Achieving high gene delivery performance with caveolae-mediated endocytosis pathway by (l)-arginine/(l)-histidine...

Developing new amphiphilic polymers with natural product moieties has been regarded as a promising way to achieve biocompatibility and certain biological functions. In prior work, we developed some natural (l)-arginine modified cationic polymers (PAHMAA-Rs) as cationic gene carriers. For the sake of continuing optimize the gene delivery performance, herein, a new series of (l)-arginine and (l)-histidine co-modified cationic poly (ω-aminohexyl methacrylamide)s (PAHMAA-R-H) were synthesized and characterized with ¹H NMR, GPC-SLS and FT-IR. Their proton buffering capacities were studied by acid-base titration assay. pDNA binding affinity and self-assembly properties of the polyplexes were analyzed by agarose gel retardation assay, DLS and AFM, respectively. In vitro cytotoxicity of the PAHMAA-R-H was determined by MTT and LDH assays in H1299 cells, the gene transfection efficacy and intracellular uptake capability were evaluated by luciferase assay and FACS, respectively. Moreover, the endocytosis pathways and intracellular distribution of the polyplexes were investigated by using specific endocytic inhibitors and fluorescent co-localization techniques. The results demonstrated that co-modification of (l)-arginine and (l)-histidine onto the PAHMAA polymer could enhance proton buffering capacity, shield surface charge, decrease cytotoxicity, and improve gene transfection efficiency and serum-compatibility. Moreover, the gene transfection and intracellular uptake behaviors were disclosed strongly rely on the (l)-arginine/(l)-histidine modification ratios. The polyplexes tend to be internalized through caveolae-mediated endocytosis gateway and localized with endosomes/lysosomes in H1299 cells. Notably, among the polymers, the PAHMAA-R₁₈-H₆ exhibited remarkable gene delivery efficiency and serum compatibility, which made it promising gene transfection agent for practical application.