nanomicelles (PDDT-Ms) and PDDT-Ms/siRNA polyplexes rapidly disassembled, leading to promoted cytosolic release of internalized siRNA and enhanced silencing activity evident from comprehensive analysis of the colocalization and gene silencing using a lysosomotropic agent (chloroquine) and an endosomal trafficking inhibitor (bafilomycin A1). In addition, PDDT-Ms/siPLK1 dramatically repressed tumor growth in both HepG2-xenograft and highly malignant patient-derived xenograft models. PDDT-Ms-armed siPD-L1 efficiently blocked the interaction of PD-L1 and PD-1 and restored immunological surveillance in CT-26-xenograft murine model. PDDT-Ms/siRNA exhibited ideal safety profiles in these assays. This study provides guidelines for rational design and optimization of block polymers for efficient endosomal escape of internalized siRNA and cancer therapy.

Ionizable lipid-assisted efficient hepatic delivery of gene editing elements for oncotherapy

“…Increasing evidences demonstrated that only 3.5% (even less than 1%) internalized nucleic acid can escape from endosome and be released into the cytosol to mediate gene silencing [ [45] , [46] , [47] , [48] ], necessitating the development of delivery vehicles with the ability of rapid endosomal escape. Hence, we conducted the experiments to explore the endosomal escape of iLP181 and compare the advantages between iLP181 and commercial transfection reagents Lipo2000.…”

Development of a Rapid-Onset, Acid-Labile Linkage Polyplex-Mixed Micellar System for Anticancer Therapy

“…In addition, the acid-cleavable ketal linkage in mPEG-b-P(HEMA-ketal-VB6) might increase the efficiency of the endosome escape. As Li et al identified, the hydrophobic core of a polyplex micelle results in the reduction of the endosome escape efficiency of the siRNA [ 42 ]. During internalization, the hydrophobic core of a polyplex micelle was suggested collapse [ 9 , 42 ].…”

“…As Li et al identified, the hydrophobic core of a polyplex micelle results in the reduction of the endosome escape efficiency of the siRNA [ 42 ]. During internalization, the hydrophobic core of a polyplex micelle was suggested collapse [ 9 , 42 ]. In our study, the core of the polyplex could be destroyed upon the cleavage of the pyridoxal from the copolymer (as shown in Figure 3 c) at low pH.…”

mRNA vaccines for COVID-19 and diverse diseases

“…At certain pH, these lipids are positively charged and thus feasible for the mRNA to interact electrostatically, and easily fused with cellular membrane [ 116 ]. After endocytosis, the ionizable cationic lipid becomes more positively charged due to proton-pump mediated pH reduction [ 117 ]. Once inside, the cationic lipids are removed by the endogenous anionic lipids and resulting in the release of mRNA in to the cytoplasm [ 118 ].…”